Plywood under engine mounts

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Speakrdude

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Feb 25, 2004
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I am installing fresh 350 GM/ Alpha 1, Gen 1, in an 88 Bayliner 2455 Ciera Sunbridge.

Beneath the engine mounts, there is a 3/8 inch piece of plywood, paint matched, laying in between the stringers and the engine mount, on each side. They appear to be factory. I cannot figure out why someone would put those there. The stringers are solid. There is plenty of adjustment in the engine mount to compensate for the 3/8" plywood thickness. The tops of the stringer/mounts are nice and flat.

Any ideas?
 
Bondo

Bondo

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Apr 17, 2002
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70,524
Re: Plywood under engine mounts

Ayuh,... With shims, yer not backed Way out on the mount studs when tryin' to get it Aligned...

I'd put 'em back in... Try the alignment, 'n decide from there...
 
S

Speakrdude

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Feb 25, 2004
Messages
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Re: Plywood under engine mounts

I figured if I were to put em back, I might replace them with starboard. At least they would last.
 
W

wca_tim

Lieutenant Commander
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May 28, 2007
Messages
1,708
Re: Plywood under engine mounts

I found that some of the vibration damping style mounts are a bit taller than the standard mounts, and after going with the standard mounts I had to add a shim under the mounts. I used 3/8 aluminum stock... to get th mounts to be at roughly the same height that they were with the original mounts... Just a thought
 
Brentathon

Brentathon

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Dec 29, 2009
Messages
385
Re: Plywood under engine mounts

I would go with aluminum, also.
I HATE wood in almost all marine applications. It's too bad so many transoms are made with wood...........ughh.
 
T

telstar1

Petty Officer 1st Class
Joined
Jun 20, 2008
Messages
226
Re: Plywood under engine mounts

Wood does some good things re vibration damping sound deadening. Might be why they did that. Lots of aluminum boats have this plywood under mounts, I always assumed that to be the reason,not sure though.
 
Brentathon

Brentathon

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Re: Plywood under engine mounts

I wonder how that affects (or allows) any relative motion of engine-to-transom assembly. Given the exacting requirements on engine alignment to the gimbal bearing, I always thought that engines are installed into the hull (i.e. stringer) fairly solid..............at least, that's how my engine appears to be installed; on 3/4" Al brackets.
 
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