Someone wrote in asking about tables, because thay had a 1/8 inch sag in the middle of theirs??? This is how I did mine to overcome that very problem, I went to the local tiimber mechant and bought two lengths of pine about 8 inches deep by 1/2 inch wide, and about 10 feet long, stood them up side by side on the shed floor, spaced them apart with about five lengths of the same material about 2 1/2 feet long, so you end up with a box, 10 feet long, 2 1/2 feet wide, and ten inches deep, screwed and glued it all together, and when dry, depending on the quality of the timber, which is pretty crappy in this part of the world, you may have to sand the top so that everything is flush, and then fitted a sheet of this compressed chip board stuff which they use for flooring, which is available in slightly less than 12 foot lengths, to the top as a bench top, and then screwed and glued again. The 8 inch deep pine acts as a beam over the length of the bench to prevent any sagging. The cross peices do nothing other than to hold the side bits vertical so they can do there anti sagging job. You need a reasonable amount of depth in the beams, other wise they will do exactly that, sag. When dry, fit some legs with screwable feet to make minor adjustments to the table, and stand up, fit a steel rule on its edge across one end, wirth a second rule just behind, and sight to check both rules are parallel, move the second in successive steps along the table and continue checking for true, and adjust the screwable feet to keep out any warps or twists. Something the manual does not tell you, is KEEP THE BENCH PERPENDICLULAR TO YOUR PLUMB BOB. Works liks a charm. The 12 foot length is a bit short for side frames, a bit hangs over the back but is no problem, as when you fit the tailpost, the overhang makes it easy to tip it all up side down, I made my bench three feet high, which is great for the side frames, but when you get the boat section done, you are always having to reach up and over the side, so two and a half feet is about a good height, you may have to bend over a bit more for the side frames, but it is much easier to do this than to have to keep reaching up all the time, or else take Mohammud to the mountain and build a small six inch catwalk on the floor around you boat, this works great too, just dont forget when you go to step off you are working on elevation.
Chris Johnston North Richmond Australia.