Drain plug removal

Discussion in 'Powerboats' started by Stumble, Feb 29, 2012.

  1. Stumble
    Joined: Oct 2008
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    Stumble Senior Member

    This weekend I almost sank my 26' Twin Vee thanks to a faulty drain plug. It was actually in, but after looking at it instead of a through hull fitting it is just a one sided flange held in place with three screws (into fiberglass). At least two of the screws failed, and the 5200 over 6 years has failed.

    My though was to just glass in the hole where the plug was, and remove the problem. Particularly since the boat is only hauled out of the water a few times a year, and spends probably 340 days a year in the water in its slip.

    Any thought or critiques of this plan? Is there some justification for these things I am missing?
     
  2. alan white
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    alan white Senior Member

    You don't go offshore so you probably ought to install a new drain except this time do it properly.
    You don't need a flange and plug. A simple 1/2" (pipe size) threaded hole will do the same thing with much higher reliability. To thicken the hull where the plug goes through, you can make an approx 3" diameter thickened (with high strength filler) epoxy "pancake" shape about 3/4" total thickness including the hull.
    Drill and tap and buy a brass stainless or bronze plug, ideally with a socket head rather than a square head.
     
  3. Stumble
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    Stumble Senior Member

    Alan,

    The boat routinely Is 20-30 miles off shore in deep water fishing for tuna. Right now we have a Garboard drain, which is what failed, and I am not really happy trusting something without a mechanical seal holding it in. I looked at putting a through hull fitting in its place, but there isn't room where it would need to bed without doing major fiberglass work to create a ledge for the flange.
     
  4. rasorinc
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    rasorinc Senior Member

  5. alan white
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    alan white Senior Member

    Either patch the holes or as said, make a new and better drain plug.
    What's dangerous is what you have now. Any hole through a hull should be through-bolted and backed with a solid block. If you want to install this kind of through hull and there's no room to do this where the original plug was, there should be another location that would work. Otherwise, as said a plug that threads directly into the glass is okay. No screws to fall out in any case.
     
  6. Fanie
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    Fanie Fanie

    I was thinking the same thing, just add a soft rubber washer to seal and a piece of string so you won't drop it overboard...
     
  7. alan white
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    alan white Senior Member

    My own boat has a pipe thread plug with a socket head. It's tapered so it gets tighter as it goes deeper. I don't use any sealant since it fits tightly enough. A little pipe thread compound would be extra insurance but not really necessary.
    I haven't lost it yet though I always set it on the foredeck off season.
     
  8. PAR
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    PAR Yacht Designer/Builder

    What he has now is an acceptable part, just installed improperly. As pointed out, it needs new bedding, through bolts (typically 1/4" machine screws with nylon lock nuts and washers) and a sufficient backing plate.

    Most manufactures skip the backing plate in favor of washers only, which serves sufficiently through their warranty period. Off shore craft, need the more substantial support of an actual backing plate. On a dry sailed boat washers and machine screws will be fine, as the loads on a garboard drain are minimal. An off shore vessel will have higher loading, mostly slamming, so a backing plate wouldn't be a bad idea. The best material is a flat plate of the same material the drain is. Second up on the list is a hunk of plywood.

    A bullet proof install with a plywood backing plate, is to taper the edges of the plywood on all sides (45 degrees or more) to lower stress risers and bond to the hull shell, with thickened epoxy. Drill the drain hole over size, then fill with thickened epoxy. When cured, drill the now epoxy filled hole, to the size necessary for the drain. Bed the drain in polyurethane and fasten down securely.
     
  9. Stumble
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    Stumble Senior Member

    Thanks for the thoughts guys.

    I have decided to go ahead and just epoxy fill the holes, And eliminate the possibility of a problem. While I understand why these drain plugs exist for boats on trailers, I just can't see the justification to have two extra holes in the boat while off shore.
     
  10. troy2000
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    troy2000 Senior Member

    I dunno. Putting a proper drain plug in is such an easy task I see no reason to skip it. If you never use it, great. If you want to drain rainwater out of it while it's hauled up for repairs, you can do that too....
     
  11. Stumble
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    Stumble Senior Member

    Troy,

    Would you advocate putting a drain plug in a 40' cruiser so when it is on the travel lift you can drain the bilge? Pretty much the same issue here.
     
  12. tunnels

    tunnels Previous Member

    The least amout of holes through the hull the better non is best !! :D
     
  13. Stumble
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    Stumble Senior Member

    Tunnels,

    This is pretty much my philosophy. I have gone ahead and sealed the old drain plug holes, painted over the patch job, and other than about a cup of water that the bilge pumps can't get i am happy with the job. For this boat we just don't have it out of the water enough to justify a drain plug that can only be used on the trailer.

    We did explore through bolting something, but because of its location there just isn't room without redesigning the bilge, or lifting the drain plug higher on the transom, which would drain less water than the bilge pumps anyway.
     
  14. PAR
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    PAR Yacht Designer/Builder

    Nothing personal intended, but this is absurd and usually not possible, in all but a day boat. Even a trailer sailor needs a transom drain to let accumulated rain run out it's butt.

    The folks having difficulty with thru hulls, are the ones that don't include them in a regular maintenance routine. If you ignore them until they bite your butt, then you shouldn't blame the thru hulls, for the negligence of the owner.

    I have couple of large yachts, each with many thru hulls. The newest of the bunch had those cheap plastic, production builder fittings. I plugged them when I first got the boat and now am systematically replacing them, because they can't be trusted, 25 years after they were installed.
     

  15. Stumble
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    Stumble Senior Member

    Par, I have no problem with through hulls, I do however object to them if they are no longer in use.

    For instance, one boat I worked on came from the factory with a generator, two AC systems, water maker, and a water cooled hydrolic pump. After a major refit, all of the above were pulled out, since the new owner wanted a minimalistic cruising boat. we could have left the five through hulls installed, and they were all in good condition, bronze through bolts, well installed and not leaking. But decided instead to yank them from the boat since they didn't add anything to the boat operation, and while they were not, could have become sources of water intrusion.

    I feel the same about my drain plugs. Since they are not accessible while the boat is in the water, the only use is to drain the oat on the trailer. Excluding the maintenance days caused by the leaking plugs this last week, the boat has been out of the water a total of 10 days in the last two years. Three for a bottom job, six really were half days as the boat is towed from its winter to summer fishing grounds, and the last day was when we pulled it to install a new fish finder.

    In short the boat is in the water almost as much as the big power boat, and even on the days it isn't the time period is too short for the drain plugs to provide any advantage.
     
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