: Hi. Darel.

: Going back to the glue problem, you don't say what glue you are
: using or what temperature you are working at.
: Like all compounds a glue will have a minimum temp. at which it
: will form a proper bond.
: For example;- For Titebond 111 the manufacturers state a minimum
: temp. of 7 centigrade and from experience I would not use it
: below 10c for stripping.
: The glue and the timber need to be at this temp. when the joint is
: made and maintained until finaly set. Just a thought worth
: checking for the glue you are using!
: Regards Les C.

Many good points in this discussion. I would suspect either bad glue or glue starved joints. Two most made mistakes by amateur wood workers, 1) Not giving the glue a chance to be absorbed into the wood grain before clamping and replacing the glue as it is absorbed and 2) over clamping and squeezing the glue out.
I tried scarf joints and had a problem with not getting perfect alignment which required sanding inside and out to level the strips. I now use 100% butt joints centered over a former and glued together at assembly. I have never had a problem. All you are doing with the wood is creating a mold for the fiberglass, it adds no strength to the finished product although it will influence the strength if you have several joints in the same vicinity so - - don't.
I buy my boards in 10' lengths so I have quite a few butt joints scattered about the boat. Unless you specifically look for them you will never notice them.
As far as using splice blocks behind the scarf joints - don't do that either. It is not necessary, it adds nothing except problems when applying the glass cloth.
All this information is worth exactly what you paid for it :))