Lots of ways to lose - but only one way to win
There are many ways to lose an America's Cup race, tactical errors, equipment damage and bad luck among them.
There seems to be only one way to win: Have the fastest boat.
'As far as I'm concerned the America's Cup is a design race,' said Brad Butterworth (pictured), defending champion Alinghi's likely skipper. 'It's always been a fast boat that has won the Cup.'
The Swiss yacht and challenger Emirates Team New Zealand start their best-of-nine contest today for the oldest trophy in international sports. It's a rematch of the 2003 race, when the roles were reversed.
'Without question the fastest boat will win,' said Terry Hutchinson, the American tactician aboard the Kiwi boat.
Both teams have spent years developing their 24-metre ultralight carbon fibre racing yachts, but the design approaches are radically different.
Alinghi's newest yacht, SUI-100, is wide and rounded, almost bulbous. The Kiwis will probably also race their newest boat, NZL-92, which is at the other extreme - narrow and with so many flat surfaces that it can seem boxlike.
'At first, they look very similar, but from a designer's point of view there are many differences,' said Ian Burns, the design team co-ordinator for BMW Oracle Racing, which lost to Luna Rossa of Italy in the America's Cup challengers' series.
The Kiwis clearly do have a fast boat in their bid for the Auld Mug trophy. In the challenger selection races, which began with 11 teams, New Zealand trounced Luna Rossa 5-0 in the finals to win the right to challenge Alinghi.
The Swiss are also known for having fast boats. Although SUI-100 has yet to be tested in competition, speed was a major factor in Alinghi's 5-0 win in the 2003 America's Cup.
According to the rules, boats must be roughly 24m long and weigh 21 metric tons.
But within those limits, designers have great freedom. 'One of the main drivers is how wide the boat is,' Burns said, because this affects the design of the mast, rigging and sails.
Teams seek to increase the yacht's waterline to gain speed, while decreasing its wet area - the part of the boat in the water - to reduce drag.
Alinghi's approach was to build a rounded, broad front section, which looks almost inflated, giving it a longer waterline while minimising drag when it leans with the wind.
So far the Kiwis seem to have an edge in light winds, while Alinghi's boats perform better in stronger winds.
As far as I'm concerned the America's Cup is a design race
Alinghi's likely skipper