Low Pitch prop vs direct drive.

[chambers1517]

My boat is a Caravelle Interceptor with a 350 mpi. A friend has a wakeboard boat with a 400hp vdrive. His boat will pull strong but is slow. My boat will hit 60 but won't stay on plane below 20. My prop is a 21p but I had an old 13p 4 blade laying around from a previous boat. I decided to try it and was surprised by the results. The IO was incredibly strong with the low pitch prop. It was as strong as the wakeboard boat. I really couldn't feel when it fell off plane. It just seemed to pull at any speed. I could still go as fast as my friend but I was only at 1/2 throttle or I would over rev. I used a lot less fuel than he did also. I didn,'t make as big of a wake as him but I was Really surprised at the power and towing economy compared to the vdrive.

 

[Fleetwin]

Somewhere in there is a compromise.

Smart Tabs or Trim tabs on your boat would help you accomplish the low speed planing you are seeking.

 

[Scott Danforth]

Which Drive do you have? Caravelle like to use VP if I recall correctly

I would suspect you will be looking at a 17P 4-blade or a 19P 4-blade for your towing needs. However you will have to probably try a few.

 

[Maclin]

If you are serious about improving all around performance, and it is a VP then convert it to DuoProp. With right propset it will stay on plane at lower speeds, and come out of the hole like never before.

 

[Chris1956]

Wakeboard and professional ski boats are generally equipped with large inboard motors and are propped to pull strongly at 36 MPH, with a very quick hole shot. To accomplish that, top speed is sacrificed. Other kinds of boats are generally propped to keep the max RPM in the suggested range, at full throttle.

I am not sure what you are trying to accomplish.

 

[ssobol]

... With right propset it will stay on plane at lower speeds, ...

Propset will have little to do with staying on plane. The speed of the boat determines when a particular hull planes or not. How it gets to that speed makes little difference. Things like trim tabs or "whale tails" can help a boat plane a lower speeds by providing additional lift to the rear of the boat and by helping counter the bow up pitching caused by the engine thrust line (the more level the boat is the faster it will plane).

 

[Maclin]

Prop bite and pitch contribute to staying on plane by keeping it from dropping off plane too easily when the hull fights back against the engine's torque.

 

[H20Rat]

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