> Here's my question: is it ok if I don't correct the bowing and instead
> just go ahead and plumb the forms up using the laser level? can I be
> assured that the bowing won't get worse going forward and screw things up?

Prop up the center as best you can first. then go about leveling the forms.

The most important thing is that the forms be aligned properly. You could line them up on a long corkscrew if you had enough shims, so the issue with the box beam saggin is not the amount of sag. Rather, the issue is that if the box beram is saggin under its own weight, then the sag will increase as you add weight to it. That means that it will get worse as you add the strips. You could start out perfectly aligned, and rapidly work your way into trouble. So, get the center of that beam propped up and solid. It is a lot cheaper to add a couple of 2x4 legs now than to deal with problems later on.

For those who are not in the Boston area, or who do not otherwise have access to a laser level, a 25 foot piece of 3/8 inch clear vinyl tubing makes a wonderful level for around $6. Just add water. Fill it so that there is about 6 inches air at each end, and leave the ends of the tubing uncapped so the water can seek its own level naturally. Line up the water line in the tubing with the left sheer line on one form, then shim (or otherwise adjust) the form until the right sheer line lines up with the water line at the other end of the tube. Once the first form is aligned, duct tape one end of the tube in place, with the water level matching a sheer line (or a centerline)and move the other end of the tube around to the other forms.

Using water to align the forms for a boat seems rather appropriatel but the laser sounds like more fun to play with.

Paul G. Jacobson