Dynamic Positioning - Comparison Between Position-keeping Options

Comparison Between Position-keeping Options

Other methods of position-keeping are the use of an anchor spread and the use of a jack-up barge. All have their own advantages and disadvantages.

Comparison position-keeping options
Jack-up Barge Anchoring Dynamic Positioning
Advantages:
  • No complex systems with thrusters, extra generators and controllers.
  • No chance of running off position by system failures or blackouts.
  • No underwater hazards from thrusters.
 Advantages:
  • No complex systems with thrusters, extra generators and controllers.
  • No chance of running off position by system failures or blackouts.
  • No underwater hazards from thrusters.
 Advantages:
  • Maneuverability is excellent; it is easy to change position.
  • No anchor handling tugs are required.
  • Not dependent on waterdepth.
  • Quick set-up.
  • Not limited by obstructed seabed.
Disadvantages:
  • No maneuverability once positioned.
  • Limited to water depths of 175 meters.
 Disadvantages:
  • Limited maneuverability once anchored.
  • Anchor handling tugs are required.
  • Less suitable in deep water.
  • Time to anchor out varies between several hours to several days.
  • Limited by obstructed seabed (pipelines, seabed).
 Disadvantages:
  • Complex systems with thrusters, extra generators and controllers.
  • High initial costs of installation.
  • High fuel costs.
  • Chance of running off position by system failures or blackouts.
  • Underwater hazards from thrusters for divers and ROVs.
  • Higher maintenance of the mechanical systems.

Although all methods have their own advantages, dynamic positioning has made many operations possible that were not feasible before.

The costs are falling due to newer and cheaper technologies, and the advantages are becoming more compelling as offshore work enters ever deeper water and the environment (coral) is given more respect. With container operations, crowded ports can be made more efficient by quicker and more accurate berthing techniques. Cruise ship operations benefit from faster berthing and non-anchored "moorings" off beaches or inaccessible ports.

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