> . . . I have a question:

> Which method is best for holding the forms, 2x4, box beam, or the aluminum
> extrusion? . . . This is a 19' boat and a wood 2x4 seems too weak for
> this job. The wood box beam does not seem much better. <

A 2 x 4 is cheap and plenty strong, as long as you have enough saw horses under it to support it so it doesn't sag.

Did you plan to just use two sawhorses? That would be the bare minimum, of course. If so you would put them about 8 to 9 feet apart, and have the ends overhang about 5 feet on each side. Even though the end forms are smaller and lighter, the strongback might droop a bit with such an overhang, and with such a long, unsupported center. With 3, 4 or 5 sawhorses, though, the strongback has plenty of support. Set your horses in a row and use shims, wedges or scraps of wood to get them aligned. A level or a laser pointer should help to get to get the tops even. Then set your 2x4 on these and add the forms.

You'll of course want to get all the forms lined up after you have them all threaded onto the 2x4, and approximately positioned. If you start with just 2 or three forms on your 2x4, align those first, and then add more, the added weight from the new forms might cause a sag, messing up the previous work.

It is much more important that the forms be aligned than that the strongback be straight, or the sawhorses aligned. Even if your 2x4 was significantly warped, as long as it didn't move around once you got your forms threaded on and aligned everything should work out OK.

As you add strips they tend to stiffen things even more, so the small increase in weight from the strips is accompanied by a greater increase in stiffness.

Hope this helps.

Paul G. Jacobson