vibration from air conditioner

[Jim Hardesty]

I just installed an air conditioner, an Ocean Breeze 16,000 btu.  The installation came out very well, everything but the duct work fits under the v-berth.  The problem.  When the compressor is running it vibrates the whole boat.  You can feel it (bare footed) standing on the cabin top.  The sound is a low drone, loudest in the head.  The AC unit is mounted on 3/4 plywood, sits on 1/8 rubber and 1/2 foam (antifatigue mat) and rubber bushings between the screw heads and the unit.
What can be done to isolate the AC unit?   Rubber mounts come to mind, but where to get them?
Jim

[Steve McGill]

Jim,

When I first read your post I thought I wrote it. I just installed a Flagship Marine 16.5K BTU unit in the same location as yourself. glassed in
a shelf and bolted the unit to it. I thought this weekend I would put down rubber between the unit and the shelf. It appears you have done that
with little success. I am trying to determine if rubber bushings at the attachment points bolted to the shelf will isolate the noise, not sure it that will provide sufficient support for the unit.

On eBay, searching under rubber bushings they offer rubber stock that you/we could cut to size or an automotive type rubber bushing may help.

As is often said here, there are not questions that have been asked before.

We can only hope for a positive response/s

Steve

[Jim Hardesty]

Here is what I did.  I had some half inch foam floor pads left from the pack bought from Big Lots for $12 for protecting the cabin sole during the AC instillation.  They looked like they would stop some vibration.  I carpet taped some under the vberth lid and laid some beside the hull.  I bought more.  At $12 I was generous, only making sure air flow was not affected and keeping them away from hot spots. 
It helped a lot.  The only noticeable noise and vibration is in the head and the vberth and it's not much.  Going to try it overnight and see, worst possibility is that I may have to move to the aft berth.
Took some pictures, but having trouble getting them here.  The floor pads are half inch foam about 3' * 3' with interlocking edges.  One side smooth one side sort of a diamond plate, I put the diamond plate side to the AC unit.
Still have some finishing work to do on the AC instlation, don't like the metal air return grill, and just prototyped a box for the AC vents in the vberth.  That will wait till end of season.  Perhaps replace some of the foam pads with engine sound proofing foam.  Always more to do.
Jim

[Ken Juul]

Mine vibrate....that's how I know they are working!  Jelly fish (nettles) and eel grass are a big problem in the Chesapeake.  I can tell from the change in noise level when the water strainer is getting plugged.  20+ years around jet engines and Rock and Roll, maybe my ears aren't as sensitive as yours.

[lazybone]

We have a rotary type compressor under our V-berth and have no problems.

My quess is that your unit is a piston type which is both noisier and prone to vibration.

[Jim Hardesty]

To improve and make permanent the sound proofing I'm considering
http://www.sailorssolutions.com/index.asp?page=ProductDetails&Item=SPM01
Has anyone used them?  To what success?
Jim

[Ron Hill]

Jim : I'm sure that the compresser itself has its own rubber bushings - are they all OK??

The next item to check is the platform the compressor unit sits on - is that touching the hull??

[Jim Hardesty]

OK.  Yesterday I got to Joe, at Ocean Breeze, he thought that my compressor got out of balance during shipping.  Told me to loosen the 3 mounting screws at the compressor then re-tighten with the compressor running.  It helped, if it would have been this smooth and quiet at first perhaps I would have been satisfied.  Now I'm on a quest for quiet.  Going to buy the soundproofing tiles.
Jim

[Roc]

Doesn't the Flagship Marine unit have a rotary compressor, which should be quiet?

[lazybone]

Their site I think says they don't use "scroll" compressors which are very quiet.

but I can't find any reference to what they do use.

If your really curious you could just look at the info-plaque on the compressor.

edit: Just look again and they use Emerson compressors.  They make Scroll type and reciprocating, no rotory.