Stumbled across a video on the net the other day about tiller to sheet self steering.
got a me a bit excited as i realised that its a good option for me and a good back up if you had a electronic tiller steerer.
So the next day i bought a few bits and bobs, cam cleats a pulley, a few shackles, some spectra line and a bungy.
attached cam cleats to tiller. attached spectra line to end of boom that runs through the pulley and gets locked off on the cam cleat on tiller. bungy goes from opposite side to other cam cleat. (ive since realised that a bungy isnt ideal and need something lighter in elasticity)
Once you have the sails nicely trimmed i lock off the main self steering rig(pulley/spectra side) and the bungy on the cam cleats on tiller. then release the main sheet line on the block leaving the control of the main sheet to the spectra line on the tiller. takes a few adjustments on the bungy side, but once you got it balanced, my god its awesome. had a compass heading between 320 and 330 for over 45 minutes. it really works well until the wind changes direction, and then all you have to do is move the tiller to compensate.
The forces that move the boat off course are used to counter this in that when the wind hits the main sheet, the tiller is pulling the boat back on course and the bungy takes up the slack. Brilliant.