My Custom Hydrofoil

[maintenanceguy]

My 17' PolarKraft has trouble keeping the bow down. I've adjusted the outboard to every position and some are better than others but none are great. I wanted to add a hydrofoil but somebody in the past drilled holes in the cavitation plate that don't fit the standard hydrofoil bolt pattern. I didn't want to add 4 more holes and weaken the plate.

so, I sketched up a hydrofoil in CAD and had a friend cut it out of 1/8" SS with a water jet and bend it for me.

I took the boat out for the first time this season and tried the hydrofoil for the first time. Amazing difference. The bow still rises slightly but by the time I'm moving at 15mph, the bow is down and boat is rock solid flat. The back end even has more "purchase" on the water and I don't get that feeling of the back end slipping to the right or left. I never had a problem getting up on plane but it definitely gets up faster now - although it's only a couple of seconds faster.

I did lose 3mph on the top end. I could run my boat at 29mph before and today the top end was 26. I'll live with a 3mph loss.

I am very pleased with how great this worked out.

 

[Attwanl]

It looks great!!!

 

[Weldorthemagnificent]

Might be able to play with the motor height and get those 3mph back.

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[maintenanceguy]

Might be able to play with the motor height and get those 3mph back.

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Maybe. Right now, the cavitation plate is perfectly in line with the keel. Motor is bolted right to the transom with no jack plate so experimenting would be tough. I rarely travel more than a 20 mile round trip anywhere so an extra 3mph isn't critical.