We are looking at adding some hydrofoils to our 18 ft flat bottom aluminum sea ark boat with a 90hp Yamaha 2 stroke engine.

Anyone have experience with them? Positive or negative? Also suggestions on brands etc....

Thanks!

They are a bandaid for a poor setup. The right prop set at the right motor height is a much better answer.

Unless it's a tunnel hull which require a compression plate not a foil. Which is a different conversation.

No one can give a definitive answer without more information.

What if any, problem are you trying to solve? Also, does your motor have power trim/tilt, what propeller, what is your max RPM with current setup, fixed or portable fuel tanks, location of trolling motor and battery if any etc.? Some issues can be addressed by adding a hydrofoil, others are best resolved by changing prop, weight distribution, motor height on those setups that allow for that.

A hydrofoil is not necessarily just a "band aid" as some may suggest. A description of your problems and some photos of your rig would help.

I noticed in your post you referred to "adding some hydrofoils" to your boat. A hydrofoil attaches to the foot of your motor, not the boat. Are you possibly thinking of trim tabs for your boat?

No we are not thinking about trim tabs. we took out to a guy near Fork that manufactures Jack Plates and does work on props, he was the one who recommended the hydrofoil. We recently got a tune up on the boat, the guy that did the work, near ray hubbard said we wouldn't need one after the tune up. We were having a hard time getting the boat to reach a plane when running on a lake.

We don't really want to invest in trim tabs or a jack plate because it is a hunting boat that we happen to use for fishing and the trim tabs wouldn't fit with all the electronics we have on the back and the jack plate would require us to get a new custom boat cover which we recently got replaced.

Most of the weight is in the back of the boat. It is a sea ark similar to the one on the top of this web page https://bfemc.sharepoint.com/Pages/SeaArkAluminumBoats.aspx

it has power tilt, with a 90 hp yamaha 2 stroke engine. it has been hitting 4500 RPM but the guy that makes the jack plates said we should be getting 5500, we have not tested it out since the tune up to see if it is up to 5500. We are going out on Thursday. I do not know a ton more about the situation was just asking for my dad. I already let him know that it was a bandaid for a different issue but he was just wanting to research it a little bit more.

I suggest you test the motor first, and see if the tune up gets you into the proper maximum RPM range. If so, that will likely solve your problem. If that does not resolve the issue, check your motor mounting height to have the anti cavitation plate flush with, or barely above the bottom of the hull. Also check your trim adjustment to make sure you are getting full trim down. Some motors have an adjustable rod or pin to limit trim range. If the motor is running properly, you may need a different pitch propeller to obtain maximum RPM.

If none of this resolves the issue, and you cannot readily redistribute any weight, then a fin such as the original Doel-Fin may take care of the problem. Let us know the outcome of the above before adding the fin though.

If you do need one, get one shaped like the Doel-Fin, (shaped like a wing, not one of the long narrow tunnel type, as they are for a slightly different application).

Ok,
This gets easier.
When you prop it to run at the proper rpms: 5,500 your holeshot problem will go away.

A foil on a flat bottom hull is a very bad combination, it makes an already ill-handling rig worse, by raising the transom even more, it will want to spin out a lot easier. Get with Steve at Steve's prop at fork, the correct answer is the right prop, which is a powertech 4 blade, with small vents, it'll do everything right.

If you decide that the foil is your answer, remember you're still not running at proper rpms, which puts a much heavier load on your bearings, and will shorten your motor's life. Band AID.

Steve is who made the suggestion of the hydrofoil, said the prop was fine, he also said a jack plate would help but like I said earlier the dilema we have with getting that installed.

You told Steve you were running 4,500 rpms? Somehow I don't think he got that pearl.

Pat he hasn't even tested it since the tune up to know what rpm`s it is turning.

That doesn't matter to Pat. He is more interested in defending his shoot from the hip "band aid" comment, than in paying attention to the issue.


"Let go of your attachment to being right, and suddenly your mind is more open. You're able to benefit from the unique viewpoints of others, without being crippled by your own judgment." -- Ralph Marston

It's turning 4,500.
Without anything else that statement is automatic you've got the wrong prop. Now if your tune up finds a thousand rpms you'll probably be happy with the holeshot.

Ummm. Steve is the one who pointed out it should be running 5500 not 4500....