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AQ131D Noise level and setting up trim tab

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rasky333

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AQ131D

I think think the noise level from my engine is too loud. I sound insulated the engine cover, with little change. I am also getting a vibration through the hull that does not seem right. The engine is cantalevered off the transom, which I do not like.

How far, and which direction, do I adjust the trim/exhaust fitting, to neutralize the steering. My prop turns right, looking from the stern.
 
rasky333 said:
AQ131D

I think think the noise level from my engine is too loud. I sound insulated the engine cover, with little change. I am also getting a vibration through the hull that does not seem right. The engine is cantalevered off the transom, which I do not like.

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The reason sound insulation did not work is that most of the noise is in the form of vibrations transmitted thru the hull. The only sound insulation system that have ANY effectiveness use lead sheets.

Actually, the engine is technically not cantilevered off the transom. The weight of the engine when boat is not stationary, is more than balanced by the weight of the sterndrive itself plus the thrust vector of the propeller.
When at rest, the engine weight is only partially offset by the weight of the drive. So technically, the engine and drive are "balanced" on a pivot point on the transom. Volvo has used this system with success on small 4 cylinder engines since their first product in the early 60s and for small engines of low HP (relatively) it works very well. By contrast, outboard motors also represent pivot supported loads, with the attachent or pivot point, clamped to the transom near the center of gravity of the motor drive combo, instead of via a thru hole. Large HP I/O engines, rest part of their weight on mounts on stringers to the hull , while the outdrive still represents a pivoted load thru the transom.
 
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Hi Capt. Bob:

I understand the balance feature, which makes sense, but why is my engine so loud. I agree that much of the vibration is coming through the hull, I can feel it, but how do I reduce it? The transom mounting bolts look almost impossible to get to. My boat is a: 1990, 16', GW Invater, which is very well built, and in excellent shape.

Cheers: Jack
 
Invader, not Invater. I figured our the trim tab today. My adjustments had been too big. My Teleflex, rack and pinion steering, system has way too much slack in it. Another thing I have to fix. I am down to noise, and steering problems to solve.
 
Further "whence the loud".... if the exhaust boot (lower and smaller of two boots between the drive and the transom shield) is degraded or ripped, it will get a bit noisy. No marine engine is ever as quiet as a car.
There are good noises and not so good noises. Its hard to talk about definatively. Could you be a bit more descriptive?
 
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