What's causing the boat to list?

[TUGBOAT]

84
They make a Torque Tab (T-H Marine) It helps to eliminate some of Your right hand steering torque.Screws on the bottom of Your hull.But if You had Tabs down , I don't think this is Gonna Help !! Did You check Yet & see if Your Cupped.I'd like to follow this one thru.NOT that I want this Problem (Or Expecting)My bet is Your engine is not PERFECTLY straight up & Down.The faster Ya go the More list/twist You'll get .
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Scream'n Reels' [img]images/icons/confused.gif[/img]

[PipeDreamsMarine]

Well... I've seen a hook caused by many things. Most common is from sitting on a trailer that was not adjusted right. Too much of the boat hanging off the back unsupported. Thus caving-in the last 2 to 3 foot of the boat, making a reverse trim tab to say. This will make the stern lift or in your case lay over at speed. If the boat hasn't been this way long it may come out just by reblocking the boat on the trailer to hold the boat the right way or use a bunk trailer. You may have a soft spot in your hull and underpower the hull will buckle causing the list. I would put a straight edge on the hull and look for cups in the hull, they will be large in size and width. Once you find it then you can figure out what caused it and then how to fix it. I know the hook fin is for taking out feed back in the steering, but I've seen it work for list to a point. Does this happen with the motor trimed up or down..Do you trim your motor up and use the tabs?. I had a 25 grady that would roll at speed like you say. Though watching someone else run the boat for me and riding on another I notice that the motors where kick under when trimed down. I moved the pin up one hole and the boat never did it again. Your motor may be causing the problem try move the motor down one bolt hole and put the trim pin back one hole so the motor doesn't kick under as far and use the tabs to bring the bow down. you could be running to flat and the boat is chine walking and falling over to port because of the motor rotation.

[ScottM]

Eric,
That fin is located on the lower unit on the underside of the trim tab. It can be rotated to counteract prop torque.

[Jason LaVey]

Pipe Dreams...I'll check for the cupping. The boat is currently on, and has been for the last two years that its not in the water, on a bunk trailer. This may be a dumb question but should the cup appear on the port or starboard side. And if there is a large cup, how can it be corrected?

[barnacle]

Like Don said there is a good chance the bottom developed a hook to it causing this problem. It is hard to find and is best done by someone that knows what to look for. Most of your fiberglass shops can make this type of repair.

[Jason LaVey]

Don, Thanks for getting back to me. I checked the hull with a four foot level, and nothing unusual. The boat is sitting on a bunk trailer. I measured the motor mount, 33 inches from port to motor mount and 32 inches from starboard side to motor mount. Could that one inch offset cause that much of a problem?

Also, the boat settles down with a full load of gas, only as it empties does the problem get worse. The tabs don't completely push it over, and if I trim it too hard with the tabs it just dumps the bow down and still dives to port. Craziest thing I've ever seen. Regardless of the trim positioning of the motor, the problem is persistent. It is mounted on the highest hole on the motor mount, no pin on my Merc. And its a 175 so no problem with power, it will top out near 50 mph. Any other ideas? Also it has a four blade prop. and a big T-top on it, but I don't think that would cause the problem. Jason [img]images/icons/confused.gif[/img]

[Eric McNiff]

Thanks Scott - much appreciated. I will try adjusting slightly.