Originally Posted by Gunkhole57
I am seeking info regarding engines in sailboats.
Some specifications, and discussions I have seen here, mention engine figures like 3000 rpm for a max speed.
My question is, "Is that engine speed also the speed of the prop?"
In other words, if my engine is cranking 3000 rpm is my prop also spinning at that rate?
Maybe, but unlikely, as that high speed prop is inefficient for slow boats. Most transmissions have gear
reduction, it should be on the spec. plate on the tranny. If you have a v-drive the reduction might be there. My boat is apparently unusual as Walter says the reduction is preferably in the v-drive but since Yanmar
only makes reduction transmissions, the 2.3:1 reduction happens at the tranny and my v-drive is 1:1.
Also max rpms for engines vary depending on the manufacturer, under 2000 to 4000 is what I believe I've seen so far.