I've heard good things about hydrofoils. My outboard has them but it's still on a motor mount (I haven't even attampted to get it running yet).<br /><br />Try searching the board for hydrofoils and you'll find lots of info.
As a weldor I love it when someone puts a hydrofoil on thier cavitation plate....makes for a good living for me when it breaks them off and I fix the cavitation plate. They also tend to slow the boat down a good bit.<br /> Porposing is caused by many things; hull design(trying to make the boat go faster than it was designed to go), improper weight distribution, improper motor trim angle, improper storage of hull on trailer or bunks creating concave or convex bulges in the hull. Some of the more "sensible" cures without damaging your cavitation plate are to lower the motor so that the cavitation plate is 1" below the keel, use a transom set back plate with verticle manual adjustment and in some cases using a 4 or more bladed prop....and of course try to trim the boat out better and redistribute the weight. Try starting trim point by eyeballing the cavitation plate to be parallel with the keel....If you you have puckers and bulges in the glass..welp' your on your own...
I've got an 18' Nitro NX 882 that was porpoising REALLY bad with just a little bit of trimming up. I had to lower the engine a notch to get it to quit. Now I can trim my engine up quite a bit and still have alot of stabillity...<br /><br />Thanks,<br />Mike Carlson
Porpoising is caused by the engine being trimmed UP to far. The engine and/or prop. set up does not have enough power or bite to hold the bow up. Thus the bow falls and the whole cycle keeps repeating itself.<br /><br />If you have enough horsepower, sometimes a four blade prop. helps. Otherwise you have to deal wiuh the trim issue. Lowering the engine can also help.
Be sure the boat is trimmed best possible. Then<br />consider a hydrofoil they do wonders.The boat will<br />plane easier and stay on plane at lower power.<br />They also help to keep the bow from bounding around as much.Ran a dolfin on my mothers boat for<br />about 8years no problems.Only took it off because<br />she got a pontoon.My sister has the same type on her Mercruiser about 12 years she loves the performance.Yes they do rob some top speed and are probably not for high speed boats.
I agree with FlyBoyMark. Proper verticle position of the motor relative to the boat and the amount of trim while under way are the best fixes. I've been driving boats for over twenty years, and I've never had a problem with porposing that couldn't be fixed with a height/trim adjustment.
