Being able to average 9- 10 knots on a catamaran rather than 6-7 knots on a monohull will give you more options in your strategy to avoid bad weather.

Catamaran hull speed. This is a measure of the fullness of the ends of the hull. Instinctively you might think that fine ends would be faster as they would cut through the water better. So the rules about limiting displacement speeds still apply to Cats its just that the slim hull gives then a much higher displacement speed.

Hull speed or displacement speed is the speed at which the wavelength of a vessels bow wave is equal to the waterline length of the vessel. Generally a wider catamaran will be capable of carrying more sail than a narrower catamaran of the same LOA. While a standard boats performances are limited by her maximum hull speed multihulls and racing yachts are able to go beyond this speed.

Personally I find the most important benefit of speed of a multihull is the ability to outrun bad weather. Smaller ones giving 3 to 5 mpg and offering lots of room. The famous victory of the Americans with their small 60-foot catamaran facing the New Zealanders and their big 90-foot monohull at the Americas Cup in 1988 is a good example.

Theres a misconception I come across quite a bit that you can add weight and windage and youll still be fast as long as your hulls are fine. Catamaran Hull Speed Calculator For Beginners Table and Free Spreadsheet Speed is important it can get you out of harms way and it makes sailing much more fun but figuring out how fast a catamaran will be able to sail can be tricky. Catamarans excel in more leisurely recreational activities.

But in fact you want a high Cp for high speeds. On average cruising catamarans can reach top speeds of 15 knots around 173 mph 2784 kph. Because catamarans have less water resistance they are generally faster than mono-hull vessels.

Cruising catamarans are some of the fastest boats available often used for racing. The concept of hull speed v 134 sqrt LWL for waterline in feet v in knots assumes that the boat is essentially limited to the speed of a wave thats as long as the hull- a rough at best approximation for monos and almost meaningless for cats. Obviously this formula doesnt apply to catamarans.