Question on hydrofoil

countryboy26047 · Aug 20, 2012

Ok, I've been kicking around the idea of buying a hydrofoil, or "whales tail" as I know em. I have a '75 Sea Star 16' tri hull with a merc 850 85hp O.B. I'm looking for opinions on whether I should buy one or not. I'm mainly looking for lower planing speeds as I don't have power T/T and most times we're just cruising maybe
15mph. Problem is, I have found that I don't get on a good plane until about 23-25mph.

Another retired guy · Aug 20, 2012

Re: Question on hydrofoil

Smart tabs would be a better solution.

countryboy26047 · Aug 20, 2012

Re: Question on hydrofoil

Been reading up a little on smart tabs. They sound good, but is it really worth it for the price difference between a whales tail and tabs? Lookin at about $40 for the tail, and $120 for tabs.

jestor68 · Aug 20, 2012

Re: Question on hydrofoil

Mention the word "hydrofoil" here and get booed off the stage.
I had never heard of putting any sort of trim tab on a small boat until I read this forum.

Itr sounds like all he really needs to do(with manual trim) is set his motor in a hole closer to the transom and get on plane quickly. :facepalm:

Another retired guy · Aug 20, 2012

Re: Question on hydrofoil

countryboy26047 said:
Been reading up a little on smart tabs. They sound good, but is it really worth it for the price difference between a whales tail and tabs? Lookin at about $40 for the tail, and $120 for tabs.

I can't speak from personal experience but previous threads on Smart Tabs vs Hydrofoil convinced me that Smart Tabs is the way to go. I'll be putting them on this winter.

countryboy26047 · Aug 20, 2012

Re: Question on hydrofoil

I just did some more research on it... It does sound like the smart tabs would be a better route to take, just gotta come up with the money. (Wife and three kids, the only green i see is when i have to mow grass lol)

Let me add another sub-question, we do a good bit of trolling also, are there any downfalls to tabs or hydro when running the lower speeds for extended amounts of time?

Silly Seville · Aug 20, 2012

Re: Question on hydrofoil

I can answer your initial question with two questions...

How many boat manufacturers equip their vessels with a "whale tail" from the factory?

Now, how many manufacturers equip new vessels with trim tabs?

You should not have to be a naval architect to come to the same conclusions that Formula, Cobalt, Sea Ray, Fountain, Cigarette and others did.

You get what you pay for.

Your follow up answer is simple. The tabs are underwater when at trolling speed and have virtually no effect on the attitude of the boat. The tiny amount of parasitic drag they might induce will never be felt by you or the engine.

ondarvr · Aug 20, 2012

Re: Question on hydrofoil

Silly Seville said:
I can answer your initial question with two questions...

How many boat manufacturers equip their vessels with a "whale tail" from the factory?

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Every outboard and I/O comes a "whale tail" it's just a smaller version referred to as an AV plate, which is all any of these types of products are, just larger in size. They get used incorrectly for other purposes, but hey have their place as a possibly useful tool.

In this case tabs are what he needs though, they will do a much better job.

jestor68 · Aug 21, 2012

Re: Question on hydrofoil

This is the iboats forum. Iboats sells Smart Tabs.

H20Rat · Aug 21, 2012

Re: Question on hydrofoil

jestor68 said:
This is the iboats forum. Iboats sells Smart Tabs.

I'm assuming you are implying there is bias because of the connection... iboats also sells hydrofoils, lots of them in fact!

http://www.iboats.com/Hydrofoil-Stabilizers/

smoedog · Aug 21, 2012

Re: Question on hydrofoil

I had a 92 glastron repowered with a 4.3 alpha one. Had problems finding the right prop to get my hole shot and also get me in my WOT range.

Had to go with a big prop to get my wot but had a hard time getting on plane, threw the attwood tail on there and saw no improvement what so ever.

YMMV

joewithaboat · Aug 21, 2012

Re: Question on hydrofoil

I had experience with whale tails on 3 previous boats, my current i/o has Smart tabs. I will never have a tail again. Tabs work much better!

countryboy26047 · Aug 21, 2012

Re: Question on hydrofoil

Well, ya'll got me looking more 'in-depth' at the smart tabs. I'm looking at the ones they sell on here made by nauticus, specifically the SX series. Only thing I'm questioning on them is, would I want to go with the SX9510-40 or SX9510-60? Going by the specs for them, it would seem that I would want the SX9510-60 as the 40's only go to 80hp. However, my only concern is will they be too stiff? (Assuming that is the diff. between the two, a stiffer 'shock')

bruceb58 · Aug 21, 2012

Re: Question on hydrofoil

Silly Seville said:
You should not have to be a naval architect to come to the same conclusions that Formula, Cobalt, Sea Ray, Fountain, Cigarette and others did.

Those are helm adjustable tabs not smart tabs.

smoedog · Aug 21, 2012

Re: Question on hydrofoil

post a picture of your transom so we can tell you which ones to get.

I got the SX tabs for my glastron but couldn't mount them due to the way my transom was built

tboltmike · Aug 21, 2012

Re: Question on hydrofoil

I HAD a foil on 18' trihull, 115 hp. Took it off after first run.
It should have been obvious to me. Anything in the water creates drag, especially if it designed to create lift. Drag cuts speed and increase fuel consumption.

Another retired guy · Aug 21, 2012

Re: Question on hydrofoil

tboltmike said:
I HAD a foil on 18' trihull, 115 hp. Took it off after first run.
It should have been obvious to me. Anything in the water creates drag, especially if it designed to create lift. Drag cuts speed and increase fuel consumption.

True, but tabs/foils raise the hull out of the water thus reducing drag.

UncleWillie · Aug 21, 2012

Re: Question on hydrofoil

countryboy26047 said:
Only thing I'm questioning on them is, would I want to go with the SX9510-40 or SX9510-60? Going by the specs for them, it would seem that I would want the SX9510-60 as the 40's only go to 80hp. However, my only concern is will they be too stiff? (Assuming that is the diff. between the two, a stiffer 'shock')

I have the SX-9510's on an 18 ft glass bowrider. ~3000lbs, 220 hp.
Originally had the 80# shocks. Way too Stiff.
Nauticus swapped them for the 60lb shocks. Much better.
I have stayed in plane well into the low teens!
You want them to retract when on plane and digging in, and only drop when the boat gets slow or light in the stern like when crossing a wave.
Unlike the hydrofoil, tabs will trim provide DOWN trim with the engine trimmed UP for Maximum speed.

I would get the 40's in your case. You can always swap them out for 60's if they don't perform.
Nauticus does swaps for FREE all the time. Your return shipping will be the only cost.

Question on hydrofoil

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