Making a shiplap joint

A shiplap jointShiplap joints are made by mating two rabbets. Not the furry kind, but the kind that is cut out of the edge of a board.

CAUTION: To make a rabbet on a board with a table saw requires removing the blade guard and kick-back preventer. This is because you won’t be cutting through the board, but just into it. BE VERY CAREFUL!

 

Making a rabbet is relatively easy with a table saw. The trick is to adjust the rip fence and cutting depth so that the depth of the first cut, with the edge of the board guided by the fence, is the same as its distance from the edge of the board. Make trial cuts on some scrap of the same thickness as your workpiece until you get the adjustments just right.

Once you’ve got the saw adjusted, make the first cut in the normal way with the board’s wide surface on the table.

The second cut is a bit trickier, especially with a long board. For this cut you need to run the board through the saw on its edge. Cut slowly and pay close attention to make sure the edge of the board stays in full contact with the table and the wide face of the board stays in contact with the fence.

Chances are you’ll have to clean up your rabbet a bit with a sharp chisel or utility knife. As a bonus you also wind up with a bunch of long square sticks about the size of fat pencils. I haven’t found a good use for them, but they’re too cute to throw out!

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Rebuilding the cabin corner

Aft cabin rotThe first sign of trouble was a discoloration of the mahogany rail inside the aft cabin. Further inspection reveals dry rot had pretty much claimed the corner of the cabin.

After some poking around I realized that I’d have to replace a couple of entire side boards at the corner of the cabin. Fortunately the boards do not support the roof, corner and side pillars do. The side boards are attached with screws and glue at the top and bottom to horizontal beam. The are joined along their edges with a glued shiplap joint.

I started by removing the horizontal trim strip running along the base of the side boards on top of the side deck. This required prying it out and making a scarf joint cut so that I wouldn’t have to remove the entire strip. I used a type of Japanese saw that cuts a very thin kerf.

Sawing a scarf jointSome of the short side boards under the windows were rotten at the bottom. I decided that instead of replacing the entire boards I would just cut off the rotten ends. This wouldn’t show when the job was done because the trim board would cover the joint between the old side boards and the new wood below. This was my first big mistake, as I would only discover four years later.