Here's an inside view of the muffler. This was before we finished up the glass on the tubes, they are just stuck on there with cabosil and resin in the picture. We got those glassed in and the middle wall glassed in after the photo. On the top, we are going to do the top half at a time, like the left half and then the right half, so in the middle we can tie the top to the partition with at least one layer of 1708. We got it cut down to floor height though so it fits right under the floor nicely. I did make a mistake, I wasn't there when they stuck the tubes in to the sides (where the air enters and leaves the muffler), I would have liked to see them about 3-4 inches deeper, but it didn't happen and I don't think it makes that much difference. If I get some noise on the transom, that's why, but it's kind of fun to experiment, I know it'll knock down 90 percent of the noise either way.
Here's my Engineering plans which I made with Paint!
And then spent the rest of the morning building birdcages! Birdcages are 2 inches strips of 5/16 plywood that we use to make a pattern so we can cut out the corecell when it gets here. We are sticking it together with a nail gun, which is not OSHA friendly, but you can also use a staple gun, and I've seen some people use hot glue, although that would be painfully slow. Hopefully by the end of the day we will have the rest of the birdcages done and the muffler stuck to the floor, and I'll stick up some more pictures later!
We are going to do bulkheads at 24 inch centers, that's what we did on the gamefisherman and my other 28 footer, and those floors are very stout, so I'm sticking with it! Here is the strength of 1/2 inch corecell with 1 layer of 1708 on each side. This was placed perfectly between the bulkheads on top of a hatch opening on my other 28 foot boat, and I didn't know the floor could hold this up but it did nicely:
The motor weighs about 1300 pounds plus the transmission, so if it'll hold that, we should be alright walking around on it!