I wish I had had a perfect strongback. I actually came up with this method because my box beam strongback had a "tendency" to one side. It became apparent when I stretched a string between the two ends and found that there was a deviation of almost 1/4" in one spot. To correct, I cut the form holes bigger to give me room to align on the true center. Unfortunately, that also made them impossible to hold, align and secure without an extra 4 or 5 hands. During the alignment process, I also used a bar clamp on each end, aligned to the "true" center. I stretched a string between the clamps high enough to clear the highest form and used this as an additional alignment point. It helped a great deal to be able to have a multi-axis view and immediately see if a particular tweak had thrown off the overall alignment.

For what it is worth, the alignment has remained true through the build. I now have the hull and deck glassed and just ("just" haha) need to finish my cockpit and hatches, glass the two pieces together and fit it out. I have a tendency to over document things, so my build log is about 90 pages and 200 or so photos. If you are interested in any part in particular about the build, send me an e-mail.

Regards,

Marcel