: I just finished assembling a box-beam external strongback, a la KayakCraft.
: Although all of the individual pieces seemed straight before assembly,
: when they went together, the top edge of one side section wound up
: slightly concave. This happened on one side only. Judging from a
: stringline, I'd guess that the concave section is about 1/8" to
: 3/16" off of straight, at the center of its eight foot length.

: I'm not expecting perfection, but how close is "close enough"?
: Would I be better off fixing this now, or should I just forge ahead,
: compensating for it in the form setup (ie. by shimming the bottoms of the
: form extensions)?

The importance of the strongback is that it be totally rigid, it need not be perfectly straight.

The reference point in Ted's and my station set up is the top reference string, stretched AS TIGHT
AS POSSIBLE, to measure your rocker from.

I use an upper and lower string to align my stations by visually aligning the station centerline
with the upper and lower strings on the strongback. The strongback and station supports
provide stable anchor points. They can be off as long as they remain stationary.

All the best,

Rob Macks
Laughing Loon CC&K
www.LaughingLoon.com