Multihull sails are a different breed, which require unique and innovative thinking in sail design and construction. Cats and tris are much harder on their sails since they heel less and go faster than single-hulled boats. Multihulls achieve their stability from being wide while monohulls get their stability from deep, heavy keels that are often 40-50 percent of the boat's displacement. By eliminating the heavy ballast and gaining stability with wide beam instead, multihulls can be built much lighter.
The wide beams can support tall rigs and larger sails, which creates higher sail area to displacement ratios. Many performance multihulls are capable of speeds equal to or as much as twice the true wind speed. At such high speeds, the apparent wind that the sails see is quite high. And since the boats aren't heeling as much as monohulls, the sails don't depower. Heeling reduces the wind in the sails. Stable platforms mean the rigging and sails are under much higher loads as the wind builds.
Multihull sail design is yet another world. Sails must be designed to optimize the high apparent winds. They also need special attention paid to “twist” since wind differs both in speed and direction from the surface to the masthead. The profile and three-dimensional shape must also be optimized -- sails that are too full and too flat are slow. The multihull designers at UK-Halsey have gone through the learning curve. They have learned the shapes that work well on different types of multihulls – from beach cats to offshore trimarans to the mega catamarans