Re: transom questions
I am in the process of going thru this as we speak, let me give you some up to the minute on-the-job info. I just gutted a '78 Sylvan Sea Master... new floor, new transom, new wiring, new lower unit.
Use Marine plywood for the transom, it is far superior to the Outdoor plywood, stronger and more stable, marine has more plys and no voids. My outdoor plywood warped when just sitting around, the marine stayed in shape no matter what. I paid $79 for a sheet for 3/4" as compared to $39 for outdoor ACX, the marine was worth every penny. I used outdoor wood with polyester resin for the floor, I wish I knew then what I know now. I probably would still have used outdoor for the floor but no question I would have used epoxy over polyester. I would not be suprised if you made your transom and by the time you tried to bond it the warpage would make it tough to fit. Prime example, I cut out my transom and didn't bond it together for 2 -3 days, when I did, they fit perfectly. My outside transom piece that cushions the motor against the outside of the transom warped so bad that I had to soak it with water and set a trolling motor battery on it to straighten it out, I then let it dry out straight before coating it.
Use epoxy resin instead of polyester resin, again far superior, full strength to laminate the two sheets of plywood and then cut with 10% acetone or MEK to seal the entire assembly. I used Max Bond A/B low viscosity, got it on Ebay. $20 worth was enough to do my transom, top transom pieces, new dash panel, outside motor cushion on the transom, and still have some left over. Another side benefit, the polyester resin stunk so bad that it literally drove my neighbors off their deck when I did the floor, on the other hand, epoxy has a mild odor and work time was 80 minutes rather than probably 15 with the polyester.
Here is a link to the epoxy that I used... seems to be great stuff. If you have questions, call them, their tech support was fantastic.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280255931847