The genie’s out the bottle
Higher line and rigging loads will almost always translate directly into higher performance on the water… It’s hanging on to the ends – while being able to adjust them properly – that is the more difficult equation
A system is only as strong as its weakest point. It’s a universal truth that applies to many things in life, and certainly to the world of rope holding. A racing team that’s always looking to make performance gains, by upgrading sails, spars or rigging or rope-holding equipment, should also bear in mind that as each of these modifications stiffen the system, so the peak dynamic loads on the line increase. Something has to give, unless you take the necessary precautions.
Balancing act When considering rope holding, it’s vital you look at both halves of the equation, because the grip on a rope is dependent in equal measure on the characteristics of the gripping surface and the surface being gripped. In the design and development of jammers and clutches you also need to make your assessments in the context of rope manufacturers’ continued development of fibre and braiding technologies. Good partnerships with the
rope manufacturers are critical to 68 SEAHORSE
Spinlock being able to develop the best possible rope-holding products, as head of the Special Projects Team, Charlie Carter explains: ‘Spinlock enjoy close relations with all the major rope manufacturers to make sure the two fields develop in sympathy with one another, the objective being that the customer is able to hold the load he needs, on the line he chooses. ‘Every competitive sailor
understands the need for reducing weight and windage aloft; so as we see strength and stiffness improvements in rope fibres we also see rope diameters becoming smaller and smaller. This means that trying to develop the best possible rope-holding equipment, the goalposts are always moving.’
Tougher challenge Load-holding performance is dependent on a number of factors, both in rope and hardware. According to Carter, the key factors for the hardware are the pressure exerted on the rope and the area over which it is exerted, coupled
Above: the XX0812 Powerclutch, these three examples are mounted on a new TP52. Maximum safe holding load is 2,350kg on a tiny footprint, and with the ability to release fully under load with minimal line wear. Ceramic coated jaws, all titanium parts and a machined body offer massive holding in a compact body. The lines are led through a TSR20 High Load Diverter, again in full titanium as are all of the fastenings
with the friction generated by the gripping surface. ‘The mechanism determines the force, the profile and section of the cam or jaw affecting the area of contact and consequently the pressure, and the grip pattern and surface texture govern the friction.’ These factors are also affected
by the rope’s characteristics. Fibre material, braid pattern and tightness and thickness of the cover relative to the core affect the coefficient of friction, the cover stretch and section form stability under load and under compression (change in the shape of the line and consequentially the contact area) and the transfer of load from cover to core. Fibre blends in ropes are chosen to suit the different applications; durability, strength, stretch, creep, water absorption and heat resistance are important criteria to be considered alongside rope-holding performance, so rope- holding technology has developed to meet the compromise.
Theory and reality Recent years have seen project
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