Using composite materials in rigging
by Andrew Rice
Hall Spars’ president, Eric Hall, admits he was very worried about how his SCR product would survive the impact tests during the Germanischer Lloyd approval process.
‘I thought we were going to get stopped cold in the impact tests,’ he says. ‘For the GL test they have a swinging one metre arm with big weights on the end, and you watch that thing swing down and you think it’s going to slice through the cable like a knife through butter. But, boing, and it bounces off! So I think it’s probably stronger than you worry about.’
Murray Jones, the four-times America’s Cup winner, is now working in partnership with Winistoerfer at Carbo-Link. He echoes Hall’s concerns that it’s the slacker rigging that’s most at threat from damage.
‘It’s when it’s loose that it’s a little vulnerable and you just have to be aware of those limitations. For instance, we’ve been using solid carbon on the Version 5 Cup boats for the last few years,’ says Jones. ‘We had them on the runners, the forestay and our jumper stays and the solution we came up with for the runners was we just had a soft strap right at the bottom so that even if the runner went under the boom, it was the soft strap that bore against the boom.’
However, Anniss argues that the better way to address the issue of carbon’s impact resistance on longer stays is to build some flexibility into the product, something that he says Future Fibres is currently working on.
‘We’re doing something completely unique,’ claims Anniss. ‘It is a wound carbon, consolidated with braided covers and moulded ends, but it’s flexible. We’re in the middle of a test programme at the moment and will be launching the product formally later this year.’
Ease of coiling is important for logistical reasons, and one of the benefits of composite rigging compared with rod has been the ability to take replacement rigging on a plane to any remote destination in the world and take the rigging to the boat. With rod, you need to take the boat to the yard, and when you’re cruising the South Pacific, for example, the nearest yard could be thousands of miles away.
Winistoerfer’s solution is to bring the coiled carbon rod to the boat and complete the final phase of production on site: ‘Basically you bring an uncured carbon composite to wherever the mast is, and then you cure it on site with electricity,’ he says.
For a Volvo Ocean Race team this is probably an acceptable solution, but for the superyacht world, quality assurance issues will need to be addressed.
One of the benefits of solid carbon rigging is the ability to produce a cable to a more aerodynamic profile. For Alinghi’s catamaran, Carbo-Link created elliptical rigging to help reduce windage.
With Alinghi 5 travelling at up to four times true windspeed, the apparent wind angles were very low. However, for slower boats he acknowledges the potential windage reduction is not so clear. Winistoerfer believes that provided you can keep your apparent wind angle to below 15 degrees, then there are windage benefits. ‘But if your misalignment angles become too big, you are creating more drag compared to a round section,’ he says.
Eric Hall, on the other hand, is much more bullish about the windage benefits of profiled rigging for monohulls, and argues that his new SCR aerofoil rigging creates a lift component as well as a drag component.
The big question to consider before buying any rigging product is the primary function of the boat. Phil Anniss says, ‘We believe it is about selecting the right type of composite cable for the right application. The various rigging elements on a yacht experience wildly different loadings and there is no single fibre out there that can provide the perfect solution for all situations. Yes, we’re excited about the possibilities of our new carbon product, but equally there is a lot further to go with all the composite materials: PBO, carbon, Dyneema and Kevlar.
‘For example, PBO is still the lightest fibre for a given modulus and we have just developed our new Enduro product, which is more flexible than our current PBO cables and testing suggests it will last almost twice as long,’ he says.
However, Anniss points out that Enduro will be tested extensively in the racing scene before they start promoting to the superyacht world. ‘We want this to be “Volvo qualified” before we start piling it out to the wider market. The racing world has been, and continues to be, a great place to trial new developments in real-world situations. By the time the product goes on to a superyacht it will have been through more than a million miles of testing.’