Boating New Zealand - May 2018

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THE AC75 RULE – A LOOK UNDER THE HOOD

It returns to a box rule as we had before the AC50 cat, in which a box of

dimensions sets the envelope, and teams optimise their design within

that envelope. his ensures closeness of racing, by limiting how far a

team can depart from the rest of the leet while leaving enough room

for creativity (and cunning) to play a role.

Some parts are speciied in their geometry (such as the rig) and

some are supplied (such as the foil arms) to limit the degree of spending

• both in terms of money and design hours – allowing teams to focus
  on the areas that do make the biggest diference.
  he hull length is set at 20.7m (68ft) plus a 2.16m bowsprit,
  taking the length to 22.86m (75ft). Beam is set at between 4.8m and
  5.0m. he weight (ex-crew) is set at 6,195kg, while the D-section
  mast is 26.5m long.
  he pivot points for the foils are set at 4.10m apart and 0.52m above
  the measurement water plane (MWP) within a zone 10m to 12m from
  the transom reference plane (TRP).
  Foils may only cant through a range that does not cross the centre
  line, but there is no outboard limit other than that set by the allowable
  range of articulation of the Foil Cant System (FCS).
  Unlike the AC50s, foil rake is not adjustable. Foil forces are varied
  by changing the global angle of the yacht (by raking a single 3m-wide
  rudder T-foil) and adjusting a trailing-edge foil lap to induce camber.
  he foil arms are supplied, as are the batteries and rams in the FCS,
  but foil wings and foil tabs are open in terms of design and must fall
  within a boxed area that limits span to 4m and chord to 1.1m.
  Foil wing/lap assemblies must be symmetrical about the foil arm
  and weigh around 1,150kg each. hese form a ballast keel to hold the

Lucia 40

Contact our

team today

NEW ZEALAND Phone +64 (0)21 418 420 [email protected] http://www.multihullsolutions.co.nz

$8675$/,$ Phone +61 (0)7 5452 5164 [email protected] http://www.multihullsolutions.com.au

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