KEY POINTS:
They stole the show in 2003 when their boats emerged from the water sporting radical hull appendages
Tomorrow in Valencia, Team New Zealand's black boats will again be an attraction but probably not the main one.
All 12 teams competing in the America's Cup, including Alinghi, will drop the skirts on their yachts tomorrow night and leave them off until the regatta is over.
In the past only the top two challengers and the defender have had to reveal their yachts towards the end of the regatta. Tomorrow the skirts will come off all 18 yachts built for this cup, which starts on Tuesday.
Team New Zealand brought the unveiling day to a standstill last time when their boats were revealed sporting hull appendages and long, skinny keel bulbs.
Their boats will again be of interest, but this time because they are fast. Unveiling day reveals the underbody of the yachts, exposing the entire hull shape, the keel, bulb, finn and rudder.
The evolution of bulb shapes will have continued with many expecting long lean bulbs to feature. The winglets on the bulbs are likely to be at maximum width and positioned towards the centre.
Rudder shape will differ among the teams as will the position of the keel strut in relation to the mast which gives an indication of how the boat is balanced. BMW Oracle Racing designer Bruce Farr said many different concepts would be revealed, however, as the appendages are easily changeable there is no guarantee that what is revealed is what will be raced.
"It will be great to get an impression of each team's hulls in terms of inferred stability from the beam and the hull form, the characteristics of the underwater hull shape in terms of volume distribution, and of course the appendages," Farr said.
"Keel design in particular is very challenging in that there are many interacting considerations, which trade off stability, lift efficiency and drag. There are therefore big variations possible in keel area, thickness, taper, bulb length, height and section shape, and the detail of the winglets."
Asked if he was expecting anything radical, Farr said probably not. "It has been an intention to make the [design] rule more stable and more clearly understood. However, I never believed that the hula [Team New Zealand's hull appendage] was rule viable, so who knows.
"I think some of the appendage details will be interesting but more at a detail level, rather than a radical departure from the norm."
Emirates Team New Zealand were the first to reveal a fuller bow on NZL84, a concept which has been copied by a number of their rivals.
Farr said Team New Zealand looked like their toughest opponent in the challenger series.
