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Hydraulic muscle backs Australia II - again

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ENERPAC has put its hydraulic muscle behind Americas Cup winner Australia II's campaign to relive its glory days when it became the first foreign yacht to lift the Auld Mug from the USA.

Enerpac once again provided high-force hydraulics to tension the rigging for optimum performance from sporting icon Australia II as it headed back to the water and competitive sailing in preparation for the America's Cup 150th Jubilee Regatta at Cowes, Isle of Wight.

Assisting the 2001 team with equipment to set the mast of the yacht was history repeating itself for 700 bar (10,000psi) hydraulic specialist Enerpac, which also donated hydraulic gear for the cup-winning races in 1983.

The Cowes regatta in August 2001 was scheduled to be Australia II's final sailing event before she becomes a centrepiece of the new $35 million Western Australian Maritime Museum, now under construction in her home port of Fremantle. Sailing trials off Fremantle were conducted to get the yacht back in shape to race competitively after 15 years of retirement.

The hydraulic mast setting system used with Australia II is the same as that used for the 1983 races, with two Enerpac hydraulic cylinders positioned inside the hull of the boat, on each side of the pre-rigged mast, to apply upward pressure to a horizontal spar inserted in the mast.

Enerpac's hydraulic muscle comes into play in tensioning Australia II's rigging to the optimum level, after which shims are inserted beneath the mast. The hydraulic pressure is then released and the cylinders removed. The 27-metre mast is secured by shrouds made of very low stretch multiphase alloy rod consisting of molybdenum, nickel and cobalt.

"The rod looks like stainless steel but in fact has an iron content of less than one per cent," marine management consultant Skip Lissiman said.

"About 30 tonnes tension must be applied to the main rigging and this is physically very difficult to achieve using conventional method like a hand-spanner.

"We use two 50 tonne RC-506 cylinders to tighten the rigging by applying 15 tonnes of upward pressure to the base of the mast, raising it by 75 mm and then sliding in slims to maintain the tension."

The required force is easily achieved with an Enerpac P80 hand pump, which powers both cylinders equally via a T-piece and needle valves. The desired pressure is read off a gauge.

Skip explained that the mast tuning process involves trial and error.

"The ten pieces of mast rigging must be set to be the right length so that when the shims are in place, the rigging is correctly tensioned and the mast is transversely straight.

"We adjust the rigging screws, tension the mast using the Enerpac cylinders, check for mast alignment, then ease it back down to slacken the rigging to make further rigging adjustments as required to get the mast transversely straight. This process is repeated a number of times in the two or three hours that the complete task normally takes.

"Once the mast rigging is set to the correct lengths and the hydraulic cylinders removed, very little fine tuning is required and it's rare to have to reinstall the equipment to make further adjustments."

Skip said that this was a standard mast-setting procedure for 12 metre and other hi-tech racing yachts.

After sea trials, Australia II departed for the UK on June 26 aboard P&O Nedlloyd's Contship Action. Crewed by members of the 1983 team, the Australia II crew was particularly keen to contest the International 12 Metre Class section of the re-enactment of the first America's Cup race held on the original course around the Isle of Wight in 1851, as well as the International 12 Metre Class World Championships. Applied Power Australia 02 9743 8988.

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