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Thread: Installing a drain tube

  1. #1
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    Default Installing a drain tube

    Before I assemble my jon boat, I want to drill the holes for two drain tubes in the transom. I plan to use 1 inch diameter brass drain tubes like this one:

    355511.jpg

    Read that to prevent rotting of the wooden transom by water leaking around the drain tube:
    - Drill a hole larger than the drain tube.
    - Fill it with thickened epoxy.
    - Redrill a hole through the epoxy to fit the drain tube.

    QUESTIONS:

    1. How much bigger than the drain tube should the hole for the epoxy be? I assume it has to be rather large to allow for the re-drilling not being perfectly parallel with the epoxy hole.

    2. How hard is it to drill a 1" hole through cured epoxy that was thickened with colloidal silica? (That's what I have)
    --- a) Would using 2 part epoxy putty be better?

    3. How high above the floor does the drain tube need to be to use either a screw type or flip type drain plug from the inside?

    Drain plugs Screw & Flip.jpg

    4. Any other advice?
    Last edited by DayTripper; 05-07-2022 at 10:36 PM.

  2. #2
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    Default Re: Installing a drain tube

    My thoughts really are that if you bed the drain tube in properly the idea of the epoxy is a redundancy that is unnecessary.
    I don’t think I ever saw a small boat with rot developing around a drain tube when I was growing up.

  3. #3
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    Default Re: Installing a drain tube

    I would use the epoxy as needing compound, then the hole is exactly the right size.
    If you need to remove the tube for any reason, a bit of heat will release it.
    I would put it right at the bottom of the hull so that it fully drains.

  4. #4
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    Default Re: Installing a drain tube

    I feel your need to seal it but I’d only drill it 1/16” over size and seal it up with a couple of goings over with epoxy, sand it, then goo it in. As far down as you can get it.

  5. #5
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    Default Re: Installing a drain tube

    Firstly, don’t use brass, it has very poor corrosion resistance in a marine environment. Instead simply use an off the shelf plastic transom drain plug - cheaper, easier to install, won’t corrode and is made for the job:



    You can easily drill through the epoxy once the hull is finished, though you must seal the end grain of the ply that will be exposed when you drill through that.

    Also with these transom bungs you can still the hole pretty much at it’s lowest point level with the bottom of the hull so that it drains properly
    Larks

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  6. #6
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    Default Re: Installing a drain tube

    use just the epoxy.
    no tube
    it's ridiculous

  7. #7
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    Default Re: Installing a drain tube

    Quote Originally Posted by wizbang 13 View Post
    use just the epoxy.
    no tube
    it's ridiculous
    And put whateveryouchoose for plug on a tether, so it stays close when it pops out.
    I prefer true but imperfect knowledge, even if it leaves much undetermined and unpredictable, to a pretence of exact knowledge that is likely to be false

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  8. #8
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    Default Re: Installing a drain tube

    Quote Originally Posted by DayTripper View Post
    Before I assemble my jon boat, I want to drill the holes for two drain tubes in the transom. I plan to use 1 inch diameter brass drain tubes like this one:
    ..... snip .....
    NedL, Slacko and Andrew,
    Thanks for sharing your thoughts and tips.

    .................

    Larks,
    Thanks for reminding me that brass can corrode in salt water. Saw that mentioned about screws.
    Have not been able to find a source for the flat bottom bung housing in the US. Learned that TENOB is in New Zealand.

    It appears that the bung & housing is installed on the outside of the hull. I wanted to pull the drain plug to drain water while the boat is in water and underway. But I could live with the drain plug on the outside of the hull and not drain water while underway.

    The bottom of my transom will be 1-1/2" thick. So to install that type of bung and housing, I assume:
    - drill the hole through the transom.
    - seal the 1-1/2" of hole in the transom using unthickened epoxy.
    - Install the bung housing on the outside of the hull.
    - Is that it?

    Thanks.

    .....................

    Sp_clark,

    Yes, having the plug on a tether so it doesn't get lost is very important. Thanks.

  9. #9
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    Default Re: Installing a drain tube

    I might do it a different way; a slightly oversize hole with a couple of coats of paint and then bed the tube in a generous splodge of Sikaflex.It won't leak and it does have a little flexibility.Brass wouldn't be my first choice for salt water use.

  10. #10
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    Default Re: Installing a drain tube

    Quote Originally Posted by John Meachen View Post
    I might do it a different way; a slightly oversize hole with a couple of coats of paint and then bed the tube in a generous splodge of Sikaflex.It won't leak and it does have a little flexibility.Brass wouldn't be my first choice for salt water use.
    Thanks. I'm investigating a DIY tube using 1" Schedule 40 PVC pipe. That would eliminate the brass problem for salt water use. The 1" T-handle and snap-handle drain plugs shown in the pictures in my original post should work in the 1" PVC pipe and I'll be able to pull the plug from inside of the boat while underway.

  11. #11
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    Default Re: Installing a drain tube

    Listen to wizbang.

    Jeff

  12. #12
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    Default Re: Installing a drain tube

    Quote Originally Posted by DayTripper View Post
    NedL, Slacko and Andrew,
    Thanks for sharing your thoughts and tips.

    .................



    The bottom of my transom will be 1-1/2" thick. So to install that type of bung and housing, I assume:
    - drill the hole through the transom.
    - seal the 1-1/2" of hole in the transom using unthickened epoxy.
    - Install the bung housing on the outside of the hull.
    - Is that it?

    Thanks.

    .
    That’show I’d do it.

    You should be able to get transom bungs anywhere, the one that I showed was just an example. Here’s another:
    https://www.velasailingsupply.com/ro...gaAvKDEALw_wcB
    Larks

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    “Give it a try”, whispered the heart.

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  13. #13
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    Default Re: Installing a drain tube

    Yep - thats the way I'd do it too.

    But i wouldn't discount Wizbangs idea - fill the hole with epoxy, drill to 1" and use one of those expanding cam style plugs in that hole.
    It's all fun and games until Darth Vader comes.

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    Default Re: Installing a drain tube

    Quote Originally Posted by gypsie View Post
    Yep - thats the way I'd do it too.

    But i wouldn't discount Wizbangs idea - fill the hole with epoxy, drill to 1" and use one of those expanding cam style plugs in that hole.
    Had no idea that's what he was saying.
    Thanks.

  15. #15
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    Default Re: Installing a drain tube

    Here's a sequence showing a garboard drain set into an epoxy filled hole...









  16. #16
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    Default Re: Installing a drain tube

    for a jon boat it is nice to be able to pull the plug from the inside to drain while under way. Hard to do if your plug is outside - cam style on the inside is easy.

  17. #17
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    Default Re: Installing a drain tube

    inch n a half thick transom!!!!
    angle the hole down then.
    ta da !!

  18. #18
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    Default Re: Installing a drain tube

    now what ?

    tap threads in the epoxy?
    use tube goo ?
    screw the bronze in dry?
    butyl rubber under the flange?

  19. #19
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    Default Re: Installing a drain tube

    The brass drain tube will work fine. With the plug like the Attwood. I get mine from Jamestown Dist. I do a lot of small boat drain tubes when I replace transoms. Use a Forstner bit. Just drill the same size as the tube and epoxy inside edges of the hole, let dry and seat the tube with a good sealant. Done.
    David Satter www.sattersrestoration.com
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    Default Re: Installing a drain tube

    installed brass tube in my skiff in 1991

    the hole i drilled was just one RCH larger than the tube

    with a small rat tailed file i created a spiral set of scratches on the outside of the tube

    coated the inside of the hole with un-thickened epoxy first then smeared a heavy coat of thickened(ketchup) epoxy in the hole and on the outside of the tube

    gently pushed the tube in the hole w/ the factory flange inside

    once the pox had cured for a few days i filed the outside end of the tube to almost flush and by wallering a heavy drift punch round n round on the inside of the raw outside end of the tube gave it a gentle flair for good looks

    get my flip handle Attwood rubber plugs @ WalMart for chump change

    i install the plug from the inside of the boat

    she plays in fresh and salt watebr />
    NO ISSUES

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    Default Re: Installing a drain tube

    Quote Originally Posted by wizbang 13 View Post
    now what ?

    tap threads in the epoxy?
    use tube goo ?
    screw the bronze in dry?
    butyl rubber under the flange?
    No threads, Wiz, I don't have a tap the right size. Butyl would have been a good choice but I hadn't any at the time. It was your advice that made me get a roll of it. Nope, it was tube goo I used, pulled up with the nut just enough to get squeeze out all around and then tightened up another quarter turn a few days later.

  22. #22
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    Default Re: Installing a drain tube

    Quote Originally Posted by Jim Ledger View Post
    Here's a sequence showing a garboard drain set into an epoxy filled hole...

    .... pics snipped to save bandwidth ....
    Very helpful pictures Jim. I like how you used a plastic tube as a form for the hole instead of drilling through the filled in epoxy. If I go a similar route, I'll use your plastic tube idea. Thanks for taking the time to post your pics!

  23. #23
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    Default Re: Installing a drain tube

    Quote Originally Posted by gray duck View Post
    for a jon boat it is nice to be able to pull the plug from the inside to drain while under way. Hard to do if your plug is outside - cam style on the inside is easy.
    Yes, my thoughts in pulling the plug from the inside while underway. I just bought two plugs. One T-handle and one Flip-handle. I'll try both and see which one works best for me. Then I'll buy a third plug of that type and keep the unused plug as a spare for emergency.
    Thanks.

  24. #24
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    Default Re: Installing a drain tube

    Quote Originally Posted by wizbang 13 View Post
    inch n a half thick transom!!!!
    angle the hole down then.
    ta da !!
    Still designing my drain tube method. Thanks.

  25. #25
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    Default Re: Installing a drain tube

    Quote Originally Posted by DayTripper View Post
    Very helpful pictures Jim. I like how you used a plastic tube as a form for the hole instead of drilling through the filled in epoxy. If I go a similar route, I'll use your plastic tube idea. Thanks for taking the time to post your pics!
    The plastic tube was just a filler. The actual hole was bigger and was cut with a router.

  26. #26
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    Default Re: Installing a drain tube

    Quote Originally Posted by David Satter View Post
    The brass drain tube will work fine. With the plug like the Attwood. I get mine from Jamestown Dist. I do a lot of small boat drain tubes when I replace transoms. Use a Forstner bit. Just drill the same size as the tube and epoxy inside edges of the hole, let dry and seat the tube with a good sealant. Done.
    Thanks so much for sharing your brass drain tube experience!

    I bought two drain plugs and tried them in a 1" PVC pipe and it wouldn't work. The ID of the 1" PVC pipe is slightly larger than 1" while the ID of the brass tube is slightly less than 1". The difference is huge when it comes to the drain plugs expanding enough for a seal.

    So I bought two brass drain tubes because of your post. The drain plugs work fine in the brass tubes.

    As far as drilling the hole, the OD of the brass tubes I bought are "exactly" 1 inch. If I drill a 1" hole it appears that the brass tube will be a tight fit in the hole. Was yours the same? If I apply epoxy to the inside of the hole and let dry, it appears that the tube would no longer fit.

    Thanks!
    Last edited by DayTripper; 05-10-2022 at 01:56 PM.

  27. #27
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    Default Re: Installing a drain tube

    Quote Originally Posted by swoody126 View Post
    installed brass tube in my skiff in 1991
    the hole i drilled was just one RCH larger than the tube
    with a small rat tailed file i created a spiral set of scratches on the outside of the tube
    coated the inside of the hole with un-thickened epoxy first then smeared a heavy coat of thickened(ketchup) epoxy in the hole and on the outside of the tube gently pushed the tube in the hole w/ the factory flange inside

    once the pox had cured for a few days i filed the outside end of the tube to almost flush and by wallering a heavy drift punch round n round on the inside of the raw outside end of the tube gave it a gentle flair for good looks

    get my flip handle Attwood rubber plugs @ WalMart for chump change
    i install the plug from the inside of the boat
    she plays in fresh and salt water
    Thanks so much for your post! I bought two brass drain tubes because of your and David's posts.

    I like your expression of drilling a hole RCH larger than the tube. I had to Google RCH and got a laugh at the definition.
    My Forstner bit set has 1" and then 1-1/8". Seems I'll need to buy a 1-1/16" Forstner bit to drill the hole.

    I'll check our local Walmart for the Attwood rubber plug. The ones I bought were from West Marine for $10.99 each. I'll need to buy one more plug so I'll have at least one spare plug.

    Thanks again!
    Last edited by DayTripper; 05-11-2022 at 01:10 PM.

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    Default Re: Installing a drain tube

    Quote Originally Posted by Jim Ledger View Post
    The plastic tube was just a filler. The actual hole was bigger and was cut with a router.
    Perfect router cut Jim. I wonder if my Dewalt plunge router base can plunge through 1-1/2"? I'll have to check it out.
    Thanks.

  29. #29
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    Default Re: Installing a drain tube

    Quote Originally Posted by DayTripper View Post
    Perfect router cut Jim. I wonder if my Dewalt plunge router base can plunge through 1-1/2"? I'll have to check it out.
    Thanks.

    If you have to wonder if it’ll work it will probably be a disaster. A router can cut the cleanest hole and with more control than any drill, but you really have to know what you’re doing.


    This is a hole for an exhaust fitting going through in inch and a half of material. You can still see in the dust where the jig was clamped on. I cut that with a three horse router and a half inch diameter straight bit. The router had a five-eighths collar in the base which guided the bit. The template was a hole in a piece of half inch plywood with a hole bored through. Because the collar was an eighth of an inch bigger in diameter than the bit, the hole in the template needed to be an eighth inch bigger than the desired finish opening. Folla?

    This is the only way to do it by routing because with this set-up the bit can be lowered in small increments, only nibbling away a little bit at a time. Still, it's a nerve-wracking process and no place to experiment.

    Last edited by Jim Ledger; 05-10-2022 at 03:18 PM.

  30. #30
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    Default Re: Installing a drain tube

    Quote Originally Posted by Jim Ledger View Post
    If you have to wonder if it’ll work it will probably be a disaster. A router can cut the cleanest hole and with more control than any drill, but you really have to know what you’re doing.


    This is a hole for an exhaust fitting going through in inch and a half of material. You can still see in the dust where the jig was clamped on. I cut that with a three horse router and a half inch diameter straight bit. The router had a five-eighths collar in the base which guided the bit. The template was a hole in a piece of half inch plywood with a hole bored through. Because the collar was an eighth of an inch bigger in diameter than the bit, the hole in the template needed to be an eighth inch bigger than the desired finish opening. Folla?

    This is the only way to do it by routing because with this set-up the bit can be lowered in small increments, only nibbling away a little bit at a time. Still, it's a nerve-wracking process and no place to experiment.

    I've decided on a simple route, not using epoxy. Will post the procedure that I decided on.
    Thanks much.

  31. #31
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    Default Re: Installing a drain tube

    Just thinking...a hole saw would probably be your best bet. Make an oversize hole filled with thick epoxy with a wood plug in the center. Then run your hole saw through. That's how you cut a hole in a fiberglass hull. You don't even need a wood plug, it just saves some resin and helps with the slump.

    Jim

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    Default Re: Installing a drain tube

    Quote Originally Posted by DayTripper View Post
    Before I assemble my jon boat, I want to drill the holes for two drain tubes in the transom. I plan to use 1 inch diameter brass drain tubes like this one:

    355511.jpg
    Decided on the simplest solution for installing transom drain with available tools. I'm going to forget the epoxy idea and just use Loctite PL Marine Sealant. It is rated as providing a waterproof, flexible bond above or below the water line. And it's paintable.

    I'll use the brass drain tube. I'll drill a 1" diameter hole through the transom using a 1" Forstner bit which I have. A test drilling through a 2x4 shows that the brass tube is a snug fit but easily inserts through the hole. Light filing with a half round file, the tube can drop through the hole without pushing.

    Will thoroughly coat the inside of the drain hole with the Loctite Marine Sealant, working it into the wood with my gloved finger. Then coat the outside of the brass tube and insert it from the inside of the hull.

    Then whatever it is, it is. Thanks all.
    Last edited by DayTripper; 05-10-2022 at 08:52 PM.

  33. #33
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    Default Re: Installing a drain tube

    A hole saw runs more true than a forstner bit. One of the disadvantages of using a forstener bit with a hand drill is that they tend to wander. They're really made to use in a drill press. Then there's also the problem of breaking out. When the forstner bit exits the cut they do so without warning, often carrying a big chunk off one side as they rarely break out evenly. With a hole saw you can see the pilot bit come through and then cut from the other side.

    I think about this stuff a lot.

    Jim

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    Default Re: Installing a drain tube

    Quote Originally Posted by Jim Ledger View Post
    A hole saw runs more true than a forstner bit. One of the disadvantages of using a forstener bit with a hand drill is that they tend to wander. They're really made to use in a drill press. Then there's also the problem of breaking out. When the forstner bit exits the cut they do so without warning, often carrying a big chunk off one side as they rarely break out evenly. With a hole saw you can see the pilot bit come through and then cut from the other side.

    I think about this stuff a lot.
    Jim
    Very good tips about Forstner bit hand drilling Jim.

    I just finished drilling two holes in the bottom frame of my transom. (Transom has 1" thick frames with 1/2" marine plywood back).
    I drilled the holes using a Forstner bit and my drill press. Set the depth so that the Forstner bit's small tip poked through the frame without the blades cutting through the frame. Then flipped the frame over and completed the drilling from the other side. Using the drill press, the hole is very perpendicular so the tube's flange factory flange fits flush all around against the frame. After I epoxy the frame to the back ply, I'll finish drilling through the plywood, being careful to monitor when the point of the bit pokes through the ply.

    Thanks.

  35. #35
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    Default Re: Installing a drain tube

    Yanno, DT, sometimes it's good to break down and just buy an fresh drill bit. Put another arrow in the quiver, so to speak, have another trick up your sleeve,

    I'm glad things worked out, that's the important thing, but if you haven't even fastened the transom on yet there's gonna be plenty more drilling opportunities ahead. Those forstner bits don't stay sharp long.

    As for the brass tube, count me in with wizbang on this one, bag it! Round the edges of the hole, inside and out and apply multiple coats of epoxy resin, then paint.

    G'luck!

    Jim

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