Hydrofoil problem

jak2108

Seaman Apprentice
Joined
Oct 3, 2009
Messages
30
We have fitted a hydrofoil to our mercruiser 4.3L with alpha one drive. The boat is planing much faster but the boat leans to one side when planing. We have checked the mounting of the hydrofoil and it is central and square. If we raise the drive up slightly the boat levels out. I know many people dont like the hydrofoils but it was the most cost effective method of improving the planing we coiuld afford. Any ideas why the boat is leaning and what can we do to rectify it without trimming up???
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,468
Re: Hydrofoil problem

and what can we do to rectify it without trimming up???

Ayuh,... You have 2 choices,...
Trim it up,...
Or,..
Take it Off....
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,924
Re: Hydrofoil problem

The drive is supposed to be trimmed under power.
You start off,drive down then accellerate as you go faster hit the trim button up to raise the nose.You will hear it when you get the drive out too far.It will make the boat perform better as you have part of the hull out of the water.
Hydrofoils are ok but most boats when ran right don't really need them.J
 

jak2108

Seaman Apprentice
Joined
Oct 3, 2009
Messages
30
Re: Hydrofoil problem

We have been told that the boat should always be run with the drive all the way down otherwise damage can be caused. Is this incorrect??
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Hydrofoil problem

We have been told that the boat should always be run with the drive all the way down otherwise damage can be caused. Is this incorrect??

Yes it's incorrect. The drive has a certain range of trim. What you don't want is to run the motor with the drive up in the trailered mode.
You can trim the drive up to 21 3/4" as shown in the picture below. This will give you better speed and control. Trim too low and the bow will plow, you will not get full speed and your engine will be overloaded with low rpm. Trim too high, and the boat will loose speed and the engine rpm will go to high because the prop is coming out of the water. In the right spot you will have good speed, the rpms will be correct for the speed and the boat will run nicely.

attachment.php
 

Attachments

  • trim.jpg
    trim.jpg
    49.2 KB · Views: 0
Top