Sail developments break the speed barrier
by Rob Kothe & the Sail-World Team on 30 Dec 2007
When Rani took line honours in the first Sydney to Hobart race in 1945, she had been at sea for more than six and a half days. Thirty years later the American maxi ketch Kialoa became the first yacht to sail the course in under three days, recording a time of 2 days 14 hours 36 minutes 56 seconds and Kialoa’s record stood for 21 years.
Wild Oats XI off Cape Raoull © Rolex/Daniel Forster http://www.regattanews.com
It was finally broken, but only just, by the American-designed, Australian-built, German-owned 80 footer Morning Glory in 1996, with a time of 2 days 14 hours 7 minutes 10 seconds. These times were shattered in the 1999 Telstra Sydney to Hobart when the former Whitbread Round the World racer Nokia, the 60 footer, slashed the race record by an extraordinary 18 hours as she surfed southwards in 1 day 19 hours 48 minutes 2 seconds.
The weather was extra ordinary that year with sixteen boats, including a group of five 40 footers, breaking the old record running down the NSW coast, across Bass Strait and down the Tasmania Coast with spinnakers set in 30-40 knots winds. Those perfect record breaking conditions were calculated to have been a 'one in a hundred year weather' pattern.
The IMS rating system was by 2000 and onwards, discouraging the development of really fast boats; they were heavily penalised on rating. Then came the new IRC handicapping system and fast boats were again in vogue, but in 2004 the CYCA set a maximum allowable IRC handicap which effectively capped the overall boat speed. In 2005 race organisers removed the artificial IRC limits, while retaining a maximum boat length of 30 metres.
Masts got taller, keels deeper and sail areas increased. So in 2005 Wild Oats XI, a state-of-the-art 30 metre, carbon fibre super maxi designed by Reichel/Pugh with CBTF (Canting Ballast Twin Foil technology) set a new record with a time of 1 day 18 hours 40 minutes 10 seconds.
As Iain Murray, the tactician aboard Wild Oats for the last three years said dockside before the 2007 race start ‘From 2005 on our focus was all about overall speed. We now carry many sails which increase our handicap rating, but deliver extra speed even in ordinary conditions.’
This year while there have been some periods of favourable wind speeds each night the conditions have been much less favourable than in 1999, yet this year's line honours winner, (barring accidents as she is still at Iron Pot) Wild Oats XI will only be an hour outside the 1999 record.
The 30 metre 98 foot supermaxis' can sail much faster than the older designs because of some rapid improvements in sail design. Wild Oats XI can reach speeds of 11-14 knots in 7 knots of breeze at certain wind angles - she is generating her own wind.
The lead up to this year’s race for Wild Oats XI was less than perfect; she dropped her rig in September at the Rolex Maxi Worlds. Her 44 metre mast and attached sails were cut away from the boat. It was not until 7 December that her new mast was built and stepped in the boat and her sails were hoist for the first time two days later. Yet just another two days after her first sail, she showed the blistering speed in the Big Boat Challenge on Sydney Harbour and in the Rolex Trophy offshore series.
Last week Michael Coxon, the CEO of North Sail Australia explained how the fastest and most consistent super maxi in the southern hemisphere recovered from catastrophic event.
'It was the combination of South Spars and North Sails working together that had the boat out sailing and winning in a very short time frame. She has a new stiffer Hi Modulus carbon rig; this stiffer mast is a more stable platform. It makes the sailmakers and trimmers task easier, it allows the use of a larger roached mainsail.'
‘These days we are using new technology that has trickled down from the work North Sails have done with the America’s Cup and Volvo programs and we are now using that on Hobart racers, and the 18 footers. Those engineering developments have moved us up a lot of notches.'
To get Wild Oats XI back on the water, our Australian loft sail designer, American Keith Lorenz, who has been 25 years with North Sails, worked closely with Southern Spars designers. Together they were using a program called Flow and Membrane, to design the rig and sail combination.'
‘We have a very good handle on the stress and strains on any corner of the sail; this allows much more precise specifying of the sizes of all the lines from halyards to reefing lines. We know the loads on pad eyes on deck and that enables the specification of fittings of reduced sizes and therefore weight.'
‘All around, there are less surprises, this allows us to dock tune, enable us to leave the dock for the first time and load the boat, without long exercises. The boat is virtually race tuned from the time it leaves the dock. In building a new mainsail, with a stiffer mast, we were able to go to a next generation of mainsail, this allowed us to increase sail area, at profile and flying shapes. Certainly this combination of spar manufacturer working with sail maker produces best designs. The new mainsail was probably the nicest main sail to come new out of a bag.
'Some of major developments have been in building sails for light wind sailing conditions and that is certainly a factor in breaking race records. During the light winds of the Rolex Trophy series we were using new Code Zero down wind sails.
'We learnt on Alfa Romeo, Neville Crichton’s 98 footer in Sardinia (sailing against Wild Oats XI until her mast fell down) that a new sail an experimental first 3DL spinnaker, was delivering better speeds in light conditions. What was needed was a big flat sail. Under the IRC rules the mid girth of the code zero has to be 75%. But sails that wide can be unstable which means they can flog themselves to death if made under spectra.
'So the approach we’ve been able to take in building a new Code Zero for Wild Oats XI with the stronger 3DL material is to sacrifice the luff and the exit of the leech and just recognise they won’t be setting inefficiently. The sail is set with the luff inside itself, allowing it to back wind and the back of the sail fishtailing off.
'Previously if a Code Zero like that was made of Spectra, they’d shake themselves to pieces so we would have had to make them deeper, which defeated the purpose of the sail. Now we’ve been able to make the big flat sail and we have found this to be faster than the Code 1 spinnaker and we can sail lower and faster on our VMG running. Another major benefit is that it’s a furling sail, there is no sail packing and the crews are loving it.'
As Wild Oats XI reached Iron Pot this morning in a dying breeze, she tacked gently (in four knots of breeze) and unfurled the new Code Zero for the run up the Derwent.
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