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I had an interesting conversation with a guy about my porpoising issue, and whether or not my prop may be contributing to the problem. During the discussion he mentioned the poly may be causing drag at higher speeds.
Naturally I told him how slick the material was, and how airboats use it, and how I didn't think that was a factor. BUT, without me mentioning it to him, he stated the poly is most likely 'gripping' the water surface. This was interesting to me because that's precisely the sensation I got when the hull smacks the water on the downward bounce of the porpoising thing. It actually feels like it IS grabbing my hull.
I tried a hydrofoil and having people move to the front of the boat, which helped some, but there's still a good bit of bounce.
Most importantly, I've noticed my prop is only turning 4500 RPM at WOT, which 'in theory' would mean I'd need a 17P prop instead of a 21P. However that literally would not make sense, and my prop guy totally agreed.
With airboats their hulls are designed differently obviously, and they are using full poly vs strips like me. They also have their thrust coming from a totally different angle, so maybe they aren't experiencing the same effects? I've seen mod-V jet boats with full poly bottoms, that obviously run fine. Maybe it's the mix of poly and aluminum on my boat? Different drag coefficients?
I'm grasping at straws here-the only difference between my last boat and this boat is the poly and the prop. Same hull, same weight motor, same jack plate, same setback, same mounting height. The bottom of my hull is perfectly flat, and I've got no flex in the transom or keel.
So....given the facts, what say the masses?
Naturally I told him how slick the material was, and how airboats use it, and how I didn't think that was a factor. BUT, without me mentioning it to him, he stated the poly is most likely 'gripping' the water surface. This was interesting to me because that's precisely the sensation I got when the hull smacks the water on the downward bounce of the porpoising thing. It actually feels like it IS grabbing my hull.
I tried a hydrofoil and having people move to the front of the boat, which helped some, but there's still a good bit of bounce.
Most importantly, I've noticed my prop is only turning 4500 RPM at WOT, which 'in theory' would mean I'd need a 17P prop instead of a 21P. However that literally would not make sense, and my prop guy totally agreed.
With airboats their hulls are designed differently obviously, and they are using full poly vs strips like me. They also have their thrust coming from a totally different angle, so maybe they aren't experiencing the same effects? I've seen mod-V jet boats with full poly bottoms, that obviously run fine. Maybe it's the mix of poly and aluminum on my boat? Different drag coefficients?
I'm grasping at straws here-the only difference between my last boat and this boat is the poly and the prop. Same hull, same weight motor, same jack plate, same setback, same mounting height. The bottom of my hull is perfectly flat, and I've got no flex in the transom or keel.
So....given the facts, what say the masses?