So my buddy just bought a totally original 1977 donzi 18'.
It came with a 14x19 prop which is correct for high altitude lake tahoe.
We actually had to change the prop to the same size, just cupped.
With the original prop we got 45mph and the rpms were way too high. The cupped prop we got about 49mph at 4800 rpms.
How do we make it any faster?
Its all original so there are no trim tabs and you cannot trim that outdrive.