help with leak

[garycorbett]

On my old 70s V20 I have a leak around the drain hole in the transom - I think it is leaking behind the metal tube (in back of it) and the boat is getting a fair amount of water in it that the bilge pump handles but it needs fixing. In the meantime - what kind of tape can I put over the hole on the outside of the transom that will be watertight and adhere to the fiberglass? Or should I see if i can get a disc to screw on there that has a screw-in plug? West Marine? Thanx G