OK guys I need some advice on transom repair.I have all the wood out with some grinding left to do.Have a 1" lip where new wood will lay in and bottom of bilge as shown in first pic,should I bevel this down toward bilge floor so fiberglass will flow better? I also can't fit one piece of plywood in so I will have to piece in two sections per layer and stagger layers,thinking a 5/8" and two 1/2" to get my thickness.My question is should I cut these pieces horizontal or vertical?If I go horizontal I will not have to cut any stringers.Anybody replaced transon on a Mistress?
Thanks
Ben

Personally I would grind that lip all the way off. You should run the tabs out onto the floor about 4 inches or so.

As for the not being able to fit the 1 piece in, how hard would it be to seperate the hull halfs? That would keep you from having to cut the pieces.

Are you sure that the original transom was only 1 5/8" thick?

Jon

go with Cooza bluewaterboard to save some weight.

Yeah I think grinding down lip would help my glass lay better,as for taking cap off to fit one piece of plywood that would be a major job!!Cigarette really glassed cap down all the way around.The thickness of transom was 2"1/8' before tear out ,I got the 1" 5/8 from glass skin left to stringers.

Thanks I will look into coosa bluewater board!

I did mine with Okumee (marine Mahogony). Water does not penetrate Mahogony. If I had to put them in in multiple pieces then I would go with horizontal cuts on one layer and vertical cuts on the other. I would also put a layer of glass between the two layers of wood.

Audio, water does penetrate mahogany. Any ply will delaminate if it gets wet for a moderate length of time. Some are better than others due to the density of the grain and the glue used for laminating the plys together. The advantages of using the Okume ply is that it is tight-grained, dry-rot and worm resistant, and is laminated using marine-grade adhesive. It is very popular with wooden boat builders. It's an excellent material to use if you want to go back with wood for a transom.

CC yes you are correct I should have said resists water..

Coosa is 30% lighter and lots stronger!!!!!!! and will never rot.

The Coosa Bluewater 26 is a good product but probably not best suited for this application. You'll probably have an easier and less expensive project by using 3 layers of Okoume. I would orient the sheets vertically and use 8" offsets per side in the center. That gives you 16" of bonded overlap. You're going to have to cut back the ends of the stringers at 45 degrees to get the sheets in- it's unavoidable. Alot of Mistress owners replace the hatch center support with one fabricated from aluminum. It makes working in the engine compartment easier and you may have to do this to get the sheets in. If you need a pic, I can snap one off of mine.

For bonding the sheets in. I would make a template and fit the boards outside, then drill thru all the transom holes for pulling the sheets up. Then you'll need some back-bracing. Maybe just some pieces of 2" angle steel. This will help pull them tight to the transom. You might consider using glass mat to fill any voids between the transom and the first sheet. You could go all the way and use a heavy cloth between the transom and each layer and you'd never have to think about it. Since you're in there, line each thru hole with copper or brass tubing and epoxy them in. Then seal the outdrive cutouts with several coats of resin. This eliminates the reason the transom rotted the first time.