What Is The Best Way To Seal The Exposed Transom Wood In The Drain Hole. Do They Make A Sleeve Or Should I Use A Silicone. Thanks In Advance.

If it's dry, I would mix up some fiberglass resin and soak it into the wood.

TRYING TO GET IT DRY NOW THIS NO RAIN IS HELPING.THANKS

I just did t his in my brand spanky new transom, but I might have erred on the anal side.

I cut the new hole (same size as original) with a spade bit.
Then cut the new tube about a quarter of an inch longer than the total transom thickness.
Drilled down into the 'new passage' from the inside of transom at a 45deg angle with a bit the same size as the tip of a syringe.
Put a bead of 5200 around the outer lip of new tube and inserted it in place from the outside of trans.
Mixed up an epoxy micro-baloon paste and sealed around the inside of tube. Then filled the syringe with epoxy resin and gently injected enough down into the drilled passageway to soak around the new drain tube in its new hole. After a while the new wood stops soaking up the resin and you just seal off the drilled hole with a little more epoxy paste.
Done carefully this should NEVER leak water into the new transom.

Mind you , it's all a waste of time if you don't pay the same attention to your transom cutout and bolt holes too. (Which I also did )
Like I said .... anal ..

This is one of the areas that I found rot in my transom, also 1 k-plane and where the swim platform mounts.

Did away with the drain plug, have 3 bilge pumps instead. 3 layers of resin around and through all transom holes.

Dont want to do a transom ever again

cement

concrete