Development of Experimental Techniques and Sea-keeping Tests of Catamaran Model in Open Water

by

Eduardo Manuel Gonzalez

Bachelor of Science Ocean Engineering

Florida Institute of Technology 2002

A thesis Submitted to Florida Institute of Technology

in partial fulfillment of the requirements for the degree of

Masters of Science in

Ocean Engineering

Melbourne, Florida May, 2005

©Copyright 2005 Eduardo Manuel Gonzalez All Right Reserved

The author grants permission to make single copies________________________

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We the undersigned committee hereby approve the attached thesis

Development of Experimental Techniques and Sea-keeping Tests

of Catamaran Model in Open Water

by Eduardo Manuel Gonzalez

_______________________________________ Andrew Zborowski, Ph.D. Professor and Program Chair Ocean Engineering

_______________________________________ Eric D. Thosteson, Ph.D., P.E. Assistant Professor Ocean Engineering and Oceanography

_______________________________________

Chelakara S. Subramanian, Ph.D. Associate Professor and Program Chair Aerospace Engineering _______________________________________ Gorge A. Maul, Ph.D. Department Head Department of Marine and Environmental System

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Abstract

Title: Development of Experimental Techniques and Sea-keeping

Tests of Catamaran Model in Open Water

Author: Eduardo Manuel Gonzalez

Committee Chair: Dr. Andrew Zborowski, Ph.D.

The presented project is a part of a larger project aiming at the development of the

experimental facility for testing marine vehicles in coastal waters. The purpose of

this project is to design an instrumented remotely controlled model in order to

establish the testing facilities to evaluate ship motions in waves. The LOMAC

(Littoral Operates Multi-Purpose Auxiliary Craft) catamaran model was selected

as the test platform. The unfinished hull, used previously by a Marine Field

Project group, was reshaped, rebuilt and restored and the propulsive and steering

systems where redesigned to work at an optimal level. Once the LOMAC multi-

hull was completed, tests were done to evaluate the linear motions about three

axes and the rotational motion about the longitudinal axis. To acquire this data,

the instrumentation designed and constructed by Doug Guardino was adapted and

used aboard the LOMAC multi-hull. The sensor package consists of two

accelerometers, an inclinometer, and GPS. The instrumentation sends near real

time data wirelessly from a remote location using TCP/IP and wireless Ethernet

(802.11b) and is accessed using Telnet. Procedures were developed for model

operation, data acquisition, calibration and data processing of the LOMAC multi-

hull in conjunction with Douglas Guardino Data acquisition system. Tests were

successfully performed with different propellers in different wave conditions and

propulsion, hull and motion analysis were done on the LOMAC multi-hull with it

onboard instrumentation.

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Table of Contents ABSTRACT............................................................................................................................ III TABLE OF CONTENTS........................................................................................................ IV LIST OF FIGURES................................................................................................................ VI LIST OF TABLES............................................................................................................... VIII ACKNOWLEDGEMENT...................................................................................................... IX DEDICATION..........................................................................................................................X 1.0 INTRODUCTION........................................................................................................1

1.1 GOALS.......................................................................................................................1 1.2 BACKGROUND ...........................................................................................................2

1.2.1 LOMAC Multi-hull Model.....................................................................................2 1.2.2 Wireless Data Acquisition System..........................................................................4

2.0 LOMAC RECONSTRUCTION ..................................................................................5 2.1 FIBERGLASS WORK ....................................................................................................6 2.2 PROPULSION DRIVES ................................................................................................10 2.3 ACRYLIC DRY BOXES...............................................................................................12 2.4 MOTOR CONTROLLERS AND BATTERIES ....................................................................13 2.5 DATA ACQUISITION SYSTEM ....................................................................................16 2.6 STEERING SYSTEM ...................................................................................................17 2.7 PROPELLER SELECTION ............................................................................................18 2.8 RESTORATION RESULTS AND CONCLUSIONS..............................................................20

3.0 LOMAC SYSTEMS...................................................................................................21 3.1 DRIVE SYSTEMS.......................................................................................................21 3.2 STEERING SYSTEM ...................................................................................................26 3.3 RADIO CONTROL SYSTEM ........................................................................................27 3.4 DATA ACQUISITION AND COMMUNICATION SYSTEMS................................................29

4.0 LOMAC INSTRUCTIONAL MANUAL ..................................................................34 4.1 CATAMARAN MODEL TEST PREPARATION.................................................................34 4.2 OPERATION OF CATAMARAN MODEL ........................................................................37 4.3 WIRELESS COMMUNICATION SETUP..........................................................................38 4.4 DATA PROCESSING...................................................................................................40 4.5 PROBLEMS AND SOLUTIONS......................................................................................41

TESTING AND RESULTS .....................................................................................................43 4.6 STATIC AND DYNAMIC STABILITY ASSESSMENT........................................................44 4.7 STEERING SYSTEM TEST...........................................................................................49 4.8 DATA ACQUISITION SYSTEM TEST ............................................................................50 4.9 LOMAC DATA ACQUISITION TESTS .........................................................................57 4.10 PROPULSION TEST AND ANALYSIS ............................................................................64 4.11 CALM WATER TESTS................................................................................................70

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4.12 LITTORAL TEST........................................................................................................76 4.13 PLANING PERFORMANCE TEST..................................................................................86

5.0 DISCUSSION.............................................................................................................91 6.0 CONCLUSIONS AND RECOMMENDATIONS .....................................................99 REFERENCES......................................................................................................................103 APPENDIX A: CAMPUS MAP ...........................................................................................105 APPENDIX B: SAMPLE DATA FROM TEST...................................................................106 APPENDIX C: TEST PICTURES .......................................................................................107 APPENDIX D: CONSTRUCTION PICTURES..................................................................109 APPENDIX E: PRO SURF HYDROSTATIC CURVES.....................................................111 APPENDIX F: STATIC STABILITY ILLUSTRATIONS..................................................112 APPENDIX G: EXPERIMENTS SETUP............................................................................113

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List of Figures Figure 1: Excessive Trim on LOMAC Model ..................................................... 5 Figure 2: Hull Imperfections............................................................................... 6 Figure 3: Hull Imperfections 2............................................................................ 6 Figure 4: Hull Fairing......................................................................................... 7 Figure 5: Restored Hull 1 ................................................................................... 8 Figure 6: Restored Hull 2 ................................................................................... 8 Figure 7: Deck Hatch Construction..................................................................... 9 Figure 8: Graupner Speed 700 BB Turbo and Propeller Drive .......................... 11 Figure 9: Installed Motor and Drive.................................................................. 11 Figure 10: Acrylic Dry Boxes........................................................................... 12 Figure 11: Comparison of Traxxas and Initial Motor Controller System ........... 14 Figure 12: Comparison of Traxxas and JES System.......................................... 15 Figure 13: Comparison of JES and Initial System ............................................. 16 Figure 14: Data Acquisition System Size Improvement .................................... 17 Figure 15: Rudder Assembly ............................................................................ 18 Figure 16: Propellers, Shafts and Tap Set ......................................................... 20 Figure 17: Traxxas EVX 3014 Motor Controller............................................... 23 Figure 18: JETI JES 600 Navy Motor Controller .............................................. 24 Figure 19: Graupner Speed 700 BB Turbo, Couplings and Drive...................... 26 Figure 20: Rudder System Diagram.................................................................. 26 Figure 21: Futaba SkySport4 Transmitter and FP-R127DF Reciever ................ 27 Figure 22: Data Acquisition System ................................................................. 30 Figure 23: Data Acquisition System Parts Identification Picture ....................... 33 Figure 24: Propulsion System Connections Diagram ........................................ 35 Figure 25: Propulsion System Connections....................................................... 35 Figure 26: Motor/Drive Connections ................................................................ 36 Figure 27: Servo/Rudder Connections .............................................................. 36 Figure 28: Wireless Communication System Setup........................................... 39 Figure 29: LOMAC Catamaran Model ............................................................. 41 Figure 30: Location of Calm Water Test........................................................... 50 Figure 31: 2001 Dodge Ram 1500 2x4 ............................................................. 51 Figure 32: Truck Trajectory during Test 1 ........................................................ 52 Figure 33: Truck Heading during Test 1 ........................................................... 53 Figure 34: Truck Acceleration during Test 1..................................................... 53 Figure 35: Truck X Axis Acceleration and Inclination during Test 1 ................ 54 Figure 36: Truck Trajectory during Test 1b ...................................................... 55 Figure 37: Truck Velocity during Test 1b ......................................................... 55

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Figure 38: Truck Heading during Test 1b ......................................................... 56 Figure 39: Truck Accelerations during Test 1b ................................................. 56 Figure 40: Model Velocity Recorded on Test 2................................................. 58 Figure 41: Model Accelerations for Test 2........................................................ 60 Figure 42: Trajectory of LOMAC Model during Test 2a................................... 61 Figure 43: LOMAC Model Heading during Test 2a.......................................... 61 Figure 44: Trajectory of LOMAC Model during Test 2b .................................. 62 Figure 45: LOMAC Model Heading during Test 2b.......................................... 62 Figure 46: Trajectory of LOMAC Model during Test 2c................................... 63 Figure 47: LOMAC Model Heading During Test 2c......................................... 63 Figure 48: Propellers, Shafts and Accessories ................................................... 65 Figure 49: Velocity of LOMAC Model during Test 3 ........................................ 72 Figure 50: LOMAC Model Accelerations Recorded during Test 3.................... 72 Figure 51 : Trajectory of LOMAC Model during Test 3a................................... 73 Figure 52: LOMAC Model Heading During Test 3a......................................... 73 Figure 53: Trajectory of LOMAC Model During Test 3b.................................. 74 Figure 54: LOMAC Model Heading During Test 3b......................................... 74 Figure 55: Trajectory of LOMAC Model during Test 3c................................... 75 Figure 56: LOMAC Model Heading During Test 3c......................................... 75 Figure 57: River Test Locations........................................................................ 76 Figure 58: 17 ft Research Boat ......................................................................... 77 Figure 59: Trajectory of LOMAC Model during Test 4a................................... 78 Figure 60: LOMAC Model Heading during Test 4a.......................................... 78 Figure 61: Model Velocity during Test 4a ........................................................ 79 Figure 62: LOMAC Model Acceleration during Test 4a ................................... 80 Figure 63: X Axis Acceleration and Model Inclination during Test 4a.............. 80 Figure 64: Velocity of LOMAC Model during Test 4b ..................................... 81 Figure 65: Trajectory of LOMAC Model during Test 4b .................................. 82 Figure 66: LOMAC Model Heading during Test 4b.......................................... 82 Figure 67: LOMAC Model Acceleration during Test 4b ................................... 83 Figure 68: Model Velocity Recorded during Test 4c......................................... 84 Figure 69: Trajectory of LOMAC Model during Test 4c................................... 84 Figure 70: LOMAC Model Heading during Test 4c.......................................... 85 Figure 71: LOMAC Model Accelerations during Test 4c.................................. 85 Figure 72: Model X Axis Acceleration and Inclination during Test 4c.............. 86 Figure 73: Planning Performance in Calm Water during Test 5 ........................ 87 Figure 74: Model Velocity Recorded during Test 5 .......................................... 87 Figure 75: Trajectory of LOMAC Model Recorded during Test 5..................... 88 Figure 76: LOMAC Model Heading Recorded during Test 5............................ 88 Figure 77: Accelerations and Velocity Recorded during Test 5......................... 89 Figure 78: Planning Performance in Littoral Conditions ................................... 89

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List of Tables Table 1: Traxxas EVX 3014 Motor Controller Specifications ........................... 23 Table 2: Graupner Speed 700 BB Turbo Specifications .................................... 25 Table 3: Futaba Transmitter Configuration 1 .................................................... 28 Table 4: Futaba Receiver Configuration 1......................................................... 28 Table 5: Futaba Transmitter Configuration 2 .................................................... 28 Table 6: Futaba Receiver Configuration 2......................................................... 29 Table 7: Troubleshooting Procedures................................................................ 42 Table 8: LOMAC Model Parameters ................................................................ 44 Table 9: LOMAC Model Dimensional Ratios................................................... 45 Table 10: LOMAC Model Form Coefficient..................................................... 45 Table 11: LOMAC Model Centers.................................................................... 48 Table 12: Turning Radius of Steering Systems ................................................. 50 Table 13: Propeller Thrust Data........................................................................ 65 Table 14: Propulsive Analysis and Parameters.................................................. 68 Table 15: LOMAC Model Planing Speeds........................................................ 90

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Acknowledgement I wish to express my sincere gratitude to Dr. Andrew Zborowski for guiding me throughout my undergraduate and graduate studies and for serving as my committee chairman. I am thankful to Dr. Eric Thosteson and Dr. Chelakara Subramanian for serving on my thesis committee.

I greatly appreciate the help of Bill Battin for his advice and for letting me use his tools.

I wish to express my sincere gratitude to my parents for their support and

encouragement.

I am thankful to Nakul Saran for providing advice and sharing a work space and supplies and helping me with field test

Special Thanks to Kurt Leyba for teaching me TCP/IP and Ethernet connection.

Special thanks to Mike Walghren, Derek Tepley, Jose Vargas, Nicole Botto, Rebecca Hasman, Brandi Alderson, Markus Holla and Vince Salvo for assisting me with field tests. Without these individuals this project would never have been realized.

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Dedication

To my family who supported me.

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1.0 Introduction

In the last decades, there has been increased interest in small, fast,

maneuverable, and relatively inexpensive vessels that can operate in the littoral

zone. Taking into consideration these requirements, Dr. Andrew Zborowski

designed a small water-plane area single chine multi-hull that could be used in the

littoral zone. L.O.M.A.C, which stands for Littoral Operated Multi-hull Auxiliary

Craft, is an experimental hull form intended for fast ocean transportation and/or

multi-mission military use in the littoral zone.

1.1 Goals

The goal of this research is to restore the LOMAC multi-hull model, to re-

design the systems within LOMAC, and to evaluate the performance

characteristics of the model by collecting data with an instrumentation package.

This involves re-shaping and re-constructing the model, re-designing the steering

and propulsion systems and minimizing the weight of the instrumentation

package. Once these tasks are completed, the data obtained from the

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instrumentation will be used to measure the model behavior in both calm and

wave conditions.

1.2 Background

The LOMAC project is an ongoing project that began during the fall

semester of 2002. Multiple faculties, undergraduate and graduate students have

contributed to the success of the entire project.

1.2.1 LOMAC Multi-hull Model

The process of development of the LOMAC catamaran hull began as part

of a Marine Field Project presented by Cencer et al (Cencer 3). The hull was

design using Pro Surf and it was constructed using fiberglass and polyester resin

on a male mold carved from foam. Due to insufficient time, the senior design

group was unable to finish the shaping procedure of the hull. This left multiple

hull imperfections that affected the performance of the model. These

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imperfections included unbalanced hulls, excess resin in the bows, un-even decks,

internal leaks, hull dents, and deformed chines.

For propulsion, a set of Graupner Jet Drive system and Graupner Speed

600 series motors where installed in each hull. These motors although good in

reputation, lack the capacity to power the LOMAC model. To drive these motors,

Doug Guardino built two motor controllers and an R/C controller interpreter as

part of his graduate work. The overall system did not meet expectations since the

motors did not deliver enough power, and the jet drives were incorrectly installed

which made the drive system obsolete. The motor controllers worked

excellently, however they were bulky and were heavy. Other disadvantages of

this system were the fact that the jet drives had no reverse, therefore

maneuverability was limited.

Similar to the motor controllers, the steering system was built by Doug

Guardino. The system was not successful because it worked under the

assumption that differential power of the model would steer the model and there

was not enough power to create a turning moment to act on the model.

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The control system of the LOMAC model is a Futaba FP-R127DF FM

receiver and a Futaba SkySport4 controller. With multiple channels, it is a system

that is highly adaptable to future changes in the model drive system.

1.2.2 Wireless Data Acquisition System

The wireless data acquisition system was designed and constructed by

Doug Guardino. Its main purpose was to acquire data from sensors and send it

from a remote location to a computer were the data would be processed. The

sensor package employs two accelerometers on three axes, an inclinometer, a

digital compass, and a global positioning system (GPS). The communication is

facilitated by the use of the stand alone TCP/IP stack and Ethernet controller in

the Wiznet IIM7010A system (Guardino). The sensor package is composed of

five different sections. These are the PICNIC board, accelerometer board, GPS

board, LCD/inclinometer breadboard, digital compass and the wireless Ethernet

bridge. All of the boards are connected via a 40 pin IDE cable that pass power

and access to the pins of the PICNIC to the other board and provides for future

expandability (Guardino).

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2.0 LOMAC Reconstruction

The first stage of this project involved the reconstruction of the LOMAC

Multi-hull model. When the model was acquired, it was in unfinished conditions.

The model’s center of gravity was six inches off to the bow, which made the

model trim excessively by the bow. The hull leaked through the jet drive into the

motor and motor controller compartment. The model was also 20 lbs over the

required weight and had a maximum velocity of less than 1 knot. The restoring

process, which took place during spring 2004 through spring 2005, was well

documented and it is described in details in this section.

Figure 1: Excessive Trim on LOMAC Model

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Figure 2: Hull Imperfections

Figure 3: Hull Imperfections 2

2.1 Fiberglass Work

The first step taken to improve the model was to remove hull

imperfections, leaks and to move the center of gravity further to the stern. This

involved re-shaping both inside and outside surfaces of the hull and painting the

model. In addition to fixing the leaks located at the bow of both hulls, major

reconstruction was needed since excessive polyester resin and micro-balloon

compound from earlier construction had caused the center of gravity of the model

to shift 6 inches towards the bow, creating an excessive trim that would later

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affect the planing performance of the model. The excessive polyester resin and

micro-balloon compound were removed with the use of a dremel tool and the

bows were re-shaped and strengthened with a fiberglass reinforced filler (bondo

glass).

Figure 4: Hull Fairing

As part of the restoration project, the un-even freeboard was re-

constructed and leveled using bondo-glass and new decks were constructed out of

1/8 in. pine wood to replace the older decks. The decks were then sealed with

Interlux Pre-Kote primer and painted with Interlux one-part polyurethane “steel

gray” paint. To assure a water resistant seal between the decks and the hulls, self

adhesive foam strips were attached to the under-side of the deck were it rest on

the lip of the hull.

The preparation of the model for the painting procedure consisted of

sanding the outside hull surface with decreasing sandpaper roughness starting

with 80 grit and finishing with 280 grit (80, 120, 150 and 180 grit). The painting

procedure consisted of wet-sanding each paint layer with 150 grit sandpaper and

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cleaning the hulls with Interlux Brush-Ease 433 after each layer was applied.

This process was repeated for 2 layers of Interlux Pre-Kote primer and 4 layers of

Interlux one part polyurethane “steel gray” paint. The finished hull was then wet-

sanded with a 400 grit sandpaper to remove surface blemishes and minor

scratches.

Figure 5: Restored Hull 1

Figure 6: Restored Hull 2

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An idea propose by Dr. Stephen Wood, a set of openings were cutout on

the decks to improve access to the on board systems. A series of hatch frames

were made out of balsa wood, which was sealed with 3 coats of Interlux Prime-

Kote and 2 layers of Interlux one-part polyurethane “steel gray” paint. To fit

these frames, ¼ in. acrylic hatches were cut-out and placed on the openings. With

acrylic hatches, the onboard instrumentation could be visible at all time. The

finished decks included three hatches per hull, two of which are removable for

fast accessibility to the internal compartments.

Figure 7: Deck Hatch Construction

To improve the model efficiency, the jet drives were removed and

replaced with a straight shaft propeller drive in each hull. To install the new

propeller drive, the jet drive openings were sealed using bondo-glass. Then 0.5

10

inch holes were drilled in each hull at the angle the drive shaft would exit the

hulls. This angle was estimated to be 16 degrees. After completing the drive

installment, the same painting procedure explained earlier was followed for that

section of the model.

2.2 Propulsion Drives

The existing Graupner jet drives were tested for propulsion efficiency and

it was noticed that both jet drives had leaks and not enough thrust was being

produced to overcome the resistance of the model. The drives were then

dismantled and inspected to identify possible reasons for the lack of propulsion.

As a result, the drives were not properly assembled and the shaft had been bent in

the assembling process. These jet drives were removed and a Graupner straight

shaft propeller drive was installed in each hull, eliminating the leakage of the

previous drive system.

The motors were also upgraded from a set of Graupner Speed 600 with a

3:1 gear ratio to a Graupner Speed 700 BB with no gear ratio. The new Graupner

Speed 700 BB Turbo was capable of delivering more torque and thrust. To secure

the Graupner Speed 700 BB Turbo, motor mounts were attached to the hull using

bondo-glass. To connect the motor to the propeller shaft, a set of flexible

couplers were used rather than a conventional u-joint since these are known to

11

decrease the efficiency of motor drive systems. The propellers used for this

application were a set of Graupner 4 blade propellers.

Figure 8:Graupner Speed 700 BB Turbo and Propeller Drive

Figure 9: Installed Motor and Drive

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2.3 Acrylic Dry Boxes

A set of dry boxes were built using ¼ in. acrylic and adhesive

caulk(Figure 8). The dimensions of the boxes were 17in. by 4in. by 4in and

weighted 3 lbs each. The main purpose of these boxes was to keep the batteries

and motor controller protected from water. Even though the restored model no

longer had leaks, the deck seal was only water resistant therefore some

precautionary measures needed to be taken in case water made it into the motor

controller compartment.

Figure 10: Acrylic Dry Boxes

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2.4 Motor Controllers and Batteries

Initial test with the new motors and propeller drives demonstrated that the

model was to heavy for proper operation. In an attempt to decrease the model

design weight from 58lbs to 36lbs, the lead acid batteries, motor controllers, and

acrylic dry-boxes were replaced with a 6 cell 3000 Ni-MH (Nickel Metal

Hydride) batteries, a TRAXXAS motor controller and a plastic box.(Figure 11)

This new system had been built by Casey Connor et al. during the marine field

project of the summer 2004 semester (Connor 28). With the new Traxxas motor

controller and Ni-MH batteries, the model total weight was of 39 lbs and it had a

maximum velocity of 3.5 mph. The model steering, which consisted of using

differential steering with the motors, did not create enough turning moment to

make it turn effectively.

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Figure 11: Comparison of Traxxas and Initial Motor Controller System

To increase the maximum velocity of the model, a set of 10 cell 2400 mAh

Ni-Cd(Nickel Cadmium) batteries and Jeti Jes 600 Navy water cooled motor

controllers replaced the 6 cell 3000 mAh Ni-MH and the Traxxas motor

controller. The new motor controller system was installed within the model’s

hull, eliminating the use of a dry box in the deck of the model. The motor

controllers can be water cooled for improved efficiency. The model maximum

speed with the Jes motor drive and Ni-Cd batteries was of 5.8 knots. The only

negative aspect of the new system is that it does not have reverse operation and it

operational time is shorter than with the Traxxas drive system. Figure 10 through

15

Figure 12 show the comparison on size of all three drive systems used during this

project.

Figure 12: Comparison of Traxxas and JES System

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Figure 13: Comparison of JES and Initial System

2.5 Data Acquisition System

As suggested by Dr. Thosteson, the data acquisition system was reduced

in size in an effort to decrease the model weight. This was done by re-arrange the

data acquisition instrumentation in a smaller, more compact box. The data

instrumentation system was previously mounted on a ¾ in. ply wood board and

stored on an 11 in. by 12 in. by 7in. plastic box. The instrumentation box initially

weighted 16 lbs. To decrease this weight, the existing plastic box was replaced by

a 6in. by 12in. by 7in. box and the instrumentation was mounted on a 1/8 in. pine

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wood board. Also, a computer hub that was not been used was removed from the

data acquisition package. The re-arranged data acquisition system was smaller,

more compact and had a total weight of 10 lbs.

Figure 14: Data Acquisition System Size Improvement

2.6 Steering System

A rudder system was necessary since differential steering did not supply

the model with acceptable maneuverability. The new system consisted of both

differential and rudder steering to create a turning moment on the model. The

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rudder system was constructed using a Graupner rudder, a stainless steel L

support bracket and a Futuba S3004 high torque servo. The specifications of the

steering system are further explained in Section 3.2.

Figure 15: Rudder Assembly

2.7 Propeller Selection

To increase the model maximum velocity, Dr. Thosteson recommended

replacing the nylon propellers with a metal propeller. He argued that a plastic

propeller would bend at higher revolutions decreasing it efficiency drastically.

With a large variety of propeller dimensions, types and materials, 3 set of

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propellers were selected to test it performance. These propellers were Octura 3

blade brass propellers, Prather 2 blade stainless steel propellers and Graupner 2

blade carbon fiber propellers. (Figure 16) These propellers were compared to the

existing 4 blade Graupner nylon propellers that had been used in previous trial

tests. After a propulsive analysis and comparison between all 4 type of

propellers, the existing 4 blade propeller was discovered to be the least efficient of

all and the Prather two blade propellers was determined to be the best option for

model. In addition to this propulsive analysis, new, longer shafts were

constructed from 4mm stainless steel pipes to give the propeller a larger clearance

from the hull. Also, mounting adaptors better known as “drive dogs” were used

to secure the propeller to the shaft. This increased the shaft efficiency by limiting

the propeller slip on the shaft. The addition of the more efficient Prather propeller

made the model reach planning speed of over 7.3 knots.

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Figure 16: Propellers, Shafts and Tap Set

2.8 Restoration Results and Conclusions

At the end of the model restoration, the model had a smoother surface, more

accessibility to it compartments, no leaks and new drive and steering system. The

model was place in the water to observe how it would trim with the decreased

weight and arrangement of new systems. As a result, the model still trimmed

toward the bow; however it was a small enough trim that the addition of weight

on the stern compartment of the model would solve the problem. By placing the

data acquisition system aft of the longitudinal center of gravity, the trim on the

model would be adjusted. As a result, the fully equipped LOMAC catamaran

would trim approximate 1 degree toward the bow.

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The model maximum velocity recorded by the data acquisition system at the

end of the restoration process was of 7.321 knots. This was achieved by using the

Graupner Speed 800 Turbo BB motors, JES motor controller and 2700mAh 10

cell Ni-Cd batteries. Also, maneuverability of the model was greatly improved

with the addition of rudders behind each propeller.

3.0 LOMAC Systems

The LOMAC model employs several systems for optimal operation.

Theses systems are the drive, steering, radio control and data acquisition/

communication systems.

3.1 Drive Systems

During this research, the model was equipped with two drive systems.

The first system consisted of a Traxxas 3014 motor controller with 6 cell 3000

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mAh Ni-MH batteries and the second system used a JES motor controller with 10

cell 2700 mAh Ni-Cd batteries. Both systems powered a set of Graupner Speed

700 BB motors.

The Traxxas system was assembled by a marine field project group during

the 2004 summer semester. The motor controller, which controls two motors at

once, can be used with a maximum of 12 cells batteries. Among it features, it has

Novak Electronics Smart Braking™ technology (Traxxas.com). This braking

technology applies brakes to the motor between forward and reverse rotations. It

also has 3 programming modes, which are: the normal mode with forward, brake

and reverse, the racing mode with forward, and no brakes or reverse, and the

marine mode with forward, 20-percent reverse and no brakes.

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Figure 17: Traxxas EVX 3014 Motor Controller

Table 1: Traxxas EVX 3014 Motor Controller Specifications Input Voltage: 12 cells (14.4 volts nominal) Published Motor Limit: 19 turns (550 size) On-Resistance: 0.006WBrakes with Novak Electronics’ Smart Braking™ Three Drive Profiles Normal: Forward/ Reverse/ Smart Braking™ Racing: Forward/ Brakes/ (no reverse) Marine: Forward/ 20% Reverse/ (no brakes) Novak Electronics’ One-Touch Set-Up Thermal Shutdown Protection Microprocessor based Gold plated battery connectors BEC Voltage: 5.0 DC BEC Current: 1.5 Amps

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Rated Current Forward and Reverse: 160 Amps Braking Current: 320 Amps Continuous Current @ 100 F: 30 Amps Reverse Delay (after Smart Braking): 0 sec. Power Wire 14G/9"Input & Switch Harness 23G/9" (replaceable) Transistor Type HYPERFET III PWM Frequency 1000 Hertz

The JES system consists of a JES 600 Navy motor controller that is

powered by a10 cell Ni-Cd battery. The motor controller, which is water cooled,

has dimensions of 2in. by 1in. by 9/16in. and weights 1.5 oz. including the wires

(Hobby-Lobby). It is designed to be used with up 30 cells and the maximum

current load for 10 cells or more is 60 amps (Hobby-Lobby). It has adjustment

for setting the motor start point and a two color LED that indicates zero power

and maximum power even without a motor connected (Hobby-Lobby). The JES

600 Navy also has Opto coupling which keeps the controller free from motor

induced interference and a current limiter to prevent burnout. Unfortunately, this

motor controller does not have reverse.

Figure 18: JETI JES 600 Navy Motor Controller

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The motors selected for the LOMAC model are the Graupner Speed 700

BB Turbo. These motors are suitable for drive systems of model boats over 30

lbs. The specifications of the motors are shown in Table 1.

Table 2: Graupner Speed 700 BB Turbo Specifications Nominal voltage 9.6 V Operating voltage range 14.4 V No-load rpm 15000 rev/min No-load current drain 2 A Current drain at max. efficiency 12.5 A Current drain when stalled 65 A Max. efficiency without gearbox 75 % Length of case, excl. shaft 67 mm Diameter 42.2 mm Free shaft length 14 mm Shaft diameter 5 mm Weight 320 g

26

Figure 19: Graupner Speed 700 BB Turbo, Couplings and Drive

3.2 Steering System

The steering system of the LOMAC Model consists of using differential

steering and rudder steering. Differential steering can be controlled by simply

applying different amount of thrust to each motor to create a turning moment on

the model. The rudder assembly consists of a Graupner rudder with dimensions

of 2.5 in. by 1.25 in. Each rudder pivots on an external mounted hinge located at

the stern of each hull. The effectiveness of this system is shown in Section 5.2.

Figure 20: Rudder System Diagram

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3.3 Radio Control System

The LOMAC model is operated using a Futaba Sky Sport 4 transmitter

with a FP-R127DF receiver. This 4 channel system has a range of approximately

1300 ft and controls the power delivered to each motor and the servo motors

controlling the rudder system. Tables 2 through Table 5 show both configurations

of controls for the LOMAC model.

Figure 21: Futaba SkySport4 Transmitter and FP-R127DF Receiver

Channel Location Movement Controls

1 Left Right-Left Not used

2 Left Up-Down Port Motor

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3 Right Up-Down Std Motor

4 Right Right-Left Servo Motors

Table 3: Futaba Transmitter Configuration 1

Channel Controls

1 Port Servo

2 Std Motor

3 Port Motor

7 Std Servo

Table 4: Futaba Receiver Configuration 1

Channel Location Movement Controls

1 Left Right-Left Port Servo

2 Left Up-Down Port Motor

3 Right Up-Down Stbd Motor

4 Right Right-Left Stbd Servo

Table 5: Futaba Transmitter Configuration 2

Channel Controls

1 Port Servo

29

2 Std Motor

3 Port Motor

4 Std Servo

Table 6: Futaba Receiver Configuration 2

The only difference of the configurations is that configuration 1 uses one

channel to control both servo motors connected to the rudder system. In the case

that the operator prefers having separate rudder control, configuration 2 must be

used. Separate rudder control will be useful for decreasing the forward motion of

the model if necessary.

3.4 Data Acquisition and Communication Systems

30

The data acquisition system (Figure 20) was built during the fall 2003

semester by Doug Guardino as part of his graduate work. As mentioned in

Section 1.2.2, the data acquisition system is comprised of six sections. These are

the PICNIC board, accelerometer board, GPS board, LCD/inclinometer

breadboard, digital compass and the wireless Ethernet bridge. The location of

each component is shown in Figure 21.

Figure 22: Data Acquisition System

The PICNIC is the communication system that gets the data from all the

sensor systems. (Guardino) It gathers the sensor data by use of the analog

channels or the I2C bus and also controls the IIM7010A via the I2C bus,

controlling the TCP/IP functions. (Guardino)

31

The Accelerometer Board, which uses analog acquisition, acquires data 25

times a second. The board includes two channels for each accelerometer axis.

These channels are use to calibrate the center and the gain of each accelerometer

axis. The accelerometers are read by the PICNIC directly using the analog inputs.

This GPS records position, velocity and heading. Position and velocity

are always acquired while the heading is only acquired when the GPS is in

motion. It uses a PIC to read one of the many sentence from a GPS making that

sentence available on-demand to another PIC via the I2C bus. (Guardino) Overall,

the GPS system sends one set of data every second.

The inclinometer is an optical encoder that displays it inclinations in

degrees times 10. Every time the system is started, the inclinometer will calibrate

to zero regardless of the inclination at which it is when it get initialized.

32

The digital compass outputs its heading via two analog values that

represent the magnitudes of the North/South and East/West components. Since

the pic microcontroller does not support trigonometric functions, by using

geometry, these values can be used to find the actual heading (Guardino).

Unfortunately, the compass only read magnitudes, therefore all values are positive

and heading values can only range between 0-90 degrees, instead of 0-360

degrees. The digital compass board is connected to the system’s accelerometer

board. It is also used in the system to backup the GPS heading data since the GPS

will only provide heading data while the model is moving.

The wireless communication of this data acquisition system is supplied by

a Linksys wet11 wireless Ethernet bridge. The , which has frequency band of 2.4

GHz and complies with IEEE 802.11b, has an outdoor range of 980 ft and a data

transfer rate of 11 Mbps.(Linksys.com). The IP address of the Ethernet bride

located in the sensor package is 192.168.1.50.

33

Figure 23: Data Acquisition System Parts Identification Picture

34

4.0 LOMAC Instructional Manual

The following section of this report serves as an instructional manual for

the use of the LOMAC multi-hull model and the instrumentation package built by

Doug Guardino. It will help users to prepare the hull, perform all necessary

internal connections, create a wireless connection between the instrumentation

package and a computer, record useful data, perform model operation, data

processing and model maintenance.

4.1 Catamaran Model Test Preparation

The propulsion system of the multi-hull model was designed to be simple

in nature. As a result, no complex connections are required and the preparation of

the system can be completed within 60 seconds. To properly setup the propulsion

system of the model, see Figure 23 and 24.

35

Figure 24: Propulsion System Connections Diagram

Figure 25: Propulsion System Connections

36

Figure 26: Motor/Drive Connections

Figure 27: Servo/Rudder Connections

37

4.2 Operation of Catamaran Model

The operation of the model is performed with the FUTABA sky sport 4

shown in Section 3.3. It is important for the operator to know that every time the

model is turned on, the motor controller will set zero speed to the initial setting of

the Transmitter. Therefore, it is crucial that the Transmitter is set at zero speed in

channel 2 and 3. The following step by step instruction will properly calibrate the

motor controllers.

1. Turn on the model (on/off switch is located on starboard hull).

2. Make sure Channel 2 and 3 are at zero. Turn on the Futaba Sky

Sport 4 Transmitter

3. Immediately after turning on both model and transmitter, the

motor controllers will beep. Slightly move both channel 2 and 3

in the Transmitter below zero and return to zero. Beeping will

stop.

4. The Model is now set to respond to the Futaba Sky Sport 4

Transmitter.

The operation of the model is simple. To operate the motor speed, use

vertical motion in the transmitter. Channel 2, located to the left of the transmitter,

38

controls the port motor while channel 3, which is located to the right of the

transmitter, controls the starboard motor. Individual motor control gives

increased maneuverability by creating differential steering. Depending on what

configuration you use on the receiver (see Section 2.1), the two rudders will be

controlled in one or two channels. To control the rudders as one unit use channel

4(horizontal movement on transmitter right lever) and to control the rudders

individually use channel 1 for the port rudder and channel 4 for the starboard

rudder.

4.3 Wireless Communication Setup

The data acquisition system communicates to any computer using TCP/IP

and can be access in a computer with the use of Telnet or Hyperlink. Doug

Guardino recommended using Telnet over Hyperlink since Microsoft Office

Excel imported the data from Telnet better than the data from Hyperlink. The

following step by step instructions show how to communicate between the data

acquisition package and the computer via a wireless connection. The instructions

can be only apply in computer with Windows XP operating system.

39

Figure 28: Wireless Communication System Setup

1. Turn data acquisition package on.

2. Turn on computer and start windows XP.

3. Go to the Start menu and click Run.

4. In the “Open” box, type Telnet and click Ok. Telnet will initialize.

5. Right click the upper left corner of the Telnet window and go to

Properties.

6. Increase the buffer size from 80 to 150, click Ok.

7. Make sure properties are applied to current window only, click Ok.

8. In the Telnet window, type set logfile x.txt where x will be the name of

the data file, press Enter.

9. Type open 192.168.1.50, press Enter

40

10. A connection should now be open between the data acquisition system

and the computer. Data should now be streaming.

11. If, GPS data displays a “Hello World” message, restart the data

acquisition system until “Hello World” is no longer displayed.

12. NOTE: Make sure the GPS readings on Telnet display an “A” before

starting any tests.( “A” stands for “acquiring data”)

4.4 Data Processing

The data obtained from the sensor package via Telnet is saved in the

computer as a txt. File. To convert the data to a useful form, import the data to

Microsoft Office Excel. The following instructions show step by step of how to

do this data import.

1. Open Microsoft Office Excel.

2. Go to Data>Import External Data>Import Data.

3. Choose the txt. file that is being imported, click ok.

4. In the “Original Data Type” box, choose Delimited, click Next.

5. In the “Delimiters” box, choose Tab, Semicolon, Comma and

Space, click Next.

6. Click Finish.

41

4.5 Problems and Solutions

Even though the systems used in LOMAC catamaran model work

properly, they are experimental systems that are capable of working improperly

from time to time. This section includes the solution to every problem

encountered during this research.

Figure 29: LOMAC Catamaran Model

42

Table 7: Troubleshooting Procedures Component or

System

Problem Solution

Rudders Do not work, delayed control response, works

sometimes.

Change receiver batteries

Rudders Only one rudder work Check connection on servo-receiver

Motors Do not work, does not work properly Charge batteries

Motors Shut down during testing Check connection between motor/motor controller/battery

Motor Excessive noise. Check coupling connection, make sure the motor is properly fasten in

it bracket, and ensure that the motor is properly align with the shaft.

Motor Does not responds when it is suppose to respond. Charge transmitter batteries.

Check receiver batteries

Ensure that all receiver connections are proper.

Motor Following the motor controller beeping after turning

it on, the motor accelerates without control.

Restart the model and follow the calibration procedure from Section

3.1.

Data Acquisition GPS does not initialize. Restart the system.

Data Acquisition GPS gives no position coordinates( displays a “V”) Leave the GPS on for 5 minute and then check if the “V” changes for

“A”( acquiring)

Data Acquisition Fails to turn on. Charge Battery.

Data Acquisition Inclination data is not calibrated. Make sure that the instrumentation box is leveled when turned on.

Drive System Water leak is present in the shaft housing. Remove the white cap from the shaft enclosure and fill enclosure

with EP bearing grease (Pennzoil).

Drive System Vibrate Excessively. Make sure the coupling is properly fastened.

Calibrate Propellers.

Make sure Motor is properly align with shaft.

Drive System Shaft or motor slips in the coupling connection Clean coupling with WD-40 and ensure that the connection are tight

between the motor, coupling and shaft.

Receiver/Transmit

ter

Model does not respond Charge batteries

Check connections

Make sure receiver antenna is fully extended

Motor Controller If there is current going thought the motor controller

but motors do not work

Make sure the connection on the transmitter is not reversed.

43

Testing and Results

Several tests were performed during the course of this project. The tests

were conducted in three sections. The first section included tests using a truck to

acquire proper acceleration data from the data acquisition system. The second set

of test involved the trials of the refurbished LOMAC multi-hull model. These test

trials were done at a freshwater pond at the university premises. The main goals

of these tests were to achieve planning speed of the model and to familiarize with

the model controls and maneuverability. After all the systems performed

optimally, a test with different propellers were conducted to identify the most

efficient propeller. Finally the third section of the graduate work involved sea

trials of the LOMAC model with the onboard data acquisition system on calm and

littoral conditions to obtain near real-time data of the motions of the model.

These tests were conducted at 2 different locations. These locations were the

wave tank pond located at the Florida Institute of Technology(Figure 30) and

areas in the Indian River adjacent to the SR-192 causeway in Melbourne, Florida.

(Figure 57)

44

4.6 Static and Dynamic Stability Assessment

The static and dynamic stability assessment was done for the LOMAC

multi-hull during the Marine Field Project of 2003. Unfortunately, the model

underwent an extensive reconstruction process which included re-shaping and the

re-design of internal systems. This led to the necessity to perform the stability

assessment once more. The model dimensions and given parameters were

organized in a table and the dimensional ratios and form coefficients were

calculated. The results which are shown in Table 7 were obtained using

Definition 1 through Definition 10. (Gilmer and Johnson 43-47)

Table 8: LOMAC Model Parameters Parameter Symbol Fall 2003 Spring 2005 Units

Length Over All LOA 5.37 5.36 ft.

Length Over All LOA 64.40 64.33 in.

Length at Waterline LWL 5.19 5.19 ft.

Length at Waterline LWL 62.31 62.25 in.

Hull Beam B 5.95 5.95 in.

Hull Spacing s 11.37 11.37 in.

Beam Over All BOA 23.27 23.27 in.

Draft (light ship) TL 2.24 2.10 in.

Draft (batteries & drives) TL 4.58 3.13 in.

Draft (data acq system) TF 5.12 3.63 in.

Displacement (light ship) ? L 31.80 28.46 lbs.

Displacement (batteries & drives) ? 43.80 36.30 lbs.

Displacement (data acq system) ? F 58.90 46.78 lbs.

Volume of Displacement at Tf ? 1039.80 694.72 in.3

Area of Mid-ship Section at Tf AM 20.05 11.19 in.2

Area of Max Section at Tf Ax 23.03 14.16 in.2

Area of the Waterplane at Tf Aw 226.48 226.06 in.2

45

Table 9: LOMAC Model Dimensional Ratios

Parameter Symbol Fall 2003 Spring 2005

Length/Beam Ratio L/B 10.47 10.46

Length/Beam Overall Ratio L/BOA 2.68 2.68

Length/Draft Ratio L/T 12.17 17.15

Beam/Draft Ratio B/T 1.16 1.64

Beam Overall/Draft Ratio BOA/T 4.54 6.41

Table 10: LOMAC Model Form Coefficient

Parameter Symbol Fall 2003 Spring 2005

Block Coefficient CB 0.53 0.50

Prismatic Coefficient CLP 0.88 0.87

Vertical Prismatic Coefficient CVP 0.86 0.84

Waterplane Area Coefficient CWP 0.94 0.93

Max transverse Section Coefficient CX 0.59 0.57

Mid-ship Section Coefficient CM 0.56 0.52

Volumetric Coefficient ? /L3 260.00 216.00

Block Coefficient LBT

CB?? Definition 1

Prismatic Coefficient x

P LAC ?? Definition 2

Vertical Prismatic Coefficient W

VP TAC ?? Definition 3

Water-plane Area Coefficient BL

AC

WL

WWP ? Definition 4

Maximum Transverse Section Coefficient xx

xx TB

AC ? Definition 5

46

Midship Section Coefficient BTA

C MM ? Definition 6

Another set of important stability parameters are the centers of

gravity of the model. The center of gravity consists of the longitudinal, vertical

and transverse center of gravity. Since the model must be symmetrical, it will be

assumed that the transverse center of gravity is at the center of the beam. In order

to determine the longitudinal center of gravity, the hull was balanced on a pivot

point with a known distance to the aft perpendicular. A fish scale was then

attached with fishing line to the bow and the model was then leveled. The

distance from the pivot point to the longitudinal center of gravity (LCG) was then

calculated with moment balance. (Definition 7) The location of the LCG with

respect to the aft perpendicular is then calculated with Definition 8(Appendix G).

To determine the vertical center of gravity, the inclining experiment was

performed. This experiment consists of mounting a mast at the transverse

centerline of the model. A small weight on a string is then attached to the mast

creating a pendulum. Known amounts of weights are then applied at the deck of

the model to create a righting arm and an inclination angle. The inclination angle

is determined with the use of basic trigonometry, using the length of the string

and the distance between the mast and the weight at the end of the string. The

inclination or heeling angle is then plotted at three different weight intervals and

the slope is then identified. The Metacentric height of the model is then obtained

using Definition 10 and the vertical center of gravity (KG) can be calculated with

Definition 11. The KM value was obtained from Pro Surf hydrostatic curves from

47

“LOMAC: Littoral Operated Multi-purpose Auxiliary Craft”. (Cencer) Due to

changes in KG from the addition of weights, a more accurate GM and KG must

be calculated. These new values are obtained with Definition 12 and Definition

13 respectively. To obtain the distance between the keel and the center of

buoyancy, the Moorish equation (Definition 14) was used. The distance between

the vertical center of gravity (KG) and the vertical center of buoyancy (KB) is

then obtained with Definition 15.

Moment Balance WxFa ? Definition 7

LCG Location pxLCG ?? Definition 8

Heel Angle lwArcTan?? Definition 9

Metacentric Height ?Tan

wtGM?

? Definition 10

Vertical Center of Gravity GMKGKG ?? Definition 11

Metacentric Height ?

? slopeGM Definition 12

Vertical Center of Gravity ???? 000 wkgKG

KG Definition 13

Center of Buoyancy ????

???? ??

WP

B

CCT

KB25

3 Definition 14

Center of Gravity/Buoyancy Distance KBKGBG ?? Definition 15

48

The dynamic stability of the model depends on how well the vessel can

right itself as well as the radius of gyration about it axes and it determines how

stable the vessel is while in motion.(Connor et al. 2004) Due to time constraints,

the determination of the radius of gyration will not be included in the scope of this

project. The static and dynamic stability assessment was done following the

procedures from “LOMAC Monohull”.(Connor et al. 2004) The roll frequency is

dependent upon the ship’s beam and the metacentric height (Gillmer and Johnson,

1982). Finally, the longitudinal trim on the model was obtained with the use of

the data acquisition system.

Roll Period GMkB?? Definition 16

Table 11: LOMAC Model Centers

Parameter Symbol Fall 2003 Spring 2005 Units

Metacentric Height GM 61.07 68.17 in. Metacentric Radius BM 62.32 70.11 in. Vertical Center of Boyancy KB 3.30 2.37 in. Keel to Metacenter Distance KM* 65.62 72.48 in. Distance between VCG and VCB BG 1.25 1.94 in. Longitudinal Center of Gravity LCG 30.78 25.63 in. aft Vertical Center of Gravity VCG 4.55 4.31 in. Longitudinal Center of Boyancy LCB 18.58 23.56 in. aft Vertical Center of Boyancy VCB 3.30 2.37 in. Aproximate Trim Angle F -4.03 -1.05 degrees Trim Angle with Data Acq Sys. F F -2.12 -0.80 degrees Avg Roll Frequency Coeff K 0.2028 0.2028 Average Roll Frequency ? 0.9542 0.9498 sec

49

4.7 Steering System Test

To determine the effectiveness of the steering system, the model was

tested with the use of the differential, rudder and differential/rudder steering.

This experiment was conducted in the Florida Institute of Technology Wave Tank

Lake (Figure 30). The experiment consisted of driving the model through a full

circle at a velocity of 3-4 knots. This velocity corresponds to the speed of the

model using only one motor for propulsion. Three circular trajectories would be

measured using a tape measure. The circles would be done using differential

steering, rudder steering and the combination of both differential and rudder

steering. The turning radiuses of the different steering methods are shown in

Table 12. Recording the circular trajectory with the data acquisition system

would have been a more accurate option; however, this was not possible since the

system was non-operational at the moment of the experiment.

50

Figure 30: Location of Calm Water Test

Table 12: Turning Radius of Steering Systems Approximate Turning Radius at V= 3-4 knots

Differential Steering 14.0 ft.

Rudder Steering 8.5 ft.

Differential/Rudder Steering 4.5 ft.

4.8 Data Acquisition System Test

The objective of this test was to familiarize with the data acquisition

system and to check that all sensors were functioning correctly. In the test, the

data acquisition package was secured into the front passenger seat of a Dodge

51

Ram 1500 (Figure 31). The GPS antenna was placed on the roll bar of the truck to

maximize signal reception.

Figure 31: 2001 Dodge Ram 1500 2x4

The test consisted on logging data while driving from the Link building to

the wave tank building on the campus of Florida Institute of Technology in

Melbourne, Florida (Appendix A). All sensor work properly and acceleration,

inclination, position, heading and velocity readings were collected. However,

during the test, the GPS did not acquire data for 49 seconds. It was notice that the

sky was mostly cloudy, therefore it was concluded that the weather conditions

affected the GPS signal. In future testing, cloud cover would be taken in

52

consideration before conducting tests. The digital compass also malfunctioned by

not recording the east/west vector of the heading.

In Figure 32, the trajectory and position of the truck as the data was been

collected is shown. Notice how the data taken while the truck drove through

Country Club Road is erratic. With the exception of that section of the data, the

data collected was accurate. Figure 34 shows the four accelerometer outputs.

Inspection of the acceleration data reveals that the accelerometers are not

calibrated. In Figure 35 the inclination data revealed a trend which is best

understood when overlaid with the acceleration data on the X axis.

Position and Trajectory for Data Acquisition Test 1

8037.3

8037.35

8037.4

8037.45

8037.5

8037.55

2803.6 2803.65 2803.7 2803.75 2803.8 2803.85 2803.9 2803.95 2804

Latitude North

Long

itude

Wes

t

Figure 32: Truck Trajectory during Test 1

53

Truck Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300 350

Time (sec)

Hea

ding

(deg

rees

)

Figure 33: Truck Heading during Test 1

Truck Accelerations Recorded by Data Acquisition System

-2

-1.5

-1

-0.5

0

0.5

1

0 50 100 150 200 250 300 350

Time (sec)

Acc

eler

atio

ns (g

)

Z1 AxisY AxisZ2 AxisX Axis

Figure 34: Truck Acceleration during Test 1

54

Truck X Axis Acceleration and Inclination Recorded by Data Acquisition System

-0.4

-0.2

0

0.2

0.4

0.6

0.8

0 28 56 84 112 140 168 196 224 252 280 308

Time (sec)

Acc

eler

atio

n (g

)

-15

-10

-5

0

5

10

15

20

25

30

incl

inat

ion

(deg

rees

)

X AxisAcceleration

Inclinometer

Figure 35: Truck X Axis Acceleration and Inclination during Test 1

A second data acquisition system test was performed to prove that the

GPS lack of signal reception during the first test was caused by cloud cover. For

this test, there was no cloud cover and the GPS recorded data flawlessly.

55

Truck Trajectory Recorded by Data Acquisition System

8037.25

8037.3

8037.35

8037.4

8037.45

8037.5

8037.55

2803.55 2803.6 2803.65 2803.7 2803.75 2803.8 2803.85 2803.9 2803.95 2804

Latitude (North)

Long

itude

(Wes

t)

Trajectory

Figure 36: Truck Trajectory during Test 1b

Truck Velocity Recorded by Data Acquisition System

0

5

10

15

20

25

30

35

40

45

0 20 40 60 80 100 120 140 160 180

Time (sec)

Vel

ocity

(kno

ts)

Velocity

Figure 37: Truck Velocity during Test 1b

56

Truck Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120 140 160 180

Time (sec)

Hea

ding

(deg

rees

)

Heading

Figure 38: Truck Heading during Test 1b

Truck Acceleration Recorded by Data Acquisition System

-2

-1.5

-1

-0.5

0

0.5

0 20 40 60 80 100 120 140 160 180

Time(sec)

Acc

eler

atio

n(g)

Z1 AxisY AxisZ2 AxisX Axis

Figure 39: Truck Accelerations during Test 1b

57

During both test all sensors functioned and accurate data were transmitted

from the data acquisition package to the computer. Even though the system

performed acceptably, several observations were noted. The GPS bases it

heading readings on change in position, therefore if the data acquisition package

is stationary, a heading of 0 degrees will be recorded. To compensate for this

problem, the digital compass records a reading regardless of whether the system is

in motion or not. Unfortunately, the digital compass provides two readings, a

North/South component and an East/West component, both of which are of a

positive value. This prevents the reading from exceeding a value of 90 degrees

when the ATAN2 function is used to find the true heading. According to

Guardino, the method used to process the heading data has a problem. The

method requires the data acquisition package to travel a full 360? degrees in the

course of the test to be properly calibrated (Guardino).

4.9 LOMAC Data Acquisition Tests

The model sea trials were performed in the freshwater pond in front of the

Florida Institute of Technology wave tank (Figure 30). The primary goals of this

test was to understand the model controls, record accurate data from the data

58

acquisition system and to observe how the model maneuvered in calm water.

Achieving planning speed was a secondary goal.

For this test, the model was controlled through a series of turns in the

pond. In addition, the data acquisition system was used to trace the perimeter of

the lake. By tracing the perimeter of the lake, easier interpretation of the model

trajectory would be allowed.

Model Velocity Recorded by Data Acquisition System

0

1

2

3

4

5

6

0 64 128 192 256 320 384 448 512 576 640 704 768

Time(sec)

Vel

ocity

(kno

ts)

Model Speed

Figure 40: Model Velocity Recorded on Test 2

During the 13 minute test, the maximum velocity of the model was of 5.33

knots. The control configuration A discussed in Section 3.3 in which each motor

is connected to a different channel and both rudders are connected in one channel,

59

proved to be adequate. Several observations were taken during this test. The

model could turn 180 degrees within a 10 ft radius, making it a highly

maneuverable vessel and the trim of the model with the added weight of the data

acquisition system was acceptable (nearly zero degrees).

The data collected from the GPS was accurate and is shown in Figure 42,

44 and 46. It must be noted that the reason why the test is divided in three

sections( a, b & c) is because it proved to be a simpler, more readable method to

analyze and display the data. During these tests, the acceleration data was not

calibrated (Figure 41), and the digital compass and inclinometer failed to record

data. The accelerometers were then calibrated as close as possible to where it

needed to be and the gain was set at an optimal level. Since the GPS heading

reading was accurate and the model would always be in motion, the digital

compass was removed. The digital compass was initially installed to serve as a

backup system for the GPS when the model is not in motion. Since the model is

in motion most of the time, and the digital compass is troublesome, the digital

compass was removed. The inclinometer was fixed after the first sea trial and

accurate readings were obtained.

60

Model Accelerations Recorded by Data Acquisition System

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0 96 192 288 384 480 576 672 768

Time (sec)

Acc

eler

atio

n (g

)

Z1 AxisY AxisZ2 AxisX Axis

Figure 41: Model Accelerations for Test 2

61

Model Trajectory Recorded by Data Acquisition System

8037.37

8037.375

8037.38

8037.385

8037.39

8037.395

2803.685 2803.69 2803.695 2803.7 2803.705 2803.71 2803.715 2803.72 2803.725

Latitude North

Long

itude

Wes

t

TrajectoryLake Perimeter

Figure 42: Trajectory of LOMAC Model during Test 2a

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

40 50 60 70 80 90 100 110 120

Time (sec)

Hea

ding

(deg

rees

)

GPS Heading

Figure 43: LOMAC Model Heading during Test 2a

62

Model Trajectory Recorded by Data Acquisition system

8037.37

8037.375

8037.38

8037.385

8037.39

8037.395

2803.685 2803.69 2803.695 2803.7 2803.705 2803.71 2803.715 2803.72 2803.725

Latitude North

Long

itude

Wes

t

Model TrajectoryLake Perimeter

Figure 44: Trajectory of LOMAC Model during Test 2b

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

378 388 398 408 418 428

Time (sec)

Hea

ding

(deg

rees

)

GPS Heading

Figure 45: LOMAC Model Heading during Test 2b

63

Model Trajectory Recorded by Data Acquisition System

8037.37

8037.375

8037.38

8037.385

8037.39

8037.395

2803.685 2803.69 2803.695 2803.7 2803.705 2803.71 2803.715 2803.72 2803.725

Latitude North

Long

itude

Wes

t

Model TrajectoryLake Perimeter

Figure 46: Trajectory of LOMAC Model during Test 2c

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

420 430 440 450 460 470 480 490 500 510

Time (sec)

Hea

ding

(deg

rees

)

GPS Heading

Figure 47: LOMAC Model Heading During Test 2c

64

4.10 Propulsion Test and Analysis

The purpose of the propulsion test was to determine the thrust delivered by

each propeller and to determine which propeller was more efficient for the model.

For this test, four pairs of propeller were tested. These were a set of Graupner

carbon fiber two blade propellers, a set of Graupner nylon four blade propellers, a

set of Octura brass three blade propellers and a set of Prather stainless steel two

blade propellers. (Figure 48)

The test was conducted on the swimming pool of Southgate Apartment at

the campus of Florida Institute of Technology (Appendix A). For the experiment,

the model was attached to a scale with 50 lbs braded fishing line (Appendix H).

The model was then run at full speed for a ten second interval and the thrust in

pounds was recorded. This process was done three times and an average value for

thrust was taken for each set of propellers. The results of the propeller test are

shown in Table 13.

65

Figure 48: Propellers, Shafts and Accessories

Table 13: Propeller Thrust Data Propellers 1st Trial

(lbs)

2nd Trial

(lbs)

3rd Trial

(lbs)

Total Thrust

(lbs)

Graupner 2 Blade 14.2 14.1 14.3 14.20

Graupner 4 Blade 13.7 13.9 13.8 13.80

Prather 2 Blade 16 16.3 16.3 16.20

Octura 3 Blade 15.5 15.45 15.55 15.50

After the thrust of each propeller was determined, a propulsive analysis

was done for each set of propeller. Definitions 17 through Definition 33 were

used to determine the parameters shown in Table 14. (Gillmer and Johnson 1982)

66

Advance Coefficient nDv

J A? Definition 7

Thrust Coefficient 42 DnTKT ?

? Definition 8

Torque Coefficient 02? ?

TQ

JKK ? Definition 9

Torque 52 DnKQ Q ?? Definition 10

Propeller Loading 4

1

4 ????

???

JK

P TL Definition 11

Pitch/Diameter Ratio DP

Definition 12

Shaft Horsepower 550

2 snQSHP

?? Definition 13

Thrust Horsepower 550

ATvTHP ? Definition 14

Propeller Horsepower ATvTHPnQPHP )(2?? Definition 15

Effective Horsepower 550

ST vREHP ? Definition 16

Shafting Efficiency SHPPHP

S ?? Definition 17

Hull Efficiency )1()1(

wt

THPEHP

H ????? Definition 18

Relative Rotative Efficiency 0?

?? BR ? Definition 19

67

Propeller Efficiency RB ??? 0? Definition 20

Total Resistance TtRT )1( ?? Definition 21

Propulsive Efficiency RHD PHPEHP ???? 0?? Definition 22

Propulsive Coefficient SRHSDSHPEHPCP ?????? 0.. ??? Definition 23

68

Table 14: Propulsive Analysis and Parameters Propeller Parameters Graupner Graupner Prather Octura

Blades 2 4 2 3 No.

Pitch P 2.02 1.88 3.60 3.04 in.

Pitch 2 P 0.17 0.16 0.30 0.25 ft.

Diameter D 1.68 2.36 2.30 2.17 in.

Diameter 2 D 0.14 0.20 0.19 0.18 ft.

Rev per Sec n 128.33 128.33 128.33 128.33 rev/sec

Rev per Min n 7699.8 7699.8 7699.8 7699.8 rev/min

Pitch x Rev pxn 12.94 12.06 23.10 19.51

Apparent Slip Ratio Sa 0.4 0.4 0.4 0.4 assumed

Water Density ? 1.94 1.94 1.94 1.94 slugs/ft3 assumed

Thrust T 14.20 13.80 16.20 15.50 lb. .+/- 0.2 lb.

Torque Q 3.37 3.32 2.09 2.48 lb-ft.

Thrust Coefficient Kt 1.16 0.29 0.38 0.45

Torque Coefficient Kq 1.96 0.35 0.25 0.40

Advance Coefficient J 0.53 0.35 0.69 0.61

Open Water Prop Efficiency ?0 0.56 0.50 0.71 0.68 %

Propeller Loading pl 1.97 2.10 1.14 1.34

Pitch/Diameter Ratio P/D 1.20 0.80 1.57 1.40

Speed of Advance Va 6.44 6.01 11.50 9.71 mph

Speed of Advance Va 9.45 8.81 16.87 14.25 ft/sec

Speed of Advance Va 5.60 5.22 10.00 8.44 knots

Speed V 7.76 7.24 13.86 11.70 mph

Speed V 11.38 10.62 20.33 17.17 ft/sec

Speed V 6.74 6.29 12.04 10.17 knots

Wake Speed w 0.17 0.17 0.17 0.17 assumed

Thrust -deduction factor t 0.11 0.11 0.11 0.11 assumed

Shaft Horsepower SHP 4.93 4.86 3.07 3.64 hp

Propeller Horsepower PHP 4.69 4.62 2.92 3.46 hp

Thrust Horsepower THP 2.37 2.06 1.89 2.17 hp

Effective Horsepower EHP 2.44 2.13 1.95 2.24 hp

Efficiency behind Propeller ?B 0.98 0.98 0.98 0.98 % assumed

Shafting Efficiency ?S 0.95 0.95 0.95 0.95 % assumed

Relative Rotative Efficiency ?R 0.96 0.95 0.97 0.98 %

Hull Efficiency ?H 0.97 0.97 0.97 0.97 % assumed

Total Resistance of Model Rt 12.64 12.28 14.42 13.80 Lb.

Quasi-propulsive Efficiency ?D 0.52 0.46 0.67 0.65 %

Propulsive Coefficient P.C. 0.50 0.44 0.63 0.61

69

After conducting the thrust experiment, it was discovered that the

previously used Graupner 4 blade propellers was the least effective propellers.

The Graupner 2 blade propellers delivered the most thrust followed by the Octura

3 blade and the Graupner 2 blade propellers. The propulsive parameters of each

propeller were then calculated and compared (Table 14).

After completing this analysis, it was discovered that the pitch/diameter

ratio coincide with the propeller thrust, giving the Prather propellers the largest

and the Graupner 4 blade propeller the least. This leads to the conclusions that

the larger the pitch/diameter ratio is, the more effective the propeller will be for

the model.

The predicted velocity of each propeller was higher than any velocity

reached experimentally. This is mainly due to the fact that several conditions

were assumed when developing the propulsive analysis. A more accurate

prediction could be done by performing multiple iterations of this analysis. Also,

the freshwater density, instead of saltwater, was used. In Section 4.13 it is discuss

how freshwater tests limited the maximum velocity acquired by the model.

70

The efficiencies of each propeller also yield results that showed the

Prather propeller being the most effective with an open water efficiency of 71%

and a quasi-propulsive efficiency of 67%. The previously used Graupner

propellers had efficiencies below 56%. The efficiencies of the propellers are also

comparable in the calculations of required horse power (hp). The Prather

propeller was estimated to require 1.95 hp to push the model at 12 knots while the

Graupner 4 blade propeller requires 2.44 hp to push the model at 6.74 knots.

4.11 Calm Water Tests

In Section 5.5, a set of 2 blade Prather Propellers were selected as the most

efficient propellers for the catamaran model. Previously, the model had achieved

a maximum velocity of 5.33 knots. This second sea trial was also performed in

the wave tank lake at the Florida Institute of Technology campus. The new set of

propellers gave the model a maximum speed of 7.33 knots (Figure 49). At this

speed, the model was fully-planing.

The data acquisition system recorded heading, trajectory and velocity

accurately (Figure 51 through Figure 56); however the acceleration, although

accurate, was off by +/- 0.2 G (Figure 50). It was concluded that the

71

accelerometers could not be calibrated mechanically (adjusting the y-intercept

potentiometer) and could only be calibrated by altering the program within the pic

microcontroller. The inclinometer worked properly during this test. It displayed

data in the LCD screen of the data acquisition system. Unfortunately, the

inclination data was not sent through the wireless communication therefore no

data was recorded.

During this test, the model was controlled over a series of loops and

sprints. The test was divided into three sections to simplify the data analysis.

Figure 51, 53 and 55 display the trajectory of the model at each of the three tests

while Figure 52, 54 and 56 display the heading of the model recorded by the GPS.

72

Model Velocity Recorded by Data Acquisition System

0

1

2

3

4

5

6

7

8

0 40 80 120 160 200 240 280 320 360 400 440 480 520

Time(Sec)

Vel

ocity

(kno

ts)

Model Velocity

Figure 49: Velocity of LOMAC Model during Test 3

Model Accelerations Recorded by Data Acquisition Package

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0 100 200 300 400 500

Time (sec)

Acc

eler

atio

n (g

)

Z1 AxisY AxisZ2 AxisX Axis

Figure 50: LOMAC Model Accelerations Recorded during Test 3

73

Model Position Recorded by Data Acquisition System

8037.37

8037.375

8037.38

8037.385

8037.39

8037.395

2803.685 2803.69 2803.695 2803.7 2803.705 2803.71 2803.715 2803.72 2803.725

Latitude North

Long

itude

Wes

t

PositionLake Perimeter

Figure 51 : Trajectory of LOMAC Model during Test 3a

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

342 347 352 357 362 367

Time (sec)

Hea

ding

(deg

rees

)

GPS

Figure 52: LOMAC Model Heading during Test 3a

74

Model Position Recorded by Data Acquisition System

8037.365

8037.37

8037.375

8037.38

8037.385

8037.39

8037.395

2803.685 2803.69 2803.695 2803.7 2803.705 2803.71 2803.715 2803.72 2803.725

Latitude North

Long

itude

Wes

t

PositionLake Perimeter

Figure 53: Trajectory of LOMAC Model during Test 3b

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

193 198 203 208 213 218

Time (sec)

Hea

ding

(deg

rees

)

Heading

2 per. Mov.Avg. (Heading)

Figure 54: LOMAC Model Heading During Test 3b

75

Model Position Recorded with Data Acquisition System

8037.365

8037.37

8037.375

8037.38

8037.385

8037.39

8037.395

2803.685 2803.69 2803.695 2803.7 2803.705 2803.71 2803.715 2803.72 2803.725

Latitude North

Long

itude

Wes

t

PositionLake Perimeter

Figure 55: Trajectory of LOMAC Model during Test 3c

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

400 405 410 415 420 425 430 435 440

Time (sec)

Hea

ding

(deg

rees

)

Heading

Figure 56: LOMAC Model Heading during Test 3c

76

4.12 Littoral Test

Once the LOMAC model was tested in calm water, the model was taken to

the Indian River for littoral tests. The first test was performed north east of the

SR-192 causeway while the second test was performed south of the SR-192

causeway (Figure 57). To facilitate the operation of these tests, a 17 ft aluminum

boat was used (Figure 58).

Figure 57: River Test Locations

77

Figure 58: 17 ft Research Boat

The location of the first test was selected because the wave action was

minimal and wind was not present. During this test, the model performed a series

of sprints and loop in a 150 ft by 100 ft area. These maneuvers are shown in

Figure 59. The velocity data recorded by the data acquisition system reveals the

highest ever recorded velocity which was a velocity of 7.728 knots. (Figure 61)

Several field observations were taken during this test. The wind and wave action

were not a factor on the model velocity since the model sprinting maneuvers were

always done perpendicular to the wind and wave action.

78

Model Trajectory Recorded by Data Acquisition System

8034.595

8034.6

8034.605

8034.61

8034.615

8034.62

8034.625

2805.335 2805.34 2805.345 2805.35 2805.355 2805.36 2805.365

Latitude North

Long

itude

Wes

t

Series1

Figure 59: Trajectory of LOMAC Model during Test 4a

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

400

0 20 40 60 80 100 120 140

Time (sec)

Hea

ding

(deg

rees

)

Model Heading

Figure 60: LOMAC Model Heading during Test 4a

79

Model Velocity Recorded by Data Acquisition System

0

1

2

3

4

5

6

7

8

9

0 20 40 60 80 100 120

Time (sec)

Vel

ocity

(kno

ts)

Velocity2 per. Mov. Avg. (Velocity)

Figure 61: Model Velocity during Test 4a

The acceleration data was also recorded during this test. (Figure 62)

Although not calibrated, the data reveals the accelerations increasing at the

beginning of each sprinting maneuver. During the last sprinting maneuver, the

model was navigated through its own wake, creating a larger oscillating

acceleration data.

80

Model Accelerations Recorded by Data Acquisition System

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0 20 40 60 80 100 120

Time (sec)

Acc

eler

atio

n (g

)

Z1 AxisX AxisZ2 AxisY Axis

Figure 62: LOMAC Model Acceleration during Test 4a

X Axis Acceleration and Model Inclination Recorded by Data Acquisition System

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0 20 40 60 80 100

Time (sec)

Acc

eler

atio

n (G

)

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

Incl

inat

ion

(Deg

rees

)

X Axis AccelerationInclination

Figure 63: X Axis Acceleration and Model Inclination during Test 4a

81

The second set of tests took place south of the SR-192 causeway. The

main goals of these tests were to successfully operate the model in littoral

conditions and to obtain inclination data. During these tests, the data acquisition

system was oriented so that the inclinometer would measure the inclination in the

longitudinal axis(x axis). In theory, the acceleration and inclination in the x-axis

would be directly related since the model increase its angle of attack as it increase

velocity and as the model reaches planning velocity, the angle of attack decreases

and so does the acceleration. The inclination data is shown in Figure 72.

Velocity, accelerations trajectory and heading graphs for this tests are shown in

Figure 64-71.

Model Velocity Recorded by Data Acquisition System

0

1

2

3

4

5

6

7

0 20 40 60 80 100

Time (sec)

Vel

ocity

(kno

ts)

Velocity 2 per. Mov. Avg. (Velocity )

Figure 64: Velocity of LOMAC Model during Test 4b

82

Model Trajectory recorded by Data Acquisition System

2805.34

2805.345

2805.35

2805.355

2805.36

2805.365

2805.37

2805.375

2805.38

8034.595 8034.6 8034.605 8034.61 8034.615 8034.62 8034.625

Latitude North

Long

itude

Wes

t

Velocity (knots)

Figure 65: Trajectory of LOMAC Model during Test 4b

Model Trajectory Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

400

0 20 40 60 80 100 120

Time (sec)

Model Trajectory

Figure 66: LOMAC Model Heading during Test 4b

83

Model Accelerations Recorded by Data Acquisition System

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0 20 40 60 80 100 120

Time (sec)

Acc

eler

atio

n (g

)

Z1 AxisX AxisZ2 AxisY Axis

Figure 67: LOMAC Model Acceleration during Test 4b

X Axis Acceleration and Inclination Recorded by Data Acquisition System

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 20 40 60 80 100

Time(sec)

Acc

eler

atio

n(G

)

-6

-4

-2

0

2

4

6

8

10

Incl

inat

ion(

Deg

rees

)

X Axis AccelerationInclination

Figure 68: Model X Axis Acceleration Recorded during Test 4b

84

Model Velocity Recorded by Data Acquisition System

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 10 20 30 40 50 60 70 80 90

Time (sec)

Vel

ocity

(kno

ts)

Velocity2 per. Mov. Avg. (Velocity)

Figure 69: Model Velocity Recorded during Test 4c

Model Trajectory Recorded by Data Acquisition System

8034.599

8034.6

8034.601

8034.602

8034.603

8034.604

8034.605

8034.606

8034.607

8034.608

8034.609

2805.346 2805.348 2805.35 2805.352 2805.354 2805.356 2805.358 2805.36 2805.362 2805.364

Latitude North

Long

itude

Wes

t

Model Trajectory

Figure 70: Trajectory of LOMAC Model during Test 4c

85

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

0 10 20 30 40 50 60 70 80 90 100

Time (sec)

Hea

ding

(deg

rees

)

Heading

Figure 71: LOMAC Model Heading during Test 4c

Model Acceleration Recorded by Data Acquisition System

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0 10 20 30 40 50 60 70

Time (sec)

Acc

eler

atio

n (g

)

Z1 AxisY AxisZ2 AxisX Axis

Figure 72: LOMAC Model Accelerations during Test 4c

86

X Axis Acceleration and Incliantion Recorded by Data Acquisition system

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0 18 36 54 72

Time (sec)

Acc

eler

atio

n (G

)

-21

-16

-11

-6

-1

4

9

14

Incl

inat

ion(

degr

ees)

X Axis AccelerationInclination

Figure 73: Model X Axis Acceleration and Inclination during Test 4c

4.13 Planing Performance Test

The LOMAC model underwent planning performance test on the spring

2005 semester. The primary goal of this test was to collect data that could show

the angle of attack of the boat changing as the model went from displacement to

fully-planning. To obtain the angle of attack, the data acquisition system was

oriented so that the inclinometer could record the inclination on the longitudinal

axis. This test was performed in both calm (Figure 73) and wave (Figure 78)

conditions for comparison. A new test was done for the calm water test while

data from Test 4a (Section 5.7) was used for the littoral test. For the calm water

87

test, an acceleration graph was plotted with the model velocity to observe how the

velocity increases as acceleration increases. (Figure 77)

Model Velocity and Angle of Attack vs Time

0

1

2

3

4

5

6

7

8

9

0 16 32 48 64

Time(sec)

Vel

ocity

(kno

ts)

-10

-8

-6

-4

-2

0

2

4

6

8

10

12

Incl

inat

ion

(deg

rees

)

Velocity

Angle ofAttack

60 per.Mov. Avg.(Angle ofAttack)

Figure 74: Planning Performance in Calm Water during Test 5

Model Velocity Recorded by Data Acquisition System

0

1

2

3

4

5

6

7

8

9

0

8.28

16.6

24.8

33.1

41.4

49.7 58

66.2

74.5

82.8

91.1

99.4

108

116

124

132

141

149

157

166

174

182

190

199

207

215

224

232

240

248

257

265

273

282

290

298

306

Time (sec)

Vel

ocity

(kno

ts)

Figure 75: Model Velocity Recorded during Test 5

88

Model Trajectory Recorded by Data Acquisition System

8037.374

8037.376

8037.378

8037.38

8037.382

8037.384

8037.386

8037.388

8037.39

2803.692 2803.696 2803.7 2803.704 2803.708 2803.712 2803.716

Latitude (North)

Long

itude

(Wes

t)

Figure 76: Trajectory of LOMAC Model Recorded during Test 5

Model Heading Recorded by Data Acquisition System

0

50

100

150

200

250

300

350

0 10 20 30 40 50 60

Time (sec)

Hea

ding

(deg

rees

)

Figure 77: LOMAC Model Heading Recorded during Test 5

89

Model Accelerations Recorded by Data Acquisition System

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0 10 20 30 40

Time (sec)

Acc

eler

atio

n (g

)

0

1

2

3

4

5

6

7

8

9

Vel

ocity

(kno

ts)

Z1 AxisX AxisZ2 AxisY AxisSeries53 per. Mov. Avg. (Series5)20 per. Mov. Avg. (Y Axis)20 per. Mov. Avg. (Z2 Axis)20 per. Mov. Avg. (X Axis)20 per. Mov. Avg. (Z1 Axis)

Figure 78: Accelerations and Velocity Recorded during Test 5

Model Velocity and Angle of Attack Vs. Time

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 20 40 60 80

Time (sec)

Ang

le o

f Att

ack

(deg

rees

)

0

1

2

3

4

5

6

7

8

9

Vel

ocity

(kno

ts)

Angle ofAttack

Velocity

60 per.Mov. Avg.(Angle ofAttack)

Figure 79: Planning Performance in Littoral Conditions

90

The results of this test show that the fully planing speed of the model is at

7.15 knots in calm conditions and 7.3 knots in wave conditions. This show how

efficient the hull shape is since it does not get greatly affected by wave

conditions. Also note how the maximum velocity is within 0.1 knots for calm and

wave conditions. The main reason why the salt water tests recorded higher

velocity than the freshwater tests is because at the freshwater test, the model

velocity was limited due to the testing facilities (freshwater lake). The model was

unable to maintain a maximum velocity for more than 4 seconds due to the size of

the lake. Therefore the model was decelerated before it would reach the

maximum velocity.

Table 15: LOMAC Model Planing Speeds Calm Conditions Littoral Conditions

Approximate Displacement Velocity V< 4.10 knots V< 4.15 knots

Approximate Semi-Planing Velocity 4.10 knots < V < 7.15 knots 4.15 knots <V< 7.30 knots

Approximate Fully-Planing Velocity V> 7.15 knots V> 7.30 knots

Approximate Maximum Angle of Attack 5 degrees 6 degrees

Maximum Recorded Velocity 7.658 knots* 7.728 knots*

*At maximum power with both 10 cell Ni-CD fully charged.

91

5.0 Discussion

The reconstruction of the LOMAC catamaran model and re-design of its

new systems was highly successful. The main purpose of this procedure was to

finish the hull, lower the weight and move the longitudinal center of gravity closer

to the stern of the model. All objective were completed by fairing and re-shaping

the hull. In the end, the model still trimmed by the bow, however, the addition of

on-board systems and the data acquisition system would correct that trim angle.

Re-designing the drive and steering system of the model led to the success

of this graduate work. Two drive systems were tested within the scope of this

research. The first system was the Traxxas drive system, which used 6 cell 3000

mAh Ni-MH batteries. The Traxxas drive system had the advantages of longer

range, and increased maneuverability; however, maximum velocity and

acceleration were lower than those in the second drive system. The improved

maneuverability was due to the reverse operation offered by the Traxxas motor

controller.

92

The second system was the JES drive system, which was powered with a

pair of 10 cell, 2700 mAh Ni-Cd batteries. With this system, the maximum

velocity and fastest initial accelerations were reached. Unfortunately, the JES

motor controllers did not have reverse like the Traxxas motor controller, therefore

maneuverability was limited. Also, the range of the model was reduced due to the

increased current draw from the motors allowed by the JES motor controller. In

the present conditions, the Traxxas drive system is better for further research,

however, an addition of 2 10 cell batteries on the JES system will not only

duplicate the operational time of the model, but it will also trim the model further

to the stern. This will eliminate the 1 degree bow trim that the model has. By

eliminating this excessive trim, the model will be balanced and will navigate more

efficiently at planing speed. The steering system of the model was design to

further improve the existing steering system. Initially, the model relied on the use

of differential steering to be maneuverable. The new system employed the

combination of rudders and differential steering. In the initial system, the thrust

in the model was not enough to propel it and was even less efficient in turning the

motor around. By re-designing a more efficient drive system, differential steering

was now a useful method of turning the model. However, the model

maneuverability using only differential steering was still unacceptable, giving the

model a turning radius of 14 feet, making it impossible to properly test the model

in the wave tank pond. To improve on the steering system, rudders were added to

93

each hull. This improved the maneuverability drastically to less than a 5 ft

turning radius. In addition to the turning maneuverability, the model can be

steered at high velocity with the rudders without decreasing maximum velocity

performance with the use of differential steering.

The test performed during this research involved different aspect of naval

architecture. This included propulsion analysis, static stability experiment, and

sea trials in both calm and littoral conditions. The first test performed was the

static stability experiment. The experiment was performed in the same manner as

it was done by Mark Cencer et al. The purpose of this experiment was to re-

calculate several of the static stability parameters. Since the model had been

reconstructed and the center of gravity had been moved further to the stern, it was

necessary to perform this experiment again. The result show that although the

longitudinal center of gravity was moved approximate 5 inches to the stern, most

of the other parameters yield similar results. Several differences between both

experiments were present. First, the 2003 experiment was performed on the

LOMAC model with no drive or steering system within the hull. The 2005

experiment included a fully loaded LOMAC model, with drive and steering. The

striking similarities between both tests are due to the fact that the 2003 model was

tested with nothing on board and the model itself was heavier than the restored

94

2005 model; however, the 2005 model was tested with all systems on board,

except the data acquisition system. Once all model systems were operational, the

data acquisition system was tested by recording the movement of a Dodge Ram

Pickup truck. The data acquisition system successfully recorded most of the

trajectory. Unfortunately, cloud cover proved to affect the reception of the global

positioning device. A second test was performed in a day were the cloud cover

was minimal. During this test, the data acquisition succeeded in recording

trajectory, heading, velocity, accelerations and inclination. The first sea trials

were conducted using the Traxxas system and 4 blade nylon Graupner propellers.

An average maximum velocity of 5.3 knots was reached in calm water conditions.

Previously, the model had not exceeded the 2 knot mark.(Cencer 2003) However,

the model did not reached planning speed. This lack of velocity was caused by

the amount of current allowed by the motor controller to go through the motors

and the efficiency of the propeller. The Traxxas motor controller can deliver up

to 30 amps continuous current while the JES NAVY 600 can deliver 60 amps

maximum current. The propeller efficiency was the other problem that led to

lower velocity. The propeller in use was the 4 blade nylon propeller by Graupner.

The propeller was mainly design to operate at lower revolutions. The low pitch

propeller became flexible under high revolutions, which decreased the efficiency

of the propeller.

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A propulsive analysis was done for 4 different pairs of propellers to

determine the most efficient one. The experiment led to the selection of the

Prather propellers which had the highest pitch and only 2 blades. Contrary, to the

Graupner 4 blade propeller, these propellers are made of stainless steel, therefore

the propellers suffer from minimal deformation at higher revolution. The

Graupner 4 blade propeller proved to be the least efficient propeller of all four.

This was due mainly to the material it was made and the application it was made

for (low revolution propeller). The Octura three blade propellers followed the

Prather propellers in efficiency. These were made out of brass; however, they had

a smaller pitch than the Prather propeller. In both three and four blade propellers,

the revolutions per minute (rpm) were to high for the design rpm, therefore some

cavitation existed. By using a 2 blade propeller, cavitation is kept to a minimal.

The replacement of the drive system from the Traxxas to the JES system

and the conversion of propellers proved to be a major step in obtaining the

planning speed. During these test, which are shown in Section 5.6, the model

exceeded the theoretical planning velocity of 7.3 knots. The JES system utilize

10 cell NiCd batteries and also allows the motor to draw more current from the

batteries. One negative aspect of this system is the decreased operational time

due to the increase current draw by the motors. Fortunately, this problem

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becomes an advantage with the addition of two more identical 10 cell batteries.

With this addition, the operational time of the model would increase by 100% and

the added weight in the motor compartment would improve the less than -1

degree trim angle. This addition will further improve the overall performance of

the LOMAC multi-hull model.

The model was also tested in littoral conditions. To perform these tests,

the model was navigated in the Indian River. The approximate height of the

waves encounter by the model during the river tests were of 0.2 to 0.4 ft. At these

tests, all systems performed flawlessly and a maximum velocity of 7.6 knots was

achieved. It was expected for the model to reach a lower maximum velocity due

to the increased wave action. However, two factors were not considered. Calm

water tests were performed in a small freshwater pond. The lack of space in the

pond prevented the model to maintain a high velocity for extended period of time.

Also littoral tests were conducted in saltwater, which is denser than freshwater,

therefore increasing the thrust delivered by the propeller and decreasing the model

draft. Increased thrust and decreased draft were minor changes but they could

affect the performance of the model by increasing the model velocity by a fraction

of a knot.

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After conducting all necessary testing to prove the effectiveness of the

LOMAC model and systems, a planning experiment was performed. This

experiment consisted on using the inclinometer (previously oriented in the y axis)

in the x axis to measure the angle of attack as the model went through

displacement, semi-planing, and fully-planing mode. By collecting such data, the

fully-planing velocity and the average trim of the model at high velocity could be

measured and compared to theoretical values. This test was done in both calm

and littoral condition. As a result, the model reached planing speed at

approximately 7.3 knots which was the theoretical value for the model planing

and the trim at high velocity was approximately -1 degree (1 degree toward bow).

The acceleration, inclination and velocity values resemble striking similarities

with the exception of an increased oscillated acceleration values. The oscillations

were present in the littoral test and were related to the wave action during the test.

Maximum velocities of 7.658 and 7.728 knots were achieved in the last calm

(Figure 73) and littoral tests (Figure 78) respectively. It was observed that wave

action did not affect the velocity of the model since the velocity in both calm and

littoral tests were within 0.1 knots of each other. The angle of attack and

velocities of the LOMAC catamaran model as it travel from displacement to fully-

planing also yield similar results in both calm and littoral tests (Table 15). The

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model was minimally affected by the wave tests, proving the effectiveness of the

model in wave conditions.

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6.0 Conclusions and Recommendations

The reconstruction and evaluation of the LOMAC catamaran model

concluded in March 2005. The model, which went through a reconstruction of

the hull and re-design of the internal systems, is now capable of attaining

maximum velocity of 7.7 knots with the JES system and 6.0 knots with the

Traxxas system. The differential/rudder system gives the model a turning radius

of less than 10 ft. The operational time of the vessel is of approximately 32

minutes using the Traxxas system and 24 minutes using the JES system. The

model’s range is limited to the radio controlled range of approximately 980 feet.

All systems are in working conditions, however, the digital compass data output

requires extensive data processing before obtaining a useful set of data. The

accelerometers require calibration since the potentiometers used for calibration do

not have the range to calibrate the accelerometers to zero.

During the reconstruction of the model, several recommendations have

been suggested to be able to improve the performance and appearance of the

model. An upgrade of motors from the Graupner Speed 700 BB Turbo to the

Speed 800 BB Turbo would add torque and thrust, which will make the model

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have a better initial acceleration and a higher maximum velocity. The addition of

2 more 10 cell 2700 mAh Ni/Cd batteries connected in parallel would increase the

model operational time to approximately 48 minutes, if the motors in use are the

Graupner Speed 700 BB Turbo. Operational time for the model using the

Graupner Speed 800 BB Turbo and 4 10 cell batteries would be of approximately

40 minutes due to the increase current draw from the larger Speed 800 motors.

The spacing between the propeller and hull was increased after the propellers

were assigned, therefore a set of bigger Prather propellers would improve the

velocity of the model. An excellent replacement for the Prather 250S model

(diameter =2.3, pitch=2.6) is the Prather 255S model which has diameter of 2.4

inches and a pitch of 3.8 inches. To increase maneuverability, a larger fiberglass

rudder can be designed and manufactured to increase the turning moment on the

model.

The system that requires the most improvement is the data acquisition

system. Making the system smaller enough to fit within the LOMAC model is

very important since it will decrease the wind resistance and lower the center of

gravity of the model. Also, the system could be used in smaller and less stable

mono-hull models such as the catamaran model. The size reduction could be

accomplished by eliminating some components and by replacing other

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components with smaller components that can perform the same operation. For

example, the breadboard that connects the inclinometer and LCD screen to the

PICNIC board can be replaced with a smaller circuit board. Once, all sensors are

properly calibrated, the LCD screen is no longer required in the system.

Therefore, the LCD can be eliminated or replaced by a smaller LCD screen. The

lead acid battery used to supply the power to the system should be replaced with a

smaller NiCd or NiMH battery that can weigh up to 50% less.

The addition of several sensors would make the system more effective at

recording ship motions. Installing an inclinometer, oriented in the X-axis would

help understanding how the boat inclines in a three-dimensional environment.

Replacing the linear accelerometer with accelerometers that can measure both

linear and rotational acceleration would highly also improve the effectiveness of

the data acquisition system.

The addition of a software program that could analyze the data as it is

collected by the data acquisition system would give the operator a better

understanding of the behavior of the model during tests. This would prevent the

operator from having to spend hours organizing the data for further review.

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During this project, the LOMAC catamaran model surpassed expectations

by reaching planning velocity and by successfully recording accurate data from a

variety of sensors. The system proved to be simple, efficient and easy to operate.

In the future, the LOMAC catamaran model could be use for many applications.

Among them, research on beach topography, wave studies, and catamaran ship

responses.

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References

Gillmer, Thomas C. and Johnson, Bruce. Introduction to Naval Architecture. Annapolis, Maryland: Naval Institute Press. 1982. Littoral Combat Ship. United States Navy Warfare Development Command. February 2003 Cencer, Mark et al. Littoral-Operated Multipurpose Auxiliary Craft. DMES.

Melbourne, Florida: Florida Institute of Technology. July 2003. Guardino, Doug. Design of Wireless Data Acquisition for Field Testing of Hull Models. DMES. Melbourne, Florida: Florida Institute of Technology. December 2003. Florida Institute of Technology, University Publications. (2005) “Florida Tech

Campus Map”. Traxxas WWW EVX 3014 Motor Controller Specifications Retrieved November

8, 2004, from htttp://www.traxxas.com/products/accessories /trx_accessories_evx.htm.

Graupner WWW Speed 700 Specifications Retrieved September 12, 2004, from

http://www.hobby-lobby.com/speed700.htm Jes Jeti Navy 600 WWW motor Controller Specifications. Retrieved December

27, 2004, from http://www.hobby-lobby.com/boatcont.htm Graupner hydro Drive WWW Specifications. Retrieved September 12, 2004,

from http://www.hobby-lobby.com/hydrodrives.htm. Prather Propellers WWW Specifications. Retrieved January 10, 2005, from http://www.aeromarinerc.com/prather.htm Octura Propellers WWW Specifications. Retrieved January 10, 2005, from http://www.geocities.com/scopesniper/props.html Graupner Propellers WWW Specifications. Retrieved January 10, 2005, from http://www.hobby-lobby.com/grboatprop.htm

104

Linksys WWW Router Specifications. Retrieved January 12th, 2005, from http://www.linksys.com/products/product.asp?grid=33&scid=36&

prid=602 Mapquest.com WWW Melbourne, Florida Map. Retrieved February 2, 2005,

from http://www.mapquest.com

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Appendix A: Campus Map

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Appendix B: Sample Data from test

Time Z1 Axis

Y Axis Z2 Axis

X Axis Digital Compass Inclination Signal Latitude Longitude Velocity Heading

(sec) (g) (g) (g) (g) X Vector

Y Vector (degrees) A or V North West (knots) (degrees)

0 -0.161 0.151 -0.137 0.068 0 1012 23 0.0 A 2805.349 8034.5992 0 0

0.04 -0.181 0.176 -0.117 0.083 0 1011 23 0.0

0.08 -0.161 0.181 -0.088 0.102 0 1011 22 -0.1

0.12 -0.181 0.151 -0.127 0.088 0 1014 23 0.0

0.16 -0.161 0.161 -0.102 0.078 0 1012 24 0.1

0.2 -0.166 0.171 -0.098 0.098 0 1012 25 0.2

0.24 -0.181 0.156 -0.117 0.088 0 1012 26 0.3

0.28 -0.171 0.171 -0.147 0.078 0 1012 29 0.6

0.32 -0.176 0.181 -0.137 0.122 0 1013 32 0.9

0.36 -0.186 0.186 -0.122 0.107 0 1013 36 1.3

0.4 -0.151 0.21 -0.068 0.102 0 1011 39 1.6

0.44 -0.166 0.2 -0.112 0.122 0 1014 42 1.9

0.48 -0.161 0.21 -0.098 0.117 0 1011 45 2.2

0.52 -0.147 0.225 -0.083 0.127 0 1011 46 2.3

0.56 -0.181 0.21 -0.122 0.132 0 1015 47 2.4

0.6 -0.161 0.205 -0.112 0.142 0 1012 48 2.5

0.64 -0.181 0.22 -0.102 0.122 1 1012 48 2.5

0.68 -0.156 0.24 -0.078 0.156 1 1012 49 2.6

0.72 -0.147 0.225 -0.073 0.151 1 1012 51 2.8

0.76 -0.147 0.215 -0.083 0.156 0 1013 55 3.2

0.8 -0.151 0.215 -0.078 0.171 0 1012 58 3.5

0.84 -0.137 0.191 -0.088 0.137 0 1012 60 3.7

0.88 -0.117 0.196 -0.058 0.166 0 1013 59 3.6

0.92 -0.112 0.181 -0.068 0.147 0 1014 57 3.4

0.96 -0.132 0.151 -0.068 0.132 0 1013 56 3.3

1 -0.132 0.127 -0.083 0.127 0 1014 55 3.2 A 2805.349 8034.5992 0 0

1.04 -0.147 0.102 -0.083 0.132 0 1013 55 3.2

1.08 -0.127 0.127 -0.107 0.147 0 1012 54 3.1

1.12 -0.151 0.137 -0.093 0.166 0 1013 53 3.0

1.16 -0.137 0.142 -0.083 0.171 0 1012 53 3.0

1.2 -0.147 0.181 -0.078 0.147 0 1011 52 2.9

1.24 -0.151 0.181 -0.107 0.166 0 1013 52 2.9

1.28 -0.137 0.2 -0.083 0.142 0 1011 53 3.0

1.32 -0.142 0.21 -0.078 0.196 0 1011 55 3.2

1.36 -0.171 0.196 -0.102 0.166 0 1012 60 3.7

1.4 -0.147 0.186 -0.053 0.186 1 1012 69 4.6

1.44 -0.142 0.196 -0.063 0.176 2 1011 77 5.4

1.48 -0.137 0.21 -0.063 0.191 2 1012 83 6.0

1.52 -0.142 0.22 -0.098 0.21 2 1011 86 6.3

1.56 -0.151 0.225 -0.102 0.24 5 1012 89 6.6

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Appendix C: Test Pictures

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109

Appendix D: Construction Pictures

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Appendix E: Pro Surf Hydrostatic Curves

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Appendix F: Static Stability Illustrations

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Appendix H: Experiments Setup

Thrust Determination Experiment

Static Stability Test