hydrofoils....do they help in any way?

steelhead1

Seaman Apprentice
Joined
Jan 18, 2003
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40
i was looking at putting a stingray hydrofoil speed xp on my 140 evinrude replacing the trolling plate i have on it and have no use for anymore.i am pushing a 22ft starcraft islander.i was wondering if anyone has had any benefits from the use of a hydrofoil.i can tell that the aluminum trolling plate probaly has caused a lot of drag threw the water at top end.i was wondering if the speed xp would give me any more mph's?<br />thank you<br />scott
 

Spidybot

Lieutenant Commander
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Apr 4, 2002
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1,734
Re: hydrofoils....do they help in any way?

There has been a lot of posts on this before.<br /><br />Appearantly those fins (several makes) do what they claim and - what they often forget to mention - costs top end performance.<br /><br />Depending on what you are looking for it could be the answer.
 

steelhead1

Seaman Apprentice
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Jan 18, 2003
Messages
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Re: hydrofoils....do they help in any way?

thank you for your reply.i was looking to see if anyone has gained any speed from installing these.i have heard that the new stingray speed xp is the best to get.
 

ob

Admiral
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Aug 16, 2002
Messages
6,992
Re: hydrofoils....do they help in any way?

steelhead,the only speed you could possibly gain is out of hole throttle up.As UU points out you may even lose a few rpms at WOT.
 

Spidybot

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Re: hydrofoils....do they help in any way?

The issue is, that by adding the mass you pull below the surface you are adding to the drag.<br /><br />For hi-perf you'd go quite far to get most out of the water (jackplate, special props and even spicial design lower units).<br /><br />Those fins can help in getting on plane, lifting the aft, keeping plane on lower speeds.<br /><br />If you have powertrim and a good prop that would allow about the same AND give you several possible adjustments to improve top end speed.
 

steelhead1

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Jan 18, 2003
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Re: hydrofoils....do they help in any way?

thank you guys for your feedback.<br />scott
 

miloman

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Nov 3, 2002
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1,181
Re: hydrofoils....do they help in any way?

hi there stelhead other then getting you off plane faster a slightly better holeshot and lower paning speeds the fins really dont improve top end in fact like most have sadi they decrease top end<br />on a 90 di we tested this theory and in the end we did come with real clear # hole shot was improved by9% and top end speed was decreased by 11% so you do the math remember that when you install the product it will require you to drill holes in the cav plate and that isnt fun when you have to repair it
 

Dhadley

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Feb 4, 2001
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16,978
Re: hydrofoils....do they help in any way?

Ive gained speed on every one Ive installed. Remember -- the fin is a tool. The tool allows a higher X dimension. A higher X dimension means less drag from the gearcase. Less drag means more speed. <br /><br />We use the larger ones (Delta Lift and King Fin) on V4's V6's and V8's. They start at the front and extend back past the rear. They capture and "compress" water to the prop allowing for a better bite at a higher setting. <br /><br />We have used them to successfully control or eliminate chine walk and porposing.<br /><br />However, if they are mounted too low -- yes they will create more drag and slow you down. As with any performance tool, it has to be set up properly.<br /><br />Good luck!
 

walleyehed

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Jun 29, 2003
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Re: hydrofoils....do they help in any way?

Dhadley has her all right there....Each fin serves a different purpose, and when using these fins you must know what YOU want for the end result.<br /> I have also tested many Hydrofoils, and have found the most advantage to be hole shot, followed closely by porpoising, or the elimination of. And the biggy....Speed. On MY installation I gained about 2 MPH because on my Deep-Vee, it allowed me to lift (dimension X) my eng, and as a result the outer surfaces of the STINGRAY XP were still in the water-about 3" per side, and this was all it took to delete the porpoising, and I was able to go 1 step higher in pitch, and still obtain the same RPM-that was my 2-3 MPH gain yet a better hole shot.<br /> Some boats, it's a bolt-on and go, but most will require a little tweaking if you want to find the edge....... :D <br />By the way, Dhadley knows his S**T about this, follow his recommendations closely.<br />Good Luck!
 

steelhead1

Seaman Apprentice
Joined
Jan 18, 2003
Messages
40
Re: hydrofoils....do they help in any way?

thank you for the info.what is the proper motor height. how do u tell where it should be looking at the bottom of the boat straight across with the motor straight up and down.i have a deep v starcraft islander with a motor bracket extended out from the transom.how high up should the motor be mounted?<br />thank you<br />scott
 

walleyehed

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Re: hydrofoils....do they help in any way?

Scott, I'm running a Starcraft as well, only aluminum. The cavitation plate above your prop should be flush with the bottom of your boat for starters. If you are going to mount a fin, I would move up one hole at a time, and see how it performs-even try it first, as is, after you put the fin on, but the Cav. plate should be at least as high as the bottom of boat to begin with. alot of the set-up depends on your prop and at what point it will ventilate. :D
 

steelhead1

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Jan 18, 2003
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Re: hydrofoils....do they help in any way?

kenny my prop is a omc sst stainless.<br />thank you for your help.<br />scott
 

dakotashooter2

Petty Officer 2nd Class
Joined
Jun 10, 2003
Messages
125
Re: hydrofoils....do they help in any way?

No one addressed cornering with one of those beasts. My experience has been that they cause a lot of drag and probably torque on the lower unit when cornering at higher speeds. One would also assume that the metal foils probably cause less drag than the thicker plastic ones though the "flex" of the plastic ones is probably easier on the lower unit.
 

wayne h

Master Chief Petty Officer
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Apr 29, 2003
Messages
862
Re: hydrofoils....do they help in any way?

on bigger boats i have seen and heard that they are more trouble them they are worth. but on smaller lighter boats they seem to work well i have 1 on my 12 foot aluminum v-hull with a 9.5 on it.there is not alot of adjustments on that little and old of a motor so i tryed the Jr on it and it worked like a charm i plane easyer and it keeps the bow down when i am alone in the boat.yes it took away from my top speed alittle but i feel alot safer with the bow in the water and not in the wind so i dont mind losing a few mph
 

steelhead1

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Jan 18, 2003
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Re: hydrofoils....do they help in any way?

i dont think i will lose any speed because i have been dragging around a aluminum trolling plate on the motor for years that must have caused a lot of drag.i have just taken it off and havent run the boat in the water with nothing attached to the motor.i have trim tabs to keep my bow down maybe i should just run the motor with no hydrofoil instead of spending the $50.<br />scott
 

wayne h

Master Chief Petty Officer
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Apr 29, 2003
Messages
862
Re: hydrofoils....do they help in any way?

from what i understand you cant run trim tabs and a hydrofoil.
 

walleyehed

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Jun 29, 2003
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Re: hydrofoils....do they help in any way?

Dakotashooter2, I'm on the lake about 3 days a week with 1 of 3 boats that I own, and I've ran all 3 without the fins, and yes, the most difference is noticed on the smaller of the 3, a 17" Basstracker with 70 HP Merc. My deep-vee, an 18' starcraft with 115 Johnson, I can lift the bow more without porposing, and in effect gain more speed.<br /> Most people are familuar with the ole' stingray, but I don't think people are paying much attention to what is known as the "new XP"<br />it's not the same as the older(Last years model)version. It is made of a different material and the Hydrofoil shape is redesigned.<br /> As far as cornering goes, there is no more force on the fin in a corner than straight away.<br /> The simple fact is: If you want a 90 MPH boat, go buy a 17ft Bassboat with a 250 on it and go....The fins do exactly what they were built to do, 99.9% of the time.....If you want to turn sharper...slow down. I've played with trolling plates and the hydrofoils sinse Harold Endsly put his name on the stingray, and they all serve there purpose very well!!! If you've had a bad experience with a fin, chances are something else was out of whack.<br /> I even insulted JB, by saying I thought the SE300 was a joke.....I bought one right after that, drilled 2 MORE holes in my cav. plate and Now I have to apologize to JB, because It worked just as good as my XP, which taught me not to insult until you've tried it. There is no "exact science" for every boat. These are guidlines and I hope anyone who reads these posts gets a "feel" for what they might be looking for........ :p
 

walleyehed

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Jun 29, 2003
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6,767
Re: hydrofoils....do they help in any way?

Scott, BTW, it's not a real good idea to run both(tabs and fin), they are fighting against each other....<br />Good luck! :)
 

steelhead1

Seaman Apprentice
Joined
Jan 18, 2003
Messages
40
Re: hydrofoils....do they help in any way?

thanks to all of you for your respones and info.i will gladly take it into consideration on whether to purchase one or not.<br />scott
 
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