Correct way to fill in a thru hull hole

[FishStretcher]

This one looks to be 14" above the keel as you travel along the surface, maybe 10" vertically from the "keel"under the port bunk. I don't know the anatomy of the boat well yet, but I think the head discharge was above it near the waterline- I can see a patch for a larger hole a bit forward and up higher. I hope it is more than 1/4" thick there. Let me see if I can find a picture. If it is a 1/4" then that's a lot easier to deal with though.

edit-

The first photo here-
http://www.classicseacraft.com/commu...3&postcount=37
You can see the old head discharge (?) thru hull, it has been filled since this picture was taken. Plus a little bronze one lower and further aft. That is the one that I hope to fix.

Bottom line is that I need to look at it harder and see what I am up against. Other than a rotting thru hull with a pipe plug in the hose that is attached to it!