Hi Jerry,
Quite a project you have going on. I have a 38 as well. I have just got around to ordering some soundproofing insulation for Bonaventure (Paul referenced my boat earlier in your original post)last week. I have wanted to put it in my engine compartment for quite awhile. I find the engine noise travels up through the plywood overhead in the side lockers and right out through the locker doors. I ordered 2" foam with a vinyl boise barrier sanwiched between 2 1" pieces faced with the reinforced silver mylar. That is for the over head outboard of the hatches and forward of the hatches. I also ordered the 1 ' for the aft bulkhead. Forward bulkhead will have to wait until next year. Here is a link to the company I purchased from
http://www.soundown.com/
I will post some pictures when I get going on the job.
Good luck on your project.
George