Technology
Life forward of the beam
The new generation of large, high-performance luxury cruising catamarans are making great use of the latest developments in AC rig technology
You simply can’t miss them, big cats on the prowl. Their numbers have exploded in recent years as the market for luxury multihulls grows by the season. But this is far more than the product of a new trend. The rapid development of the modern performance cruiser cat scene is feeding off some of the latest and most advanced technology at the sharp end of the sport where it nurtures fast, easily driven boats that are comfortable and easy to handle. Essential to this impressive growth is a new breed of sail plans and rigs where Southern Spars is at its centre. ‘One of the big key differences
with this new generation of boats is that they sail off apparent wind most of the time,’ says Southern Spars co-founder and director Mark Hauser. ‘This means that they build their apparent wind very quickly as they accelerate which means that the sail shapes need to change to match. In the past, rigid masts restricted the amount of bend you could achieve to help this change in shape. But today, not only can the
58 SEAHORSE
rigs change shape, but they work in conjunction with the structured luff mainsails to allow the sail to be flattened off quickly and efficiently as the apparent wind speed builds and the angle reduces. Typically, these boats can be starting at five to seven knots and accelerating to 15-20kts in very little time, so you have to switch through the gears pretty quickly. A lot of the time the cunningham is the key control for making significant sail shape adjustments. It also makes it much easier to produce a set of trimming notes that are easy to follow and effective, especially when sailing shorthanded. So, like adding gears to a gearbox, this gives a much wider range to the sail plan.’ For designers, the way that the rig
and sail plan interact and the control systems that make this possible has taken them into new areas. ‘From a large cruising cat design
and engineering point of view, being able to power up the mainsail more effectively with a structured luff main coupled with a diamond spreader mast was a combination that didn’t
Above: the Highland Fling 80 was the first cruising cat to fully leverage the potential of structured luff mainsails and its Southern Spars mast is engineered in a very different way from any previous big catamaran rig project
exist before the last America’s Cup,’ says sales engineer Jarrard Wallace. ‘With cunningham tension, the structured luff allows the sail to move forwards at its leading edge while the internal structure of the mast is designed to match the shape that the sail has been designed to take. Traditionally, the cunningham would simply drag the draft forward a bit. Today, the control is far more sophisticated and effective. Diamond spreaders allow us to achieve a more predictable sailing bend range. They also allow us to use smaller, lighter mast tubes. Plus, we have the ability to change the set-up of the mast and its characteristics with the internal mast jacks which allow us to pre-tension the diamond stays. ‘Trying to pre-load the rig in place
in the yacht using halyards and then putting spanners on turnbuckles just doesn't get you there. Instead, an internal jack achieves this with relatively low effort and provides the accuracy to know how much tension you have in the diamonds. It means we can target preload and prebend
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114
