If the cutouts are not already sealed, I would use penetrating epoxy on them. No need to glass.

Bob

On the fence on sealing up cutout and applying 4200 on transom assembly...will be tackling this project in a few weeks.

Assuming you mean the foam gasket, as long as the transom is flat you shouldn't need any sealer. A little bellow adhesive in the corners between the gasket and transom assembly to help keep the gasket in place is all you need.

I agree, if your transom is flat you don't need any sealer. When I redid my transom I installed my new transom assemblies dry, still dry!!

Below the waterline, possibility of rotting the transom if it leaks, tough to see if it does, I'll put a thin layer of sealer on it vs worry about it or even think about it.

The sealant for me was added peace of mind. I know it isn't necessary and many don't use it. A little extra sealing can't hurt.

I'm removing one now that was installed dry, gasket shrank up and now it leaks BAD

Guess there is a first time for everything but never heard of a gasket shrinking. Most time it starts to leak is when the transom gets soft.

Boat has 200 hours, been out of the water for 4 years. Transom is solid and flat

Gaskets and any rubber material for that matter shrink, dry out, crack and eventually leak over time. What is everyone using 4200? Or something else? Thanks for the insight.