Drain Plug/Water in boat

I've got a 82 SN that I've owned for 4 years and it's been a great boat for something that's coming up on 40 years old.
As you would expect after several days on the lake people in and out of the boat swimming/skiing you'd expect some water near the drain plug. Recently I'm ending up with 1/2 to 1 gallon of water on the floor by the drain plug. I cleaned the threads on the base and bought a new brass T grip plug with no change in the result. I then thought maybe I was getting water leaking from an intake hose and ran the boat down the lake with the dog house open and didn't see anything?

Any thoughts? Do I need to replace the plug base from underneath the boat? Should I apply some 3M 5200 sealant on the bottom?

Thank you in advance for your help!
-Mike

A gallon of water in the bulge after several days is hardly excessive, IMO.

JQ

Our guesses are as good as yours. If you look hard enough you’ll find the leak.

Mine leaked under the rub rail.   Like HW

THANKS JQ! that makes a lot of sense to me..There wasn't noticeable water from cooling system, hoses while running, drain plug area while floating with dry bilge, or prop shaft. So if I detect water near rudder is the solution to repack the rudder? That sounds like something out of my ability, how involved is it? Guessing I should take it in...

Anyone have tricks to clean the bilge? I usually dump dawn dish soap in there and pull the plug to let some water in. (Lightly suspended in my lift of course). Then let it slosh around in the bilge for a few hours. This has given me mediocre results. I may just have to get a brush with a long handle to get under the engine etc from under the aft floor panel.

I will check the speedo tube as well. In fact the previous owner took the original air speedo tubes out and replaced it with GPS speedo. The former holes I assume are filled from the inside with epoxy or something there is some sort of black adhesive covering the holes from the outside of the hull all of which is obviously below the water line. Anything you would recommend using from the inside on those holes if in fact there is leakage from there?

Another way to double check for leaks is to put water in the bilge with the boat on the trailer, and dry. Not a ton of water, but enough to slosh around and see what happens.

Someone might say I'm nuts to suggest this, and I'm comfortable with that!

I've done it before ..... in a jet boat, not inboard. Good way to see if the water intake is properly sealed.