Silicone calk for glue and stitch

Discussion in 'Materials' started by Woody213, Mar 2, 2017.

  1. Woody213
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    Woody213 New Member

    I am looking at building a cheap one sheet plywood boat to haul extra gear when kayak camping with the wife. I want to build it a bit more sturdy than most of the people do though. I was looking at glue and stitch and was wondering if instead of a marine based epoxy (like M3 4200) if regular silicone could be used in place of it? Simply for a bit of cost savings (3M is about 3x as expensive)
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Silicone is not really a structural element, only a sealant, and you will often notice that the tube says "not suitable for inderwater use".
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

  4. Woody213
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    Woody213 New Member

    Thanks for the info. Thats not a bad price.
     
  5. PAR
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    You can't substitute an adhesive/sealant for epoxy. 3M-5200 (what I'll assume you meant with M3 4200) is about the most aggressive adhesive/sealant available, but still isn't a suitable substitute for epoxy. Modulus of elasticity is the real issue and though good, not even remotely close to what epoxy provides. You'll find you can't "wet out" fabrics with these polyurethane adhesive/sealants, so their value in taped seam construction (stitch and glue is a method) is dubious at best and highly not recommended.

    Do yourself a big favor and log onto westsystem.com and systemthree.com and download their free "user's guides" and the "epoxy book". These will nurse you through the basics.

    Lastly, most of these adhesive/sealants cost more than epoxy, ounce to ounce, so not any savings either. The convenience of a single part goo is appetizing, but you do need to understand the physical attributes of the materials involved.
     
  6. Woody213
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    Woody213 New Member

    Do you have any recommendations for inexpensive epoxy? Im trying to do this on the cheap. Itll basically just get beat around a couple times a year.

    Something like the West System Six10?
     
  7. PAR
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    PAR Yacht Designer/Builder

  8. hoytedow
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    hoytedow Wood Butcher

    Welcome, Woody213. Why not find an old kayak on the cheap and remove the paddlers seat and cover it with a closable cargo hatch and tow that to the camp?
     
  9. Scot McPherson
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    Scot McPherson Senior Member

    US Composites is pretty inexpensive.
     
  10. PAR
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    PAR Yacht Designer/Builder

    US Composites makes some good products, but typically are 20% or more higher than the other discount formulators.
     
  11. Scot McPherson
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    Scot McPherson Senior Member

    still way less than the premium marine epoxy suppliers :)
     
  12. PAR
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    PAR Yacht Designer/Builder

    Agreed . . .
     
  13. Jim Caldwell
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    Jim Caldwell Senior Member

    $70.00 for 1/12 gallon kit from US Composites is a lot cheaper that the others listed.
     
  14. PAR
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    PAR Yacht Designer/Builder

    The "others listed" range from $55 to $65, of course depending on quantity. Price breaks typically start at 3 gallons or more.
     

  15. Jim Caldwell
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    Jim Caldwell Senior Member

    All I saw on the others $90 to 96 for the 1 1/2 gallon kit which includes hardener for small stitch and glue.$128 for 3 gallons or $298 for 5 gallons.

    http://www.shopmaninc.com/
     
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