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Power Consumed

It is interesting to see approximately where the energy from the fuel consumed goes.  These are approximate figures only and will  vary by vessel type and engine / reduction gear but are of interest as a guide to understanding fuel consumption.

~ 35 % is lost in heat to the atmosphere throught the exhaust

~ 25 % is lost in heat and vibration to the water through cooling

~ 2   % is lost at the propeller shaft

This leaves only about 38 % of the energy contained in the fuel for propulsion.

Of this ~ 38 % - as a very rough guide –  wll be consumed as follows.  These are average values only and will vary greatly from one type of the boat to another.

~ 3   % is used to overcome air resistance

~ 27 % to overcoming wave resistance

~ 17 % to overcome resistance from the wake and propeller wash against the hull

~ 18 % to overcome skin friction

~ 35 % to turn the propeller

This information is taken from Dave Gerr’s  “ Propeller Handbook “