Filling a drilled hole

[boatless 4 now]

A while back I looked at a boat sitting on the hard. The bilge was filled with water as someone had left all the hatches open. I am thinking about. Urging this boat but have found out the the yard drilled a hole from the bilge to the hull to Drain the water. ?????? How would I proceed to fill this so it be water tight? I was thinking of grinding down the outside , removing some material from the hull, fill with thickened epoxy and than re-glassing the hull. Will this work?