Transom rebuild, what is strong enough?

[gcornelisse]

I've just, hopefully, completed rebuilding the transom in my 1984 Tide Craft Spitfire bass boat. I guess I'm having second thoughts as to whether or not I built it strong enough and so I'm looking for some of your thoughts....

Let me tell you what I've done:
- cut away the inside skin and thoroughly removed every last hint of old wood for the transom and the first 48" of the stringers that supported the transom
- removed as must paint, gel coat, and loose fiberglass from the surrounding areas as reasonable that would later be covered with new fiberglass
- cut a 2 new transom layers and stringers from good quality 3/4" oak plywood. Stringers are 3 layers of 3/4" on one side and 4 layers on the other mostly to fill space.
- treated both pieces of plywood and new plywood stringers with CPES from the Rot Dr.
- sanded everything down with 60 or 80 grit sandpaper and then wiped everything with lacquer thinner
- Using non-blushing epoxy resin (instead of polyester or vinyl ester resin) reinstalled the transom and stringers making sure there were no voids or large bubbles. We did have a little trouble getting the transom to bond flat to the old outer skin. We poured a thin batch of resin between the skin and the transom in several places to make sure everything was solid. We also laminated the two pieces of transom plywood together with one layer of fiberglass as it was being installed in the boat
- For added strength we used 2" galvanized threaded rod to span between the new transom and the sidewalls of the transom area into the old built-up fiberglass. These were installed in holes between the 2 transom layers through to holes in the old walls of the transom area. While fiberglassing in the new transom we put these pins in with a thicker mix of resin.
- covered the outside of the transom skin with 2 layers of fiberglass that came over the top to the inside. And, overlapped the sides of the transom covering at least 6" of old fiberglass
- 2 more layers of fiberglass on the inside coming over the top to the outside alternating with the layers originating from the outside of the transom
- added 2 more layers of fiberglass at the top of the transom covering at least 4-6" inside and outside and overlapping the old fiberglass to the sides
- the stringers were bedded with thicker fiberglass mat to the bottom of the boat and to the transom. I used a slightly thicker mix of resin to fill and hold in the gaps and imperfections between the boat, transom, and layers of the stringers.
- stringers were fiberglassed with 2 layers to cover exposed wood.
- used wide strips of fiberglass covering the connection between the transom and stringers. These strips were also alternated between the layers of fiberglass used to cover the transom.

The boat was originally design to take up to a 90hp outboard. I've only got a 35hp on it now which should be adequate power. I took a lot of old fiberglass out of the boat while taking the old transom out. In some places it was 1/4" or more. I'm suspicious about using that as a gauge for how much fiberglass I need to put back in simply because I can tell that the transom has been replaced once before by someone who took much less care than I have. However, I still want to make sure I've got enough support for the weight of the engine and the wear-n-tear its likely to get through normal use. Do I need to build up more layers of fiberglass for added strength?

PS - I'll post pictures in a minute...as soon as I find the transfer cable for my camera

[gcornelisse]

Swiss cheese


New transom laminated in place and clamped just enough to hold in place, but not enough to push the resin out


Outside of the transom with 2 layers of fiberglass and 2 more strips at the top for extra strength


New stringers fiberglasses in and lightly screwed into the transom with pocket screws...mostly to hold it in place while it sets up. Used wide strips of fiberglass alternating with skins on the transom to span the 90 degree joint between stringer and transom