Truster

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DYNAMIC POSITIONING CONFERENCE September 28-30, 2004

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J. Dang & H. Laheij, WPNL

Hydrodynamics Aspects of Steerable Thrusters

Table of Contents
1 Introduction ________________________________________________________________________3 2 Thruster Configurations______________________________________________________________4 3 Propulsion Efficiency_________________________________________________________________5 3.1 Bollard Pull Efficiency ____________________________________________________________7 3.1.1 Bollard pull design ____________________________________________________________7 3.1.2 Free sailing design____________________________________________________________10 3.2 Free Sailing Efficiency___________________________________________________________12 3.2.1 Open water efficiency _________________________________________________________12 3.2.2 Pushing or pulling arrangement__________________________________________________13 3.2.3 Thrust deductions ____________________________________________________________15 4 Matching with the engine / E-motor____________________________________________________16 4.1 Sailing/DP Vessels ______________________________________________________________17 4.2 Stationary DP Vessels ___________________________________________________________18 5 Understanding Interactions ___________________________________________________________19 5.1 Thruster Water Jet______________________________________________________________20 5.2 Thruster-ThrusterInteractions ___________________________________________________20 5.3 Thruster-Hull Interactions _______________________________________________________22 6 LIPS® HR High Efficiency Nozzle _____________________________________________________23 7 Application of Thrusters for Dynamic Positioning/Dynamic Tracking _________________________26 7.1 Semi Submersible Crane Vessel “Thialf”, Heerema___________________________________26 7.2 Cable Laying Vessel “Atlantic Guardian” Global Marine ______________________________26 7.3 Cable Ship “Knight” Dockwise ____________________________________________________27 7.4 Pipe laying vessel “Solitaire”______________________________________________________28 7.5 Submersible heavy lift vessel “Blue Marlin” _________________________________________28 7.6 AnchorHandling Tug Supply Vessel “Seabulk Badamyar” ____________________________29 7.7 DP Heavy Lift Vessel “Saipem 3000” _______________________________________________30 8 Conclusions _______________________________________________________________________31 Acknowledgement ____________________________________________________________________32 References__________________________________________________________________________32

Dynamic Positioning Conference

September 28-30, 2003

Page 2

J. Dang & H. Laheij, WPNL

Hydrodynamics Aspects of Steerable Thrusters

1 Introduction
Steerable (azimuth) thrusters refer here to those propulsion systems that can generate thrust vectors in a horizontal plane in any direction by rotating the propulsion unit around its vertical shaftcontinuously with delivered steering moments, installed with propellers of conventional controllable pitch blades (CPP) or fixed pitch blades (FPP), with open or ducted propellers, with tandem or counter-rotating propellers (CRP), in a pulling or pushing configuration. Water jets; pump jet or Voith Schneider propulsion systems are not in the scope of the following discussions. The concept of steerablethruster is not new. The first steerable thruster was launched more than 50 years ago. The original idea was not more than to increase the vessel’s capability in order to maneuver in confined waters. In the early stage, steerable thrusters were mainly used by small working boats. The increasing demands in the last few decades for dynamic positioning (DP)/dynamic tracking (DT) in the offshore industry...