Transom lift

[buzmacdowell]

Which prop would (inboard) give more transom lift 11 1/2" X15" or 11 1/2" X 16" ?

[25two.stroke]

Transom lift correlates to blade shape not really the pitch. Straighter trailing edges create more stern lift as I understand.

[AlliStan]

I agree and cup normally lifts the bow, in my experience.

[Carter Powell]

On a fully submerged propeller I don't think you will find any difference at all. On a surfacing propeller where the top blades are out of the water then many things come into play. But on a fully submerged prop there should be no difference at all.

Carter Powell

[25two.stroke]

There is a difference in blade shape even fully submerged. Big difference in bow/stern lift depending on prop. BUT pitch won't make a difference. If you are looking for maximum stern lift on an inboard you need to run a TH cleaver or a standard cleaver.
I wonder what you are talking about though saying the diameter of the prop is only 11-1/2". That is a tiny diameter prop for a sterndrive. What is the sterndrive mfr?

[OnPad]

I kinda agree with Carter on this one. If the prop is fully submerged. Any stern lift gained by the thick trailing edge of a cleaver, or bow lift, with trailing edge cup, will be negated by what the prop does at 12 o'clock vs 6 o'clock. Which is the same.

[buzmacdowell]

It's my V-Drive Rayson Craft GN race boat that I converted to a pleasure ski boat....the problem is it now Bow hunts left to right...I want less transom lift.....I am going to try a 11 1/2" X 1 5" prop and see what it does. ..I used to race with that size but I turned the motor around to get the blower belt away from people.

[OnPad]

I mess with model boats a bit. In most cases you can make a boat faster, and handle better, by downsizing the prop, and spinning more rpm. Approximately 1.5 × the diameter of prop (on your pitch number) = max effiecenty.

In the real world you need a prop big enough,... to get the weight moving, and deal with gear ratios that manufacures give ya,....You know,... the one's that work on a pontoon, or your performance boat.

I'm sure you will get different results with different props. Probably better control, and slower speeds with less pitch or diameter (if the rpm doesn't change much). But major steering oscillation is more apt to be influenced by boat design, too much wetted surface (or too little).
Drive angle, and boat speed are big factors.
Think about a inboard boat run at 10 or 15 degrees of shaft angle. It's trying to drive the nose of the boat down.
It would be much easier to tune a hull with zero degree prop shaft angle. Or better yet,.. have it adjustable.
Maybe you need a big ricer wing on the back. Or some ailerons on the front.....Just kidding,... Good luck.