Zoom Mtg. 16 May – A Reefable Soft Wingsail – Charles Magnan
Charles Magnan presented his project to develop a reefable and furlable soft wingsail. The America’s Cup has shown that multi-element wingsails can achieve high lift coefficient and good lift to drag ratio but with considerable practical difficulties in that the America’s cup wingsails are not reefable or furlable and they need large cranes to remove them from the boats. Hence there has been recent interest in ‘soft’ wingsails that typically have sailcloth skins stretched over ribs that can slide up and down on a mast to allow reefing and furling. One problem with such arrangements is that the cloth that wraps round the leading edge of the wing gets badly ‘scrunched up’ when the sail is lowered, which makes a bulky bundle and is not good for modern laminate sailcloth. Charles has incorporated a zip along the leading edge so that the skins on the two sides of the wing can be separated as the wing is reefed or furled. He is now at the stage of having made the ribs and skins for one element of what is to be the rig for a small trimaran which he is also building based on some discarded kayak hulls. The picture below shows one of the wingsail skins, part rolled and on the left one of the ribs that Charles has made very nicely from carbon reinforced epoxy vacuum bagged onto foam.
