Hydrofoil recommendation for 13

Optimizing the performance of Boston Whaler boats
jeopardy954
Posts: 13
Joined: Sun Jul 09, 2017 2:07 am

Hydrofoil recommendation for 13

Postby jeopardy954 » Fri Aug 04, 2017 10:44 am

Hello all. I'm thinking of adding a hydrofoil to my [1979] SPORT 13 with a [1995] Mercury 40-HP two-stroke-power-cycle engine. Everything I've read so far on the forum makes it seem like a great addition, gives more stablilty and better on-plane performance.

What brands of anti-ventilation plate foil extensions have people used with success? The brands I've found for sale are the SE, Stingray Jr, and the original Doel-fin. Does anyone have experience with any of these, on a 13 or similar?

Thanks,
Pete

macfam
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Joined: Fri Oct 16, 2015 9:24 pm

Re: Hydrofoil recommendation for 13

Postby macfam » Fri Aug 04, 2017 2:19 pm

On our 1987 13 Super Sport we used a StingRay Jr with our 2000 Johnson 40, and then on our 2010 30 E-TEC.
I believe they work excellent. It allows a slower planing speed for choppy conditions, and faster planing and better trim. It also helps prevent "transom squat". We had power trim and tilt on both motors. I also recommend that the motor be mounted high enough that the hydrofoil is on top of the water at full speed. If it drags under the surface at full speed it will diminish performance.

We now have a 150 Montauk with a Mercury 60 EFI Bigfoot. It does not seem to have any handling faults and planes beautifully with trim adjustments without a hydrofoil. So, I have not installed one.

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dg22
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Re: Hydrofoil recommendation for 13

Postby dg22 » Fri Aug 04, 2017 3:23 pm

I also had good results with the hydrofoil. I have a 1967 13-footer with a 1973 Evinrude 50-HP. I purchased the SE Sport. It was easy to install on the lower unit. I drilled and bolted-on the hydrofoil in about 30 minutes. The engine is mounted 1-inch higher on my transom. I didn't have any performance loss from the hydrofoil. It reduced the porpoising with me alone in the boat and keeps the bow low when getting on plane. It also makes the boat feel more stable.

jeopardy954
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Joined: Sun Jul 09, 2017 2:07 am

Re: Hydrofoil recommendation for 13

Postby jeopardy954 » Sat Aug 05, 2017 6:47 am

Great, thanks for the help. Sounds like both options are good.

So if I have this correct, the foil should be above the level of the water on plane?

Thanks,
Pete

macfam
Posts: 129
Joined: Fri Oct 16, 2015 9:24 pm

Re: Hydrofoil recommendation for 13

Postby macfam » Sat Aug 05, 2017 8:31 am

Ideally yes. The hydrofoil is attached to the anti-ventilation plate, and in virtually all cases of planing hulls, the plate should be above the water line when on full plane. It is very common to have the plate just below the water, which affects performance. When I say above, it's not by much. Often less than an inch, but it's not causing excessive drag.

Having the plate too low causing drag, in itself, can contribute to porpoising.

One of the top-five questions on this site has to do with engine mounting height. All too often engines are placed too low, even by manufacturers.

mn car guy
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Joined: Sun Apr 09, 2017 6:52 am

Re: Hydrofoil recommendation for 13

Postby mn car guy » Sun Sep 16, 2018 10:58 am

I have a 13 Dauntless with a Yamaha F50. I tried lots of different propellers and also changed the engine mounting to get rid of [a tendency for the bow to oscillate up and down when on plane], but nothing helped. [The 13 DAUNTLESS] would still bang and was slow to plane.

This summer I bolted-on an SE. It made a huge difference. [The 13 DAUNTLESS] snaps-up on plane at lower speeds and is stable as a rock. I recommend [bolting on an SE brand anti-ventilation plate foil extension].

jbillon
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Joined: Thu Jan 25, 2018 1:23 pm

Re: Hydrofoil recommendation for 13

Postby jbillon » Mon Oct 01, 2018 11:42 pm

I have a old 1971 13-footer with a 2018 Tohatsu 30-HP short shaft engine with trim and tilt. The Tohatsu engine weighs 180 lbs and I am 215 lbs. The 13-footer would porpoise at any throttle above half-throttle, until I added a lot of weight to the bow seat. With 240-lbs of sand bags added to the bow seat, the 13 would plane just fine. But that was not a solution.

I added an SE Sport 200 [anti-ventlation plate foil appendage to the Tohatsu 30-HP engine} and the porpoising stopped. I am thrilled.

Now the propeller does not lose as much bite in turns as without the foil.

I have a 13-pitch aluminum propeller. Engine speed decreases to 5,900-RPM from 6,000, and boat speed decreased perhaps 1-MPH--but, honestly, the decrease in boat speed is really hard to tell.

With the foil, now with me and wife aboard [the 1971 Boston Whaler 13-footer] will easily cruise at 28-MPH. If the river is glass-flat and if I trim-up the engine then the boat speed will reach exactly 30-MPH.

And a very pleasant bonus is [the 1971 Boston Whaler 13-footer] will jump up on plane very quickly--which is great.

jimh
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Location: Michigan, Lower Peninsula
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Re: Hydrofoil recommendation for 13

Postby jimh » Tue Oct 02, 2018 12:38 am

JBIL'--when you added the anti-ventilation plate foil appendage, did you then remove the 240-lbs of weight added to the bow?

jbillon
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Joined: Thu Jan 25, 2018 1:23 pm

Re: Hydrofoil recommendation for 13

Postby jbillon » Tue Oct 02, 2018 1:35 pm

jimh wrote:JBIL'--when you added the anti-ventilation plate foil appendage, did you then remove the 240-lbs of weight added to the bow?


Yes I removed all of the extra weight from the bow seat, and the foil still worked great.

I only chose the SE Sport because some reviews said it was better at not grabbing seaweed or grass. It has a much more forgiving angle that moves the grass away and off of the foil instead of holding and accumulating the grass. And I have noticed that it does perform this way.

My next thing to try will be to move the 60-lbs deep-cycle battery from directly behind me in the stern to just in front of the mid-seat on the port side. I figure that will be a 120-lbs swing from back to front. Then to see if this further helps performance. I think it will.

Having a lot of fun. Would much rather fish than play with my boat anytime, so I am very glad to have this porpoising thing gone.