hi there any help would be greatly appriciated i have a 21ft gulfstream fiberglass boat, with a 280 volvo sterndrive probably around the 80's model. the previous owner put a 4 cylinder 130hp nissan diesel motor in it and we are struggling to get the boat on the plain.
the gearbox ratio is a 1/1.89 to start off we had a 16 diameter by 18 pitch prop on there at we only probably got about 14knots at the max. we have since changed the pitch of the prop to a 20 and now we getting about 18-19 knots. i am thinking of going up in pitch again but the engine is revs are still quite high around 3200-3700 its sounds like it is over reving. if i was to be looking for a another gearbox with a different ratio what would be the way to go?
i was alos thinking possibly to change to a duo prop not too sure.
the gearbox ratio is a 1/1.89 to start off we had a 16 diameter by 18 pitch prop on there at we only probably got about 14knots at the max. we have since changed the pitch of the prop to a 20 and now we getting about 18-19 knots. i am thinking of going up in pitch again but the engine is revs are still quite high around 3200-3700 its sounds like it is over reving. if i was to be looking for a another gearbox with a different ratio what would be the way to go?
i was alos thinking possibly to change to a duo prop not too sure.