It follows that increases made in one area must lead to decreases in another. The trend is for heavy, narrow boats which are faster upwind.

General dimensions
Length: 80ft
Beam: Max. allowed is five metres but more likely to be around four metres.
Displacement (hull): 1.5 tons (total boat weight: 25 tons, of which 20 tons is the keel. The rest is mast and rigging).

The building process begins with the designers sketching various ideas on computer, aided by sailing data and computational fluid dynamics programmes. Scale models are then built and tank tested to analyse performance.

Once the design has been agreed, the hull is built in a mould. Materials used for the hull and deck gear include carbon, Kevlar, titanium, glass fibre, aluminium and steel.