What noise reduction foam to use to reduce noise from bilge/engine area through side walls?

[trdehmer]

On my 1998 SeaDoo Sportster 1800 I get quite a bit of engine noise that travels up through the side walls of the hull (on drivers side, I'd put right behind the shift levers) - figure I could stuff some type of foam up the side walls to help reduce the engine noise. Anyone ever done this - thoughts on what type of foam to use that could be shoved into place?

 

[trdehmer]

Anyone ever tried the DEI Boom Mat to replace the egg crate/luggage foam stuff under the accessory engine cover? I want to reduce cabin noise as its loud right in front of the twin engines!

 

[To2d]

I didn’t use foam but I did make a silencer. Here is a link to my tread.

Home Made Speedster Silencer

Maybe this will give you some other ideas on how to quite it down.