Hi Andy,

If you can sight down the length of your 2x4 and the top edges are perfectly straight, then the string will fall exactly in the center the full length, and you could simply measure-in from the edge to locate the center for the forms. However, if there's any curve in the 2x4, a string stretched end-to-end on the top will pass closer to one side than the other. Since you want the kayak to end up straight, center the forms over the straight string rather than over a local center on the curved 2x4. I hope I answered the questions I thought you asked.

Ross

: Sorry, but need to ask a simple question. I understand why one strings a line
: to get straight reference lines on the side of the strongback (the 4"
: side) but why cant one measure to the center on the top (2"side)? The
: side usually is crowned up or down but the top seems like to string a line
: if the length is cockeyed and twisted then the line will be too. Even if
: one were to lay it on the floor the floor may be out of level at such a
: long length as well. Why not just measure to the center...wouldnt that be
: even more exact? am I missing something here? Thanx guys, Andy