1968 14 Foot Mirrocraft rebuild

Today was aluminum covers for the under seat foam flotation. The original was steel and it rusted something awful. I am using a wrap around with minimum sharp edges. New wood is pressure treated. Electric shears are incredible to use instead of sheet metal shears.

:WELCOME: thanks for joining - you may want to rethink the treated lumber it may have bad effects on the aluminum

Well see how smart it was to join a site where we can share ideas and information. Thank you for the information. I looked it up and it is the reaction of copper in pressure treated lumber and moisture which causes the aluminum to be eaten up by electrolysis. A barrier is needed between the two materials. I want to keep the pressure treated for its resistance to rot so I will install a barrier. I am going to look into using tape (McMaster 76015A66, 7621A11, or 6031T898 perhaps) in the contact area of the wood strips. Maybe just shipping tape for cardboard boxes would be enough as the wood is immobilized.

The other problem I have not addressed is filling the voids in the foam that is encased in the seats. Can home construction foam in a spray can be used for flotation fill and stand up to salt water?

Putting a barrier between the pressure treated wood and aluminum won't fully protect the aluminum. When the pressure treated wood gets wet the copper will leach out of the wood and get on the aluminum.
There are several ways to seal wood that will give you many many years of rot protection without damaging the aluminum.

I appreciate the information on pressure treated wood and aluminum. I am going to paint the inside of the seat and then use a tape barrier to prevent contact between the wood and aluminum. I feel the water will not be significant under the seat area and the sun here will keep it baked out. I would never use it now (thank you) against the hull or the stern. I have to replace the stern wood and I thing a good plywood will be OK.
I had a major electrolysis problem at the depth sounder transducer stainless steel mount which ate a huge hole through the hull. Stainless steel bolts I used at the stern and seat support brackets also caused terrific corrosion. I am going to use plate aluminum 6061 to sandwich cover the area and use aluminum machine screws to fasten. In the stern I plan to use aluminum 3/4" rods through the stern wood sealed with epoxy with aluminum machine screws perhaps 1/4-20.
I got replacement rivets from Mirrocraft and they were easy to install with the help of a neighbor holding a sledge hammer for backing support.
I asked Mirrocraft what to seal the boat seams with and they said any good household caulk. If it is the same crap they use around the tub then none of it is worth a flip. I was thinking 5200 but what about painting over it? Anyone had experience with it? I have also used a car body product I think was 3M that was used to seal welded seams in unibody. It could be painted over and stayed flexible. I wonder if it would work on a boat.
Reading about other peoples projects here has been very helpful.
I also added a picture that shows the damage of stainless steel to aluminum.
You may also notice the boat metal was anodized. I used paint remover to get rid of the old paint. I am not scraping or sanding the hull as I do not want to damage the anodizing. I have always used brush painted Rustoleum inside and out but this time I am going to spray paint with a paint gun.