Rated 4.9 out of 5 by our customers
Rated 4.9 out of 5 by our customers
90 Day Risk Free Returns
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5 Star Rated by Sailors
Over 60,000+ Orders Shipped
Harken Zircon blocks are the most advanced small boat blocks Harken has ever produced, and if you're serious about your racing, they're worth every penny. At the heart of every Zircon block is a set of industrial ceramic ball bearings mounted in caged races, a design that reduces friction to levels that simply aren't possible with standard stainless or Delrin bearings. The result is a block that feels extraordinarily free-running in your hands and, more importantly, gives you a level of sensitivity through the sheets that makes it easier to feel load changes and respond to them before the instruments do.
The Zircon range is available in 40mm and 57mm sheave sizes, in single and double configurations with and without beckets, covering the mainsheet and control line systems where precise, responsive trimming matters most. All Zircon blocks use soft-attach points rather than metal shackles, keeping weight to a minimum and allowing the block to align naturally to the load path.
We stock the full Harken Zircon range here at Sailing Chandlery, and any order placed by 2pm ships the same working day. If you're not sure whether Zircon is the right choice for your boat or application, just give us a call — we're sailors ourselves and happy to help you make the right decision.
Some frequently asked questions that other customers have asked us about Harken Zircon Pulley Blocks.
What are Harken Zircon blocks?
Harken Zircon blocks are the most advanced and highest-performing small boat blocks Harken has ever made, launched in 2023 after years of development and testing with elite sailors. The big difference from every other Harken block is what's inside: industrial ceramic ball bearings mounted in caged races, rather than the stainless steel or Delrin bearings used in the Carbo range. The cages keep the bearings properly spaced so they never bunch together and slow each other down, and the ceramic material itself is more than 700% stronger in compression than stainless bearings of the same size, meaning they stay smooth and don't deform under load. The result is a block that spins with barely any friction at all, and that responsiveness translates directly into better feel on the sheets and more precise sail control, particularly in light and shifty conditions.
How do Harken Zircon blocks differ from the standard Carbo Air blocks?
Both are excellent pulley blocks, but they are designed for different sailors and different priorities. The Carbo Air range is Harken's trusted workhorse: strong, lightweight, reliable, and great value for the vast majority of dinghy and keelboat applications. The Zircon blocks are the step up from there, built specifically for sailors who want to feel every subtle shift in load and respond to it instantly. Where a 57mm Carbo Air block uses around 50 Delrin ball bearings, the equivalent Zircon uses just eight ceramic bearings in a caged race; fewer bearings, each far stronger, and none of them able to interfere with each other. The friction reduction is noticeable the moment you handle a Zircon block and the benefit is most evident in light air, where the ability to feel very slight changes in sheet load and react to them quickly can make a real difference to boat speed and sail shape.
Who should use Harken Zircon blocks?
Zircon blocks are designed for performance and racing sailors who want to squeeze every last bit of speed from their sail trim. They were developed with input from world champion sailors and first adopted ahead of the Rio Olympics for the Nacra 17 class, where the efficiency gains allowed teams to reduce their mainsheet purchase ratio while maintaining the same sail control. Since then they've been tested extensively on E Scows, A-Cats, Moths, and other high-performance classes. They work brilliantly on any system where you hand-hold lines and need to feel load changes quickly, which covers most systems on a dinghy or small keelboat, as well as light air applications and the end of cascades on larger boats. If your priority is value and durability for general sailing, the Carbo Air blocks remain a superb choice. If you race seriously and want the most responsive blocks available, Zircon is the answer.
