Whenever there is a significant technical development one team always seems to be at the forefront in terms of involvement and application. That was the case again with the latest Dyneema SK90 grade, first used in small quantities – though 100kg is a lot of Dyneema – by Alinghi in Valencia. The graphic opposite shows the steep gain in modulus moving from SK78 to SK90 grade fibre – a bigger increase than might be expected even at the expense of a small loss in terms of creep characteristics
Dyneema up their game (again) as the wraps start to come off their SK90 fibre. Dobbs Davis reports To make a high-modulus fibre still stronger takes more than just technical prowess, it takes competitive incentive to justify the added expense in development, testing, retooling in production, and marketing and sales. With the continuing success of Holland-based DSM’s range of Dyneema fibre products in running and standing rigging, it seemed there couldn’t be much more to achieve for a while yet, given that the company’s latest low-creep SK78 variant is already increasingly to be seen on top grand prix programmes. But at the pinnacle of the game – yes, in 42 SEAHORSE
an event called the America’s Cup, where there used to be regular competition on the drawing board and in the water – an even higher level of performance is sought; and the funds and talent are still available to explore new ideas on how to achieve it. In this ethereal world the quest is for what is possible, not just probable, whether in new materials or in the techniques used to manipulate them to create equipment that is stronger, lighter and thus faster. In late 2004 in the run-up to the last America’s Cup, the ACC fleet was in its fifth iteration and so undergoing only subtle refinement to proven characteristics in design, so the pressure was on to find other avenues of improvement in areas such as hardware, spars and rigging. Dirk Kramers and the engineering team at Alinghi were searching for a fibre that could outperform – reliably – the best existing grades of Dyneema SK75 for rigging applications. [It transpires that while Dyneema’s use on ACC and comparable programmes has been relatively commonplace for over a
decade in rigging applications, Kramers says they also used it in the laminate schedule of America3 in 1992 to bring the boat up to the minimum hull thickness needed for the then IACC rule. The special carbon used in the hull by Bill Koch’s science-led team was already strong enough to handle the loads, so something was needed to add bulk with little or no weight. Apparently the material was plasma-treated and cured to allow its normally slippery qualities to accept resin within a laminate…] Having the highest strength-to-weight ratio and flexural strength of any comparable fibres, Dyneema SK75 was already the only choice for applications such as runner strops, halyards and halyard lock systems, jib and spinnaker sheets, and other sailtrimming applications. And though the fibre’s characteristics of light weight, high modulus, tenacity and flexural strength are impressive, Alinghi’s boffins were wondering if it couldn’t be made just a bit better … Their timing could not have been more
TH.MARTINEZ/ALINGHI
Stronger still!