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shadow Hornbeck Offshore

Dynamic Positioning

While the advantages of DP operations for deepwater are well documented and understood, station keeping while under DP is still a complex and evolving science. Understanding the basics of DP, the ABS Classifications for DP and the questions to ask can avoid misunderstandings and potential offshore problems. 

  • Comparison of different ABS Classifications for DPS
  • Typical Class 0 System
  • Typical Class 1 System
  • Typical Class 2 System
  • Nine questions to ask a vessel operator about DP

Comparison of Different ABS Classification for DPS

Click here to download this chart in PDF format.

1. Vessel Machinery RequirementsDPS-0DPS-1DPS-2
Thrusters/Thruster Prime Movers Rated for Continuous Duty
Number of Bow Thrusters Needed
II. Dynamic Positioning Equipment Requirements

A. Basic ABS Guidelines

Central Control Station w/Automatic Heading Control 
Independent Control Station w/Automatic Heading Control

Maintain DP Qualified Position with Loss of any Single Point Failure

 Transfer of ControlNot required Manually Automatically 
B. Environmental Sensors

Positions referencing Systems Needed
Wind Sensors12
Gyro Compass
Vertical Reference Unit
Signal Processing
Not requiredNot required Required 
C. Miscellaneous   
Consequence Analysis and DP Alert SystemNot requiredNot requiredRequired
Communications between Bridge and Engine Room Control Station1 Means required1 Means required2 Means required 
Power ManagementNot requiredNot requiredRequired
Uninterruptible Power SupplyNot requiredRequiredRequired
Failure Modes and Effects Analysis (FEMA)Not required
Not required
Uninterruptible Power SupplyNot requiredRequired Required 

Typical Dynamic Positioning System - Class 0

Click here to download schematic in PDF format.

Dynamic Positioning

Typical Dynamic Positioning System - Class 1

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Dynamic Positioning

Typical Dynamic Positioning System - Class 2

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Dynamic Positioning

Illustrations reproduced courtesy of Nautronix, Ltd. 

Nine Questions to Ask a Vessel Operator about DP

  1. Ask the Operator to provide a short "break down" of the DP configuration for the vessel he proposes. 
  2. Require the Operator to provide DP capability plots for the vessels being proposed. Plot requirements should be standard for the industry. The recommended standard should be as follows. The 1st plot should should 80% thrust, 0-50 knots wind, and 0-2 knots current. The second will show 100% thrust, 0-50 knots wind and 0-2 knots current. Both plots should be at a continuous duty rating. (If an Operator cannot provide these plots, serious consideration should be given as to the Operator's knowledge of his DP equipment and its function aboard his vessel). 
  3.  Is the DP system "classed" by a recognized classification society? If so, what is the classification and which society?
  4.  If a DP vessel is "non-classed" as the Operator if the thrusters are continuous duty rated for the DP plots.
  5. Does the Operator have a written standard DP operating procedure? 
  6. Does the Operator have a DP performance resumé for his fleet? 
  7. Does the Operator have a minimum DP training requirement for his Marine Officers? If so, what is that requirement? 
  8. Can he provide resumés or "CVs" for his Marine Officers? 
  9. Are there any costs not carried in the day rate for reference systems or differential signal fees? Contractors of vessels with DP functionality need to ask about hidden costs. 

Many of our vessels can be completely customized and configured to meet your needs.

If you have additional questions or more specific requirements, please contact the us at (985)727-6945 or send us an email.

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