If your not on the boat 24/7, I would suggest a bolt.
~ 5/16" with a washer gasketed with butyl tape. Push it in from outside and put a nut on it. If you use the nut to push the plug inside, you'll hardly leak a drop. This would probably be safe for a season. I have seen plugs like this serve in 500,000 chemical storage tanks for years... which is a little frightening (the gasket material varies with the chemical).
(when asked how he reached the starting holds on a difficult rock climbing problem that clearly favored taller climbers - he was perhaps 5'5")
"Well, I just climb up to them."
by Joe Brown, English rock climber
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.