Adding a drain plug.

Amkev14 · Aug 20, 2024

Hey everyone, I have a 12 foot Montgomery Ward Sea King that apparently wasn't made with a drain plug and I would like to add one. The rear wall of this boat is thin aluminum and I'm looking for help on the best option without the need for welding if I can avoid it. Thanks guys.

lckstckn2smknbrls · Aug 21, 2024

Look up Garboard plug.

Amkev14 · Aug 21, 2024

I kinda figured that was the route I was going to have to go. I was just curious if there where any other options. Would you happen to know what type of sealant would work best and would last?

lckstckn2smknbrls · Aug 21, 2024

3M 4200 or 3M 5200

airshot · Aug 21, 2024

Haven't looked for one of these in years but...way back when, there was a two piece add-on drain for boats, one with a male thread and the other half a female thread. A hole was drilled ( guessing about an inch) then these two haves were screwed together sandwich ing the hull in between. Used a couple of these in my youth, early ones were a bronze type but later ones were plastic material. Back then found in hardware stores....today ??

Weldorthemagnificent · Aug 22, 2024

Airshot..Bulkhead fitting?

airshot · Aug 22, 2024

Weldorthemagnificent said:
Airshot..Bulkhead fitting?

Not sure what they called it, but just a male threaded half then a female threaded piece that sandwiched the hull in the middle. Left a 3/4-7/8" thru hole that a plug would fit into. I used those expanding rubber plugs to plug the hole once the two pieces were installed. Back then we just added some sealant to both halves to keep it from leaking. No idea what it was called, but installed a few over the years in the transom of my aluminum boats that did not come with a drain.

thill · Aug 23, 2024

Here is the kit I use to add drains to my boat. It was just thin aluminum, so this kit worked best:
https://www.ebay.com/itm/375217811973

You put the flare part on the inside of the boat, then the spacer, then you use the flaring tool:
https://www.ebay.com/itm/1-Drain-Tu...rine-Plumbing-Replaces-520290-1-/375541547600

You really need the spacer to give the drain tube some depth for the plug to grab onto.

Also, I have found that the tool works best if you lightly grease all components, including the dies. I also add permanent sealant, as mentioned above, as I don't trust a rubber O-ring for long term service.

Once you have the kit, and it's cheap enough, you can add drains to anything, like coolers, livewells, fiberglass boats, etc. You can buy the tube by the foot.

I also use flared tubes when going through bulkheads. Good for passing fuel lines, control wires, etc. through without risking having them get cut on the aluminum over time.

A relateive cheap but very effective and permanent solution.

I hope this helps.

Amkev14 · Aug 23, 2024

thill said:
Here is the kit I use to add drains to my boat. It was just thin aluminum, so this kit worked best:
https://www.ebay.com/itm/375217811973

View attachment 122377

You put the flare part on the inside of the boat, then the spacer, then you use the flaring tool:
https://www.ebay.com/itm/1-Drain-Tu...rine-Plumbing-Replaces-520290-1-/375541547600

View attachment 122378

You really need the spacer to give the drain tube some depth for the plug to grab onto.

Also, I have found that the tool works best if you lightly grease all components, including the dies. I also add permanent sealant, as mentioned above, as I don't trust a rubber O-ring for long term service.

Once you have the kit, and it's cheap enough, you can add drains to anything, like coolers, livewells, fiberglass boats, etc. You can buy the tube by the foot.

I also use flared tubes when going through bulkheads. Good for passing fuel lines, control wires, etc. through without risking having them get cut on the aluminum over time.

A relateive cheap but very effective and permanent solution.

I hope this helps.

I assume this tool is used to flare the other end, so with the spacer on is there any part of the tube that has to be cut down so it will flare correctly?

DaleH · Aug 23, 2024

Yes, the straight tube end needs to be cut to length. To allow for the bend radius I leave them about 1/4" longer as they stick through the hull.

At only $11 now, those flaring tools can't be beat! I remember when they were really expensive, or very few Dealers had them and would NOT loan or rent them out, so we needed to come up with our own DIY methods, like this!

Stevum · Nov 26, 2024

Amkev14 said:
I kinda figured that was the route I was going to have to go. I was just curious if there where any other options. Would you happen to know what type of sealant would work best and would last?

I had to install a drain plug on 2 aluminum boats that I have owned. The most convenient & economical method I used was to take the plug style you intend to use with you to the hardware store & find a small connection fitting of PVC that fits the outside diameter of your plug along with a nut that fits the thread pitch & a couple of rubber gaskets. Use a hole saw that will allow the fitting to go through the transom, drill the hole out and slather each side of the washers & fitting with a flexible silicon caulk & thread them together for a compression fit. Make sure when you plan where the hole will go you leave enough distance from the floor of the boat to allow the nuts on the fittings to be completely flush with the transom for a proper seal. After you have it positioned & snugged it down you can apply more silicon caulk around the whole system (I use a rubber glove to smooth out the caulk with my fingers for a better seal & appearance). I let mine set for 48 hrs before inserting the plug & using the boat. Just my 2 cents

DaleH · Nov 26, 2024

Stevum said:
... apply more silicon caulk around the whole system (I use a rubber glove to smooth out the caulk with my fingers for a better seal & appearance).

... just be AWARE that the curing agents in some/most silicones attacks aluminum, as it is acid based ...

I don't apply any goop to a tin boat without white vinegar acid etching, then priming the area 1st.

Stevum · Nov 26, 2024

DaleH,
Thanks for the tip....as stated in my post I was looking for a quick & cheap solution to the problem. I know you're not supposed to use treated lumber that will contact aluminum as it is also corrosive. How quickly does this process occur & to what extent? Are we talking something like the Alien blood in the movies or just some discoloration over time? Thanks for the feedback!

Adding a drain plug.

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