Brian wrote:
Well given that (surprisingly) there was no response I did a test. I
joined some bits of scrap by filleting and taping with a single layer of
my 2" tape. See the first two pics.

Once cured for a day I tried to break it. See next pic. The wood
delaminated and broke away from the join. With some considerable force I
managed to break the join (see 4th pic). The join broke but a lot of
wood was still attached to the tape (5th pic).

I have no doubt that a second layer of tape on the outer seam would have
made it stronger still since the tape ripping was obviously a major
reason for the failure. It doesn't look like the width of the tape was
an issue because the tape was still well attached away from the break.

So its 2" tape with a staggered double layer on the outer seam. It looks
like the seams are not be the weakest parts anyway. That is unless the
test with torque stresses around the join is not representative of those
experienced by the boat. However I would imaging that if first
millimeter of tape pulls away from the join it is seriously stuffed as
it would probably let water in.

Hope someone finds this interesting or useful,

Brian

Another option you might want to explore it using bias cut tape that you
make yourself. Bias cutting results in twice as many fibers crossing the
joint.