Twin 225HP Yamahas
We run a pair of 225HP Yamahas on one of our our 11m commerical passenger RIBs - done about 1,000 hours - basically no problems other than the trim switches which don't seem to like rain/spray.
Fuel consumption for us is
24 mile trip over 2 hours engines used circa 85 litres of fuel.
Engine revs are up to 4,800RPM
Oil filter changes on water really the only issue as can't 'catch' oil as the filter is unscrewed so slick produced and we have to use bilgex etc to control. Can't always co ordinate leg oil and engine oil change time when the RIB is on the slip
More info available if required