Catamarans rely primarily on form stability to resist heeling and capsize. Raising the dinghy centreboard can reduce heeling by allowing more leeway. As counterweight, a keel increasingly offsets the heeling moment with increasing angle of heel. This opposes the heeling moment of the wind pushing sideways against the boat's sails. Such foils provide hydrodynamic lift and, for keels, ballast to offset heeling. A sailing boat that is over-canvassed and therefore heeling excessively, may sail less efficiently. As more heeling force causes more heel, weather helm may be experienced. This increases the heeling moment&colon; the sails tend to blow the watercraft over. For this reason, crabclaws are typically used on multihulls, which resist heeling more strongly. He was also adept at back heeling penalty kicks into the goal. Photographic evidence of the severe heeling was presented. By 18&colon;45, with the engine room flooded and "Viper" heeling over, she was abandoned.