: Rob Macks does the same thing on his boats. I use an engineer's
: 45/45/90 triangle to set the frames to the string, it's light
: weight and small enough to fit easily between the frames.

Actually, I use two strings, one on the strongback and one suspended above the stations/stems for alignment.

I don't bank that the top of the strongback has no twist over 18 feet. If your strongback has twist your boat will be twisted if you rely on one string on the strongback, plus a square reading off the strongback surface.

My top string is suspended from sticks screwed to the strongback ends.

These sticks project above the strongback to the height of the highest station and then add 2-1/2" sheetrock screws in the top ends to allow for string height adjustment. To start set-up of the upper string, place one screw near the bottom of each stick and screw into the strongback ends near the bottom. (Attach plywood squares to the strongback ends if you have nothing else to screw into.)

THEN stretch the upper string, use a plumb bob to align the upper string with the lower string and add a second screw in the sticks, into the strongback ends, to lock the upper string in place. Set the upper string an inch above the station with 0 rocker, so the string will not be in the way as you strip.

NOW, it is very quick and simple to visually align the center line of each station between these strings.

Plus the upper string allow me to quickly set the rocker of stems and stations.

OH, one critical point (I almost overlooked) IS, I use a full length, (actually 6" longer than the boat length on EACH end) strongback.

THIS allows me place this upper string without it being in the way of stripping.

BUT MOST IMPORTANTLY it allows me to add blocking from the strongback to support and lock down my stem ends so I don't have to worry about unsupported stem ends getting pulled out of alignment by expanding and contracting wood stips, which is the weakness of internal strongbacks.

All the best,
Rob