New Motor, listing problem??

[Keith G]

Here's the scoop. About 12 or so years ago my Grandfather replaced his Evinrude 33hp (1960's vintage) with a 1989-1990 Evinrude 48 Special. The boat is a 1960's Glassmaster rated for 60hp. The boat has been babied and garaged at all times except for 2 week vacations up until 1991. Ever since this new motor has been on the boat, the boat torques to one side at wide open throttle. Imagine something really heavy sitting on one side of the boat. The boat tracks straight and planes out well. There is no shuddering or anything, it just feels unstable when turning due to the leaning. The problem is only from 3/4 to wide open throttle. Research I have done point at listing being the problem. Any ideas on eliminating the problem? I have been looking at self adjusting trim tabs or a prop switch. The prop on the 48 is huge compared to the prop that was on the 33. Speed is not an issue. This boat is used for fishing and I'm in no great hurry to race to a spot, but I'd like the boat to feel stable when I open the throttle all the way.

 

[roscoe]

Re: New Motor, listing problem??

Is the motor centered on the transom?

 

[Keith G]

Re: New Motor, listing problem??

Yes it is, professionally installed and that was the first thing I checked. FWIW this motor is bolted to the transon where as the old motor was clamped on. It utilizes a hydraulic cylinder that can be locked into various angles, not power trim though.

 

[ob]

Re: New Motor, listing problem??

On a small easy planing boat ,weight distribution is a must.Particularly when up on plane as the least amount of the hull is in contact with the water.Even a 50-60 lb. fuel container in the wrong place can create an issue.I'm thinking this boat rigged with the 48 spl in place of the 33 is getting the boat higher out of the water and the weight distribution is more critical.<br /><br />Does the steering seem to pull to one side or the other when boat is planed out?If it does ,move the rear of the adjustable trim tab on the lower unit in the direction of the pull and watercheck until the final placement can be attained that wi8ll afford the best all round steering feedback.<br /><br />This is of course assuming that the engine is indeed mounted on center and level side to side.

 

[Keith G]

Re: New Motor, listing problem??

I have already adjusted the trim tab. The steering does not pull to either side. I have tried weight distribution to no avail. It helps the boat ride slightly more even, but the steering stability is still spooky. ALso if it helps the boat is 16ft with approx a 5.5ft beam.

 

[ob]

Re: New Motor, listing problem??

Where is the engines anti-ventilation plate when timmed level ,in relation to the bottom of hull at the transom? Even? above? below?

 

[Keith G]

Re: New Motor, listing problem??

Not sure what you mean. Cavitation Plate? I'll need to stop by my Grandparents and take a look.

 

[ob]

Re: New Motor, listing problem??

Cavitation plate ,anti-ventilation plate.One in the same.Insure that it is roughly even with the bottom of the boats hull when trimmed level.<br /><br />Also ,you can play with the tilt/trim rod placement until an optimum angle for operating is attained.