With increasing fuel costs, vessel fuel efficiency is something that really needs to be considered. Fuel is a necessary ‘evil’ and is an essential commodity required to do the job.
For those in the market for a newbuild ship or are repowering and refurbishing, there are options to help.
Using a Controllable Pitch Propeller (CPP) is a real way of countering high fuel costs by making the vessel operate more efficiently. It is common knowledge that Fixed Pitch Propellers (FPP) have their advantages but are only designed to be efficient at one operational speed and a designed load condition. At any other speed or load, the propeller will not be able to absorb all of the engine power as it will be either over or under pitched. A correctly sized CPP can be adjusted to absorb engine power at any rotational speed.
When a vessel is fully loaded or towing, much higher propulsion is required. A CPP can be adjusted to obtain maximum efficiency by providing the same performance at a lower RPM - hence fuel savings can be made.
Mekanord A/S is now developing very deep ratio boxes (up to 11:1) for use with CPP systems which will give a very high bollard pull and can be used with cheaper and more readily available high speed engines operating between 1600 and 1800rpm but can still be adjusted to provide good thrust at lower rpms.
If a PTI is added to this, enabling running off the genset, even lower running costs are available and back up propulsion is also provided for emergency use).
Fuel prices are only going one way at present so Mekanord says that CPP is a real solution to reducing operating costs.
