I my own case I'm looking at footstraps to keep me on board when sailing under spinnaker. When trapezing under spinnaker singlehandedly in anything above 10 knots, the boat can turn so quickly that when baring down in a gust that sometimes I'm flying in mid air or waterskying 2 ft away from the hull.

Your first reaction is to pull on the spi sheet to pull you back in, but that is not really what you want to do. If the spi stalls completely then you'll pull the boat over towards you preventing you ever to get back on board.

I've done several races without chickenlines and footstraps and it can be done. But I still want to have a more secure foothold on the gunwhale when singlehanding under spi.

Wouter