How do I quiet down my SISU?

[hibanx]

I have a 22' SISU with a yanmar diesel. The engine box has foil backed soft insulation lining the underside, but it is still really loud. Any suggestions where I can reduce the noise level? I know I need to address the engine box seal where it meets the deck, but I am at a loss as to where else I can reduce noise.

 

[Frank]

If the deck has raised combing that the engine box sits over see if you can get some old 2 1/2" or 3" canvas jacket hose from your local fire station. They pressure test hose annually and if the hose doesn't make the grade they repair what they can and dump the rest. Split the hose at one of the creases (it stores flat when not charged with water) and fit it over your engine box combing. It made a world of difference on my Sisu and stops any creaking when the box shifts around from sea conditions.

 

[tunaorlater]

I am not sure what you have, Quality sound proofing material helps.

Soundown - Barrier Acoustic Insulation, Carpet Underlay, Acoustic Absorption Materials

 

[Dr Dude]

Loud Sisu

Hibanx,
I have a Fortier 26 w/ a Yanmar 230 and I have played w/ this for a long time. I finally ( by accident ) sent my prop to Hale in Conn. and they wound up getting rid of excess vibration and I also got the latest material from Soundown (seen in a previous post above) and it isn't a church BUT it's a hell of a lot better.
My Yanmar has a loud spot (2300-2600) which was a pita. That spot is now much more tolerable and the whole boat is much more comfortable.
Hope this helps.