The shape of the hull combines all these elements and set up one part of her.

Narrow catamaran hull. Make it too wide and you end up pitch-poling with too much sails on. The entry line is narrow and the water lines angle is small so there is not much running resistance. This is because boats with waterline length to beam ratios greater than 81 are not limited by hydrodynamic drag factors whereas smaller boats need to plane to do so planing requires enormous amounts of power for displacement hulls.

In the case of multihulls this is done through a very narrow waterline beam to length ratio and minimal interference between the waves produced by the other hulls. Americas Cup AC72 Design - Narrow Hull Catamaran. And if you think she is extreme read on.

This meets the dimensions of the Americas Cup AC72 class ships. Catamarans allow for very high stability with very narrow hull beam and deep draft. The beam of a sailing catamaran is a fundamental thing.

Beam of sailing catamaran. Similarly the narrow asymmetrical type hull such as found in the Hobie 16 beach catamaran is hardly used in todays cruising multihull. The entry line is narrow but the water lines angle is becoming wider larger hull which is making us lose the hydrodynamism of the boat.

Narrow hulls give you lower hydrodynamic resistance and higher top-end speeds. For high-speed cats above the hump very often narrow catamaran will have less drag than wide catamaran - directly due to lower tunnel wash and also becase it is actually lighter. The formula for catamaran hull speed is 134wetted length12.

Narrow hull beam allows for low wave drag so low that youll often see fairly small catamarans with a little diesel do 40 knots like its nothing no jumbo turbines no slamming no waves over the bow no drama youd think they were doing 15. A boat that can move her nearly 50 US tons 45 metric tons at 13 knots using less than 200 hp. If You look at this book they quote our research on small catamaran beam selection - High Speed Catamarans and Multihulls - Technology Performance and Applications Liang Yun Springer.