Winding Sticks.

Checking for Twist

I use a pair of 4 ft bubble levels as winding sticks described above.  I have them left over from work so I use them. I had a little twist in a sailboat hull once that would go to weather on  a port tack like it had a motor. But other points of sail were real disappointing.

I also plumb  the bow and stern, plus a centerline symmetry check.  Symmetry is good to check when fitting the bulkheads and ribs.  The bow and stern must be plumb for a symmetry check  to work right.