Just to give you an idea of the amount of twist that is sometimes needed...



This pic was taken last Saturday showing me going upwind in 22mph of breeze with a combined 170Kg+ on the wire. The top two leech streamers are flowing nicely and I'm nearly block-to-block on the main but the top of the sail has flicked off and given a twist in the region of 5-600mm by my guesstimate. Gotta love those square tops!