Boat speakers- treating existing fiberglass to improve the "box"

[chazzy]

I'm replacing the speakers in an old sailboat with a pair of Rockford RM1562. They're mounted under the seat and are essentially infinite baffle... the seat is open to the cabin below. I'm only wanting to stiffen/deaden the fairly flat, 1/8-1/4" thick fiberglass panes that they're mounted in. The current plan is to just surround the speakers (1' radius or so) with dynamat. Any other tips?

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[audiobaun 5,000+ posts]

Id look at some ABS

 

[chazzy]

Id look at some ABS

Rethinking it, dynamat cars are space restrictive. I have basically no restrictios behind the wall. Could roughen up the fiberglass and glue something dense to it. Thick piece of abs/acrylic/some plastic sounds good. cementitious construction material like hardie board or something bathroom related?

 

[audiobaun 5,000+ posts]

Rethinking it, dynamat cars are space restrictive. I have basically no restrictios behind the wall. Could roughen up the fiberglass and glue something dense to it. Thick piece of abs/acrylic/some plastic sounds good. cementitious construction material like hardie board or something bathroom related?

Maybe Concrete Board also?( May last quite a while also?) if you are Inclined to work with it with a Diamond blade and Small grinder to make your cuts?Or Skill Saw? May be worth the effort? ABS is pretty Cheap

 

[TheRadio]

I would use a composite like Coosa board and a high grade epoxy resin.

A less expensive option would be to add layers of glass mat and resin.

When you're done it would be a good idea to use sound deadening to lower panel resonance.

 

[Bobbytwonames 5,000+ posts]

Maybe Concrete Board also?( May last quite a while also?) if you are Inclined to work with it with a Diamond blade and Small grinder to make your cuts?Or Skill Saw? May be worth the effort? ABS is pretty Cheap

We used to turn our Skil (one L) saw blade backwards when cutting Hardy, cement board, stucco, and even corrugated metal.

 

[hispls 5,000+ posts]

No reason you couldn't just glue a ring of plywood up under there then paint it with some bedliner or plasti-dip or similar to keep the elements off of it. Anything to add mass and rigidity would help.

That said, is the boat body so thin that a 6.5" speaker is really vibrating it and even needs reinforcing?

How easy is it to get up behind where the speaker mounts? Could you find some sort of 6" pipe to mount back there to act as a "box"? I'm thinking 6" PVC pipe end cap or something.

Can you post pics?