The hull speed formula for displacement monohulls is 134 x the square root of the waterline length.

Displacement catamaran hull design. Required catamaran hull form is created by bonding and trimming surfaces in Maxsurf. These boats have a top speed of about 10 and a half knots are very efficient up to. Catamarans are also very light which further reduces drag and displacement.

The most important catamaran design hull shape factor is the Prismatic Coefficient Cp. A displacement hull is supported on the water entirely by buoyancy effects. Obviously this formula doesnt apply to catamarans.

Typically the optimal LB ratio is something like 201. Similar to the Sail Area to Displacement ratio the higher the coefficient the faster the boat and better is its performance in light air. This is how I think it hap-pened.

The solution to this problem is a multihull. Lower values 057 are optimized to displacement speeds and higher values. Planing hulls designed for speed but power requirements are too high.

But the wetted surface area WSA increases proportionately as fineness increases for a given displacement the half orange shape gives the least WSA so fine hulls tend to be slower in low wind speeds. What I mean is that if the hull does not generate any significant dynamic lift then it is a displacement hull. Even when not planing they will travel much faster than what the hull.

This extra beam allows for a spacious engine and machinery installation and easy access for service. Thus semi-displacementsemi-planing craft is selected for our design pleasure craft. Halme Yacht Design How to dimension a sailing catamaran.