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Author Topic:   Hydrofoil Stabilizer
Paul D Ceglia posted 11-29-2003 08:22 PM ET (US)   Profile for Paul D Ceglia   Send Email to Paul D Ceglia  
I boat in a shallow bay that is for the most part 4ft. in depth. except for the channel which is 10-16 ft. I have a 17 ft. Dauntless with a Johnson 115 hp outboard and have a problem with bow rising when I attempt to accelerate. Will the hydrofoil lessen this problem as I am often un able to lower the engine to a proper depth?
cape_rover posted 11-30-2003 05:13 PM ET (US)     Profile for cape_rover  Send Email to cape_rover     
The simple solution is to place as much weight forward as possible. A more difficult solution might be to place the engine on a bracket. The farther back the engine is mounted, the higher you can mount it. The are a number of posts and some pics in the reference section on this solution.

I don't have any experience with the 'hydrofoil' but I don't think it would help. It might get you on plane faster but you would still be digging the prop into the bottom before you get on plane (assuming this is your problem).

Jarhead posted 11-30-2003 06:16 PM ET (US)     Profile for Jarhead  Send Email to Jarhead     
I've just mounted an SE Sport300 hydrofoil on my 115 4s Merc. It's on a 160 Dauntless.

Unfortunately I haven't had a chance to test it yet.

I'll report back when I've had a chance to get it wet. Hopefully this week...

Seagull6 posted 11-30-2003 07:48 PM ET (US)     Profile for Seagull6  Send Email to Seagull6     
This spring I installed a hydrofoil on my Starcraft 170LE - 75 4-stroke Mercury. The installation was a piece of cake and it changed the whole personality of the boat. It planes sooner than before and stays up on a plane at much slower speeds, something like 6 - 8 MPH dpending on the load. Adding weight up forward helps, but the hydrofoil worked for me.
Moe posted 11-30-2003 10:55 PM ET (US)     Profile for Moe  Send Email to Moe     
A hydrofoil will only help hold the bow down if the motor is trimmed vertical or in (down) past that. If the motor is trimmed out (up), the foil will help the motor lift the bow. If you really do have to launch with the motor trimmed out, you need trim tabs for the boat.


JohnJ80 posted 11-30-2003 11:49 PM ET (US)     Profile for JohnJ80  Send Email to JohnJ80     
I have a dauntless 15 with a 75HP evinrude FICHT on it.

I added a Grand island Marine Turbo-lift fin (requires no drilling). Hole shot was dramatically reduced as was the bow rise (much less).

I also have now added trim tabs because I need to control the attitude of the boat in the waters I boat in (I'm a little boat in big big wakes). this also allows you to keep the bow down big time.

Short answer - A decent fin will help you keep the bow down. I did not have as great of luck with a Sting ray (different motor though too, in all fairness).

Also make sure the vertical mounting of your motor is set up properly.


Tom2697 posted 12-01-2003 12:37 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
If you are trying to take off with the motor angled up. Not even trim tabs will help. As soon as you hit the throttle, the prop will try to squat the stern down. You will not have enough forward motion to benefit from the tabs. A jack plate will be your only help...
Moe posted 12-01-2003 01:56 PM ET (US)     Profile for Moe  Send Email to Moe     
I don't disagree with Tom. The trim tabs won't bring the bow down until you develop some forward speed.


lakeman posted 12-01-2003 02:54 PM ET (US)     Profile for lakeman  Send Email to lakeman     
Old florida trick or maybe you know this one. Start in a circle and create a wake then ride you boat into the wake and power up. It will give you a foot or more water to get on plane. The other devices work well also and help you to a quicker plane.
Tom2697 posted 12-01-2003 02:59 PM ET (US)     Profile for Tom2697  Send Email to Tom2697     
The other benefit of the circle trick is that, when running in a tight circle, the boat leans into the turn. This angles the outdrive up (versus being perpendicular to the bottom) and you can run a little shallower. Only problem is that this can eat up your prop if the bottom is sandy or hard and if it is will scar the bottom.
Jarhead posted 12-01-2003 05:04 PM ET (US)     Profile for Jarhead  Send Email to Jarhead     
Just got back from the Suwannee Paul. Here's the report as promised.

The SE Sport300 hydrofoil mounted on my 115hp Merc. 4s on a '03 Dauntless worked great. Faster on plane, smoother ride, stayed on plane at lower RPM, much lower bow rise both getting up and coming off plane.

However I don't think it did much to reduce stern drop on take off. Some perhapes but nothing substantial.

BTW. It was a beautiful day here. High in the low 70's, very little wind and blue skies....

kingfish posted 12-01-2003 07:00 PM ET (US)     Profile for kingfish  Send Email to kingfish     
"Hydrofoils" like Doel-Fins, with which I am familiar (used them on two Montauks, the outdrive of a 24' modified V cuddy and on my Outrage 22 until I got Lenco trim tabs), are designed to lift the stern as the boat is powered onto plane, which in turn keeps the bow down. They do a good job of that, and are an inexpensive solution absent trim tabs. If your motor is mounted at more or less the correct height, the 'foils will be above the surface of the water at full planing speeds, so they will not affect performance once on plane or at speed. They typically will allow slower planing speeds before falling off. The motor should not be trimmed "up" or "back" when using 'foils and trying to get up on plane, any more than it should be when not using them.


Badger posted 12-03-2003 08:35 AM ET (US)     Profile for Badger  Send Email to Badger     
I have used Doel Fins on my 17 montauk w/120 Evinrude and my 13' w/50 Suzuki. They were great additions to reduce the "bounce" in the bow and also help with hole shot. On my 13' it was like getting a new boat. Much smoother ride and greater positive steering control.

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