: Every reference in strip canoe & kayak building that I've run across use
: either a simple butt joint or a "diagonal" scarf joint. This
: caught me by surprise.

: In all the other hobbies I've pursued over the years these types of joints
: would NOT be recommended, but the a long "lap" scarf joint would
: have been the preferred method of joining 2 wood sections in this type of
: application. It's very obvious from a strength stand point that the
: "lap" scarf is superior, because of the very large surface area
: in the mating surfaces as opposed to the end-grain-only joints that result
: from a butt or "diagonal" scarf.

: Any explanations?

Hi Lurker Bob. Actually, I'm not sure that the Lap Scarf would in fact be stronger than the diagonal scarf. In the "diagonal" you really don't have a true " End-Grain " in that you are making contact with the lengths of the wood fiber. With the " Lap " you Do have a long surface area that is a more positive glueing surface, but, at the same time, you have two pieces of " End-Grain " to glue up and since one is on top and the other is on the bottom, you effectively have a total depth of end-grain butted up within s short distance.

As for strength, I have seen a test done where two 2 x 4's were butt-jointed with Titebond glue and pressure was applied for 1 hour. When taken out of the clamps, it was placed on two saw horses about 10' to 12'apart and a man stood on the joint. Didn't break !! When he bounced on it, it broke, but, not at the glue joint. These folks who are using butt-joints are not using clamps to press them together, but, the epoxy and glass, I'm sure is just as, or stronger than the wood glues. Plenty of strength for this purpose.

As to the difficulty....... I don't think that it would be any harder to make a jig for cutting laps than it would be to make a feather board, or any other jig for that matter. I do believe it would be easier to glue up the lap-scarf than it is to glue up the diagonal. No Slippage. It might be interesting to try making both and applying equal pressure to each joint and see which is stronger. ???

Rehd

: I realize that its a smidgen more time consuming, but if you build a jig, it
: would almost be the same time spent making a "diagonal" scarf.
: Also, I realize that the fiberglass sandwich will provide the greatest
: increase in strength, but since all this effort is being expended to make
: a work of art (hopefully), then why not improve on the excepted method by
: using a "lap" scarf?

: Thanks

: Bob H (The Serious Lurker)