Transom reinforcing 34 Silverton for outboard conversion

[keysdisease]

The PIRATE House comment was a refferel to what locals call the PILOT House restraunt and tiki bar oceanside at mm100.

BTW, you won't be using any "cloth". As mentioned mat is what will be appropriate for between layers. As for the "knees" you will want to make them out of plywood laminated to at least 1.5" + and to be as big as possible, to at least go as high on the transom as the top bracket bolts and preferably be at least an equalateral if not reaching as far forward on the stringers as possible. I would also bolt them to the stringers as well as adhere and glass.

Steve

[naturewaterboy]

OH, de pirate house, yep, they rebuilt the place recently... don't make it all the way up there much...all of 2 miles away...hard to get back on my Schwinn when it gets late....

[naturewaterboy]

I'm gonna get some 12mm Okume plywood, put three layers with glass mat and plenty of (epoxy or vinylester resin between layers, cant them 10 degrees, stagger the joints (10 ft beam at the transom), screw them together every foot oc. The transom is about 60 inches hi at the center, deadrise of ? so about 50 inches hi at the sides.

The top 20" of the transom inaccessible without removing the entire cockpit (single piece 10' x 10' glass/resin structure). If I build up the bottom of the transom only, the bracket (with 2 x 300hp engines) will bolt up to the reinforced transom. I may end up cutting a door in the top part of the transom for easier access to the swim platform.

After doing all of this work, I want to insure the boat. I'm guessing that the insurance company will want some proof that this design was ok. Any suggestions on how to find someone qualified to look at the design, give me some sort of ok?

[naturewaterboy]

I finally finished reinforcing the transom with 6 layers of 3/8" okume marine plywood with 1.5 oz glass mat between, and a final layer of biaxial. Turned out to be just over 3" thick when I drilled thru for the bracket. I haven't put the braces in yet, figured I should bolt the bracket on first so I don't block any bolt holes.

This turned out to be more work than expected - like most of my projects. If I had to do it over I'd weld up a steel framework for the reinforcing. Getting 10 ft. wide pieces of plywood in there was a problem - I had to cut each layer in half to fit them in place in the bilge. I could have used them full size if I'd have taken the cockpit floor out - but this would mean taking the whole damn boat apart.

The other part that made it difficult was that I screwed each layer down with about 100 screws per layer, cause the transom is curved 24 ft. radius. This didn't look like it was much curve, but when I started screwing it down, in order to get the ply to follow the transom, I needed screws about every 6 inches. That made about 300 screws going thru the glass transom - that I had to cut off, divot out and patch.

Now I'm working on mating a used 4 engine Stainless Marine bracket made for a flat transom boat to my curved transom.