Combinator optimizing

For controllable pitch propeller an operational measure is to run the system using a “combinator curve” with optimized pitch settings and propeller speed, making it possible to operate the total propulsion system with optimum efficiency.

Applicability and assumptions

Engine power curves

Engine power curves, source: DNV GL

Combinator optimizing is applicable for vessels with controllable pitch (CP) propeller respective of ship type and age.

Combinator curves take into account engine requirements, propulsion efficiency, cavitation patterns in different conditions and the mission profile of the vessel. The curves are applied for improving the propulsive performance for vessels with (CP) propellers.

The following points are procedures for improving the propulsive performance by applying combinator curves:

  • Evaluate the current combinator curves and make sure that curves for different operational modes exist, especially for AHTS vessels
  • Run simulations and develop new curves if you have any reason to believe that the existing curves are not optimized for your operations
  • Make sure that the optimum combinatory curves always are used
  • Evaluate and document the effect of optimal usage of combinator curves
  • Train crew on expected ship speed and thrust relation

Cost of implementation

There are no costs of implementation.

Reduction potential

The expected fuel reduction is 0.25% to 1% of total fuel consumption on main engine for all modes at sea.

Other References

  1. The ship power supplier / Technology guidelines for efficient design and operation of ship propulsors
  2. Air pollution and energy efficiency study series / Study on the optimization of energy consumptions as part of implementation of a ship energy efficiency plan (SEEMP)

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