Rounding the mark, white swings upwind (8) of black, hoping to cut off black's wind and overtake him. But black, in position of leeward boat being overtaken, has right of way, retaliates by forcing white to turn into wind until sails shake, or luff (9), and both boats lose speed. Black may continue luffing white until white's helm is opposite black's mast; then black must resume his course for the leeward mark.
Resuming course (10), black may be slow handling sails and white may blanket black—cut off his wind—and overtake him (11, 12). But black is not allowed to luff white again so long as some part of white's boat stays within two boat lengths of some part of black's. However, if black can keep some part of his boat overlapping some part of white's, black may then demand room to round the buoy (13).
Rounding leeward mark (14), white is now blanketed by black Therefore he abandons straight course for finish and, as the leeward boat, forces black to run across the wind (15), hoping black's spinnaker will collapse, so that black will slow down and white can escape. If white fails, he may then change direction by quickly jibing (16)—and black jibes to cover. By now, committee boat will have crossed to other side of starting buoy to set up finish line.
Approaching finish, black matches white's jibe, crossing white's stern (17) to stay on his wind. At finish, white must allow black room (18) to cross the line—unless white wants to force both boats to wrong side of buoy and gamble on winning wild scramble as boats break away from each other to circle back to finish line.
Spotting the sails
Each boat will have about two dozen sails. However, the contenders probably will use no more than six basically different combinations, the extra sails being duplicates or near duplicates, with only the tiniest variations in canvas weight or cut, invisible often to the eye of the novice and sometimes the most expert sailor. For example, each boat will have different mainsails for light and heavy winds. For bearing, i.e., going against the wind, they will have genoa jibs, not only of different sizes (see diagrams) but also different canvas weights. For running before the wind—and sometimes for reaching (across the wind)—they will carry light-and heavy-weather spinnakers, plus small spinnaker staysails to catch the wind low to the water. If you study the diagrams at right, however, you will be able to spot all basic types of sails likely to be used during the America's Cup races.
Mainsail and No. 1 genoa is usual combination for light work to windward (upwind).
No. 2 Genoa is used when wind freshens and larger No. 1 "genny" tips boat over too far.
No. 3 Genoa is cut high along bottom to keep heavy seas and winds from bursting sail.
Reefed, or shortened, main and storm jib help boat sail upright in heaviest weather.