PDRacer Sailboat - Articles

One simple method to join plywood together is to use a chine log (or frame log, if used on the deck). It is a strip of wood about 3/4" to 1" square that both pieces of plywood are attached to with glue and screws / nails. Typically you would attach the log to one piece of plywood, then sand it flush so that the log and edge of plywood is smooth, and then you attach the other piece of plywood to it. After the 2nd piece is attached, you trim and sand it flush. A very simple method that is fairly easy to do with loose tolerances, yet makes a very clean and strong joint.

So here I have cut lots of chine and framing lumber. The one that I used on the chine is cut with a diagonal on the top that slopes to the center. This will let all the water run off the top of the log and fall into the middle of the boat where it will be easier to clean or drain. If you use external chine logs, I would suggest doing the same - because standing water in a stored boat is it's worst enemy.

Before nailing on the logs, I marked the sides so I could tell where I could drive nails.

I started at the stern end because as I curved the log around, I would need the most leverage making that turn, and have a long stick to push against.

I firmly believe that a 65% loss of glue is perfectly acceptable. I use lots of glue, and clean it up afterwards with paper towels. Better to have a little mess, than a joint that is starved for glue.

After starting the log at the stern end, it is easy to pull the side towards me as I drive the nails. It is easier to put the side against something that doesn't move, and push with your foot to position the chine log for nailing.

There is also another chine log laying loosly on the floor underneath the side. That is to support it so that as I drive the nails thru the plywood into the chine log, that they will be straight in.

Presto, I have both sides framed. Notice the extra stringer - I will be using that later as a backup support for an external daggerboard trunk. I have one on each side so I can have trunks to match the variety of sail rigs that I'll be flying.

Another method you can use instead of bending the log around, is to put 3 planks along the curved edge. You can then trim them with a saw to get a rough curve, and sand it the rest of the way.

After the glue dries, stand upright and clamp together. Now I can sand them together and smooth out the edges so the chine logs are flush with the edge of the plywood. With the loose tolerances of the boat, it probably doesn't matter that the sides are exactly alike, but it is nice to have them together so can smooth all at once.

I have 7 different power sanding tools, and the one I use the most is a 5" disk that is chucked into my drill. That plus a roll of sticky backed 80 grit sand paper disks. Nice to have plenty of sand paper on hand, that way when the paper starts to go smooth, I just slap on another sheet instead of trying to extract every last grain of sand off each disk.

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