Getting easier, getting lighter

New soft-fibre based standing rigging solutions have many advantages

The use of Armare Ropes’ PBO-Zylon fibres for the standing rigging of high-end raceboats from 25-28ft up to around 70-80ft is well proven and brings advantages equivalent to and in some cases greater than carbon rigging, yet at a fraction of the cost.

Armare has been producing PBO-Zylon for standing rigging for 20 years and has built thousands of individual custom cables during that time. The Italian firm is also ropes official supplier to Emirates Team New Zealand and many Class 40s and Imoca 60s. Most of its PBOZylon cables are retrofitted to existing boats. Custom solutions for interface and other potential problems can be created within short lead times.

Key criteria for standing rigging include minimal elongation under load (axial stiffness), weight and finished diameter. Despite its lower cost, PBO-Zylon can outperform carbon micro rod in all these areas.

In lab tests against equivalent 29m long carbon micro rods, Armare PBO Zylon showed broadly equal elongation up to a load of 1,500 daN with both materials having around 0.05 per cent elongation. However, the PBO-Zylon was better at higher loads of 3,000 daN (about half the MWL), where elongation averaged 0.1222 per cent, while the figure for carbon micro rod was more than a quarter higher at 0.157 per cent.

With a weight of 5.4kg, the PBO Zylon cable is 10 per cent lighter than the carbon micro rod cable. It’s also narrower, with 13.8mm diameter versus 14.5mm, which helps reduce aero drag. When replacing rod rigging, PBO Zylon costs well under one third as much as a carbon alternative.

Compared with rod rigging, the benefits of Armare’s PBO-Zylon are enormous, including a 5:1 weight advantage over Nitronic 50 rod sized to give the same elongation under load. In practice it’s possible to reduce both weight and elongation.

It’s easy to underestimate the scale of the benefit this reduction of weight aloft brings. On many yachts 1kg in the rig has an equivalence to 3-4kg in the keel bulb. Saving weight in the rig can therefore significantly increase righting moment, allowing the boat to carry more sail in a given wind speed. Pitching and rolling are also reduced, minimising the loss of speed from these factors and giving a more comfortable motion.

Above: PBOZylon rigging cables are light and perform very well under high loads even when compared with carbon cables. They are also comparatively inexpensive

The only downside is a greater requirement for periodic inspections and a shorter overall lifespan. Nevertheless, PBO-Zylon is still seen as a reliable and very cost-effective option for many owners of highperformance craft. Last year, for instance, Armare Ropes signed agreements to supply standing rigging to the Melges 32 class. The higher axial rigidity of its PBO-Zylon improves performance of these boats, especially in gusty conditions, where the vessel’s response and acceleration is faster and more immediate.

Armare’s in-house engineers also developed new rigging terminals and backstays for various one design classes, including the Melges and the Cape 31, which the company says were “immediately welcomed with great enthusiasm for their careful and very refined aesthetics.” These are similarly well finished aesthetically and provide a more immediate response that “translates into greater thrust on the sails and less loss of power.” Further benefits of PBO Zylon is that it’s easy to handle and to roll into coils, which facilitates shipping, installation and maintenance.

What about longevity and reliability? To date no cable supplied by Armare has failed within the manufacturer’s stated life limit and some owners have continued to use cables well beyond this time.

Armare CEO Stefano Finco points out that, while there’s some debate between manufacturers as to longevity, ‘we all tend to be very conservative, even if the cable is constructed in a good way.’ He adds: ‘lifespan is strictly connected to the type of boat and the application.’

Armare recommends that cables are returned to the factory every three years, where they can be checked for excess elongation. At the same time Armare’s technicians will also look at wear points in the terminals and check the pins. This process allows for a lifespan of six to eight years, depending on the application on board.

The structural fibres are protected by the Dyneema cover, plus layers of engineering plastic that protect against UV light, humidity, dust, and salt. In the event of mechanical damage covers can be replaced in the factory, creating a cable that Finco says is ‘like new, providing that the structural fibres have not been damaged.’

For the majority of owners, the most surprising aspect of Amare’s PBO-Zylon standing rigging is the cost. While this varies depending on the boat and application on board, it’s typically only 40 per cent of the cost of carbon standing rigging. That ought to make upgrading to PBOZylon a very easy decision.

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