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Marine Technical SocietyDynamic Positioning Conference
1
DPS Notations: Clarifying the Role of Classification
Frequently Asked Questions
Houston, Texas12-13 October 2010
George ReillyManaging Principal Engineer, Marine Technology
ABS
1994 Guide
2
IMO Consequence Classes/FMEA
3
Class Prescriptive Rules
4
DPS notation dependent on Redundancy targets
Single point of failure
FMEA generation
Plan review
Sea trials
DPS Not Just an “Add On”
Needs to be considered throughout design Cable routes
Ventilation
Fire extinguishing
Power supplies• High power
• Control power
– Switchgear
– Sensors
5
DPS Vessels Entering ABS Class
6
ABS Class (1994 to 2004)
Elements of a Typical DP System
7
Tunnel Thrusters
Vertical reference unit
DP Console
Acoustic Transponder
Rudders
Propellers
Weight
Gyrocompass
Anemometer DGPS
Artemis
Taut Wire PositionMeasuring System
TunnelThruster Thruster
Azimuth
Laser Reference
Acoustic Positioning System
Possible Developments
Environmental criteria
Reliability (other than through redundancy)
Different (vessel) applications
More detailed guidance
More survey guidance
8
DPS Vessels Entering ABS Class
9
ABS Class (2005 to 2009)
ABS Vessels with DPS Notation
0
2
4
6
8
10
12
14
16
18
20
2006 2007 2008 2009 2010
10
%
Dynamic Positioning Systems
11
Question 1
12
ABS DPS Class notation numbers mirror the IMO consequence classes,
yet neither demand any particular environmental capability.
Is this an omission?
How do we verify the capability plot?
Question 2
13
Question 3
14
The IMO Guidance states “Bus-tie breakers should be open during
equipment class 3 operations, unless equivalent integrity of power
operation can be accepted according to…”
ABS does not have an equivalent statement, but is this intent applied?
Question 4
15
ABS requires an Emergency Shut Down, but this could
introduce a single point of failure which is to be avoided for
DPS-2 and DPS-3 operations.How can ABS have such
contradictory requirements?
Question 5
16
In real life equipment is subject to wear and tear and breakdowns.
What is the ABS position when equipment, which is subject to
the ABS DP Class requirements, is not available day-to day and
at the time of survey?
Question 6
17
ABS requirements are silent on the subject of combined operations, but combined
operations are frequently the norm rather than the exception?
Question 7
18
Last year ABS introduced more DP-specific survey requirements.
Does ABS have any plan to accept the reports of other
independent specialists in lieu of ABS surveyor attendance?
Question 8
19
What about the future?
20
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