Plug the hole with some dowel stock, use some 5min epoxy to make sure
it doesn't move. Also make it flush with the transom. Now you can
redrill the hole off-set to the larger size.
:: My stern drain holes are leaking around the rubber :: stoppers and I want to correct this by boring bigger :: holes and putting in a about a 1/2" pvc pipe with plug :: in each hole. Problem: the existing holes are about :: 1/8th inch from the bottom of the transom. Suggestions?