Improved boat performance with a hydrofoil

techwriter

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Joined
May 19, 2009
Messages
13
First I would like to mention that I was sold on the idea of putting the self adjusting trim taps on a boat that I had recently purchased. I bought the tabs from iboats and when I got the boat off of the lift at the marina and brought it home to install the tabs. I discovered that I could not mount tabs on my boat because of the way the hull is designed.

I now had no choice but to try a hydrofoil that mounts on the motor and I would like to share how it worked out with anyone that is interested. There may be others that cannot fit tabs to their boat. By the way I returned the tabs to iboats for a refund and that was no problem at all.

I did a lot of research before buying and I picked the SE Sport 300 Hydrofoil because it seemed to have the best reviews from what I could find. I found that some people do not like hydrofoils and many more think that they are great. From what I have read self adjusting trim tabs should work better but there is no place to install them on my boat because of the way the hull is designed.

In considering a hydrofoil to improve something about a boats performance it seems that these add on devices are to make up for deficiencies in the hulls design. It is the law of physics that when you improve in one area you will usually lose in another. With the Sport 300 it is my experience that this is not necessarily so, at least in my situation.

I wanted something to stop my boat from porpoising when I was trimmed to the most efficient angle. I was also hoping to increase fuel economy as so many of the reviews that I read said that it would. The Sport 300 corrected both of the problems. I originally thought that my boat lost some of the top speed with the hydrofoil installed. I soon figured out that the speed loss was due to poor fuel and the higher speed has since returned.

I have read reviews where they said that the hydrofoil cut their top speed. I wonder if they made certain that the cavitation plate was high enough for the hydrofoil to ride on the water and not in the water at speeds that has the boat on plane.

Even if it did cut the top speed by a couple of miles per hour I would consider that a fair trade for the increase in fuel economy provided by the Sport 300 as it increased fuel economy by 40%. I would have never believed it possible. Another benefit is that I can now make sharp high speed turns without a cavitation problem. I can also now keep it on plane at a slower speed than I could have before without the hydrofoil. According to the boats speedometer the minimum plane speed was about 20 MPH without a hydrofoil. With the Sport 300 it will stay on plane down to about 10 MPH. That is difficult to read for sure since 10 MPH is the minimum that my speedometer will read.

The fuel consumption is based on the amount of fuel used to travel the same distance meaning the same point A to point B to point C and so on with and without the Hydrofoil installed and all other variables being the same on the same lake. With my boat, once on plane fuel economy seems to be about the same at slow speed or at high speed. I have never operated it at a continuous WOT.

My boat is a 16' open bow runabout ski boat that never pulls skiers or anything else. It has a 110 HP 2 cycle Evinrude outboard motor. Total listed empty weight of the hull and motor is 1520 pounds. On top of that is 16 gallons of gasoline to start with, about 50 pounds of equipment including the anchor, myself, my wife and the 90 pound yellow dog.

If you are trying to figure out if a hydrofoil could help with the performance of your boat. I hope that this information will help you. With the high price of gas at the fuel dock the Hydrofoil 300 has already paid for itself in less than the first three uses of the boat that was used for short trips. That is a total of about 70 miles. If I would have bought the gas at a gas station rather than at the fuel dock it would have taken about 5 trips for it to pay for itself.

The downside to the hydrofoil in my situation is that according to the guy at the marina. I cannot mount a trolling motor on top of the hydrofoil and expect the trolling motor to work properly. He is probably right. I will probably not trade that kind of an improvement in fuel economy for anything.

Obviously there are other brands of hang on the outboard motor hydrofoils. The other brands may work as well or better. I picked the SE Sport 300 Hydrofoil because I found the least amount of negatives from ratings of all of the hydrofoil ratings that I could find.

I still think that the self adjusting trim tabs would have been a good to possibly better choice if I could have hung them on my boat.
 

5150abf

Vice Admiral
Joined
Aug 12, 2007
Messages
5,808
Re: Improved boat performance with a hydrofoil

I am going the other way this weekend, I am gonna take mine off and see what the difference is.

Can't measure mileage but last time I had it out it ran 28.7 gps with my foil on it, made mine myself from 3/16'' aluminum, kinda like one I saw in Cabelas but they wanted like $200 for it, I made mine for $0 and it works really well.
 

countvlad

Chief Petty Officer
Joined
Jun 29, 2009
Messages
439
Re: Improved boat performance with a hydrofoil

I am going the other way this weekend, I am gonna take mine off and see what the difference is.

Can't measure mileage but last time I had it out it ran 28.7 gps with my foil on it, made mine myself from 3/16'' aluminum, kinda like one I saw in Cabelas but they wanted like $200 for it, I made mine for $0 and it works really well.

i had a hydrofoil on mine for few months and didnt really see the diffrence at first because at the same time i had a SS prop installed.. but once i removed the hydrofoil i gained about 300 rpms and better bow lift so i dont think im going to put the hydrofoil back any time soon...

from what ive been reading hydrofoil works for some boats doesnt work for others... give it a try.. good luck
 

techwriter

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Joined
May 19, 2009
Messages
13
Re: Improved boat performance with a hydrofoil

countvlad, I hope that you will let us know how you made out by removing your foil.
 

fishrdan

Admiral
Joined
Jan 25, 2008
Messages
6,989
Re: Improved boat performance with a hydrofoil

I removed the hydrofoil from my outboard (7.5HP, 14' jon boat) to see how the boat would do with out it. The change was horrid, took longer to plane and top end dropped off since the boat's bow was riding too high, even after adjusting the outboard's tilt pin. I couldn't wait to get the foil back on the outboard, just did it a few hours ago... :D

I wouldn't run down and get one from my recommendation, just saying it works very good on my small boat.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: Improved boat performance with a hydrofoil

i had a hydrofoil on mine for few months and didnt really see the diffrence at first because at the same time i had a SS prop installed.. but once i removed the hydrofoil i gained about 300 rpms and better bow lift so i dont think im going to put the hydrofoil back any time soon...

from what ive been reading hydrofoil works for some boats doesnt work for others... give it a try.. good luck

C V
Your correct, they don't work on all boats, if the boat/motor comb needs one and its set up corrctly, then you shouldn't loose any top end, or have handling issues. On an I/O you don't really have a way to do much fine tuning, so while it may help in some ways, its not the correct tool.

T W
On a O/B (if needed) you can set it up and possible see improvements in performance, nice to see it worked for you.
 

countvlad

Chief Petty Officer
Joined
Jun 29, 2009
Messages
439
Re: Improved boat performance with a hydrofoil

countvlad, I hope that you will let us know how you made out by removing your foil.

I did :)

CountVlad said:
i had a hydrofoil on mine for few months and didnt really see the diffrence at first because at the same time i had a SS prop installed.. but once i removed the hydrofoil i gained about 300 rpms and better bow lift so i dont think im going to put the hydrofoil back any time soon...
from what ive been reading hydrofoil works for some boats doesnt work for others... give it a try.. good luck



im not going back with the hydrofoil... i mean yes it was better from hole shot, bow didnt go up in the air but running WOT or cruising i wasnt able to trim the bow much and didnt seem to help... plus i gained 300 RPMS by removing it...
 

techwriter

Cadet
Joined
May 19, 2009
Messages
13
Re: Improved boat performance with a hydrofoil

Here is a picture of the stern of my boat. As you can see there is no place to put the self adjusting trim tabs.
 

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mickjetblue

Chief Petty Officer
Joined
Aug 23, 2007
Messages
509
Re: Improved boat performance with a hydrofoil

I have had similar improvements with the use a a hydro-foil.
I have used 4 different ones, and agree with your findings.

I think there is a threshold of weight where the trim tabs are more
advantageous, and that is probably on boats where the total weight
is more than 2,000 to 2,500 lbs. That is my ball park guess, with no
technical expertise to back it up. There are many other factors that
enter into this improvement or none, and some things are experimental
to the situation.

Enjoy your boating!

Guess that covers it, somewhat....
:rolleyes:
 
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