3" Drain Plug under Hull

[A.Parks]

Hello everyone !! I am new to boating and I have a question. I recently purchased a 1986 Sun Dancer 210B with a 4cylinder volvo and a 290A sp outdrive. The motor was not running when I purchased the boat but all I had to do was change a timing belt add a pertronix electronic ignition and change the oil. I have been using it for a bout 2 months now with out any issues. Here is my question though, I have a standard drain plug that I put into the lower part of the transom when I launch and then remove when I retrieve, standard right? but in front of my engine on the bottom of the bilge ( starboard side) there is another large drain plug. If you look under the boat there is a 3" in diameter black plug that comes up through the hull and has what appears to be a large plastic wing nut on the inside of the bilge. I always seem to have a little bit of water in the bilge when I remove the standard drain plug ( never bone dry) but not a lot. Yesterday we where out and I pulled the engine cover forward I could see a little stream of water flowing from that plug. So my question is what is this plug? should I pull it out and put plumber tape around the threads? should I even worry about it?

PS sorry for the long post!!

 

[briangcc]

Without a picture it's hard to tell but I would guess that you're actually looking at an in-hull transducer for a fishfinder/depthfinder. This is based off size and the wire going somewhere - probably your dash if you have a small round depthfinder.

Provided you have access, I would simply remove, clean, reseal, and reinstall which should remedy the leak. Don't use department store silicone for this as it won't hold up. Instead buy a marine caulk for below waterline use. I believe the guys/gals here rely on 3M 5200 but don't hold me to that.

Otherwise, post a pic and I'm sure someone much more knowledgeable than I can provide a better reply.

 

[A.Parks]

Thanks for the reply. Here are some pics of the said plug.

 

[StingrayMike]

yes, that is a thru hull fitting for a transducer, but what you have is the plug for the hole that you install when you need to pull the transducer for cleaning or replacement.. You can pull the transducer and install the plug while the boat is on the water. The plug has 2 or 3 orings that seal out the water. If the water is leaking from there, then you might just need to replace or grease the orings, but if the leak is from around the base, you are getting water into the hull. You should remove the thru hull and check for water damage and if lucky reinstall and reseal the thru hull.

If you don't need it, maybe look into getting it removed and fill/glass the over the hole.

 

[A.Parks]

Great!!! So I am going to go ahead and pull it off and then put new sealant on it and tighten it back down. I do not need a thru hull transducer I have one on the transom already so sealing this one is OK by me as long as it doesn't leak.

 

[StingrayMike]

where is it leaking from? if its from the the actual plug, then pull the plug out and take a look at the orings, hopefully they are still good and just needs some new grease. If you have the opportunity, it wouldn't be a bad ide to get new orings. I do not know the size, but if you pull one off you might be able to go and find new ones and grease them up.

You could try and just apply new grease to the old, but if it leaks, then you will have to wait to haul it out gain, unless you trailer it,

big question...... where is the water coming from???

 

[A.Parks]

It isn't leaking from the plug with the ring on it, it is from the piece that is sitting on the hull itself. The leak is not bad it is a very small amount. I can wipe the water away then a couple of minutes later there is a little line of water down to the lower part of the bilge. I've been running the boat for a couple of months and haven't had any issues. I check the engine compartment regularly when on the water just because, I guess I am a little paranoid as it is my first boat. I think I am going to loosen the wingnut lower the plug out and reseal it with 3M 4000 caulk then just reinsert and tighten. I do not use this plug for anything, the transducer for the fish finder is mounted to the transom.