License Help for Canadian Engineers - 1st Class ME Naval Architecture

License help for Canadian engineers

Canadian First Class ME Naval ArchitectureBrought to you by www.dieselduck.net comments to [email protected]

Disclaimer

Transport Canada has ask us to advise users of this webpage to keep in mind that these questions are not theexact questions found in their exams. Martin's Marine Engineering Page - www.dieselduck.net is not affiliatedwith Transport Canada and these questions have been gathered from various sources.

1 What are the three principal sources of shipboard vibration. Explain howyou would trace the forces causing these vibrations and the measures thatcould be taken to reduce the severity of the vibrations.

2 Describe with the aid of sketches a keyless propeller showing how it isfitted to the tail shaft. Discuss the advantages of this design. Describe themethod of driving the propeller on to the shaft and how it is locked inposition.

3 Derive the Admiralty Coefficient formula and show how this may bemodified to suit a fast ship. B) A ship of 14500 tone displacement requires24000KW to drive it at 24 knots. Using the modified Admiralty Coefficientformula, calculate the shaft power required for a similar ship of 12000 tonedisplacement at 20 knots.

4 Describe the procedure for calculating the righting moments for a vesselfor a) small angles of heel b) large angles of heel. A homogeneous block ofwood (relative density 0.64) 3.0m long, 0.9 m wide and 0.5m deep floats inwater of density 1025kg/m3. Calculate the righting moment when it isheeled to an angle of 8.5 degrees.

5 What is meant by 'stability'? a) what factors does a Master need to knowbefore commencing a voyage b) what factors affect stability c) a vessel hastake a sudden list in calm seas, what could be the reasons?

the 5 above submitted Aug 2005

C01. For a ship 55 m in length, floating in water of 1025 kg/m3 the equallyspaced half-breadths of the waterplane commencing from the afterperpendicular are: 0.0 6.9 7.2 6.0 0.0 m respectively. Calculate theposition of the longitudinal center of flotation from midships and the

License help for Canadian engineers - 1st Class ME Naval Ar... http://www.dieselduck.ca/library/02 exam_stuff/1st_naval_ar...

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moment to change trim one centimeter

note: assume KB = KG

C02. For a ship 61 m in length floating in water of 1025 kg/m3 the equallyspaced half-breadths of the waterplane commencing from the afterperpendicular are: 0.0 7.0 7.4 6.1 0.0 respectively. Calculate theposition of the longitudinal center of flotation from midships and themoment to change trim one centimeter.

note: assume KB = KG.

C03. For a ship 65 m long the half ordinates starting from aft are: 0 2 5 3 0 . Find the LCF. Given KB = KG find the moment required to change thetrim 1 cm.

C04. For a ship 65 m in length floating in water of 1025 kg/m3 the equallyspaced half-breadths of the waterplane commencing from the afterperpendicular are: 0.0 7.6 8.0 6.7 0.0 m respectively. Calculate theposition of the longitudinal center of flotation from midships and themoment to change trim one centimeter.

Assume KB = KG

REF:JAN91

C05. For a ship 85 m long the load waterplane is defined by the followingequidistant half breadths commencing from the after perpendiculars:

Stn AP 1 2 3 4 5 6 7 8 9 FPHalf 0 5 10.5 15 16.3 16.5 15.2 12.9 7.7 3.4 0

breadths (m)

Determine:

a) the area of the waterplane

b) the position of the longitudinal center of flotation

c) the second moment of area of the waterplane about the center of


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flotation.

REF:FEB82

C06. A ship of 90.0 m length between perpendiculars contains ballast waterin a forward compartment and has the following equidistant half areas ofimmersed sections commencing at the

after perpendicular. 0.3 7.5 21.3 33.4 40.7 45.4 48.3 51.9 51.0 34.3 0.0

respectively. If prior to ballasting the ship's displacement was 5600 tonnesand the position of the longitudinal center of buoyancy (LCB) was 4.6 mforward of midships, calculate:

a) the mass of water of density 1025 kg/m3 added as ballast

b) the distance of the center of gravity of the ballast water contained in theforward compartment from midships.

C07. A ship 90 m long with half breadths of the load waterplane

commencing from aft are: 0.3 3.8 6.0 7.7 8.3 9.0 8.4 7.8 6.9 4.7 0.0

respectively. Calculate:

a) the area waterplane

b) distance of LCF from midships

c) 2nd moment of area about a transverse axis through the LCF

REF:83 REF:FEB90

C08. A ship 90 m long displaces 8300 tonnes when floating in seawater atdraught of 5.2 m forward and 5.6 m aft. GML = 97, TPC = 10.0, LCF = 3.0 maft of midships. It is decided to

ballast the ship to a draught aft of 5.95 m to submerge the propellor. Ifballast tank 34 m aft of midships is available. Calculate the least amount ofwater required and final draught forward.


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REF:FEB82 REF:APR91


AP 1 2 3 4 5 6 7 8 9 FP 0.0 5.5 11.0 15.5 16.8 17.0 15.7 13.4 8.2 3.9 0.0

Determine:



c) the second moment of area of the waterplane about the center offlotation

C10. A ship of 93 m length between perpendiculars contains ballast water ina forward compartment and has the following equidistant half areas ofimmersed sections commencing at the

after perpendicular 0.6 7.8 21.6 33.7 50.0 45.7 48.6 52.2 51.3 34.6 0.0 meters2. If prior to ballasting the ship's displacement was 6000 tonnesand the positions of the longitudinal center of buoyancy (LCB) was 4.6 mforward of midships, calculate:

a) the mass of water of density 1025 kg/m3 added as ballast

b) the distance of the center of gravity of the ballast water contained in theforward compartment from midships.

C11. A ship 100 m long and 15 m beam floats at a mean draft of 3.5 m. Thehalf ordinates of waterplane at equal intervals are: 0.0 3.0 5.5 7.3 7.5 7.5 7.5 7.05 6.10 3.25 0.0 respectively. The section amidships isconstant and parallel for 20 m and the submerged cross sectional area is 50m2 at this section. Calculate the new mean draft when a midships

compartment 15 m long is opened to the sea. Assume the vessel to be wallsided in the region of waterplane.

REF:83 REF:JAN87


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REF:Reeds P300 Q33


AP 1 2 3 4 5 6 7 8 9 FP0.0 6.0 11.5 16.0 17.3 17.5 16.2 13.9 8.7 4.4 0.0

Determine:



c) the second moment of area of the waterplane about the center offlotation

REF:OCT92

C13. A ship 100 m long floats at draughts of 4.15 m forward and 4.5 m aft. MTC 1 cm = 60 t/m, TPC = 10, LCF = 2.0 m forward of midships. Calculatethe new draughts after the following masses have been placed onboard:

15 tonnes 38 m aft of midships



60 tonnes 10 m forward of midships

20 tonnes 35 m forward of midships

C14. A ship 110 m long displaces 10500 tonnes and has a wetted surfacearea of 2900 m2 At 15 knots the shaft power is 4000 kW, propulsivecoefficient = 0.6 and 60% of the thrust is available to overcome thefrictional resistance. Calculate the shaft power required for a similar ship140 m long at the corresponding speed. Given that f = 0.42 and n = 1.825

REF:MAR89


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C15. A ship 120 m long and 18 m beam floats at a mean draught of 3.8 m The semi-ordinates of the waterplane at equal intervals are: 0.0 3.2 5.6 7.5 7.8 7.8 7.2 6.0 3.1 0.0m

respectively. The midships section is constant and parallel for 24 m, theimmersed cross-sectional area at this section is 58 m2. Assuming the ship tobe wall-sided in the region of the waterplane, Calculate the new meandraught when a midships compartment 20 m long is opened to the sea.

C16. A ship 120 m long has a light displacement of 4000 tonnes and LCG inthis condition 2.5 m aft of midships. The following items are then added:

cargo 10000 tonnes LCG 3.0 m forward of midships

fuel 1600 tonnes LCG 2.0 m aft of midships

water 400 tonnes LCG 8.0 m aft of midships

stores 100 tonnes LCG 10.0 m forward of midships

Using the following hydrostatic data, calculate the final draughts.

DRAUGHT DISPLACEMENT MCTI LCB from midships LCF from midships

8.50 16650 183 1.94 forward 1.20 aft8.00 15350 175 2.10 forward 0.06 forward

REF:Reeds P301 Q41

C17. A ship of length, 120 m floats in water of relative density 1.025, theforward draft is 6.8 m and the after draft is 7.4 m. For the conditionsstated, the hydrostatic data is:

TPC = 18.1

MTCI = 125 tm

LCF = 2 m aft of midships

Calculate the distance from amidships at which a mass may be added to theship without altering the draft aft. Assume the position of the LCF remainsunaltered


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REF:Specimen 3

C18. A ship 120 m long floats at draughts of 8.0 m forward and 8.8 m aft. MCTI cm = 150 tm, TPC = 28 and LCF = 1.5 m aft of midships. It is desired toballast to an even keel and there is a tank available 55 m forward ofmidships. Find the mass of water required to ballast to the even keel andthe new draughts.

REF:FEB89

C19. A vessel 125 m long floats at a draught of 8.5 m in sea water of density1025 kg/m3 and has the following hydrostatic data:

Draught Displacement (tonne)

8.5 145008.0 13430

At a draught of 8.5 m the KB is 4.46 m and the KM is 7.35 m. Calculate theKB and KM at the 8.0 m draught, assuming the vessel is wall-sided betweenthe above two waterlines.

C20. A ship 125 m in length, 18.5 m breadth and 7.5 m draught in water ofdensity 1025 kg/m3 has a block co-efficient of 0.5. During trials thefollowing results were obtained:

Ship speed (knots) 16 17 18 19Effective power (kW) 2420 3000 3750 4600(naked)

Determine for a ship of similar form having a displacement of 15500 tonnesand operating at a

corresponding speed of 19.5 knots:

a) length

b) breadth

c) draught

d) the effective power

REF:FEB82 REF:JAN87


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REF:Munro Smith P3.159 Q30

C21. A ship 130 m long displaces 9600 tonnes. It loads in fresh water of1000 kg/m3 to a level keel draught of 7 m. It then moves into sea water of1025 kg/m3. T.P.C. in sea water is 17. MCT 1 cm is 124 t/m. LCF is 0.5 maft of midships and LCB is 2.4 m forward of midships. Calculate the forwardand aft draughts in sea water.

C22. A ship 130 m long displaces 12200 tonnes. When a mass of 105 tonnesis moved 75 m from forward to aft, there is a change in trim (by the stern)of 60 cm. Calculate:

a) M.C.T. 1cm

b) the longitudinal metacentric height

c) the distance moved by the C. of G. of the ship

REF:FEB89

C23. A ship 130 m long displaces 14500 tonnes when floating at draughts of7.7 m forward and 8.2 m aft. GML = 127 m TPC = 19, LCF = 2.5 m aft ofmidships. Calculate the final draughts when a mass of 190 tonnes lying at 35m aft of midships is removed from the ship.

C24. For a ship 135 m in length, 16.0 m breadth the values of tonnes percentimeter immersion (TPC) in water of density 1025 kg/m3 are as follows:

Draught 1.2 1.8 2.4 3.0 3.6 4.2 4.8TPC 14.6 14.83 15.1 15.36 15.54 15.7 15.82

The displacement of the ship below the 1.2 m draught is 1200 tonnes. If ata draught of 4.8 m the position of the longitudinal center of buoyancybelow the metacenter (BML) is 140 m and the second moment of area of thewaterplane about midships is 935000 m4, calculate:

a) the distance of the longitudinal center of flotation (LCF) from midships


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b) the block coefficient

C25. For a ship 135 m in length, 15 m breadth the values of tonnes percentimeter immersion (TPC) in water of density 1025 kg/m3 are as follows:

Draught 1.3 2.1 2.9 3.7TPC 15.2 15.46 15.63 15.72

The displacement of the ship below the 1.3 m draught is 1400 tonnes. If ata draught of 3.7 m the position of the longitudinal center of buoyancy belowthe metacenter (BML) is 138 m and the second moment of area of thewaterplane about midships is 710000 m4, Calculate:



C26. For a ship 137 m long the equally spaced half-breadths of thewaterplane commencing from the after perpendicular are: 0.0 6.71 8.9 9.45 9.6 9.6 9.6 9.56 8.85 5.18 0.0 m respectively. Calculate thechange in end draughts of the ship if a mass of 300 tonnes is loaded on thecenter line at a position 30 m aft of the mid-ships. The moment to change

trim 1 cm is 147 tonnes-m.

C27. For a ship 137 m in length, 15.3 m breadth the values of tonne percentimeter immersion (TPC) in water of density 1025 kg/m3 are as follows:

Draught 1.5 2.3 3.1 3.9TPC 15.32 15.58 15.75 15.84

The displacement of the ship below the 1.5 m draught is 1500 tonnes. If ata draught of 3.9 m the position of the longitudinal center of buoyancy belowthe metacenter (BML) is 140 m and the second moment of area of thewaterplane about midships is 730000 m4, calculate:



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C28. The immersed cross-sectional areas of a ship 140 m long, commencingfrom aft are:

3 42 81 103 107 109 109 107 94 52 0 m2

Calculate:

a) displacement

b) longitudinal position of the center of buoyancy from midships

note: sea water density is 1025 kg/m3

C29. For a ship 140 m in length, 15.5 m breadth the values of tonne percentimeter immersion (TPC) in water of density 1025 kg/m3 are as follows:

Draught (m) 1.7 2.5 3.3 4.1TPC 15.5 15.76 16.95 16.1



b) the block co-efficient.

C30. A ship 140 m long, 16 m beam floats at a draught of 7.6 m in sea waterof 1025 kg/m3. It's block co-efficient is 0.74. Calculate the power requiredto overcome frictional resistance at 18 knots if f = 0.422, n = 1.825 andwetted surface area = 2.55 times sqrt of delta L.



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Draught 1.2 1.8 2.4 3.0 3.6 4.2 4.8TPC 15.0 15.4 15.82 16.1 16.36 16.6 16.78





Draught (m) 1.2 2.1 3.0 3.9 4.8 5.7 6.6TPC 16.5 18.7 19.4 20.0 20.5 21.1 21.7


a) the distance of the longitudinal center of flotation from midships

b) the block co-efficient

C33. A ship 150 m long has 1/2 ordinates of waterplane of: 1.8 6.0 9.2 10.4 10.8 10.8 10.8 9.8 7.6 4.5 0.0 respectively. Calculate the secondmoment of area of the waterplane about the centerline.

C34. A ship 150 m long displaces 8200 tonnes when floating in sea waterwith a density of 1025 kg/m3. The half ordinates of the waterline are: 0.0 2.4 4.8 7.1 7.5 7.7 7.7 7.6 5.3 2.6 0.0 respectively. While floating atthis waterline the ship develops a list of 8o due to instability. Calculate thenegative metacentric height when the vessel is upright in

this condition.


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C35. A ship 160 m long and 9 m draught has a rudder whose area is onesixtieth of the middle-line plane, the rudder stock is 340 mm diameter. Thedistance from the center of the stock to the center of effort of the rudder is1 m and the maximum rudder angle is 35o. If the stress in the stock is notto exceed 75 MN/m2. Calculate the maximum ship's speed.

note: Fn = 580 Av2 (N)

C36. A ship 165 m long and 21 m beam floats at a draught of 8.5 m in seawater of 1024 kg/m3 the block co-efficient is 0.7.

a) if the admiralty co-efficient is 620, calculate the shaft power required at19 knots

b) if the speed is now increased to 22 knots, and within this speed rangeresistance varies as the speed cubed, find the new shaft power.

C37. The draughts of a ship 180 m long are 7.0 m forward and 7.85 m aft. MCT 1 cm 310 t/m, TPC 30, LCF 2.5 m forward of midships. Calculate thenew draughts after the following changes in loading. 165 tonnes added 62m aft of midships, 195 tonnes added 30 m forward of midships, 120 tonnesremoved 78 m aft of midships, 75 tonnes removed 15 m aft of midships.

C38. A ship of 4800 tonne displacement in salt water of density 1025 kg/m3has a double bottom tank 15 m long. The half-breadths of the top of thetank are: 7.5 7.0 5.0 and 3 m respectively. The tank has a watertightcenterline division. Calculate the free surface effect if the tank is partiallyfull of fresh water on one side only.

C39. A ship displacing 4800 tonnes has a rudder area of 11m2. The distancebetween the center of lateral resistance and the center of the rudder is 1.7m and the ship's metacentric height is 0.26 m. If the ship is travelling at 15knots, calculate the initial angle of heel if the rudder is put over to 35o. note: Fn = 580 Av2 sin alpha N.

C40. For a vessel 5080 tonnes displacement the KM is 6.4 m. The vessel is


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inclined in sea water of density 1025 kg/m3 by moving a mass of 5.0 tonnestransversely a distance of 14.6 m, causing a pendulum 6.1 m long to deflect10.2 cm. During the inclining experiment a double-bottom tank 7.3 m long,9.1 m broad and 1.22 m deep, contains sea water to a depth of 0.61 m. Determine the KG of the light vessel, if the only dead-weight on the vesselduring the experiment is the water in the double bottom tank.

REF:MAR8?

C41. For a ship of 5100 tonnes displacement, 120 m in length, the even keeldraught in water of density 1025 kg/m3 is 7 m and the center of gravity is2.5 m above the center of buoyancy. Calculate the moment to change trimone centimeter (MCT 1 cm) if the ship's load waterplane is defined by thefollowing half breadths commencing from the after perpendicular:

Station AP 1 2 3 4 5 6 7 FPHalf 3.3 6.8 7.6 8.1 8.1 8.0 6.6 2.8 0.0 breadths

C42. A ship of 5500 tonnes displacement has a KM of 6.5 m. When 6 tonnesare moved 16 m across the ship a pendulum 5 m long has a deflection of 10cm. A double bottom tank 8.0 m long, 9 m wide and 1.5 m deep is half fullof sea water. For a sea water density of 1025 kg/m3 calculate the KG ofthe light ship.

C43. A ship of 5600 tonnes displacement in sea water has three rectangulardouble bottom tanks, A is 11 m long and 15 m wide, B is 13 m long and 14m wide, C is 14 m long and 15 m wide. Calculate the free surface effectfor any one tank and state in which order the tanks should be filled with seawater when making use of them for stability correction.


C44. For a ship of 5600 tonnes displacement, 128 m in length, the keeldraught in water of density 1025 kg/m3 is 7 m and the center of gravity is3.0 m above the center of buoyancy.

Calculate the moment to change trim one centimeter (MCT 1 cm) if theship's load waterplane is defined by the following half breadths commencingfrom the after perpendicular:

Station AP 1 2 3 4 5 6 7 FPHalf breadths 3.7 7.2 8.0 8.5 8.5 8.4 7.0 3.2 0.0


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C45. A ship of 5800 tonnes displacement in seawater has a rectangulardouble bottom tank 9.5 m wide and 13 m long, half full of sea water. Calculate the reduction in metacentric height due to free surfaces.


C46. A ship of 6800 tonnes displacement in sea water has it's center ofgravity 6.1 m above the keel and its transverse metacentre 6.7 m above thekeel. A rectangular double bottom tank 11 m long, 13 m wide and 1.5 mdeep is now half filled with sea water. Calculate the metacentric height.

note: density of seawater = 1025 kg/m3

C47. A ship of 6900 tonnes displacement has a K.G. of 3.9 m and a K.M. of4.7 m. A mass of 55 tonnes is now lifted from the quay by one of the ship'sderricks whose head is 18 m above the keel. The ship heels a maximum of9.750 when the mass is lifted. Calculate the outreach of the derrick fromthe ship's center line.

C48. A ship of 7000 tonnes displacement has a wetted surface area of 2800m2 and a speed of 16 knots. Calculate:

a) the corresponding speed and wetted surface of a similar ship of 2500tonnes displacement.

b) if the skin resistance is of the form R = 0.45 SV1.83 N, find the resistanceof the 7000 tonne ship.

C49. A ship of 7200 tonne displacement in sea water has a double bottomtank 15 m long, 11 m wide and 1.5 m deep full of sea water. The center ofgravity is 6.6 m above the keel and the metacentric height is 0.5 m. Assuming that the K.M. remains constant, calculate the new G.M. if half ofthe water is pumped out of the tank.

note: density of sea water is 1025 kg/m3.


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C50. A ship of 7500 tonnes displacement, 105 m long, floats in sea water of1025 kg/m3 at draughts of 5.6 m forward and 6 m aft. The TPC is 16, LCB is0.5 m aft of midships, LCF is 3

m aft of midships and MCT 1 cm is 63 t/m. The ship now moves into riverwater of 1008 kg/m3. Calculate the distance a mass of 60 tonnes must bemoved to bring the ship to an even keel and determine the final draught.

C51. A ship of 8100 tonnes displacement floats upright in sea water. KG =7.5 m and GM = 0.45 m. A tank, whose center of gravity is 0.5 m above thekeel and 4 m from the centerline contains 100 tonnes of water ballast. Neglecting free surface effect, calculate the angle of heel when the ballastis pumped out.

REF:APR89

C52. A ship of 8400 tonnes displacement floats upright in sea water ofdensity 1025 kg/m3. KG = 7.8 and GM = 0.6 m. A tank, whose center ofgravity is 0.75 m above the keel and 5 m from the centerline, contains 120tonnes of water ballast. Neglecting free surface effect, calculate the angleof heel when the ballast is pumped out.

REF:OCT92

C53. For a ship of 8500 tonnes displacement in water of density 1025 kg/m3the metacentric height is 0.6 m. Calculate the final effective G.M. of theship is 100 tonnes of oil fuel of density 900 kg/m3 is pumped from aninitially full rectangular double bottom tank 24.3 m long by 12.2 m wide by1.2 m deep into an initially empty tank 9.15 long, 9.15 m wide by 7.6 mdeep, situated on top of the double bottom tank.

REF:JAN91

C54. A ship of 9000 tonne displacement in sea water has it's center ofgravity 4.8 m above the keel and transverse metacentre 5.4 m above thekeel when a rectangular tank 8 m long and 15 m wide contains sea water. Amass of 12 tonne is moved 13 m across the deck. Calculate the angle ofheel:

a) when the tank is pressed up


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b) if the water does not fill the tank

note: sea water density 1025 kg/m3

C55. A vessel of 10600 tonnes displacement floats upright at a draught of6.7 m in water of density 1025 kg/m3. A mass of 140 tonnes is loaded by theship's derrick which has a maximum outreach of 9.14 m. The point ofsuspension is at 18.29 m above the keel. Estimate using the hydrostaticdata below, the angle of heel after the derrick at maximum outreach, hasjust lifted the mass from the quay. The ship's hydrostatic data before liftingthe mass is: Center of buoyancy above the keel (KB) = 3.4 m Center ofgravity above the keel (KG) = 3.66 m Tonnes per centimeter immersion (TPC) = 20.0

note: second moment of area of the waterplane about the centerline is22788 m4

C56. A ship whose displacement is 10800 tonne when floating in sea waterof density 1025 kg/m3 has a double-bottom tank containing oil, whosecenter of gravity is 15.6 m forward and 6.2 m below the center of gravity ofthe ship. When the oil is use the ship's center of gravity moves 360 mm. Calculate:

a) the mass of oil used

b) the angle which the center of gravity moves relative to the horizontal

REF:FEB82

C57. A ship of 11000 tonnes displacement in sea water has KM = 8.1 m andGM = 0.5 m. A rectangular double bottom tank is 1.5 m deep, 19 m long and14 m wide. Assuming that the KM remains constant, calculate the new GMwhen the tank is:

a) filled with sea water

b) half filled with sea water

note: sea water density 1025 kg/m3


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C58. A ship of 12200 tonnes displacement and length 110 m floats inseawater density 1025 kg/m3. The half ordinates of the load water plane atequal intervals commencing from aft are: 0.0 5.27 7.2 7.72 7.45 5.5 0.0 respectively. Given that KB = 5.7 and KG = 6.1 m. Calculate:

a) the T.P.C.

b) the GM

C59. A ship of 12000 tonnes has a locomotive of 180 tonnes loaded in thecenter on the tank top below a derrick whose head is 18 m above the centerof gravity of the load. Find the shift in center of gravity when:

a) the load is just clear of the tank top

b) the load is lifted to the deck head

c) the load is landed on a deck 12 m above the tank top

d) the load is swung 14 m outboard

REF:MAY81

C60. A ship of 12500 tonnes displacement has a rudder 16 m2 in area, whosecenter is 5.2 m below the waterline. The ship's GM is 0.4 m and the centerof buoyancy is 3.4 m below the waterline. When travelling at 22 knots therudder is turned through 300 allowing 20% for the race effect,

calculate the initial angle of heel given that Fn = 577 AV2 sin alpha(N). REF:MAR89

C61. A ship of 12500 tonnes displacement and length 110 m floats in seawater of density 1025 kg/m3. The half ordinates of the load waterplane atequal intervals commencing from aft are: 0.0 5.4 7.35 7.9 7.6 5.85 0.0respectively. Given that KB = 5.8 m and KG = 6.0 m. Calculate:

a) tonnes per centimeter immersion

b) metacentric height.


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C62. A ship of 12190 tonnes displacement in seawater of density 1025 kg/m3has the following hydrostatic data:

KB = 3.66 m KM = 7.31 m

KG = 6.1 m

Four hundred tonnes of liquid cargo of density 890 kg/m3 is pumped into amidships rectangular center deep tank 21.34 m long by 15.2 m wide by 2.44m high. If the bottom of the deep tank is 6.7 m above the keel, calculatethe new metacentric height of the ship. Assume the KB is

proportional to the displacement and the BM is inversely proportional to thedisplacement.

C63. A ship of 13000 tonnes displacement and length 120 m floats in seawater of density 1025 kg/m3. The half ordinates of the load waterplane atequal intervals commencing from aft are:

0.0 5.5 7.45 8.0 7.7 5.8 0.0 m respectively. Given that KB = 5.9 and KG= 6.2 m. Calculate:

a) tonnes per centimeter immersion

b) metacentric height

REF:FEB90

C64. A ship of 13000 tonnes displacement and 16 m beam has a GM of 1.4m. A mass of 90 tonnes is lifted from its position in the center of the lowerhold by one of the ship's derricks, and placed on the quay 3 m from theship's side. The ship heels to a maximum angle of 3.5o when the mass isbeing moved.

a) does the GM alter during the operation?

b) calculate the height of the derrick head above the original center ofgravity of the mass.


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C65. The following ordinates define the GZ curve of a ship of 13000 tonnesdisplacement:

Angle of inclination 0 15 30 45 60 75 90Righting lever GZ (mm) 0 140 315 430 250 -200 -800

Calculate the angle of list and the range of stability if, due to adverseweather conditions, 500 tonnes of cargo shifts horizontally, a distance of 5m and vertically, a distance of 3 m downwards.

REF:Specimen 1

C66. A ship of 15000 tonnes displacement has a G.M. of 0.4 m, it's center oflateral resistance is 4.5 m above the keel. The ship's rudder has an area of21 m2 and it's centroid is 2.4 m above the keel. Calculate the angle of heelof the ship due to the force on the rudder if the rudder is put hard over toport to a maximum angle of 35 degrees when the ship is travelling at 23knots.

note: Fn = 580 Av2

REF:APR91

C67. A ship of 15000 tonnes displacement is 130 m long and floats atdraughts of 8.1 m forward and 8.6 m aft. The TPC is 20, GML is 120 m andLCF is 4 m forwards of midships. It is required to bring the ship to an evenkeel draught of 8.6 m. Calculate the mass which must be added and thedistance of the center of the mass from mid-ships.

C68. A ship of displacement 20000 tonnes and length 150 m floats atdraughts forward and aft of 6.92 m and 7.69 m respectively, in water ofdensity 1025 kg/m3. Given that the LCF forward of midships = 3.46 m, LCBforward of midships = 0.52 m, TPC = 16.2, MTC 1 cm = 183 tonnes/m. Calculate the draughts forward and aft when the ship passes into the waterof density 1000 kg/m3.

REF:MAY91

C69. A vessel of 22000 tonnes displacement floats in sea water of density1025 kg/m3. A deep wing tank 18 m long and 9.25 m deep has a constantcross sectional area defined by the following equidistant breadths: 4.4 4.25 4.0 3.35 2.6 m. One side of the tank forms a longitudinal bulkhead


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parallel to and 5.0 m from the ship's centerline, while the other side formspart of the ship's shell. The bottom of the tank is 2.0 m above the keel. The ship has a K.M. of 5.0 m and a G.M. of 0.61 m when the tank is full ofoil of density 900 kg/m3. Calculate the ship's K.G. and the angle of heelwhen half of the oil in the wing tank has been used. The free surface effectcan be neglected and the K.M. assumed to remain constant.

C70. A ship of 80000 tonnes displacement has a double bottom tank whichholds fuel oil. The center of gravity is 15.8 m forward and 7.5 m below thecenter of gravity of the ship. When the oil is used the ships center of gravitymoves 365 mm. Calculate:

a) the mass of oil used

b) the angle which the center of gravity moves relative to the horizontal

REF:FEB90

C71. A tanker of 42660 tonnes displacement gives the following results whenon trial:

Speed (knots) 13.5 14.0 15.0 16.0 17.0 17.5

Propeller RPM 86.1 89.5 96.7 104.8 113.6 118.5

The ship is taken on a six hour continuous run during which time 15.25tonnes of fuel are used and the engine makes 38520 revolutions. Calculate:

a) fuel co-efficient for the ship

b) the fuel required per day for a similar ship 35000 tonnes displacementwhich is fitted with a similar type engine and which runs at thecorresponding speed.

REF:MAY91

C72. An oil tanker 27 m wide displaces 28500 tonne in sea water of density1025 kg/m3 when loaded in nine equal tanks each 10 m long, with oil R.D.0.85. Calculate the total free

surface effect with:


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a) no longitudinal bulkheads

b) a longitudinal centerline bulkhead

c) twin longitudinal bulkheads forming three equal tanks

d) twin longitudinal bulkheads, the center tank having a width of 13 m

C73. The displacement of a ship at draughts of :

0 1 2 3 and 4 m are:0 201 456 710 and 998 tonnes.

Calculate the distance of the center of buoyancy above the keel whenfloating at a draught of 4 m, given:

VCB below waterline = Area between Displacement curve and Draught axisDisplacement

C74. A ships speed is increased 12% above normal for 11 hours then thespeed is reduced to 10% below normal for 9 hours and for the remainder ofthe day at normal speed. If the fuel consumption is normal for the day, findthe percentage difference for the day's run.

REF:FEB89

C75. The following data applies to a ship operating at a speed of 15 knots:

Shaft power = 3050 kW Propeller speed = 1.58 rev/sec

Propeller thrust = 360kN Apparent slip = 0.05

Calculate:

a) the propeller pitch

b) real slip

c) quasi propulsive co-efficient if the Taylor wake fraction and thrustdeduction factor are 0.31 and 0.2 respectively.


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d) briefly comment on the significance of negative apparent slip.

C76. A ship travelling at 15 knots has a metacentric height of 0.4 m. Thedistance between the center of gravity and the center of lateral resistanceis 2.5 m. If the vessel turns in a circle of 1300 m diameter, calculate theangle to which it will heel.

C77. A ship is driven through the water at a rate of 15.5 knots by a propellerof 5.5 m pitch rotating at 95 R.P.M.. The power delivered by the propelleramounts to 3540 kW when the thrust is 380 kN. The thrust deduction factoris 0.198 and the actual slip is 20%. Calculate:

a) the quasi propulsive co-efficient (Q.P.C.)

b) the wake fraction

C78. A ship travelling at 18 knots turns with a radius of 470 m when therudder is put hard over. The center of gravity is 7.2 m above the keel, thetransverse metacentre is 7.6 m above the keel and the center of buoyancy is3.9 m above the keel. If the centripetal force is assumed to act at thecenter of buoyancy, neglecting the rudder force calculate the angle of heelwhen turning.

C79. A ship with a maximum speed of 17 knots has a rudder area of 24 m2. The center of effort is 1.2 m from the stock centerline when the rudder isturned to 35o. Allowing 18% for race effect calculate the diameter of thestock if the maximum allowable stress is 72 MN/m2. If the effectivediameter of the stock is reduced to 370 mm, calculate the maximum speedthat the ship may travel so that the above stress is not exceeded.

note: Fn = 577 AV2 sin a (N)

C80. A ship, whose maximum speed is 20 knots, has a rudder area of 28 m2. The distance from the center of the stock to the center of the rudder is 1.5m and the maximum rudder angle is 350. If the maximum allowable stressin the rudder stock is 88 MN/m2 calculate the diameter of the stock. Therudder force parallel to the centerline of the ship (Fn) = 580 Av2 (N)


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REF:MAY91

C81. A ship floats with an even keel draught of 8 m in sea water of density1025 kg/m3. The longitudinal center of flotation is at midships MCT 1 cm is185 t/m and TPC = 16. Calculate the magnitude and position of a mass to beadded in order to bring the ship to draughts of 8.3 m aft and 7.9 m forward.

C82. A ship model is towed at the rate of 3.6 knots through fresh water in atowing tank installation. The model is 6 m long and the total resistanceduring this operation is 40 N. A ship designed along the same lines as themodel is to be 180 m long with a displacement of 29400 tonnes. Calculatethe effective power (PE) for the ship when operating at the correspondingspeed in sea water.

f(model) F.W. = 0.492 n = 1.825

f(ship) S.W. = 0.421 S = 257 times sqrt delta L

Where L = length in meters, S = wetted area (m2) = displacement (t)

C83. A ship model 5 m long has a wetted surface area of 4.98 m2. Themeasured tow rope pull of the model, when towed in water of density 1000kg/m3 at the corresponding speed of a similar ship, is 25.57 N. Determineusing the given data the effective power (naked) for a ship 180 m in lengthwhen sailing at 18.25 knots in water of density 1025 kg/m3. The followingdata is given:

Frictional co-efficient of the model in water of density 1000 kg/m3 is 1.72

Frictional co-efficient of the ship in water of density 1025 kg/m3 is 1.42

Speed in m/sec with index (n) for ship and model 1.83

C84. A ship model 7 m long has a total resistance of 44 N when towed at 3.5knots in fresh water. The ship itself is 185 m long and displaces 22000tonnes. The wetted surface area may be calculated from the formula S=2.57 sqrt delta L Calculate the effective power (naked) for the ship at itscorresponding speed in sea water given:

f(model) FW = 0.492 f(ship) SW = 0.421

n = 1.825 density of sea water = 1025 kg/m3


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C85. A 1/25 scale model of a ship which is to be 140 m long has a wettedsurface area of 5.67 m2 and when towed through water of relative density,1.0 at a speed of 1.39 m/s, the total resistance is 22.9 N and the frictionalresistance is estimated at 17.3 N. The following data apply to the ship:

Propulsive coefficient = 0.64

Transmission loss = 3.1%

Appendage and weather allowance = 16%

Frictional coefficient = 1.44 (when ship floats in water of relative density1.025

Speed index, n = 1.825 (when speed is in m/s)

When the actual ship moves through water of relative density 1.025 at aspeed related to the corresponding model speed, calculate:

a) the effective power

b) the quasi-propulsive coefficient

REF:Specimen 4

C86. A vessel of 120 m length and 13 m breadth floats at a draught of 6.2 min water of density 1025 kg/m3 The waterplane area is defined by thefollowing equidistant half-breadths, taken from the after perpendicular:0.0 2.84 4.92 6.3 6.5 6.28 4.8 3.0 0.0m respectively Given that themidships area co-efficient = 0.9 and the block co-efficient = 0.62, calculate:

a) the displacement

b) the area of immersed midships section

c) the prismatic co-efficient

d) the position of the transverse metacenter above the center of buoyancy

REF:FEB82


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C87. A vessel of 126 m length and 14 m breadth floats at a draught of 6.5 min water of density 1025 kg/m3. The waterplane area is defined by thefollowing equidistant half-breadths taken from the after perpendicular: 0.0 3.16 5.12 6.46 7.0 6.34 4.98 3.04 0.0 m respectively. Given that themidships area co-efficient = 0.94 and the block co-efficient = 0.65 calculate:

a) the displacement

b) the area of immersed midships section

c) the prismatic co-efficient

d) the position of the transverse metacenter above the center of buoyancy

C88. A vessel of 8750 tonnes displacement has 80 tonnes of cargo on thedeck. It is lifted by a derrick whose head is 11 m above the center ofgravity of the cargo and placed in the hold 8 m below the deck and 15 mforward of its original position. Calculate the horizontal and vertical shift inthe vessel's center of gravity from its original position when the cargo is:

a) just clear of the deck

b) suspended 5 m below the derrick head

c) in it's final position

d) the angle which the center of gravity moves relative to the horizontal

C89. A vessel of 10500 tonnes displacement is 120 m long and has a wettedsurface area of 3000 m2. When delivering 4100 kW at the shaft the speed is15 knots, the propulsive co-efficient = 0.6 and 55% of the thrust is availableto overcome frictional resistance. Calculate the shaft power for a similarship 140 m in length operating at a corresponding speed.

note: F = 0.42 n = 1.825

C90. A vessel of 14000 tonnes displacement has a load waterline length of145 m. The waterline lengths at 1 m intervals of draught below this are:144 143 141.5 139.5 137 134m respectively. If the center of lateralresistance is at the centroid of this immersed area, calculate the angle to


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which the ship will heel due to centrifugal force when the ship turns in acircle of 500 m diameter at a speed of 15 knots with K.G.= 5.5 m and G.M. =0.5 m.

C91. The following data reflect the results of a tanker of 54300 tonnesdisplacement when undergoing a 6 hour continuous trial run:

Speed (knots) 13.5 14 15 16 17 17.5

Propeller speed 86.0 89.6 96.8 105.0 114.0 119.0 (revs/min)

Fuel consumption = 15.89 tonnes

Engine revolutions = 39530

Calculate:

the fuel coefficient1.

the fuel consumption (t/day) for a similar ship of 36000 tonnesdisplacement fitted with a similar type of engine and operating at acorresponding speed.

2.

REF:Specimen 5

C92. A vessel of constant triangular cross-section floats apex down with thekeel just touching mud on the bottom of the sea, the width of thewaterplane is 8 m. If the water level now drops 2 m, calculate how far thevessel will sink into the mud given that the R.D. of the mud is twice that ofthe water.

note: the original draught of the vessel = 4 m.

C93. The master of a vessel wishes to introduce water ballast into a tanklocated 33 m aft of midships in order to completely submerge thepropeller. The following data is applicable to the ship Displacement = 8100t. Initial draft fwd = 5.25 m Length = 85 m. Initial draft aft = 5.55 m

TPC = 9. Final draft aft = 5.85 m. Longitudinal center of flotation (LCF) 2 maft midships

Longitudinal metacentric height GML = 96 m Calculate:

the least amount of ballast required1.


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the final draft forward2.

C94. For a barge 9 m in length, 4.5 m breadth floating at a draught of 2.3 min water of density 1025 kg/m3 the KG is 2.15 m. The barge is dividedlongitudinally into three compartments each 1.5 m wide. The followingcargoes are loaded:

-Oil of specific gravity 0.9 is loaded into the center compartment to a depthof 1.5 m

-Gasoline of specific gravity 0.72 is loaded into two outer compartments toa depth of 1.2 m.

Assuming the KM remains constant, calculate the metacentric height takinginto consideration the free surface of the cargo. Describe briefly whateffect transverse subdivision and longitudinal subdivision has on freesurface.

REF:MAR89 REF:FEB89

C95. A box barge 34 m long and 6 m wide has a light displacement of 220tonne and a K.G. of 2.8 m when floating in sea water of density 1025kg/m3. 85 tonne of cargo is put on board and in order to maintain stability50 tonne of ballast is added at K.G. 0.16 m. The final G.M. is 0.15 m.Calculate the K.G. of the added cargo.

C96. A box shaped barge is 46 m long, 7.6 m wide and has a central full-width compartment 9.14 m long which is partially filled with oil of density920 kg/m3. In this condition the barge floats upright at a draught of 1.83 min water of density 1025 kg/m3 and has a K.G. of 2.44 m.

Calculate the angle of heel which results from lifting a mass of 5 tonnesalready onboard and moving it through a horizontal distance of 4.9 m bymeans of a derrick fixed on the centerline of the barge. Assume the mass isoriginally located on the centerline of the barge and remains suspendedfrom the derrick in its final positions. The derrick head is 9.1 m above theoriginal position of the vertical center of gravity of the mass.

C97. A box barge 60 m long and 7.5 m wide has a vertical KG of 2.15 m. The barge floats at an even keel draught of 2.5 m in sea water of density1025 kg/m3. A forward compartment is formed by a transverse bulkhead 6m from the forward end. Determine the new draughts forward and aft when


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100 tonnes of sea water is pumped into this forward compartment.

C98. A box barge 85 m long, 18 m beam and 6 m draught floats in sea waterof 1.025 t/m3. A midships compartment 18 m long contains cargo stowingat 1.8 m3/t and having a density of

1.600 t/m3 There is a watertight flat 6 m above the keel. Calculate thenew draught if this compartment is bilged below the flat.

REF:APR89

C99. A box barge is 120 m long and floats at a draught of 6 m. It has amid-length compartment 15 m long extending right across the barge, butsub-divided by a horizontal watertight flat 4 m above the keel. The G.M. is0.95 m. Calculate the new draught and G.M. if the compartment is

bilged below the flat.

REF:FEB90

C100. A box barge 120 m long, 14 m beam and 5 m draught has acompartment at the extreme aft end 9 m long, sub-divided by a horizontalwatertight flat 2 m above the keel. KG is 3 m. Calculate the end draughts ifthe compartment is holed above the flat.

C101. A box barge 120 m long, 14 m beam and 5 m draught has acompartment at the extreme after end 9 m long, sub-divided by a horizontalwatertight flat 2 m above the keel. KG is 3 m.

Calculate the end draughts if the compartment is holed above the flat withwater entering both compartments.

C102. A box shaped barge 137 m long, 18.3 m wide has a K.G. of 4.57 mwhen floating at an even keel draught of 7.32 m in water of density 1025kg/m3. Calculate the forward and aft draughts if a full breadth aft endcompartment 13.7 m long is bilged.

C103. For a box shaped barge 140 m long, 20 m wide the KG is 5 m and the


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even keel draught 8 m when floating in sea water of density of 1025 kg/m3. The barge is fitted with a transverse watertight bulkhead 14 m from theforward end. Calculate the draughts forward and aft if the space forward ofthe bulkhead is bilged. Assume the permeability of the space to be 85% andthe second moment of area of the intact waterplane about the center offlotation to be 3.4 x 106 m4.

C104. A box barge of 580 tonne displacement, 36.6 m long, 6.4 m breadthand 3 m deep floats in water of density 1025 kg/m3. Calculate thepermeability of a full depth midships compartment 9.1 m long by 6.4 mwide if the compartment is bilged and the draught becomes 2.8 m.

C105. A barge with semi-circular ends is 22 m long overall, 6 m breadth and2.5 m in depth. The barge is flat bottomed with vertical sides and ends. The rectangular section of the barge is separated from the semi-circular endsections by two full depth transverse watertight bulkheads. It floats at aneven keel draught of 1.4 m in water of density 1025 kg/m3 the KG of thebarge and cargo being 1.5 m. Neglecting the effect of free surfacecalculate the transverse metacentric height if water of density 1000 kg/m3is pumped into both end compartments to a depth of 2 m.

C106. A raft is made from two cylinders each 2 m in diameter and 8 m long. The distance between the centers of the cylinders is 4 m. If the draught is 1m, calculate the transverse B.M.

C107. A propeller of 4.4 m pitch has an efficiency of 66% when turning at130 R.P.M., the real slip is 38% and the delivered power is 2500 kW. Calculate the thrust of the propeller.

C108. A propeller of 4.6 m diameter has a pitch of 4.3 m and boss diameterof 0.75 m. The real slip is 28% at 95 rev/min. Calculate:

the speed of advance1.

the thrust2.

the thrust power3.

REF:APR89


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C109. The delivered power to a propeller is 2980 kW. The propeller of pitch5.5 m, rotating at 1.33 rev/sec with a speed of advance of 11 knots, has apropeller efficiency of 70 per cent. If the thrust deduction factor and Taylorwake fraction are 0.2 and 0.29 respectively, calculate:

the true slip1.

the propeller thrust2.

the effective power3.

REF:APR91

C110. The power delivered to a propeller is 3540 kW at a ship speed of 15.5knots. The propeller rotates at 1.58 rev/sec, develops a thrust of 378 kNand has a pitch of 4.87 m. If

the thrust deduction fraction is 0.24, real slip 30 per cent and transmissionlosses are 3 per cent, calculate:

the effective power1.

the Taylor wake fraction2.

the propulsive co-efficient3.

the quasi propulsive co-efficient, assuming the appendage andweather allowance is 15 per cent.

4.

C111. A vessel is propelled at a speed of 16 knots by a propeller ofdiameter, 5 m: pitch ratio, 0.95; rotating at 1.85 rev/sec while absorbing atorque of 290 kNm at an efficiency of 64.2%. Calculate:

the real slip, when the Taylor wake fraction is 0.31.

the ratio of effective power (naked) to shaft power when the thrustdeduction factor and the transmission losses are 0.2 and 2%respecitvely.

2.

note: Thrust deduction factor = Total resistance without 1 propeller /Thrust of the propeller.

REF:Specimen 2


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C112. A double bottom tank is 25 m long. The half breadths of the top ofthe tank are: 5.7 4.8 4.4 3.8 3.0 respectively. When floating in sea waterof density 1025 kg/m3 the ship displaces 5400 tonnes, the loss ofmetacentric height due to the free surface is 0.24 m. Calculate the densityof the liquid in the tank.

C113. The half-ordinates of the waterplane of a ship 110 m long are asfollows:

Station AP .5 1 2 3 4 5 6 7 7.5 FP1/2 0.7 2.9 4.8 6.4 6.9 6.9 6.9 5.9 4.6 2.0 0.0 Ordinate.

Calculate the waterplane area and the distance of the center of flotationfrom midships.

C114. The half ordinates of a waterplane 120 m long are: 0.7 3.3 5.5 7.2 7.5 7.5 6.8 4.6 2.2 0.0 respectively. The ship displaces 11000 tonnes. The relative density of the sea water is 1025 kg/m3 Calculate the BM.

REF:83 REF:JAN87

C115. Half ordinates of the waterplane of a ship 140 m long are: 0.8 3.5 5.8 7.6 8.0 8.0 8.0 7.2 4.9 2.5 0.0 m respectively. The ship displaces13000 tonnes when floating in sea water of density 1025 kg/m3. Calculatethe transverse B.M.

C116. The half ordinates of the load waterplane of a ship 150 m long,commencing from aft are:

0.3 3.8 6.0 7.7 8.3 9.0 8.4 7.8 6.9 4.7 0.0 respectively. Calculate:

the area of waterplane1.

distance of centroid from midships2.

the second moment of area about the transverse axis through thecentroid.

3.

REF:APR89

C117. A rectangular bulkhead 8 m wide has water of density 1000 kg/m3 to


31 de 46 13/12/13 18:50

a depth of 7 m on one side and on the other side oil of density 850 kg/m3 toa depth of 4 m. Calculate:

the resultant force on the bulkhead1.

the position of the resultant center of pressure2.

REF:FEB90 REF:MAR8?

C118. A rectangular watertight bulkhead 9 m high and 14.5 m wide has seawaterof density 1025 kg/m3 on both sides, the height of the water on oneside being four times that on the other side. The resultant center ofpressure is 7 m from the top of the bulkhead. Calculate:

the depths of water1.

the resultant load on the bulkhead2.

REF:FEB89

C119. A bulkhead is 8 m high and had vertical stiffeners 0.7 m apart. It isfilled on one side only with sea water of density 1025 kg/m3 . The stiffenersare fastened at the bottom with 8 rivets of 25 mm diameter. Calculate:

the sheer force top1.

the sheer force bottom2.

the position of zero sheer3.

sheer stress in rivets4.

draw load and sheer force diagrams5.

REF:FEB90

C120. A bulkhead is in the form of a trapezoid 13 m wide at the deck 10 mwide at the tank top and 7.5 m deep. Calculate the load on the bulkheadand the position of the center of pressure if it is flooded to a depth of 5 mwith sea water on one side only.

REF:APR89


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C121. A collision bulkhead is defined by the following equally spacedwidths, 1.53 m apart, commencing at the top: 6.1 5.49 4.8 3.36 2.44 m. The bulkhead is loaded to the top, on one side only, with water of density1025 kg/m3. Determine the load on the bulkhead and the position of thecenter of pressure from the top of the bulkhead.

C122. A rectangular block of wood of square cross-section of sides S andlength L greater than S is to float in fresh water with it's horizontal axisparallel to the waterline, it's sides vertical and in a condition of neutralequilibrium. Calculate the relative density of the wood.

C123. An 8 m model of a ship has a wetted surface area 10 m2, and whentowed in fresh water at 4 knots, has a total resistance of 70 N. Calculatethe effective power of the ship, 140 m long, at it's corresponding speedgiven:

n = 1.825, ship correlation factor = 1.15

f = 0.417 + 0.773 _ density sea water = 1.025 t/m3

L + 2.862

C124. A bulkhead 8 m wide and 6 m deep has seawater on one side to adepth of 5 m and fresh water on the other side to a depth of 4 m. Calculatethe resultant load and position of

the center of pressure.

note: the saltwater density is 1025 kg/m3.

C125. The after bulkhead of an oil fuel bunker is 9.5 m wide and 13 m high. Find the total load and the position of the center of pressure relative to thetop of the bulkhead if the

tank is filled with oil of relative density 0.85:

to the top edge1.

with a 4 m head to the top edge2.

C126. A fuel tank bulkhead is made in the shape of a trapezoid 13 m wide at


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the top, 10 m wide at the bottom and 7.5 m deep. When the tank is filledwith fuel to a depth of

5 m, calculate:

the load on the bulkhead1.

the position of the center of pressure relative to the surface of thefuel

2.

note: R.D. of fuel = 0.8

INA (rectangle) = BD3 12

INA (triangle) = BD3 36

REF:OCT92

C127. A bulkhead is in the form of a trapezoid 14 m wide at the top, 10 mwide at the bottom and 8 m deep. Calculate the load on the bulkhead andthe position of the center of pressure if it is flooded to a depth of 6 m widthsea water of density 1025 kg/m3 on one side only.

C128. A triangular bulkhead is 6 m wide at the top and 8 m deep. Whenflooded with sea water of density 1025 kg/m3 on one side only the load onthe bulkhead is 700 kN. Calculate the height of the water level relative tothe top of the bulkhead.

C129. A triangular bulkhead is 8 m wide at the top and has a vertical depthof 9 m and forms part of a tank. Calculate the position of the center ofpressure and the load on the bulkhead if the tank is filled with sea water ofdensity 1025 kg/m3 on one side of the bulkhead only:

to the top edge1.

with 3 m head to the top edge2.

REF:MAR89 REF:OCT90

REF:OCT92

C130. A large tanker is 400 m long with a beam of 50 m at the water line. The immersed cross-section areas, equally spaced from fore and aft are: (in


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m2) 130.0 226.4 587.0 825.0 825.0 825.0 587.2 262.1 139.8 Calculate:

the displacement1.

the prismatic co-efficient2.

the draught3.

note: Relative density of saltwater = 1.03 midships section area co-efficient(Cm) = 0.9649

C131. The frictional resistance of a ship in fresh water at 4 m/s is 12 Nm2The ship's wetted surface area is 2800 m2 and the frictional resistance is74% of the total resistance and varies as speed1.92 If the effective power is1200 kW, calculate the speed of the ship in sea water of 1.025 t/m3.

C132. The speed of a ship is increased to 12% above normal for 11 hoursthen reduced to 10% below normal for 9 hours. For the remainder of the daythe speed is such that the day's consumption will remain normal. Calculatethe percentage difference in the days run.

C133. The T.P.C. values of a ship at 1.75 m intervals of draught,commencing at the keel are:

4.5 6.7 8.0 9.4 10.8 12.0 1.8 respectively. At a draught of 10.5 mcalculate:

displacement1.

K.B.2.

C134. The tonnes per centimeter (TPC) of a ship is 27.5 when floating in seawater of relative density 1.026. The maximum allowance draught is 8.25 min this sea water and 8.5 m in fresh water. The vessel now loads to a draftof 8.44 m at a river port where the relative density of the water is 1.012and then moves out to sea where the freeboard is checked by the PortWarden and found to be insufficient.

a) How much mass must be removed to make the vessel seaworthy

b) describe the different methods that may be employed to lighten the shipstating the limitations imposed by each approach.


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REF:MAY81

C135. The fuel consumption of a ship at 18 knots is 52 tonnes/day. Thespeed is reduced and the consumption is reduced to 24 tonnes/day, which is20% more than the theoretical consumption. Find the reduced speed andthe percentage saving on a voyage of 4000 nautical miles.

C136. The immersed cross sectional areas of a ship 90 m long, commencingfrom aft are: 0.0 11.8 27.4 39.0 44.5 45.6 45.0 39.4 26.7 14.6 0.0 m2respectively. Calculate for a sea water density of 1025 kg/m3:

displacement1.

distance of center of buoyancy from midships2.

prismatic co-efficient3.

New Questions posted April 2002

The underwater portion of a vessel is divided by transverse sections 12 ft.,apart of the following areas commencing from forward;- 0.4, 25, 53.4, 78.6,90.2, 88.3, 65.9, 26.8, 4 sq. ft. respectively. Find the position of the centreof buoyancy relative to the middle section, the displacement of the vesselin sea water, and the prismatic co-efficient.

A vessel whose length is 330 ft., has measurements of half girth from waterline to keel as given by the following;- 7.13; 18; 29; 42; 44.1; 44.1; 43.8;39; 24; 16 and 0 ft., respectively, all measured at regular intervals fromford. Given that the approximate wetted surface can be obtained from W.S.= 15.5/of •.L. sq., ft. Where • = displacement in tons and L = length ofvessel in ft. Estimate the displacement of the vessel.

The following table gives the draught from the keel and the correspondingT.P.1" values of a vessel floating in sea water of 64 lbs., per cu. ft.Draught (ft.) 3. 6. 9. 12. 15.T.P.1" 33 39 43.5 46.5 49The appendage below the 3 ft., draught displaces 600 tons and its center ofbuoyancy is 1 ft., below the 3 ft., draught line. Determine the displacementof the vessel and the vertical position of the centre of buoyancy from thekeel when the vessel is floating at a draught of 15 ft.


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A vessel has half ordinates of water plane at equal intervals of 40 ft., asfollows;- Fwd.;- 0.4; 13.8; 25.7; 32.5; 34.7; 35; 34.9; 34.2; 32.1; 23.9; and6.9 ft., respectively. Calculate the water plane area and the secondmoment of the water plane about the longitudinal center line.

The following table gives the half ordinates of the water plane of a vesselwhose length between perpendiculars is 360 ft. Calculate the water planearea and the centre of flotation from the midship section. Station;- Ford.P. 1-1/2 2 3 4 5 6 7Half ordinates (ft.) 0 7.5 13.4 18.0 23.0 25 25 25

8 8-1/2 Aft P.16 12 0

A watertight door is 4 ft., high by 2 ft. 6 ins., wide and has a still of 2 ft.,depth measured from the tank top. Sea water rises to a height of 10 ft., onone side and to a height of 5 ft., on the other side, both heights beingmeasured from the tank top. Draw a load diagram and from it determine (a)the resultant force in tons acting on the door and (b) the position from thetop of the door at which this force may be assumed to act.

A vertical rectangular bulkhead 25 ft., high is supported by vertical channelform stiffeners spaced 30 ins., apart. The stiffeners are connected to thetank top by 10 rivets each 0.875 ins., diameter. Sea water rises to the top ofthe bulkhead. Calculate (a) the shear force at the top of each stiffener, (b)the position of zero shear force measured from the tank top and (c) theshear stress in the tank top rivets. Sketch the load distribution and shearforce diagrams for one stiffener. Assume each stiffener is simply supportedat each end.

A triangular section pontoon floats at a draught of 16 ft., and has a lengthof 210 ft., and at any draught the breadth is twice the draught. Assumingthat in all conditions the pontoon floats apex down, draw thedraught/displacement curve and using it show that the vertical distance ofthe center of buoyancy from the water line is given by the expression;- Areaenclosed by curve. Displacement

The semi-ordinates of a ships’ water plane at equal intervals of 15 ft.,starting from the bow are;- 0.5; 4.0; 8.2; 10.4; 18.0; 17.8; 10.4; 7.0; and1.0 ft., respectively. Calculate (a) the T.P.1" of this water plane, (b) theposition of the center of flotation from amidships and (c) the secondmoment of area of the water plane about the transverse axis through thecenter of flotation. Note;- the second moment of area about any axis YY,which is parallel to an axis through the centroid and at a distance of X fromit is found as follows;- Iyy = Igg + AX² Where Igg = second moment aboutcentroid and A = area.


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A rectangular block of wood of square cross section of side S and length L isto float in fresh water with its horizontal axis parallel to the water line, itssides vertical and in a condition of neutral equilibrium. What is the specificgravity of the wood to male this possible? The length L is greater than theside S.

A completely decked in scow of box form is 90 ft., long, 18 ft., beam and 8ft., deep. She is so loaded that she draws 6 ft., in fresh water, and thecenter of gravity is 6 ft., above the bottom of the vessel. If the vessel isupright and on an even keel, what will be the angle of heel if a weight of 10tons on the fore and aft center line of the vessel is shifted 9 ft., athwartships? Define the terms “center of gravity” and “center of buayancy”.

A triangular form fore peak bulkhead has a breadth at the top of B ft., and avertical depth of D ft. Find, using Simpsons First Rule, the total load on thebulkhead, in terms of B and D, if the bulkhead is flooded to the top with seawater on one side. Also determine the position of the center of pressure, ifthe depth of the center of pressure from the free surface of the water isgiven by ;- C of P = 2nd moment of area of immersed surface 1st moment ofarea of immersed surface Both moments are taken about the free surface ofthe water.

A rectangular deep tank whose height os 9 times the vertical stiffenerspacing, is filled with sea water. The maximum allowable shear load on onestiffener is 22 tons. Assuming that the stiffeners are simply supported at theends, calculate (a) the depth of the tank, (b) the total fluid load on the endof the tank, (c) the shear force at the top and bottom of each stiffener, and(d) the position of zero shear force on each stiffener.

An inclining experiment was carried out on a vessel of 2,750 tonsdisplacement and 13 ft. 8 ins., draught, having a BM of 4 ft. 2 ins., thedistance of B from the water line being 5 ft. 8 ins. A weight of 3.5 tons wasmoved 27 ft., transversely to give a deflection of 11 ins. The vessel wasthen ballasted 6 ft., below the original CG and the same experiment carriedout, this time the deflection being 5.75 ins. Due to ballasting the GMincreased by 6 ins. Find;- (a) the position of the original centre of gravity ofthe vessel before ballasting, measured from the keel, (b) the final GM, (c)weight of the ballast in tons.

A vessel of 10,000 tons displacement commences to fill a double bottomtank which is 60 ft., long 50 ft., wide and 5 ft., deep. Initially the centre ofgravity of the vessel was 12 ft., above the keel and the transversemetacentric height was 2 ft. Assuming that the position of the transversemetacentric relative to the keel remains unaltered find the metacentricheight (a) when the tank is half full and (b) when the tank is full. The vesselis in sea water and the tank is filled with sea water.


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A box shaped vessel 200 ft., long, and 31 ft., beam floats in sea water.Calculate the distance of the centre of buoyance (B) and the transversemetacentre (M) from the keel for draughts up to 15 ft., in intervals of 3 ft.Plot these values in the form of a graph against a base of draught. With theaid of the graph find the transverse metacentric height of the vessel whenthe draught is 14 ft., given that the centre of gravity is then 9 ft., above thekeel.

What do the following terms mean? “Stable equilibrium”, “neutralequilibrium” and “unstable equilibrium”? A ship of displacement 1,722 tonsis inclined by shifting 6 tons of ballast across the deck through 22.25 ft. Amean deviation of 10.5" is obtained with pendulums 15 ft., long. Thetransverse metacentre is 15.28 ft., above the keel. Find (a) the position ofthe centre of gravity of the ship with reference to the keel, and (b) themoment of statical stability if the ship is steadily inclined at an angle of 8degrees.

State briefly what is meant by ;- (a) the stability of a vessel and (b) thetransverse metacentric height. A ship of 10,000 tons displacement with abeam of 50 ft., lies close to a quay. A weight of 75 tons is in the lower holdand on the fore and aft centre line of the vessel. The weight is to be liftedto a point on the quay 5 ft., from the ship’s side by the ship’s derrick. Thehead of the derrick is 65 ft., above the centre of gravity of the weight in thehold. Does any alteration of the metacentric height of the ship take placewhen the derrick takes the load and if so, calculate the alteration. What isthe maximum angle of the heel during the operation given that the originalmetacentric height is 2 ft. 9 ins.

Deduce a formula for calculating the loss of GM due to free liquid surface ina ships tanks. A vessel of 14,000 tons displacement has a double bottomtank 68 ft., broad and 60 ft., long partly filled with water. Find thealteration in the transverse metacentric height of the vessel due to this freesurface.

A ship with a displacement of 10,000 tons has a double bottom tank whichcontains 150 tons of oil. The centre of gravity of the tank is 100 ft., forwardand 20 ft., below the centre of gravity of the ship. What distance in ins.,does the centre of gravity of the ship move through due to this quantity ofoil being consumed?

A ship of 8,500 tons displacement has a draught of 7 ft., 6 ins., a waterplane area of 48,000 sq. ft., which may be considered constant and itscentre of gravity is 22 ft., above the keel. The following changes in weightdistribution occur;- 125 tons are lowered a distance of 16 ft.; 1,500 tonsplaced 15 ft., above the keel are discharged; 270 tons and 750 tons areloaded at pints 11 ft., and 9 ft., respectively above the keel. Calculate thenew position of the centre of gravity of the vessel above the keel and the


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new draught.

A box form barge has a length of 300 ft., a breadth of 42 ft., and is floatingat a draught of 16 ft., in water of density 63 lbs., per cu. ft. A weight of 80tons, already on board, is moved from ford to aft, a distance of 100 ft. Find(a) the angle of trim and (b) the draught ford and aft. Assume the centre offlotation is amidships.

A ship whose displacement is 8,000 tons has draughts of 17 ft. 9-1/2 ins.,ford and 18 ft. 9-1/2 ins., aft. It is required to trim the ship to obtainfurther immersion of the propeller by ballasting a tank, whose centre ofgravity is 110 ft., aft of amidships. If the final maximum draught is not toexceed 19 ft. 6 ins., calculate the minimum amount of ballast waterrequired. The following particulars refer to the ship at its present draught;-Length between perpendiculars 285 ft.; G.M.(longitudinally) 350 ft.; T.P.1"21; Centre of Flotation 8 ft., aft of amidships.

Explain clearly how the formula “Moment to change trim 1 inch = W.GM tonsft., is arrived at. 12L A vessel 450 ft., long and 7,000 tons displacement hasa longitudinal metacentric height of 630 ft. Find the change of trim causedby moving a weight of 15 tons already on board through a distance of 300ft., from forward to aft.

A box shaped vessel is 200 ft., long, 30 ft., beam and floats at a draught of10 ft., in sea water. The centre of gravity of the vessel is 8 ft., above thekeel and amidships. An end compartment 30 ft., long and extending the fullwidth of the vessel is now opened to the sea and flooded. Find the ford andafter draughts of the vessel.

The draught of a ship at the completion of a voyage is 21 ft., ford and 22 ft.6 ins., aft. During the voyage the following weight changes took place;- 400tons of fuel consumed from 100 ft., ford of amidships 10 tons of storesconsumed from 250 ft., ford of amidships. 230 tons of water consumed from150 ft., aft of amidships. 300 tons of ballast added at 50 ft., ford ofamidships. If the centre of flotation is 6 ft., aft of amidships, the T.P.1" is52 and the Moment to change trim 1 inch is 1,100 tons ft., find the draughtat the commencement of the voyage. The length of the ship is 600 ft.

A floating crane has a box shaped pontoon with the following dimensions;-length 180 ft., beam 80 ft.; even draught 16 ft., when floating in water ofdensity 35 cu. ft. per ton. The centre of gravity is 20 ft., above keel.Calculate the longitudinal metacentric height. If a weight of 80 tons,already on aboard, is lifted from the deck, moved forward 80 ft., andremains suspended from the crane, calculate the fore and aft draughts. Thejib head of the crane is 100 ft., above the deck.

A ship whose length is 505 ft., has a longitudinal metacentric height of 360


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ft., and a displacement of 12,000 tons at draughts of 25 ft. 4 ins. ford and27 ft. 8 ins., aft. Estimate the value of the weight and its position frommidships which must be placed aboard the ship in order to bring it to adraught of 27 ft. 8 ins., ford and aft. The T.P.1" of the ship over thedraughts concerned is 59 and the centre of flotation is amidships.

A vessel of 13,700 tons displacement has a Moment to change trim 1 inch of1,280 tons ft., and a T.P.1" of 45. Its centre of floatation is 6 ft., aft of aamidships and its centre of buoyance is 1 ft., ford of amidships. When inwater of 1,025 ozs. per cu.ft., the vessel is on an even keel at a draught of26 ft. 3 ins. Calculate the fore and after draughts when the vessel is movedinto water of 1008 ozs. per cu.ft.

A box barge of 100 ft., length, 30 ft., beam floats at a draught of 2 ft. 6ins., in water of 35 cu.ft., per ton when empty. In a partly loaded conditionthe draught alters by 1.25 ins., when the barge passes from water of 1,000ozs., per cu.ft., to water of 1,025 ozs., per cu.ft. Calculate the weight ofthe cargo in the barge.

The following table gives the draughts and corresponding T.P.1" values for avessel when floating in sea water of 35 cu.ft., per ton.Draught (ft.) 0, 4, 8, 12, 16, 20, 24.T.P.1" 0, 30, 31.4, 32, 32.5, 32.8, 33.Find the displacement of the vessel when floating in water of density 1,012ozs. per cu.ft., at a draught of 20 ft., and also calculate the change indraught when the vessel moves into water of 1,024 ozs. per cu .ft.

An oil tanker is 525 ft., long, 72 ft., beam and floats at a draught of 32 ft.,in sea water of 64 lbs., per cu. ft. The water plane area co-efficient at thisdraught is 0.88. The midship section is rectangular except for bilges of 4 ft.,radius. The ship is divided transversely by bulkheads 35 ft., apart andlongitudinally by two fore and aft bulkheads to form oil compartments. Thecompartments are filled with oil of 50 cu.ft. per ton to a depth of 38 ft. Ifthe midship compartments, full width, were open to the sea what would bethe draught?

A vessel of constant triangular section floats in fresh water at a draught of12 ft., with the keel just touching mud at the bottom. The keel is the apexof the section and the axis is vertical. In the condition above the breadth atthe water line is 24 ft. If the water level now drops 6 ft., calculate how farthe vessel will sink into the mud given that the specific gravity of the mud is2.

A vessel having a water plane area of 20,760 sq.ft., arrives in a harbourwhere the density of the water is 1,026 ozs., per cu.ft. On arrival she pumpsout 288 tons of ballast and then proceeds to a river where the density is1,006 ozs. Per cu.ft. Her draught was taken on arrival in harbour before


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discharging ballast and again on entering the river. The change is found tobe 3 ins. Find the original displacement of the ship in tons and statewhether the 3 inch change was an increase or decrease in draught.

A ship, while traveling at 12 knots, turns in a circle of a radius of 2,000 ft.Metacentric height of the vessel is 10 ins., and the vertical distancebetween the entre of gravity and the centre of buoyancy is 14 ft. Assumingthat centripetal force acts at the centre of buoyancy what is the angle ofheel produced?

A ship at a certain draught passes from sea water density 1,027 ozs., percu.ft. To water of density 1,007 ozs., per cu.ft. If 200 tons of cargo have tobe discharged to maintain the original draught, what was the initialdisplacement of the ship?

A ship passes from sea water into fresh water and the draught increases ‘a’ins., due to change in density. The ship now discharges cargo while in freshwater and the draught decreases ‘b’ ins. The ship now returns to sea andthe draught decreases ‘c’ ins. Assuming the water plane is constant, provethat ;- density of sea water = 1,000 x b ozs., per cu.ft. b + c - a

The fluid force in lbs., exerted on the rudder when the helm angle is idegrees and the ship is moving at V knots is given by;- F (lb.) = 1.12AV²Siniwhere A is the rudder area is sq.ft. A ship when travelling at 16 knots putson a helm angle of 35 degrees. The area of the rudder is 250 sq.ft., and thecentre of fluid pressure from the centre line of the rudder stock is 5 ft. Findthe diameter of the rudder stock if the maximum shear stress is not toexceed 10,000 lbs./sq.in.

Assuming that the resistance to motion of a vessel varies directly as thespeed squared, show that the consumption of fuel per day varies directly asthe speed cubed and that the consumption per voyage varies directly as thespeed squared. For a certain vessel it was found that by reducing theconsumption of fuel by 41 tons per day the speed was reduced by 2 knots. Ifthere was a saving of 24% in fuel on a voyage of 5,000 nautical miles, whatwas the original consumption per day and the original speed?

A vessel has a rudder area of 220 sq.ft., and the distance from the centreline of the rudder stock to the centre of fluid pressure on the rudder is 3 ft.6 ins. Calculate the twisting moment in lbs.ins., in the rudder stock whenthe helm angle is 35 degrees and the speed of the vessel is 15 knots giventhat;- fluid pressure on rudder (lbs.) = 1.12 AV²Sini Where A = rudder area(sq.ft.), V = ships speed (knots), i degree = helm angle. If the shear stress inthe rudder stock is not to exceed 900 lbs., per sq.in., calculate the rudderstock diameter.

A vessel of 12,000 tons displacement, having a metacentric height of 1 ft.,


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and a centre of buoyancy 11 ft., below the water line, is steaming at 20knots when 30 degrees of helm is applied. Find the angle of heel produced.The centre of pressure of the rudder, which is 150 sq.ft., in area, is 16 ft.,below the water line. The fluid force produced on the rudder is;- where A =area rudder (sq.ft.) , V = speed of ship (knots) , i degrees = angle of helm.

A ship’s speed is increased by 21% above the normal for 7.5 hours and thendecreased by 9% below the normal for 10 hours. The ship’s speed is thenadjusted for the remainder of the day so that its daily consumption isnormal. Determine the percentage variation from normal in its daily run.

Explain, with the aid of sketches, how the ship’s structure is made strongerin spaces used for machinery such as main engines and boilers.

A vessel has a wetted surface area of 14,670 sq. ft. When travelling at 23.5knots in water of density 1,025 ozs., per cu. ft., the effective horse powerwas 19,200. If the resistance of a plate towed edgewise through water ofdensity 1,008 ozs., per cu. ft., at 10 ft. sec., was 0.28 lbs., per sq. ft., andgiven that frictional resistance varies as the speed to the 1.96 power, findthe percentage power used to over come frictional resistance.

The total resistance of a ship model 16 ft., long is found to be 4.1 lbs.,when tested in a tank. The wetted surface of the model was 52 sq. ft.Estimate the effective horse power necessary to drive the ship designed onthis model if the length of the ship is 400 ft. The speed of the model in thetank test was 2.5 knots and the model was towed in fresh water. The shipwill operate in sea water of density 1.025. The laws of Dynamic similarityapply between the speed, residual resistance and, linear dimensions of theship and model and frictional resistance can be found from;- F(lb.) = fsV6Where f = 0.01 for model and 0.0088 for ship. S = wetted surface in sq. ft. V= speed in knots. n = 1.825 Frictional resistance % fluid density.

Explain how stresses are set up in a vessel’s hull due to “hogging” and“sagging” in a heavy sea-way. How is the machinery affected under theseconditions?

The resistance of a flat plate when drawn through water of density 1,013ozs., per cu. ft., at a speed 10 ft. sec., was found to be 0.28 lbs. per sq. ft.Estimate the speed of a ship whose effective horse power is 13,500 whenthe wetted surface area is 52,000 sq. ft., and it is in water of density 1,026ozs., per cu., ft. It may be assumed that skin friction constitutes 72% of thetotal resistance of the ship to motion and that resistance due to friction %speed to the exponent 1.9 x fluid density.

State the Laws of Dynamic similarity which are applicable to the residual orwave resistance on the hull of a ship. A model 12 ft., long is towed at 300ft., min., in a test tank and has a computed wave resistance of 0.49 lbs.


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What will be the corresponding speed and wave horse power required for asimilar ship of 400 ft., length?

With regard to ballast tanks, what effect has free surface on the stability ofa ship?

I reference to stability of ships explain what is meant by centre of gravity,centre of buoyancy, meta centre and metacentric height. Under practicalconditions can the metacentric height be increased?

What is meant by the terms “Metacentric Height”? What effect wouldpumping out a double bottom ballast tank have on the metacentric height?What effect would it have on the metacentric height to allow excess bilgewater to accumlate?

If the Port and Starboard deep tanks of a sip were only partially filled withoil, explain, with the aid of sketches, how the stability of the ship would beaffected when rolling in a seaway.

What forces act on a ship’s transverse framing when, (a) the ship is at sea,and (b) when the ship is in dry dock. What parts of the ship’s structureabsorb these forces?

Describe, with the aid of sketches, how the applicable forces act to set upthe moment of statical stability when a vessel heels. What governs theposition of the transverse meta centre and what factors govern themetacentric height?

For what purpose is an inclining experiment carried out? Describe brieflyhow the experiment is carried out.

Explain clearly what the following scantling are, what their function is ,where they are found in a modern cargo ship;- shear strake; deck girder;beam knee; frame; floor; margin plate; deck stringer; reverse frame;

Define the following terms;- (a) garboard strake, (b) sheer strake, (c)keelson, (d) stringer, (e) floor, (f) intercostal.

What stresses are produced in a ship’s side plating during heavy weatherconditions? What members of the ship’s structure normally resist thesestresses and loads?

What is meant by the following terms;- (a) block co-efficient, (b) midshipco-efficient, (c) prismatic co-efficient, (d) gross tonnage, (e) displacement?

Explain with the aid of a sketch, how the deck of a ship is strengthened tocompensate for the weakness caused by the hatchway openings.


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Describe briefly the principal structure features of longitudinal framingcommonly adopted in tankers. Why is it specially adopted for tankers?

What do you understand by the following terms used in ship construction;-(a) tumble home, (b) rise of floor, (c) freeboard, (d) sheer, (e) camber, (f)scantlings.

Explain what is meant by the following;- (a) bilge keel, (b) sheer strake, (c)tumble home, (d) deck camber, (e) breast hook.

Explain what “half beams” are. Show by a sketch where they are used andhow they are attached to the ships structure.

Describe with the aid of sketches;- (a) Duct keel, (b) Bilge keel. What arethe functions of these?

Sketch a section through a Hatch Coaming. Show how the half beams areconnected to the coaming.

Describe the various types of beam sections used in ship’s construction andhow are they secured to the other parts of the ship’s structure. You mayillustrate your answer with sketches.

Describe the construction of the double bottom tanks as fitted to a drycargo vessel with engines amidships. Explain how the double bottom isstrengthened in way of the machinery space and the ford, part of thevessel.

Sketch and describe a double bottom tank that is used for the storage of oilfuel. What fittings are provided for sounding, filling, emptying ect.; How dothe arrangements differ from a tank which is used for water ballast only?

Sketch a transverse section through a ship showing clearly the doublebottom construction and indicate on your sketch the position of ; - keel,garboard strake, tank margin plate, and frame and reverse bar.

For what purpose are “ summer” tanks fitted in bulk oil carriers? Make asketch of the transverse section of a tanker showing how these tanks arearranged.

A vessel has a wetted surface area of 14,670 sq.ft. When travelling at 23.5knots in water of density 1,025 ozs., per cu.ft., the effective horse powerwas 12,200. If the resistance of a plate towed edgewise through water ofdensity 1,008 ozs., per cu.ft.,at 10 ft.sec., was 0.28 lbs., per sq.ft., andgiven that frictional resistance varies as the speed to the 1.96 power, findthe percentage power used to overcome frictional resistance.


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A vessel has a draught of 25 ft.., and a wetted surface area of 48,000 sq.ft.The effective horse power is 9,250 and the skin friction is 72% of the totalresistance of the ship to motion. Calculate the speed of the vessel in knotswhen in sea water of 64 lbs./cu.ft. Resistance of flat plate is 0.28 lbs., persq.ft., when towed through fresh water at 600 ft. min. It may be assumedthat the frictional resistance is proportional to the speed raised to thepower of 1.98 and is proportional to the density of the fluid.

A vessel consumes 47 tons of fuel per day at 17 knots. By reducing speed theconsumption drops to 22 tons per day. The consumption per I.h.p., hour atthe reduced speed is increased by 13.5%. Find the reduced speed and thepercentage saving in fuel on a voyage of 3,000 miles.

A vessel consumes 20 tons of fuel per day for the main engines at a speed of11 knots, and the consumption for auxiliary purposes is 5 tons per day,which is constant. When 1,100 nautical miles from port it is found that 60tons of fuel remain in the bunkers. Estimate the reduced speed in order toarrive in port with 5 tons of fuel remaining in the bunkers and find thepercentage reduction in total fuel consumption per day.

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