hydrafoil and trim tabs

[dan t.]

Re: hydrafoil and trim tabs

well you know we could bark at each other all day and be no further ahead. the reason I like the foil on THIS BOAT is the handling carictaristics under cruise and the lower planing speed, this hull has an 18 degree deadrise and no planing pad,yes, I could achive the same results with the tabs alone, I have tried it, I prefer the results with the foil, a different hull probably not. I know this combo works for me,

 

[ondarvr]

Re: hydrafoil and trim tabs

This is my reply to a post from a couple of months ago on the same subject.

"I have an aluminum prop on my 19' CC (200hp Evinrude), this prop would ventilate badly under hard acceleration. Now I could have invested $500.00 in a SS prop, but this boat doesn't get used all that much and I couldn't justify the expense and since I had a foil sitting in the shop I thought I'd give it a try. With a fin I was able to raise the motor another hole higher and reduced the ventilation problem too far less than what it had been before the fin was mounted. By raising the motor I reduced the gearcase drag and gained rpm's, MPG and speed. Having the gearcase (prop) higher also reduces bow rise and improves hole shot by not letting air get sucked in. With it higher, the fin is also out of the water at speed, so there are no negative handling affects."

A set of tabs can't do any of these things in the same way, so yes both could be used on the same boat with good results.

 

[Shadow66]

Re: hydrafoil and trim tabs

I'm a newbie and cannot offer any real technical info about all of this but I can offer my own experience.

My Stingray 18' Bowrider came with a Stingray hydrofoil. It was okay but porpoising was an issue for me and got on plane at only higher speeds. I installed composite trim tabs and removed the hydrofoil. Huge difference and it ran incredible...a new boat and very forgiving (tabs set on #3). Got on plane in about 10mph and overall speed wot ride quality was vastly improved. I put the hydrofoil back on to see if it would be better to run both (I never read these posts or else I would not have bothered). The boat felt like it labored and did no appreciable improvement (On my personal boat) so I took it off. Been happy ever since.

Like someone here said, it may be best for certain types of boats to run both...on mine it wasn't at all and clearly useless.

Just my $.02

 

[NSBCraig]

Re: hydrafoil and trim tabs

Wow ok that's a totally different thing there ondarvr.

I'm really not understanding why his prop was ventilating so bad and running it higher with the foil out of the water fixed this?

I really don't get that.


With everything out there there's always parts that are made for one reason or another that just get stuck in peoples heads as what you have to have.

Put 650 cfm double pumpers on a tunnel ram in your camaro with solid lifters and slapper style traction bars.

Run dual shotgun exhaust on your Harley with or without baffles.

Bolt some ladder bars to your lifted truck with leaf springs.

Put edlebrock torker II manifold in said truck.

Buy large diameter primary tube headers cause your looking for gas mileage.

*** anybody else notice the original poster hasn't post anything else***

 

[ondarvr]

Re: hydrafoil and trim tabs

The venting can be from the prop design, hull design, HP, setup, gearcase, etc.

At speed the top of your prop can be right at the surface or above it and still get a great bite, but when you accelerate at slow speed, if it's too close to the surface it can suck air, lose it's grip and then just spin. That's why a jack plate can be so useful, it can be down to take off, then raised for high speed performance. A foil "may" allow the prop to be higher to start with and not let air get to it, it just covers the spot above the prop where the air would normally come from. As a result you can improve performance by mounting the engine higher than you could without it. As the prop is raised up it also has less leverage on the hull, so under hard acceleration the bow won't come up as high.

The improvements have nothing to do with the fin dragging in the water and forcing the bow down, or being in the water at high speed to stop porpoising

Used in this manner there's no real overlap in the job being done between tabs and a foil, at least as far as how they get it done. That's why both could be used at the same time and not interfere with each other. Plus it?s not in the water, so you don?t see the possible negative effects of it dragging at speed.

This may not be the best way to get all of this done, an adjustable jack plate, several SS props, adjustable trim tabs and a very knowledgeable person to help would be much better, but for $29.00 I don?t think you can beat it.

 

[NSBCraig]

Re: hydrafoil and trim tabs

OH you mean during holeshot!

I thought about that all day yesterday and I'm like if it's sucking air how does mounting something above it but out of the water help?

I see what your saying.

Yeah having a jackplate is cool.

 

[Hitech]

Re: hydrafoil and trim tabs

A foil "may" allow the prop to be higher to start with and not let air get to it, it just covers the spot above the prop where the air would normally come from.

This may not be the best way get all of this done...but for $29.00 I don?t think you can beat it.

Got it, that makes sense. Seems like a very limited use, but a use none the less. I've never seen a 'foil marketed for that use, and that is likely a huge part of the problem.