Do hydrofoils work on bigger motors?

Question

I've read about smaller motors not having much success with hydorofoils, but they are used on smaller motors (110hp and smaller) I have a 220hp yamaha 2 stroke I feel my top speed is too low. About 45-50mph. I would like to go faster maybe a propeller too(pitch??). Does anyone have any advice or experience?

Answer 1

A hydrofoil will not improve top speed. It will help you get up on plane faster keep your front end down more and help you stay on plane at slower speeds wich saves on gas. Adding a hydrofoil does however add extra material that will be dragging the water more at top speed. A hydrofoil does also give you a little more control of the trim of the motor. When you have it on there and lift your motor part way up you have more control to lift the front end for high waves. These are ideal for getting a skier out of the hole as well. For top speed you need a diff prop. Keep in mind if you change the pitch of the prop you will gain top speed but lose low end torque and also dramatically increase your gas use. I like hydrofoils. I have them on both my boats and would recommend them to everyone not for top speed though.

Answer 2

Whats your RPM wide open should be around 5500 loaded if your turning more RPM add 1 deg of pitch>Or some more cup on the prop>

Answer 3

A hydrofoil, aka a cavitation plate extension, will not increase your boats speed...it will actually probably slow it down. You'll also lose your side-to-side (turning) handling. The only thing it will do for you is decrease your planing time and/or keep your bow down further into the water. If your boat is too heavy/powerful, the extension will snap your cavitation plate right off of the gear housing, making for an expensive fix. The other answer is correct...when you are by yourself or loaded lightly, you'll want to see 5500 RPM's out of that engine at WOT. If you're seeing that, you're going about as fast as you can. If it's higher, for every 300 RPM's you'll want to increase pitch by 2 inches, depending on brand/diameter/number of blades on the propeller. If you're lower than 5500, it's the same number of RPM's, just decrease the pitch by 2 inches. If you're running an aluminum propeller, try going to a higher-performance stainless prop, but make sure to downsize at least 2 inches of pitch when going from aluminum to stainless. Just remember...when boats come out of the factory, the propellers that are on them are there for a reason, because with the stock propeller, they perform at their ALL-AROUND best. That means it may go faster with a different propeller, but you might lose your low end power and vice-versa. Your average DECENT stainless prop will cost you $300 or so, so if you change props, make the right decision, because you can't return them...Good Luck!