As the multihull capsizes, slide into the water between the trampoline and the sail. Keep hold of something – the boat may drift quite fast. Once capsized, a multihull can be harder to right than a dinghy, especially if it turns upside down.
Move around the front beam to the underside of the boat. Climb onto the hull and throw the righting line over the upper hull. Free the sheets and traveller to prevent the boat sailing away once righted.