"Scott Vernon" wrote in message

OH! That's what I forgot to get at the chandlery yesterday. The
wood plugs I had ( they came with the boat) were still in the original
plastic bag but they turned to mush.

Obviously the plugs should be fairly soft, such as basswood, pine, or soft
maple (which is actually a hardwood, but a softer one). But those woods are
prone to rot, if allowed to remain damp for periods. Soak them in some sort
of oil, such as linseed, before storing them. Or you can make them from
teak, but they'll be more difficult to keep in a thru-hull after driving
them in.

Max