My old Islander use to love to sail back and forth. Scared the crap out of anyone anchored near us.
Cheap small Triangle of sail ( ours was 4 Fft along the back stay, 6 feet the other leggs= 12 cu ft) with gromets on the three corners. One attached to a cleat
on the single backstay above the bimini. One attachment point to the Boom. Sail pulled upright by final attachent point by the main halyard clipped thorugh the gromet . Since we always unclipped ours when anchored or moored it was available.
Our C&C is rock steady at anchor