Preview: How to Build a Caledonia Yawl, Part 7 – Scarfing the Planks

13 Responses So Far to “How to Build a Caledonia Yawl, Part 7 – Scarfing the Planks”

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  Geoffrey Coulborn says:

  Do I understand correctly that you are putting a relatively thin coat of unthickened epoxy on the scarfed ends of all planks to be absorbed into the grain as the plywood absorbs it easily? Then you are putting slightly (maple syrup) thickened epoxy on only one face of each scarf JOINT…on top of the thin coat of unthickened epoxy?

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  T Tack Ryan says:

  Fantastic demonstration. Really well presented and filmed. Super helpful. Thank you, Thank you!

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  David Robbie says:

  The pin and string method looks great. I am beginning to see the value in getting planks pre-cut like this from Hewes.
  To sand the scarf after epoxy, he said he starts with 80 grit but then did not mention what grit he finishes it to. What would be the recommended grit to work it to?

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    Gardner Pickering says:

    120 grit on the hard block sanded with the grain for a painted finish. 220 grit with the grain for a varnish finish

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  George Kaler says:

  The scarf joints in the plywood planks on this Caledonia yawl project look to be machined at Hewes & Co. as the kit is produced. I am planning on building a Chesapeake Crabbing Skiff, with plywood planks, but for which there is no kit. The machining of scarf joints has me pretty apprehensive. I have looked, but don’t see a video on cutting those scarf joints. Any advice or suggestions would be very much appreciated. I saw an ad for a West scarfing attachment for a circular saw, but that looks kind of awkward. I guess I should plan to use a hand plane to cut the scarf tapers – yes?

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    Geoff Kerr says:

    George, Cutting scarfs is just one of the skills of boatbuilding. The theories and layout are as simple as can be. I believe you’ll find that most people in the trade use an 8:1 bevel when scarfing plywood. The tool of choice is somewhat a function of what you have and what you know how to use. A sharp jack plane would be a good start. I use a hand power plane for the first 95% of the cut, and fine tune with a block plane. I’ve seen everything from belt sanders to slicks employed, and dream of duplicating a dedicated table saw tipped on its side that I saw somewhere in print. Don’t worry about the challenge. I highly recommend working with some scraps and cutting a few before tackling your prized planks. And keep that plane sharp.

    I’ve very limited experience with the circular saw jig, but have the impression that it has a limited range of thickness it will cut, and that the mounting process was such that I concluded I would want a dedicated saw on which to permanently mount the jig.

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  Peter Mumford says:

  Gardner, thanks for the tutorial! I have one of your Vivier kits with ‘finger’ cut planks, instead of the scarf. I’m not sure its possible to get such smoothly glued planks with that style kit.

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    Gardner Pickering says:

    You should be able to get a smooth finish with either method. I believe that Vivier specifies a fiberglass tab on the inside of the lower planks. You could also grind out a small hollow on the outside of the plank and fair it back in with thickened epoxy. One advantage is the ease of alignment with the locking puzzle joints. We machine a .02″ gap between the joints so that they will slide together and not push all the epoxy out.
    The scarf joints are chosen by the designer. Oughtred, Doug Hylan and Walt Simmons specify a sloped scarf joint. Vivier and Clint Chase use the locking puzzle joint. We also use the locking puzzle joint on much of our commercial marine work, e.g. Brooklin Boatyard and Rockport Marine.

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  Lee Fox says:

  I really like the pin and string alignment tip! Thanks!

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  Bert van Baar says:

  Hi,
  Can I have a comment on removing epoxy with an electric heater gun and scraper?
  Thank you.
  Bert van Baar
  http://www.bootbouwschool.nl

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    Gardner Pickering says:

    You can remove epoxy easily with a heat gun, but there are some dangers:
    1. If you soften epoxy with heat, it will not harden up again, like hot glue does. You’ve permanently compromised its strength.
    2. The fumes are unpleasant and dangerous. Use a respirator with charcoal filters and considerable ventilation.
    3. Fire
    For inaccesible areas, heating a putty knife with a heat gun and driving it between seams is effective.

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      Jeff Patrick says:

      According to the tech people at West, the epoxy is not compromised at all. My own experience confirms this. Heat guns and scrapers are a commonly used to fair epoxy.

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        Leonard De Bruyn says:

        In a way, you are both correct. There is a bit of nuance to the answer. Here is an article that sums it pretty well.
        https://www.jamestowndistributors.com/userportal/document.do?docId=363