I have a Jon boat I use for fishing small lakes. However, the plug in the stern doesn't seal out the water very well. I got another boat plug with the brass extension and added a little plumbers wrap, but that didn't work. I put vaseline around the rubber to soften it and that didn't do the trick either. Any ideas? Thanks

Please post pics of the plug and plug receptacle.
How long have you had it?
When did the leak start?
Are you sure the leak is coming from the plug?

I can't figure out an easy way to transfer images, but I'm sure the leak is from the drain hole. I got the boat used and it is about 15 years old. It has always had this leak.

Does your plug have a nut at the bottom which can be tightened to make it fill the hole better.
If not, go buy one at Academy.

https://www.academy.com/p/marine-raider-snap-handle-drain-plug

Thanks for the reply. That is the type of plug I have, But, I have just been bending the round extension at a 90 degree angle after insertion. Is that wrong ?

Great that might be the answer. Is Flex Seal easy to remove ? Thanks

You want to tighten the nut till you get a snug, leak free seal when you move the lever 90° to the sealed position. It is designed to be small enough to fit slightly undersize holes and to be adjusted to fit slightly oversized ones. Don't go overboard on tightening, just enough to stop it from leaking.
Good luck.

I have always thought it was a trial and error approach. Tighten the nut (clockwise) on the plug a little, insert the plug and fold it 90’. If it’s loose, pull it out, tighten the nut a little more, insert the plug and fold it 90’. Keep repeating until it fits snuggly.

You don’t want to over tighten the nut because the plug won’t fold over in the hole and if you force it to fold over, it could split the boat’s plug receptacle. I have seen several jon boats with split plug receptacles from forcing the plug to fit or stuffing other materials in there.

Thanks for the help !

If you are not worried about having a plug, I would silicone up the plug hole.