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RE: [Cedar Strip Canoes] How do I tell Epoxy from Polyester on a used canoe?

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  • Jim Marco
    Hi Dan, Well, you really cannot tell. There are a lot of chemical tests you can perform, but I am not familiar with them enough to suggest a home method.
    Message 1 of 2 , Apr 17, 2013
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      Hi Dan,
      Well, you really cannot tell. There are a lot of chemical tests you can perform, but I am not familiar with them enough to suggest a home method. Basically, if it is well adhered, I would not worry. As I remember, epoxy sticks over poly but poly does not stick over epoxy. Poly can absorb water, so expansion and contraction will differ between the two coats. Coating over a dry boat will mean about the same expansion/contraction, hence no loosening. Rough up the entire surface with 80grit paper (don't try to sand out any scratches, provided they didn't cut through the glass into the wood) and lay a thinned "scratch" coat of marine grade epoxy over everything. After it sets for a day, do any necessary patches etc. After a day or two, sand smooth and proceed from there. I rather doubt the original builder would have used poly on a boat, anyway.
      As far as stems go, yes. A couple partial keels can be added. I will recommend a solid external keel on the stem where wear is likely to occur. This is usually accomplished by cutting a notch in the bottom of the boat extending about 1/4 of the way up the stem. A laminated keel is glued in this area, hand planed flush with the hull, then fiberglassed, inside and out. Laying the brass strip on when all is finished with a coat of epoxy over that. Sounds simple, eh? It is not.
      Here is a video (done on a kayak): http://www.guillemot-kayaks.com/guillemot/blog/nick/installing_solid_outer_stem
      Note that Guillemot has some GOOD videos, but most are geared to kayaks.

      Though this video was done on a kayak, the technique can easily be applied to a canoe with a bent wood or laminated keel. One of the problems is that splitting the stems will tend to release any pressure holding them together. This area will need some sort of reinforcement. So, some sort of inner keel needs to be added first to hold things in place. This is non-trivial without the stem forms, but certainly possible. The cuts need to be fairly precise and the joints well done else the outer portion will not bond well, potentially, leaving voids and weaknesses. Fiberglassing stems is always painful, as shown in the video with the multiple film cuts. Other than adding wear resistance, they add little to the boat, supplying no real strength. I simply add a 1/8" rope "skid plate" over an extra layer of fiberglass on the stems, but, again, that's me and my usage...your usage will be different.

      My thoughts only . . .
      jdm
      -----Original Message-----
      From: cedarstripcanoes@yahoogroups.com [mailto:cedarstripcanoes@yahoogroups.com] On Behalf Of danf
      Sent: Wednesday, April 17, 2013 8:16 AM
      To: cedarstripcanoes@yahoogroups.com
      Subject: [Cedar Strip Canoes] How do I tell Epoxy from Polyester on a used canoe?

      Gentlemen

      I have purchased a gorgeous "Adirondack Lake" model cedar strip built about 15 years ago by a home builder. The builder is deceased and the son knows nothing about the canoe other than that his father loved it. It is in excellent shape save the gunwales, some unsanded repair patches on the hull (but original wood underneath), and 3 long scratches on the bottom from the son "trying it out". I want to restore this boat but I am unsure or what type of resin was used. How do I tell? Can the two resin types mix? Beyond removal of varnish, what prep work should I perform.

      I would like to avoid a full down to the wood strip. By way of ID, it is 16 foot, 35 inches at waterline, 33 at gunwales(tumblehomed), 13 inches deep, tandem with a simple thwart at the carrying yoke station, seats are caned, there is no stem band on either the outside or inside.

      Last question, what do you think about retro-fitting a stem band inside with epoxy and sanding down the ends enough to put a brass stem band outside? Would that weaken the structure?

      Dan
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