SAIL­ING AN ACC CATA­MA­RAN

A first­hand ac­count of what it’s like full-foil­ing aboard an Amer­ica’s Cup boat

SAIL - - Experience Under Sail - For more on what it’s like sail­ing and racing a full-foil­ing ACC cata­ma­ran, in­clud­ing video and in­sights into AC35 strat­egy and tac­tics, visit sail­magazine.com/racing/amer­i­cas-cup By An­drew Campbell, Or­a­cle Team USA

Ber­muda’s 75-de­gree wa­ter makes sail­ing foil­ing cata­ma­rans pretty fan­tas­tic. Let’s be frank, San Fran­cisco is a cold place to sail. And the fact that you’re on a boat be­ing hosed with spray and 50 knots of ap­par­ent wind as nor­mal op­er­at­ing con­di­tions doesn’t make things any eas­ier. Dry suits were com­mon, wet­suits were a must. While ad­vances in con­trol sys­tems and foil de­sign have made the modern 50ft Amer­ica’s Cup Class cata­ma­rans ca­pa­ble of sail­ing “dry” laps, the un­avoid­able splash still makes for a gen­er­ally wet ride for the six-man crews. That said, for the four grinders on board, as soon as we start our day we’re warmed up, and a good bit of spray is a wel­come re­lief from the balmy Ber­muda south­west­er­lies.

Once we’re off the dock and have gone jib-up, we slowly make our way through Dun­don­ald Chan­nel onto Ber­muda’s Great Sound. “Slowly” means close­hauled and fly­ing a hull at about 13 knots. As soon as we’re clear of the reef and happy with our sys­tems checks, it’s as sim­ple as put­ting the bow down and build­ing to take­off speed. In 12 knots of wind, this is not much of a press, al­though loads do in­crease as the boat strains, drag­ging both rud­ders, their el­e­va­tors and the L-shaped lee­ward dag­ger­board through the wa­ter, along with 50ft of lee­ward hull.

By now the grinders will have al­ready started pump­ing pres­sure be­hind the hy­draulic lines to prep for the up­com­ing ma­neu­vers and trim ad­just­ments. So as soon as take­off speed is achieved our helms­man, Jimmy Sp­ithill, sim­ply makes a quick pitch ad­just­ment to the lee­ward dag­ger­board, ac­ti­vat­ing a set of hy­draulic cylin­ders to push the head of the dag­ger­board aft, thereby chang­ing the an­gle of at­tack of the hor­i­zon­tal por­tion of the foil. Once the an­gle is high enough and the lift it cre­ates ex­ceeds the weight of the boat, there is a short jolt as the lee­ward hull breaks the sur­face of the wa­ter and the boat re­leases into full-foil­ing mode.

As it does so, a quiet comes over the boat, and there is no longer any spray wash­ing over the lee­ward bow as the boat­speed quickly dou­bles. While it’s true the ef­fort the sailors are put­ting into the pedestals com­bined with the com­mu­ni­ca­tions and 50 knots of ap­par­ent wind make for a noisy en­vi­ron­ment over­all. The boat’s ac­tual move­ment is quite damp­ened, be­cause we’re now rid­ing above the sea state. Gone is the pitch­ing, slam­ming and hack­ing into the chop of tra­di­tional sail­ing.

That said, there is lit­tle mar­gin of er­ror. The en­tire time the boat is air­borne, Jimmy’s steer­ing, the an­gle of at­tack of the foil, and the an­gle of the wing­sail and its twist all con­trib­ute to keep­ing the boat aloft. These el­e­ments, in turn, are all con­trolled us­ing hy­draulic pres­sure cre­ated by the wattage put into the grind­ing pedestals. As a prac­ti­cal mat­ter, ev­ery ad­just­ment cre­ates en­ergy de­mand, and con­ser­va­tion is para­mount to hav­ing enough en­ergy in the tank for ma­neu­ver­ing over the en­tire race­course. At the same time, any mis­step in helm, foil or wing trim can send the boat ca­reen­ing back down into the wa­ter. Thirty knots back to 10 knots makes for some sig­nif­i­cant g-force, and the ur­gency of get­ting the boat back on the rails is ob­vi­ous. In the end try­ing to keep calm and con­tinue to do your job at 90 per­cent max­i­mum heart rate is one of the big­gest chal­lenges of sail­ing an ACC cat.

Con­trol­ling an ACC cata­ma­ran means keep­ing your cool while sail­ing on a knife edge The course for AC35 is a short one: fol­low­ing a reach­ing leg there is a down­wind leg, an up­wind leg, an­other down­wind leg and beat, then a short reach to the fin­ish off...

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