Need advice with hydrofoil fins....

[charles.manifold]

Thanks for any help in advance, or at least taking the time to check out my post. Here's what I got:

I have a 18' fiberglass Mastercraft with a 3.0 Cobra I/O. This is my first boat and I am new to boating and boat maintenance. I only had a chance to get it out on the water a couple times last summer but I have some projects that I want to get a start on before the next boating season rolls around...

I was looking into hydrofoil fins because unless I'm running without any passengers it takes forever to plane out. My question is does anyone have, or know where to get the specs I would need to fabricate my own? I am currently deployed in Kuwait and have access to the tools I would need to create one if I had some dimensions to work with.

Of course I am open to other suggestions if I am going in the wrong direction with this, like I said I am new to boating.

Thanks all!!!

 

[Bondo]

Re: Need advice with hydrofoil fins....

Thanks for any help in advance, or at least taking the time to check out my post. Here's what I got:

I have a 18' fiberglass Mastercraft with a 3.0 Cobra I/O. This is my first boat and I am new to boating and boat maintenance. I only had a chance to get it out on the water a couple times last summer but I have some projects that I want to get a start on before the next boating season rolls around...

I was looking into hydrofoil fins because unless I'm running without any passengers it takes forever to plane out. My question is does anyone have, or know where to get the specs I would need to fabricate my own? I am currently deployed in Kuwait and have access to the tools I would need to create one if I had some dimensions to work with.

Of course I am open to other suggestions if I am going in the wrong direction with this, like I said I am new to boating.

Thanks all!!!

Ayuh,.... Welcome Aboard,...... 'n Thank You for yer service,...

I'm of the "Hate whale tails crowd",...
Lotsa added stresses where they don't belong,...
Anyways,....

I'd suggest ya investigate whether yer boat is propped Right,....
A slight drop in pitch, might wake up yer hull,...
Or, goin' to a 4 blade prop,....

The stickies at the top of the prop forum will give ya some Ideas, 'n help ya post yer question in there,....

If a prop change ain't what ya got in mind,...
I DO believe in hull mounted trim tabs,....
The auto style tabs, like Smart Tabs, are just the ticket for many boaters in yer situation,...
iboats sells 'em here,...

My ole barge has a set of hyd. Bennett trim tabs,.....
But my situation is entirely different,...

 

[Scott Danforth]

Re: Need advice with hydrofoil fins....

Prior to putting on a whale tale

what RPM are you running? what is the speed? what does your boat actually weigh? what is it supposed to weight.

I would lean toward a prop issue first.

 

[Starcraft5834]

Re: Need advice with hydrofoil fins....

Welcome Charles.... I can only echo what's been stated. first check out if you are currently propped right.......going from 3 to 4 blade prop will benefit you far more than a fin..

 

[jestor68]

Re: Need advice with hydrofoil fins....

The original(and still one and only) Doel Fin; designed by a really smart aeronautical engineer; will plane your boat off in half the time it takes now and enhance the handling of your boat.

Since it's a precisely designed and molded product, you can't really make one yourself. For $33, who'd bother.

Don't pay any heed to the horror rumors concerning stresses, weird handling, etc. I've used one on every boat since I discovered it in 1985. It works.

It's sold here too for just $32.29 the last time I checked. Since the original designer passed away, it's now marketed by Davis Instruments.

Your boat is not unusual. Just about any 18 footer powered by a 3.0L is a dog with more than two people in there.

The first boat I used it on(a 18 ft cuddy) was the same way. If anybody was in the back seat, forget it. Put the Doel Fin on, and no more problem; it would come right on plane with no lose of speed and better handling.

Lastly, it is unfair(to the smart guy that invented it)to lump the Doel Fin in the same category as all the other "whale tails" that followed.

It's two piece, flexible design is unique and is the only true "hydrofoil" that I know of. The rest are just rigid extensions of the av plate, and do not function in the way that the Doel Fin does.

 

[thumpar]

Re: Need advice with hydrofoil fins....

My thought is if the work so well why don't engine or boat manufacturers put them on?

 

[Frank Acampora]

Re: Need advice with hydrofoil fins....

Well, while I am no fan of hydro-foils this false reasoning argument is always proposed. The fact is that the engine and boat manufacturers have no control (in the case of outboards) over what boat and engine combination will be paired. Additionally, they have no control over the user or use of the boat. Why add an extra expense to an already luxury item when it may or may not be necessary? It is not like an auto manufacturer who builds cars in the hundreds of thousands and gains efficiency by producing a vehicle with a standard package of goodies.

To the O.P: While it may not have the same good looks as a manufactured plastic foil, you can make a simple plate from thick sheet aluminum and bolt it to the anti-ventilation plate. It would probably work just as well as the commercial product. You can experiment with size--start at about 12 inches wide and work up until you get the results you want.

 

[thumpar]

Re: Need advice with hydrofoil fins....

Well, while I am no fan of hydro-foils this false reasoning argument is always proposed. The fact is that the engine and boat manufacturers have no control (in the case of outboards) over what boat and engine combination will be paired. Additionally, they have no control over the user or use of the boat. Why add an extra expense to an already luxury item when it may or may not be necessary? It is not like an auto manufacturer who builds cars in the hundreds of thousands and gains efficiency by producing a vehicle with a standard package of goodies.

To the O.P: While it may not have the same good looks as a manufactured plastic foil, you can make a simple plate from thick sheet aluminum and bolt it to the anti-ventilation plate. It would probably work just as well as the commercial product. You can experiment with size--start at about 12 inches wide and work up until you get the results you want.

But if it worked so well the manufacturer could use it as a sales pitch. They could probably add them for a couple dollars.

 

[JimS123]

Re: Need advice with hydrofoil fins....

My thought is if the work so well why don't engine or boat manufacturers put them on?

First off, go to USPTO.gov and read the patents. That'll help splain it. Secondly, if you were the manufacturer would you admit that someone else's invention was better than yours?

Finally, my boat performed perfect right out of the box, with a proper cupped SS prop. Then I added a heavy kicker and a second gas tank right at the stern. The DoelFin solved the problem and brought back the performance.

 

[ondarvr]

Re: Need advice with hydrofoil fins....

My thought is if the work so well why don't engine or boat manufacturers put them on?

They all do.

 

[Watermann]

Re: Need advice with hydrofoil fins....

Charles thanks for serving our country and sacrificing for us here at home.

I have a like new hydro-foil I just pulled off an Alpha one drive that was on a boat I bought as a donor for my Chief project. The guy I bought the boat from put it on not because the 205 HP 4.3 L was a dog but because the boat was water logged and weighed 100's of Lbs more than it should have. When I towed it home I swore I was towing a cement truck behind me.

From what I saw of the prop, that foil was causing some serious erosion on the front side of the blades. I don't know what else would have been the cause of the ventilation if not the foil so I wasn't wanting anything to do with it.

Anyway if you shoot me a PM with a States address, I will box up the foil and ship it and the mounting hardware to you for free. I was going to just toss it in the trash can anyway.

 

[Lager]

Re: Need advice with hydrofoil fins....

Watermann, thats real nice of you. Appreciate you helping out our men.

 

[NYBo]

Re: Need advice with hydrofoil fins....

Class act, Watermann, class act.

Lots of food for thought in this thread, Charles. Stay safe, and thank you for your service from the proud father of a U.S. Marine.

 

[thumpar]

Re: Need advice with hydrofoil fins....

Charles thanks for serving our country and sacrificing for us here at home.

I have a like new hydro-foil I just pulled off an Alpha one drive that was on a boat I bought as a donor for my Chief project. The guy I bought the boat from put it on not because the 205 HP 4.3 L was a dog but because the boat was water logged and weighed 100's of Lbs more than it should have. When I towed it home I swore I was towing a cement truck behind me.

From what I saw of the prop, that foil was causing some serious erosion on the front side of the blades. I don't know what else would have been the cause of the ventilation if not the foil so I wasn't wanting anything to do with it.

Anyway if you shoot me a PM with a States address, I will box up the foil and ship it and the mounting hardware to you for free. I was going to just toss it in the trash can anyway.

:thumb::thumb:

 

[SWD]

Re: Need advice with hydrofoil fins....

Waterman.....do you ship to Canada?

 

[edthearcher]

Re: Need advice with hydrofoil fins....

ist let me thank you for your service iam a vet also 7 active in the 50s to 62. i purchased a 18 ft bass boat that had whale tails on the lower unit. couldnt get the bow to go down, took them off and opened her up and though she was going to flip over. so on this web site some one suggested i by the pre loaded smart taps correct me if i have the name wrong believe they were just a little over a $100 they go by boat length, boat wt. and horse power, even called the company they helped me choose the right ones, hit the throttle and wow the bow went right down, trim the motor and every thing was perfect

 

[charles.manifold]

Re: Need advice with hydrofoil fins....

Thanks for the support guys! And thank you to my fellow service members and parents of service members.



I appreciate the comments and feedback! **Watermann I sent you a pm**

Once I get back home I plan on getting the boat all dialed in the way I want it before the next boating season. I for sure will be removing teh vertical drive and replacing the seals (I think I have a cracked bellows seal). Plus I'd like to open that all up and give it a good look over. I bought the boat from my wife's uncle, breat guy, but doesnt appear that upkeep of the boat was of major importance to him. I'm fussy and it may be nothing special, but its mine and I like my stuff to working the way its supposed to be lol.

If anyone has any suggestions or comments on things I should be looking for feel free to leave em here and I'll review this before I get started.

You guys are great! I'm stoked that I found this forum and thank you for your feedback!

Cheers!

 

[southkogs]

Re: Need advice with hydrofoil fins....

Charles: Thanks for the work y'all are doing over there. Lotsa' folks here at home wishing you safe, well and back home soon.

One thing that's throwing me just a little bit: I can't think of a Mastercraft I've ever seen with an I/O. V-drive or true Inboard, but not I/O. Am I missing one somewhere?

MC hulls are typically setup to climb on top of the water pretty flipping fast as they are. I can't imagine a tail making a huge improvement (like 'em or not). Something a little bigger sounds wrong.

 

[MikDee]

Re: Need advice with hydrofoil fins....

Charles: Thanks for the work y'all are doing over there. Lotsa' folks here at home wishing you safe, well and back home soon.

One thing that's throwing me just a little bit: I can't think of a Mastercraft I've ever seen with an I/O. V-drive or true Inboard, but not I/O. Am I missing one somewhere?

MC hulls are typically setup to climb on top of the water pretty flipping fast as they are. I can't imagine a tail making a huge improvement (like 'em or not). Something a little bigger sounds wrong.

Mastercrafts are inboard ski boats, they don't/can't use tails? They're a whole different setup.

Well, you could actually use Smart tabs, trim tabs, or a Doel fin, either one would help you get on plane quicker, & stay there longer.

 

[ondarvr]

Re: Need advice with hydrofoil fins....

People frequently either love or hate foils, fins, tails, whatever you want to call them, and conversations can get a little emotional at times. There isn't really any need for the love em or hate em attitude because they are just a tool that allows you to do a few things that may help performance. Unfortunately they are rarely used in the correct fashion and this is where most of the intense negative opinions come from.

Also trim tabs are the correct solution to the issues most people want corrected when they look into products like these.

Used correctly a Foil allows you to possibly raise the motor higher on the transom than without it, it does this by preventing the prop from ventilating (pulling air from the surface) under hard acceleration. With the motor mounted higher you may get less bow rise, less porpoising, higher top speed, better MPH. These are only possibilities, your results may vary.

When someone just bolts a foil on and heads to the water it may or may not work well, frequently it will be dragging in the water at speed which can result in negative affects, like odd handling, lower top speed, water spraying, etc. This is where the intense anti foil opinions come from, again, it's the misuse of the product that generates these negative responses.

Unfortunately you can't do any adjusting on an I/O when it comes to how deep the outdrive sits in the water, so adding a foil may cause more problems than without it. Not everyone that puts one on an I/O has problems, but there may be some trade-offs that are worth using it to some owners, so it's up to them.

Foil is also a bad name for the product, a flat plate would do the same thing, the foil shape came about more for marketing purposes than anything else. These products started life as just a larger bolt-on AV plate than what the motor already comes with, nothing more. The fact they may also work sort-of like a trim tab to help get the boat on plane was more of a side affect, not the real purpose for using one, it's this side affect where the controversy originated.

For the OP's question, trim tabs are what you may want to look into, but water logged foam can also contribute to this type of problem, so check that first. There is no real downside to tabs even if you don't need them, and they do help almost every boat in some way.