AT THE HEART OF HY­DRO

Sailing World - - America's Cup 2017 -

The Amer­ica’s Cup grinder’s job has been trans­formed over the last two Cup cy­cles whereas the grind­ing is now vir­tu­ally non­stop. What’s up with that? Two words: hy­draulic pres­sure.

Eighty-per­cent or more of the en­ergy spent grind­ing is in­vested in mov­ing hy­draulic fluid around the boat. The need for hy­draulic pres­sure has been driven by the in­creas­ing so­phis­ti­ca­tion of the boats, specif­i­cally by the num­ber of con­trols that need ad­just­ment, above and be­low the wa­ter, some­times un­der ex­treme loads.

Every team sails its boat dif­fer­ently. Harken has de­vel­oped and sup­plied so­lu­tions based upon spe­cific de­sign briefs the teams is­sue. Gen­er­ally speak­ing, on the AC50 the func­tions con­trolled by hy­draulic cylin­ders in­clude: the two foils ( height, cant, rake), the two rud­ders (rake), and wing con­trol (twist, cam­ber, in­vert).

The foil-pitch solution is used most fre­quently. This hy­draulic con­trol’s stroke is short, and flow re­quire­ment is min­i­mal, but it’s used by the helms­man to bal­ance the boat’s fore and aft trim, so it has to re­act quickly. The foil­height solution typ­i­cally re­quires the high­est ac­tu­a­tion speed. The wind­ward foil tow­ers above the deck, re­veal­ing a cylin­der with an ex­traor­di­nar­ily long stroke. As a re­sult, this sys­tem re­quires the largest oil flow and high­est ac­tu­a­tion speed.

It’s no co­in­ci­dence then that the most so­phis­ti­cated hy­draulic com­po­nent Harken sells for AC ap­pli­ca­tion is the AC35 Ra­dial Pump (be­low). It’s a three-speed 20- pis­ton pump that looks dis­tinctly like a ra­dial pis­ton-driven air­craft en­gine in a much smaller size. There are four on the boats — mounted to the out­side of the Harken MX Pedestals in each hull. This is the heart of the sys­tem, and it’s like a big mus­cle pump­ing blood to a cham­pion race­horse.

— By Bill Faude and Mark Wiss, of Harken

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