what sealant should I use on my 'new' used plastic kayak?

Discussion in 'Boat Design' started by Squidly-Diddly, Feb 11, 2014.

  1. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member


    first boat in the reviews, Heritage Expedition Mk II.

    As reviews state, no bow or stern drain plugs, so I bought two 'kits' with hard plastic oblong mounting with screw in plug and with rivets. But both bow and stern don't have very flat places ANYWHERE, so the sealant is gonna need to work.

    Guy at kayak shop says "Marine grade silicon", but I've heard 5200 is better, but does 5200 stick to "superlinear polyethylene".

    And should I rough up surface of plug mounting kit OR boat hull before gluing?
  2. alan white
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    alan white Senior Member

    I've used polysulphide for PE plastic. It is very sticky and very water resistant.
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    This is one of the few places where a silicon adhesive/sealant works well on boats. As Alan has mentioned 3M-101 (polysulfide) works with less aggression than 3M-5200.
  4. philSweet
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    philSweet Senior Member

    Sounds like overkill. All you need to do is drill a hole and run a SS screw into it. If you are feeling fussy, chase a bigger hole with a tap and use flush nylon hexsocket screws .

    The black ones last longer

    Looks like a great boat
  5. Petros
    Joined: Oct 2007
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    Petros Senior Member

    why do you even need a drain on a boat that small? I have built over 20 small boats, including about 12 or 13 kayaks or canoes, not once did I feel the need for a drain. what you do not spill out, you just wipe up with a sponge or rag. Keep it simple, leave it out, and this will not ever come back to haunt you later.

    You are thinking of a "white man" boat when you want a drain plug. A plug does not belong on a native water craft.

    If you must, put it on the upper deck so you can drain all of the trapped water out by turning it upside down. That way the plug will not be in the water when in use. I suggest using a nylon screw as suggest by Phil.

    If you bought a "kayak" that is too heavy to lift up and flip over, it is not a kayak, but a "white man" boat that just looks like a native water craft. It is too big and too heavy to use properly. if that is the case, you should sell it and get a proper kayak.
  6. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Well, Petros, the prior owner somehow got a mess of leaves etc in the hull, then tried to clean it but it is like getting water out of a tire.

    Plus, around here we got Zebra clam thingy going on where any lake wants your boat bone dry, inside and out, before launching, with inspectors. Indians never had to deal with THAT. Worst case, they'd just mumble some mumbo-jumbo and hope for the best.

    The boat is still "King Kong" able. But the 'deal' included a really good combo golf bags/kayak dolly I post pics of later.
  7. Squidly-Diddly
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    Squidly-Diddly Senior Member

    Phil, as mentioned, drying out the insides gonna be big deal.

    As far as design, not show in pics is a approx 2" overhang on the gunnel. I think that is where the secondary stability citied comes from. Boat is 17' 4" with slick looking glassy hull(in great condition, nary a scratch) with smaller strakes than a Tarpon 16 so I've got high hopes. The 'in water' hull is quite narrow due to gunnel overhang.

    Just for fun, I might try running a rope through a bunch of pool noodles and see if the gunnel will hold them securely under tension.
  8. Nate57
    Joined: Sep 2010
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    Nate57 Junior Member

    I've been researching HDPE adhesives lately as I also recently acquired a used kayak (with a crack). It seems HDPE (linear or not) can ONLY be "glued" by heat (plastic welding, not as hard as it sounds) or with a new epoxy from West Systems called G/flex 655 Epoxy. It accepts fillers so I would think that the stuff could fit your need for a sealant.
    Info on G/flex here
    and here
    a demo video here
  9. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    If you have to put in drain plugs, put them near the ends on the top, in the deck, since you can easily turn the boat over to drain. That will avoid underwater thru holes. Or put in some access hatches so you can drain and clean the boat or even store stuff there.
  10. portacruise
    Joined: Jun 2009
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    portacruise Senior Member

    Aquaseal sticks better than the silicones I've used. It is always better to rough both surfaces to improve adhesion. Test whatever you use on a section of the hull to see how it will stick before you do the plugs.



  11. kapnD
    Joined: Jan 2003
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    kapnD Senior Member

    I repaired a large rip in a plastic kayak with the glue that came with a plastic fence from Home Depot. It has just the right amount of flexibility, and sticks like hell. Sand the area with rough paper and wipe clean with acetone. Smooth it out with some peel ply or grind it smooth after it sets up.
    Awesome stuff, comes in big tubes and is relatively cheap.
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