Variable draft means you can navigate in shallow waters too.

High speed catamaran hull design. This innovative SWATH design is based on four interconnected variable draft torpedo like hulls which increase hydrodynamic and seakeeping performance for greater speeds and superior comfort. The basic form is one of a fine entry bow and a flat box like stern section with 850mm maximum demi-hull beam giving a length to beam ratio of 12351 for our 11m hull. Motoring speed knots Vol 12R m V m con x P m Vol 356.

The hull speed formula for displacement monohulls is 134 x the square root of the waterline length. Catamaran hull speeds are very high due to several factors. Even when not planing they will travel much faster than what the hull speed formula.

To get speed the hull shape is flatter with he shallow vee absorbing less power but still adequate to cushion the ride. This is the latest generation of the seacat 20 metre high speed catamaran hull and represents the best in high performance fuel efficient hulls. In order to avoid pounding the semi-circular section should be distorted into a rounded vee or parabolic section.

Obviously this formula doesnt apply to catamarans. The question of whether to make catamaran hulls symmetrical or asymmetrical can be argued both ways. When planing a monohull will exceed its hull speed.

Lightweight Catamaran hulls can be very speedy and efficient traveling quickly even with low wind speed. An 8m catamaran fitted with 2 x 75hp diesels will weigh at least 45 tons with just 33hp per ton giving a top speed of around 12 knots. For example the HFR of a 100 luxury catamaran may be 121 providing it with a high speed potential.

This article was inspired by a question about the rocker line in the new 85m cat Design 256 and I want to stick to the point. A high speed high efficiency stable catamaran boat hull which comprises a boat hull structure having an under surface a curved bow and a generally flat stern a pair of spaced-apart sponsons on either side of the keel line of the hull and extending generally substantially from the bow of the hull wherein the sponsons generally come to a point to the stern of the hull. Higher speeds compared to equivalent power from diesels.