Harken 57 mm Zircon Double Block, 2197

Zircon blocks are the most efficient small boat blocks Harken has ever made. At the core of Zircon's performance are industrial ceramic ball bearings mounted inside caged races. The cages keep these bearings apart so they don’t bunch up, touch, and stop each other. The result is a very free-running block with less energy lost to friction than in even our current Carbo blocks. Give an unrigged Zircon block a strong spin, and it spins for an incredibly long time. Zircon bearings are more than 700% stronger in compression than stainless bearings of the same size. So, they won’t deform if used within the recommended load limits. More importantly, they don’t absorb as much energy before starting to roll. This becomes evident when you need to ease a sail in very light air. You feel even the slightest fluctuations in sheet load. When used expertly, that means better sail shape and more speed.

• All Zircon blocks have smooth, soft attachment points. This saves fastener weight, is kinder to the lace line, and lets the block better align to the load path.
• Zircon is named after Zirconium, the metallic element #40 on the periodic table of elements.
• Each ceramic bearing ball used in Zircon blocks is very hard, smooth, and expensive. That’s why we designed the block to perform using only 7.
• The white inner bearing races are molded inside the black glass fiber-reinforced sheave material. It’s a new process developed in Pewaukee.
• The ceramic bearing balls run in a curved inner-race that is also ceramic. That race needs to be made of like metal. Without it, the ceramic balls would destroy the block from the inside.