Thank's a lot for all your explains. I have a fixed prop and 2 years ago I got 3000 rpm with about 8 knots max speed.
Two years ago, all the prop entretien was done by AMEL specialist at La Rochelle.
For me it is understandable, with a heavy boat and not cleaned hull that I loose speed in the range of half to max 1 knot and not 2 knots at the situation today.
Does anybody already have changed the timing point of the injection pump or the injectors themeselves to get more speed with more gasoline that accelerates the rpm when moving with gear?
I will ask the specialists from AMEL next time when I will be back in La Rochelle at the famous shipyard.