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Using poly on back side of outwales?

Discussion in 'Wood and Canvas' started by Red Merle, Sep 2, 2019.

  1. Red Merle

    Red Merle Curious about Wooden Canoes

    I am almost finished with my recanvas/ light restoration on my Old Town Charles River 1913 model with mahogany trim.

    I have needed to do a bunch of epoxy work on the back sides of the outwales to fix a few broken or damaged areas and I am almost to the point where I am going to put a couple of coats of poly/spar varnish on them before I install them and I am wondering if I should poly the back sides? I am worried about trapping water behind the poly which might lead to rot but I am not sure if leaving it raw is any better.

    Any advice?
  2. Greg Nolan

    Greg Nolan enthusiast

    You should use a good marine varnish with good ultraviolet resistance on the outwales, and you should coat the backsides at the same time, with the same number of coats. If you do not, the raw wood will inevitably soak up water, which will net readily dry out. If well coated, the outwale wood should not take up water.

    Polyurathane coatings are not necessarily the best to use on boat wood -- you need a varnish -- yypically called spar or marine -- that has high UV resistance. Ordinary poly coatings are not UV resistant, and exposure to sunlight will destroy the coating in short order.
    Red Merle likes this.
  3. OP
    Red Merle

    Red Merle Curious about Wooden Canoes

    Thanks for the response. That's what I was thinking but I wanted to double check.

    I am using MinWax Helmsman Spar Urethane. I know it's not the highest quality, but I have used it before and it works fine for my needs. The boat will be stored in a garage and I will do my best to dry it out each time I use it before storing it. I figure I will be doing more touch up and re coats down the road, but I already have the Helmsman and I am over budget for the boat and I plan on using it, not making it a show piece.
  4. Greg Nolan

    Greg Nolan enthusiast

    The Helmsman Spar Urethane may not be a premium marine varnish, but it does have some UV absorbants in it. It may not be as durable as Petit or Epifanes. Keep an eye out for yellowing or clouding down the line; sand the deteriorate stuff off and recoat. But I think you will be ok for a few years.
    Several years ago I used some of it on a couple of paddles that don't get used much, and they have been fine.
  5. Ron Bedard

    Ron Bedard Enthusiastic about Wooden Canoes

    While giving the planking a coat of thinned varnish prior to re-canvas, I coated the outboard side of the inwhale. There didn't seem to be any original varnish there or on the inboard side of the outwhale either. Everything's got multiple coats now, even if that doesn't seem to be the way it was originally done.
  6. Michael Grace

    Michael Grace Lifetime Member

    Everything had varnish originally. Maybe not the backside, but the outwales certainly had varnish on the top and outside faces. In the inner face, much better to improve what was originally done here. There's no harm at all and a great deal of help. Protecting the wood from deterioration doesn't constitute over-restoration. Hopefully you're enjoying the project.


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