Yes I meant prop diameter (currently 14"). The hubs are OMC 13 spline.
Answered above post
"In theory that could take upto approx a 15" diameter BUT they only make them to 14" diameter for the 13 spline V4 hub"
It's a two engine rig (3 cylinder 70HP Johnsons, made in 2001). Engines
bought for a song from OMC receivers complete with props.
So at 4000 rpms what mph are you doing?
4000 RPM will give 23 knots in calm conditions with engines trimmed up.
Please confirm if the gearbox ratio is 2:1
if so slip IF 15 pitch is around 8% and if 17 19% which is high
but before these things are worked out.. things like total gross weight needed to be known.
Going back to the original post/ Poster...
5.5 stabi, 90 hp fully loaded 1500/ 1600 kg
Initial suggestion was slip was the problem, subject to power to weight ratios etc
As it turns out, slip is not the issue, but rather very under powered and too high a pitch.
Or put another way, a little 1960s mini going up the Bombays with 4 huge ppl inside, over loaded and the clutch sliping.
So reaches the correct speed for the power at the wheels that rpms.. but rpms/ power higher due to clutch slipping.
So the pitch (final gear ratio at the road) needs to be reduced substantially....and then the slip sorted...at a lower pitch/ higher rpm/ higher power range.
Even so putting the rpm/ hp data together, could be looking at min 13 possible going as low as 11 pitch.
Going back over old sea trials of this stabi with a 90 hp on with 14x17" prop... 1 person up, basic std rig, same engine the slip from 3000 rpms thru to 5500 .. indicate even then the 90 hp is min powered.
Yet the recommended manufactures power range is 75 hp thru to 130 hp. crunching numbers...ideally 120 to 140 with 3 ppl, fishing gear would be far better / sensibly powered.
hull , V4 motor, fuel, 1 person basic gear weighs in around the 750/ 810 kg.