KEY POINTS:
Spotting his team isn't a problem for Team New Zealand's sail designer, Burns Fallow (right) - he just has to look for a bright-red spinnaker billowing out.
While most of their opponents have white spinnakers Team New Zealand's have opted for red.
When one blew out in this year's racing, it was suggested that the dye used to colour the sail was responsible.
Not so, says Fallow.
"Red is a fraction better than white. White gets bleached, red is just inked. It is a very fine line and you could test 100 samples and it would be 54-46. It is very close."
Fallow says developments in sails have mostly come about due to changes in the rules.
"Other things we keep on working on is trying to have the most stable surface on the sail so it doesn't stretch or elongate for the amount of weight. You are always battling that."
Fallow is in his fourth campaign with Team New Zealand. He started as an upwind sail designer but now heads the sail design department.
The sail design programme differs from other areas of the campaign in that it never really stops until the regatta is over, he says.
"We continue designing and building right up to the final day. Whereas we are done building boats, we have just gone past the halfway point in the number of sails we have got to deliver.
The racing in the challenger series is a lot tighter time-wise than it used to be.
"When you start the Louis Vuitton Cup you are going to have to be in pretty good shape because there isn't much time to develop during it.
"We have to design our sails for the semifinals as we are doing round robin one and the finals while we are doing round robin two."
The technology
* Three main types of sail used on an America's Cup boat - mainsails, headsails and spinnakers.
* Mainsails are about 210-220m2 and weigh about 100kg.
* Each contains about 70km of carbon yarn.
Mainsails and upwind headsails (genoas or jibs) are laminated over a mould (three dimensional laminate 3DL) rather than from panels which are glued or stitched together. 3DL sails are manufactured by North Sails in Nevada, the only factory in the world capable of making them. The unfinished sails are finished at the team's base - where they are trimmed to size and batten pockets added.
* Downwind sails, spinnakers and gennakers are in excess of 500m2. They are made from lightweight nylon and weigh only 35kg.
* Wind tunnels are used to test ideas.
