Hydrofoil

Hydrofoil on 16’ w/ 40

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Orrin
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Hydrofoil

Post by Orrin » 09 Sep 2019, 20:18

Hope this is the correct spot for this. I have an Excel 1651 with a Yamaha 40. I am maxing our around 30 mph. When running the more I trim the faster it goes. Problem is it starts proposing and I have to trim back down. I usually run my jackplate all the way up. Height doesn’t change much. Slows a little at lower position. Thinking of putting a hydrofoil on. I get how they work to plane out and all. My question is , a lot of the time I am in really shallow water. I have the motor all the way up and trimmed way up. Nice thing is the Yamaha has low water intake ports and sucks water when trimmed way up. Will the hydrofoil mess this up when going slow trimmed way up?seems like it may pushes the back down.

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Weldorthemagnificent
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Re: Hydrofoil

Post by Weldorthemagnificent » 10 Sep 2019, 07:21

My experience with hydrofoils is on 20-30 HP johnnyrude outboards on 14-16' boats. I have found the hydrofoil allows me to run trim one notch higher than I would without it (manual pin trim). Plane at a slower speed, get on plane with more weight in the boat. There are lovers and haters of these things, I am a lover. Some say they will take a mph or two off your top speed. I don't know if that's a proven fact or if it just feels slower because it's smoother. If your main issue is porposing, why don't you play with weight distribution a bit first

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DaleH
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Re: Hydrofoil

Post by DaleH » 10 Sep 2019, 07:33

I love foils on fast tin boats! Check out the SE Sport 200 model, as what’s what I put on my Yam40. In testing, the SE Sport model had best performance & least drag. Be aware your motor should already be mounted at the right height, sounds like your’s could go up an inch.

And no, it won’t inhibit cooling ...
#1) 1st tin rebuild, 18' Lund http://forum.tinboats.net/viewtopic.php?f=21&t=36583
#2) 25' Parker refurb from EMPTY hull http://www.classicparker.com/phpBB3/vie ... p?f=15&t=6
#3) 16' V-tin rebuild http://forum.tinboats.net/viewtopic.php?f=21&t=36465
#4 Procraft SV14
#5) 16' Starcraft entirely NEW Transom Skins http://forum.tinboats.net/viewtopic.php?f=3&t=37548

surfman
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Re: Hydrofoil

Post by surfman » 10 Sep 2019, 11:54

I would consider something like smart tabs.

Orrin
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Joined: 03 Apr 2019, 20:06

Re: Hydrofoil

Post by Orrin » 10 Sep 2019, 16:47

My only issue is the porpoising. I have the fuel tank in the front but the batteries are in the back . I have not changed it from the way i got it from the dealer. Hole shot is also not an issue, it jumps right up on plane. I am running a 11P prop. I just wanted to work on the WOT porposing and help with the shallow running a little

Weldorthemagnificent
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Re: Hydrofoil

Post by Weldorthemagnificent » 10 Sep 2019, 17:19

Try putting 100lbs or so up front, if that cures it, I'd be moving batteries. Booster cables make good budget battery wires. I wait for the good ones to come on sale at princess auto here in Canada or look at harbor freight in Murica. Sometimes 16-20 ft come on sale for about 30 bucks. I can't buy wire for that.

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MrGiggles
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Re: Hydrofoil

Post by MrGiggles » 11 Sep 2019, 23:06

I have an older Stingray foil on my 17' Deep V with a 60hp Merc 2 stroke.

I have ran it with and without the foil. I can trim up a good bit higher with the foil. Top speed is more or less the same with or without.

The boat handles a lot better with the foil as well.

Used to own a 14' Semi V with a heavy 25hp Johnson. Without a foil I could not go more than 1/2 throttle without terrible proposing. With an SE Sport 200 foil, it handled like it was on rails and would run just shy of 30 mph. No porpoising at all.

A good 4 blade prop can provide more lift as well. Modern designs like the Mercury Spitfire will result in no loss of speed.

turbotodd
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Re: Hydrofoil

Post by turbotodd » 11 Sep 2019, 23:53

Porpoising can be helped a couple ways.

FIrst look at the bottom. If there is a rocker (hull bent downward, toward the water) in the last 3 or 4 feet of the back side of the hull, that will cause porpoising-guaranteed. Run a straight edge longitudinally (front to rear) across the bottom and see what it says. If it's bend down, bend it back up. That requires a hammer and lots of careful beating, oh and if you have neighbors that don't like noise, you might want to wait til sunday morning when they're gone to church. You get the idea.

Knock a hook in the hull, about 6" or so forward of the transom (meaning pound the hull upward a little). Just a little bit is all it takes!

Another less intrusive way is to grab some JB weld and make about a 1/8 to 1/4" bead of JB across the bottom of the hull, RIGHT where the transom meets the bottom (the corner). You don't want any bead on the back side, just the bottom. I usually run a bead across between each strake on the outsides, not so much toward the center of the hull but more to the outside. This usually solves the porpoising. Problem is, if you leave it at 1/4", it's gonna cost you a mph. Thats where it's nice to have JB weld, just sand it down a little bit at a time until your speed comes back where you want it. If you go too far (back down to aluminum), you can build it up again. Some guys aren't happy about JB weld and I'll offer to TIG a bead, but that's more expensive (obviously) and harder to "adjust".

I've run into a few that would benefit greatly from a prop change. Some props give more "bow lift" (lots of rake) which aggravates porpoising. Some rigs are overpropped, where the max RPM might be 6000, and they're grossly overpropped such that it will only achieve 4500 and runs slow, just doesn't have enough torque to power through the porpoising. Sounds odd but it's real and it happens often. When that happens, you'd have to drop an inch or more in pitch, which allows the motor to make more thrust, gets it on plane quicker and a lot of times will run faster on the top end too. Lugging it with too much prop is NEVER a good idea and always a bad one, particularly on 4 stroke motors!

surfman
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Re: Hydrofoil

Post by surfman » 12 Sep 2019, 07:02

A hydrofoil is probably the best option to try first, with tabs you need to drill holes in the transom a hydrofoil is attached to the motor so no problem drilling holes in the anti-ventilation plate really. If that works, great, if not then there is the tab option.

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richg99
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Re: Hydrofoil

Post by richg99 » 12 Sep 2019, 21:07

I've had both, a foil and 3 sets of Smart Tabs, on 3 different boats. Smart Tabs were far better, IMHO. As far as drilling holes, I'd rather drill into my boat (which can be patched if ever necessary,) than into my motor.

With Tabs (any Tabs, really)... No more porpoising; far better planing at very low speeds. No loss of speed, reasonable cost, and a very proven device.

In the last 25 years, since I put my first set of Smart Tabs on, I've only run into ONE person who actually owned Smart Tabs who didn't like them. Everyone else sings their praises.

Your money, Your boat.... your decision.

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jethro
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Re: Hydrofoil

Post by jethro » 13 Sep 2019, 09:57

richg99 wrote:
12 Sep 2019, 21:07
I've had both, a foil and 3 sets of Smart Tabs, on 3 different boats. Smart Tabs were far better, IMHO. As far as drilling holes, I'd rather drill into my boat (which can be patched if ever necessary,) than into my motor.

With Tabs (any Tabs, really)... No more porpoising; far better planing at very low speeds. No loss of speed, reasonable cost, and a very proven device.

In the last 25 years, since I put my first set of Smart Tabs on, I've only run into ONE person who actually owned Smart Tabs who didn't like them. Everyone else sings their praises.

Your money, Your boat.... your decision.
I like the idea of smart tabs for sure, but one thing that is overlooked about a foil is how much it stabilizes your boat at speed. I don't believe tabs help that but I am not sure as I've never had them. On my 14' Starcraft Superfisherman, it's a fairly light deep V. When I'm on plane the the boat is super stable through waves and turns with the foil. It robs about 3 or 4 mph on the top end, but with two people in my boat I can still do 25mph which is plenty for me. When I take the foil off the boat becomes much more squirrely through choppy water and slides more in a turn. I really prefer how the boat handles with the foil. Every boat is different though.

I don't get any porpoising with or without the foil, I just have to adjust my motor trim accordingly.

I do like the idea of being able to plane at lower speeds and not losing any top speed. That is a huge win in the tabs column.

Also, you can patch holes drilled into your motors' cavitation plate just as easy, arguably easier than you can a thin boat hull. How do I know this? By beating the ever loving ---- out of my skeg! It can be fixed and made to look like new and painted a lot easier than a boat hull.
I fish, therefore, I am.

1993 Starcraft SF 14 DLX side console with 25 hp Mercury 2 stroke
2003 Sylvan 2100 Profish walkthrough with 150 Mercury Saltwater and 6hp Mecury 4 stroke kicker

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richg99
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Re: Hydrofoil

Post by richg99 » 13 Sep 2019, 10:25

Let's talk about the balancing and stabilizing effect of tabs or foils.

Both/either definitely help the boat, especially if it has porpoising problems.

A hydrofoil is a single "pedestal" on which the boat is riding when moving quickly.
Tabs (any tabs) are TWO "pedestals" on which the boat is riding when moving quickly.

Is a one wheel wheel-barrel more stable? ....or is a two-wheel wheel-barrel more stable? We are talking balance here, remember.

Tabs (any tabs) do not cause loss of any appreciable speed. Their operating surfaces skim the top of the water.

Look at high dollar flats boats. For a mere $35,000 and UP..you can get some great boats. NONE of them come with a hydrofoil...nearly all of them have Lenco (electrically adjustable tabs); Bennett (hydraulically adjustable tabs) or some other form of tabs in the deal.

Most of the high dollar boats do NOT come with Smart Tabs because...... fully-adjustable tabs are better in most cases. Fully adjustable tabs also cost more and take up additional room with their installation and necessary components.

For my simple needs, Smart Tabs did the job. Your experience(s) may differ.

Incidentally, I do not have Tabs on either of my two present tinnys. (1652 G3 50 hp 2 cycle and a 1756 Lowe with a 50 hp 2 cycle). Neither boat seems to have porpoising issues. That probably has to do with internal balancing of the weight. Both are side-consoles, so my big butt has been moved a bit forward.

httpss://www.nauticusinc.com/

p.p.s. Bennet has now copied ( to some degree) the Smart Tab product. I guess the patent ran out. I have NO personal experience with their product so one might also want to include the Bennett version if looking.

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DaleH
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Re: Hydrofoil

Post by DaleH » 13 Sep 2019, 12:16

Some ‘facts’...

- A hydrofoil is a great low co$t option for smaller (up to 16’ hulls) hulls, especially tins. I just bought a few for $21 each, delivered. Properly installed with the OB at the correct mounting height, they add ZERO drag, as the foil is at or above the surface of the water while on the plane.

- ALL trim tabs, repeat ‘All’ tabs, work by DRAG ... to state otherwise is ignorant of the engineering effects of Bernounoulli’s ‘Theory of Hydrodynamics’.

- Spring loaded tabs, like SmartTabs or the Bennett version, will auto-adjust ‘up’ from a pre-loaded state could be a viable option for smaller boats and/or rigs without OB trim. However I will strongly CAUTION one that they could be DEADLY when used on a saltwater boat in current or following seas or in a boat on rivers w/ large standing waves. Yeah sure, they make an adjustment button to lock them in the ‘up’ position, but try doing that whilst hanging your ass off the back of the transom to when you are in an emergency situation ... not going to happen ...

Bottom line - IMHO there are advantages to each, with certain prerequisites or cautions to be noted for best and safest use.
#1) 1st tin rebuild, 18' Lund http://forum.tinboats.net/viewtopic.php?f=21&t=36583
#2) 25' Parker refurb from EMPTY hull http://www.classicparker.com/phpBB3/vie ... p?f=15&t=6
#3) 16' V-tin rebuild http://forum.tinboats.net/viewtopic.php?f=21&t=36465
#4 Procraft SV14
#5) 16' Starcraft entirely NEW Transom Skins http://forum.tinboats.net/viewtopic.php?f=3&t=37548

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richg99
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Re: Hydrofoil

Post by richg99 » 13 Sep 2019, 13:03

As usual, we disagree on Foils vs Tabs. Since you do it Full Time and I am just a User...

As far a loss of speed...of course the tabs contact the water. I said... No Appreciable Loss of Speed.
My experience with the one hydrofoil that I had was a loss of 2 or 3 mph. Perhaps the setup wasn't ideal, but the Foil (and the Tabs) can't work much unless they are touching something. I'll stay with Tabs.

I agree with you that a following-sea causes a lot of issues. Most members on this site will never experience that condition. But, if you do have to deal with that situation, then Smart Tabs or the new non-adjustable Bennett Tabs are probably not the best answer to your problem.

Whether one spends $21.00 or $121.00 Probably won't make a major difference in anyone's net worth. Now, the difference between $500./$1000 for hydraulic adjustable tabs could hurt a lot of budgets on this site.

The amazing thing is how many boats do not have porposing problems versus the ones that do have the issue. I'm convinced that moving weight around is the first approach to any such concern.

As always. thanks for your insight and input. You do know your stuff.
rich

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LDUBS
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Re: Hydrofoil

Post by LDUBS » 14 Sep 2019, 03:47

I don’t know. Only experienced porpoising once (was at WOT). Just adjust the PTT a tick or back off the throttle a tick and problem gone. I wouldn’t add tabs or a hydrofoil until I tried weight distribution already mentioned and even then only if the problem was severe.
Last edited by LDUBS on 15 Sep 2019, 14:43, edited 1 time in total.
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