Drain plug rot prevention

[NWVintage]

So, my drain plug has never seated 100%. It's always gone in snug but has always leaked a very small amount of water if I didn't wrap it several times with thread tape. It turns out that the fitting was cracked! I'm replacing it and I am wondering if there's anything that I out do to treat the wood that's exposed between the fitting and the drain tube. I've inspected closely and it's not rotten but continued exposure doesn't seem like the best solution... This is for a fiberglass boat with a wood-core transom. The drain tube is about 1/4" too short to reach the back of the plug fitting. Do I need a longer drain tube that makes contact wit the drain plug fitting? All will be bedded with 5200 but that little space between the two literally ALWAYS has water in it and that seems like a bad situation...

 

[jigngrub]

. The drain tube is about 1/4" too short to reach the back of the plug fitting. Do I need a longer drain tube that makes contact wit the drain plug fitting? All will be bedded with 5200 but that little space between the two literally ALWAYS has water in it and that seems like a bad situation...

Your drain tube is 1/4" too short because the plywood in your transom is saturated and has swollen up that 1/4".

You can get a new longer tube and install it, but that won't fix your wet transom wood.

 

[jigngrub]

I have 3 drains in the transom of my MFG:

... and the transom wood was swollen just as you described, they all looked 1/4" short. They also weren't flared on the installation side, nor were they sealed.

I removed the wood core of my transom:

... and it came out in 2 pieces. The center of the core where the drains were leaking was rotten to mulch, but the wood 6" on each side of the center was still solid... completely saturated with water, but still solid.

 

[littlerayray]

Do some core samples near the drain holes

 

[NWVintage]

Your drain tube is 1/4" too short because the plywood in your transom is saturated and has swollen up that 1/4".

You can get a new longer tube and install it, but that won't fix your wet transom wood.

I supose that's possible but that would mean that the whole transom has swollen uniformly despite the fact that the drain is the only entry point...

I have 3 drains in the transom of my MFG:

... and the transom wood was swollen just as you described, they all looked 1/4" short. They also weren't flared on the installation side, nor were they sealed.

I removed the wood core of my transom:

... and it came out in 2 pieces. The center of the core where the drains were leaking was rotten to mulch, but the wood 6" on each side of the center was still solid... completely saturated with water, but still solid.

I had a boat with a transom that looked almost that bad. This one doesn't...

 

[jigngrub]

I supose that's possible but that would mean that the whole transom has swollen uniformly despite the fact that the drain is the only entry point...




I had a boat with a transom that looked almost that bad. This one doesn't...

Yes, the whole transom will swell uniformly. Wood naturally absorbs water and distributes it throughout the entire piece, that's how trees get water from the ground to the leaves.

Your transom doesn't look that bad... yet. Your encapsulated transom core will never dry out and will eventually decompose into mulch since it has become wet, it's only a matter of time.

 

[NWVintage]

Yes, the whole transom will swell uniformly. Wood naturally absorbs water and distributes it throughout the entire piece, that's how trees get water from the ground to the leaves.

Your transom doesn't look that bad... yet. Your encapsulated transom core will never dry out and will eventually decompose into mulch since it has become wet, it's only a matter of time.

Good to know...

 

[Woodonglass]

Got any pics???

 

[Flukinicehole]

When I installed my new transom I tried to alleviate this problem. I made the hole for the drain about 1 1/4" then filled it with PB. I then drilled for the drain plug. This will keep any water in that area from getting to any wood. You might want to consider this if you can access the area.

 

[tpenfield]

Ethylene glycol ( aka automotive antifreeze) is a rot preventer and supposedly will migrate through wet wood fairly well :noidea: I had similar concerns on the plug of my past few boats, as the folks at the factory typically drill into the transom and just install the plug assembly. So I put the plug in and poured some EG into the bilge and let any exposed wood around the transom soak up up for a few weeks.

 

[Yacht Dr.]

Yes..you should get a longer fitting. No..your transom didn't expand out 1/4" or the glass would be all busted out. And no..your transom does not have leaves or roots on it thus it does not act like a tree

Seriously though..you inspected the wood and no rot. So if you bed your new one in there with 5200 you should be good in that department. Put a threaded one on there if ya have to.

 

[NWVintage]

Yes..you should get a longer fitting. No..your transom didn't expand out 1/4" or the glass would be all busted out. And no..your transom does not have leaves or roots on it thus it does not act like a tree

Seriously though..you inspected the wood and no rot. So if you bed your new one in there with 5200 you should be good in that department. Put a threaded one on there if ya have to.

Thanks!


That's my plan!

 

[GWPSR]

I believe he's talking about a garboard plug (threaded flange with an NPT plug). They are seldom longer on the neck than the thickness of the hull. I cut my transom so that there was a 1.5" radius around the drain, Cut a 1 1/8" PVC pipe 1 1/2" long, then cut it in half lengthwise. That was glued to the inside up against the opening like an upside down U, and the space between the PVC and transom wood filled with peanut butter. The flange should also be sealed with 5200 around the neck, and a bead on the inside flange face, as well as each screw being bedded in 5200 as well.

 

[Woodonglass]

Does your drain look like this?

 

[Yacht Dr.]

I believe he's talking about a garboard plug (threaded flange with an NPT plug).

I do believe your right..but Im talking about a threaded through hull style garboard plug. They are extra long..one sec..

Like this http://www.forespar.com/products/boat-marine-plumbing-garboard-drain.shtml