Hydrofoil or not ?

Bunky · Aug 18, 2006

I have a 14ft Alum boat w/9.8hp Mercury and With just me in it, it doesn't plane out very well, I was thinking of putting a Stingray JR. Hyrofoil on it.. Does anyone have any input on these or maybe another Brand

jtexas · Aug 18, 2006

Re: Hydrofoil or not ?

What kind of hull, a deep-v? Does it have a lot of decking? I would think 14ft would plane out nicely with 10hp.

Before you hydrofoil I'd encourage you to first make sure you're getting all you can from the motor, then take a look at weight & balance...just moving the gas tank to the middle of the boat can make a big difference.

Todd Gerber · Aug 18, 2006

Re: Hydrofoil or not ?

I've been thinking about adding one also - but wasn't sure about them. I've got a 1978 15' Starcraft 'glass with a Merc 65 3-cyl.

Sorry, not trying to hyjack your thread Bunky.

Are there any downsides to hydrofoils?

pecheux · Aug 20, 2006

Re: Hydrofoil or not ?

hydrofoils catch more floating weeds .... (food for thoughts)

cobra 3.0 · Aug 21, 2006

Re: Hydrofoil or not ?

Hydrofoils do work fairly well when you can properly adjust the height of the motor in relation to the bottom of your boat. Otherwise, if they are too low, they will slow down your boat as they will be trying to raise and lift the boat higher than they are supposed.

When properly adjusted, it does make riding you boat feel safer. Your boat will lean less in sharp turns and the bow will be pushed flat quickly (plane quicker usually in 1/3 time.)

I've heard some say that they put unusual amounts of pressure on your motor anti-cavitation plate and that some have broken it. Make sure the screw holes aren't right on the side of the plate with the model you choose.

I put one on my inboard bowrider, and didn't like it. It was probably too low in the water and it significantly slowed down my boat. I also couldn't create the same large wake with it on for wakeboarding.

Todd Gerber · Aug 21, 2006

Re: Hydrofoil or not ?

Cobra -

Thanks for the comments. Bunky and I have been talking about the 'foils for the last few days - since we live quite close. We've been thinking of picking up a used one to try out.

How can you tell if your motor is properly adjusted to the bottom of the boat?

phatmanmike · Aug 23, 2006

Re: Hydrofoil or not ?

not

tmcalavy · Aug 24, 2006

Re: Hydrofoil or not ?

The cavitation plate on your outboard should be even with, or slightly higher that the bottom of your boat at the stern. Too low and it will drag and not plane correctly. Too high and it will blow out, not get water traction. Set the trim so the motor is straight up and down. You may have to experiment with the trim, adjust it in or out, to get the ride characteristics you want. I put a foil on my 15 ft. 1954 tinny V-hull with a 58 Johnson 18 hp and it planes quicker and rides better. Even so, some folks don't like them but they work for me.

Pony · Aug 24, 2006

Re: Hydrofoil or not ?

Yes they can often hinder performance, and slow you down because of increased drag........BUT they have there place. In the right set-up they can help out a bit. As good as trim tabs?? NO not at all, but they do serve a purpose. My boat hapens to handle better and plane faster........ on other boats I have run, they sat too low and were horrible. Its a case by case basis, and to simply say "Not" is absurd.

IMHO Bunky, its worth a shot. I would try moving some weight foreward first, maybe even add some weight. When I boat alone I usually trim in an extra hole or two and put weights in the front bow (extra anchors). I also have an extra tank with an extra long line to move the tank further up. Try running it at a few different trim settings and weight in front. If that doesnt o anything, a foil may work..................IF it does, its way cheaper than tabs. If it doesnt work the holes wont hurt you and if you hate them, you can fill them and paint em up.

jtexas · Aug 24, 2006

Re: Hydrofoil or not ?

havin a bad day, pony?

don't often see answers like that on this side of the forum.

Pony · Aug 24, 2006

Re: Hydrofoil or not ?

jtexas said:
havin a bad day, pony?

don't often see answers like that on this side of the forum.

Nope not unless the topic is about oil or something. I guess maybe I was having bad day.................it just annoyed me. I'll edit it out.

Chinewalker · Aug 25, 2006

Re: Hydrofoil or not ?

In my experience, foils are typically a band-aid solution to another problem. These problems can include: an underpowered rig, a hull with defects of some sort (hook, rocker, dents, algae growth, etc.), running the wrong prop, improper loading/weight distribution of the boat, improper set-up of the motor to the boat (too high, low on transom), etc.

If you have eliminated all of the above possibilities as causes for poor performance, then a foil MAY help your situation...

- Scott

Dhadley · Aug 25, 2006

Re: Hydrofoil or not ?

The fins are a tool. They allow you to change the set up and take advantages of that change. You will have to play with the height or X dimension and that's a good thing.

Where your AV plate ends up in relation to the bottom largely depends on the prop. There's no such thing as a given dimension being correct for all props. You don't want the plate lower than the keel but how high you go depends on several things but especially the prop.

javsam · Aug 25, 2006

Re: Hydrofoil or not ?

I put a hydrofoil on my 40 hp johnson on a 150 alumacraft boat and the results were great,I can plane alot quicker and cut into turns quite sharply. the end result using a hydrofoil was better steering control.Like dhadley says you should play with your motor height,I raised my motor 1 inch above the bottom of the transom.
8)

Wiggy · Sep 2, 2006

Re: Hydrofoil or not ?

I found that planing was quicker and I could stay in plane at lower speeds but top speed was reduced significantly and steering was alot heavier.

Just my experiences....

davidnlaura · May 25, 2010

Re: Hydrofoil or not ?

Hi I have a 14ft speed boat not sure of the make but I have a merc 500 outboard and I am wondering is it worth fitting a doel fin to the merc or am i waisting my time I hear so many pros and cons all a wana know is do they work I wana use the boat wi ma kids buy also water ski in fresh and salt water use.

Cheers David

ondarvr · May 25, 2010

Re: Hydrofoil or not ?

This thread is 4 years old, its best to start a new one with your question.

What do you want it to do, is there a problem?

They can help at times, but need to be used correctly and more importantly there needs to be an issue it can actually help with.

Hydrofoil or not ?

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