88 Ski Supreme Steering Problem

I have a 1988 Ski Supreme. I have checked the fins below, the steering seems to be good and everything on the drive train is tight. I can go about 35-37 mph with no problem but when I get to about 40 or above the boat tries to steer to the left. It is everything I have to hold it from diving hard to the left. If I muscle it and try to steer it to the right the boat tries to nose into the water and it can hardly turn the steering wheel. It is like something else is tryin to turn the boat other than the steering. If I get under about 15mph or stop the boat and let it dive to the left then take off again I have complete steering and control of the boat again. It has happened mostly in rough water. I have taken the the rear seat out and everything looks good! I was out this weekend and noticed it again. If the boat starts to hop going across a wake or some thing it will do it again. I try to steer it back and the boat seems to be nosing over into the water like one of the tracking fins under the boat is turning. I checked it out and the front fin points slightly, I am talking 1/16th of an inch, to the direction it always trys to steer to when the front of the boat bounces out of the water. Can this slight turn in the fin only affect the steering of the boat when the front comes out of the water and grabs water?????? Just a question? I can run at 45mph in smooth water all I want, but if the front end hops out of the water slightly I am history, it starts to turn left. The out drive mount and rudder mount was redone because it had struck something and I noticed the prop is pitched just off center to the left in relation to the prop, but I think this is normal. I know a quick fix, just don't go over 35mph, but I want speed. Please HELP,
Thanks in advance for any help given.

Eric

Sounds like the mis-alignment (however small) of the fin is causing this. I have a feeling that when you hit a wake, the fin is 'grabbing' air and changing the water flow and causing the fin to create lift in that direction. At a slow speed you wouldn't notice it as much or at all because their isn't enough water velocity over the fin to create this problem. It would be a similar principal as prop cavitation. I would have your dealer re-align your fins. I just had this done, less than $150 bucks in labor. I had hit a stump when I was turning and bent all three fins. I have a SN and all the fins were custom drilled when they were originally installed, so the new holes didn't match up. I had the dealer fix this because I have been told by several people that you'll never get the boat to track right unless you get it perfect. I don't blame you I'd want speed also. I like to take a quick barefoot run every once in a while.

Thank you for your responce, but I found out the problem. I called Ski Supreme and they admitted there was a problem with this year boat. When the hull was designed it was designed a little thin and created areas on either side of the engine about 6 feet from the rear of the boat. There is a long span on either side of the engine that is actually weak and concaves in after excessive force is applied to it. This flexing changes the shape of the surface and the boat sucks down on that side and pulls the boat hard on whichever side concaves. He said it was just strong enough not to notice it when it was new but a few years later it would soften up just enough to cause this. The rep told me how to fix it but said it was too old of a boat for them to warranty. However, doesn't Ski Supreme warranty their hulls for life???????????/ There are no soft spots even in the floor!!! This problem is not from use but a design flaw..... shouldn't they pay?

I hope this helps someone else in the future?!

Thanks again for the responce,

Eric

As a matter of fact Supreme does warranty their hulls for life- AFTER 1999. And so does everyone else. But as for old A@@ boats NO they do not. This is why Supreme nowadays is a much better company than before. www.northwestmarine-ski.com