being able to ease when the pressure abates. Indeed in even the lightest air, trimmers report it feels like they can actually push the line out of the blocks. Delivered as a 12:1 mainsheet system, it can easily be reconfigured to 10:1 or 11:1 to align with wind strength or crew preference. Harken’s small boat project
manager, Matt Schmidt says: ’We optimised the Grand Prix cat mainsheet system for weight and efficiency using ceramic bearings that we now use in the Zircon. This greatly reduces rolling resistance in these high-purchase systems. This efficient power transfer to the crew makes it much easier for them to make the adjustments needed to win when racing these powerful cats at the top level.’ Applied within their designed
load capacity, Zircon bearings don’t compress or develop flat spots. The ceramic balls are actually rounder and much less porous on the surface, allowing them to move instantaneously and much more freely. The cages keep the balls the ideal distance apart so they don’t bunch up and stop each other. The result is the most efficient small boat block Harken has developed to date. A very free-running block that continues to spin for a surprising length of time unloaded and thrives within its load range. Zircon blocks are primarily designed for "hand-generated” loads and are appropriate for use in sheets and control lines or the section of a
Top, left and right: the new ceramic bearings in the Zircon range of blocks were initially developed for Olympic foiling multihulls. Above, left and right: Produced in small sizes, Zircon blocks are designed for ‘hand generated’ load applications
cascade rig where it meets the trimmer. For comparable bearing sizes, ceramic bearings can take higher compression loads than their plastic equivalent, but there is a smaller safety margin at the top end of their safe working load, beyond which they can crack or crush. They are not intended to match
the “all performance” of, for instance, Harken’s Carbo Block series, which are designed for a broader range of applications. Schmidt continues: ‘At this
point, we haven’t been using ceramic bearings in any larger or higher load applications. We do use ceramic coatings to provide extremely hard-wearing surfaces in winch drums and hydraulic cylinder rods for instance. However, it’s a case-by-case basis, where ceramics can provide improvements.’ The downside of cutting-edge
technology is very often increased costs. The material cost of an eight- ball, caged ceramic bearing dwarfs the cost of the two rows of 25 Delrin bearing balls used in a conventional 57mm Harken Carbo Block. There are even price points beyond what Harken has selected as the bearings become microscopically even rounder, but at some point, the cost no longer justifies the very slight increase in efficiency. When asked how the ceramic
balls wear compared with Delrin or Torlon, Schmidt said: ‘Contamination is the main source of any wear. As with all open bearing blocks, salt and dirt that isn’t flushed out
regularly can be a problem. Just by the nature of the Zircon design (a single row of precision fit balls/ races) these are a very tight and smooth-running bearing. Small amounts of wear are more easily noticed as compared to a block with wide rollers or two rows of balls. ‘Ceramics are very hard though,
so dirt or salt won’t as easily embed as they would in plastic or even softer metal. Keeping things clean and flushed with water and soap is important. I’ve personally had test blocks on my E scow for three seasons and they haven’t required any cleaning beyond just rinsing in fresh water.’ With regard to lubrication,
Schmidt reckons they’re better off without, or at worst the addition of just one small drop of Harken’s One Drop very occasionally. ‘The intent is for the balls to continue to roll and not end up skidding or sliding.’ he explained. ‘Also, over-lubrication can lead to contaminants sticking to the bearings.’ Peter Harken originally designed
his ball bearing blocks to make it easier to ease sails in the lightest breeze. He says of Zircon, ‘They really make a huge difference. They feel like you can push on the rope and boom, they react. Or you can load up on purchases and not worry about friction holding them back.’ At full production Harken will
offer Zircon blocks in eight model variants, in 40 and 57mm sizes with soft attach versions.
www.harken.com
❑ SEAHORSE 59
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