Brian, what is your stance on drilling scupper holes through the motor boards. In my case it would be one each just outside the foot print of the jack plate mount. I bought 8”x4” ss and plan on using a glass tube that requires 1 3/4”x5” hole. In my case with raised decks the hole pretty much centers on the router slot
It’s pretty much exactly what Chuck is doing, except my transom is structural meaning no hull extension
It's OK, but reinforcement is never bad. I'll explain...
When the 2 LVL motor boards are glued onto the transom plywood, and the forward face glassed (even if slotted for drywell), the motor boards effectively become a really wide beam on it's face. The LVL that's used is rated to have (if I recall) 2" holes through it ... if they are 2" or more from the edge of the 'beam'. In your case, your scupper 'ovals' are close enough to that rule and a long way from any edges of the 'beam' and fine if the rest of the transom is built as-is. THAT said, if you're going to put larger holes through the transom for larger scuppers, an extra layer of 10-oz or even biaxial plus woven (wet on wet, 6+ oz biax covered by 6+ oz woven) wouldn't hurt. I'd run the reinforcement glass the full length of the transom, inside and out, and about 8-10 inches wide, centered vertically over the scupper holes. The reason for inside and outside is that fiberglass is only strong in tension... when the transom tries to flex outward, the outside glass takes the strain, and vice versa for the inside glass. BUT, this is somewhat overkill and optional. If caught early enough in the build process, I'd do it. If not, then I wouldn't worry about it. Don't forget that the bottom of the drywell gives the transom a lot of stiffness too ... not to worry.