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Thread: Marine GOOP, 6800 or 3M 5200 for leaky rivets

  1. #1
    Member Maast's Avatar
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    Default Marine GOOP, 6800 or 3M 5200 for leaky rivets

    Howdy

    I have a few leaky rivets, I'd simply rebuck the rivets if I had access to the inside of the hull but I can't get to it unless I rip up my deck - which I'm not willing to do.

    - Marine Goop has a tensile strength of 3500 PSI, (also has UV inhibitors)
    - U-6800 is also a Goop product @ 3500 PSI, only supposed to have better adhesion, also has UV inhibitors
    - 3M's tensile strength is 600 or 900 PSI (slow or fast cure) and from all accounts is unaffected by UV.

    The question is not how strong they are, but which will stick to the aluminum better.

    Both are rated for permanent underwater installations, both will stay flexable indefinately.

    The Goops are a polypropylene/solvent based adhesive/sealant, the 3M is a polyurethane adhesive/sealant.

    So, has anybody actually used this to fix rivets?

    Also, GOOP makes a product called "Coat-it" its made for making the bottom of a boat slippery. It also states its used for sealing rivets and cracks. Anybody used that?

    Thanks

  2. #2

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    5200 is not recommended for aluminum. I think a product you should look into is called gluvit. I have never uesd it myself, but i've heard good things about it. People use it for the exact purpose you are, sealing leaky rivets. Its a two part system, about 65 bucks a quart I wanna say, but its good stuff. West Marine carries it.

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    Member akrstabout's Avatar
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    Default 3m 5100

    is what I have used on my boat. My aluminum is painted in most spots. My through hull for the intake on the wash down pump is bare, holding everywhere for 5 seasons now. It is nasty stuff. Sticks and sticks good. 5200 is even more permanant. Spendy stuff per tube, $15 I think. Just clean it good I would it would hold perfectly. What about that JB weld stuff, putty I think then it turns hard, made for aluminum.

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    I don't know about 5200 not being recommended for aluminum. We have used it for years on aircraft floats. It sticks like crazy if you clean the metal good first. Use Scotch Brite or similar cushioned abrasive so you don't wear down the rivet heads (assuming they are round head rivets). This will give the material some "tooth" for the adhesive to get a grip on. Then use paint thinner to remove all traces of contamination and apply adhesive.

    JB weld does stick to aluminum, but it gets hard, I would worry about vibration and flexing eventually causing it to crack off.

    I love Marine Goop, but have noticed it gets a little crispy at the edges of the repair. Then it can start to peel.

    I would go with the 3M polyurethane type sealants myself with what I know at this time. However I'm open to learn about something better.

    akrstabout, what is the difference between 5100 and 5200. (besides 100 lol.) Sound like it has worked really well for you.

    griff, tell us more about the gluvit. Maybe it would be better yet for aircraft floats . Is it a polyurethane?

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    Moderator Paul H's Avatar
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    Default

    I haven't used it for rivets, but for sealing and bedding misc stuff I've used polyurethane roofing sealent. Same black gooey nasty stuff as the 3m and sikaflex I've used, but only $5 a tube. Also great for repairing neoprne waiders, boots etc.

    I'd love to stick to the marine stuff, but so many times I have a small job or two and most of the stuff goes to waste.

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    Member Maast's Avatar
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    Default

    Hmm, I'm thinking I'll go with the 5200 then, the tube I have at home is the white stuff, I'll go down to West Marine after work and get a tube of the black.

    I'm kind of intrigued by the Coat-It, I wonder if it'd reduce the drag in the water in addition to making it slippery on rocks and gravel. I wouldnt mind getting a few more knots of speed.
    It says it has ceramic beads for abrasion resistance & graphite and kevlar fibers for slickness.

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    Member Maast's Avatar
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    Finally found an apples to apples comparison of adhesion strength of 5200 and UV6800

    5200 peel strength on aluminum, (1 inch strip of canvas pulled off substrate): .6 pounds (on gelcoat it's 11.9)

    http://www.boatdesign.net/forums/showthread.php?t=1982

    UV6800 peel strength on aluminum: 24 pounds

    http://www.biosafe-inc.com/_tds/uv6800_tds.pdf

    So I can see why 5200 isnt recommended for aluminum...

    Havent found a peel test for marine goop yet.

  8. #8

    Default heres some info

    http://www.marinetex.com/PRODUCT%20P...0prod%20in.htm

    thats the gluvit info. I didnt realize it was made by marinetex. They make some awesome stuff too. Just seeing that name on it, i know its good stuff. I looks like it stays flexible, which is always good on anything riveted. It says on canoes and such it protects the hull from rocks when beaching, I don't know if it would do anything for a heavy boat/plane though. hope this helps.

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    Member Maast's Avatar
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    Default

    That gluvit looks pretty good. I'll dig around to see how well it sticks to aluminum hulls

    I couldnt find UV6800 anywhere in town, and when I went to buy some from Creative Wholesale online I found out its considered hazmat because of the solvent in it and incurred additonal shipping charges, even for a stinking 3.5 oz tube. It would have more than doubled the cost of the order.

    As a test I covered a couple of rivets in marine goop and a couple in 5200, I'll see how it does tomorrow when I go out.

  10. #10

    Default Gluvit

    I use gluvit on my aluminium drift boat bottom and it works great. It does get hard (not flexible). I use it more to make it slide over rocks and gravel more easily, and compared to the aluminum without any kind of coating it is MUCH better. Don't know if it would get you more MPH though. You apply it fairly thick like resin and let it harden. I'm sure it would seal in leaky rivets.

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