Harken 57mm High Load Double Block – Black Magic Air (3217)
Twin-sheave power for high-load sail control systems
The Harken 57mm High Load Double Block (3217) from the Black Magic® Air series is designed for high-performance big boat racing and cruising, where powerful sail controls and flawless line handling are essential. With twin sheaves, this block is ideal for multi-part mainsheets, runners, halyards, and spinnaker gear, offering enhanced purchase and distribution of high dynamic loads.
Its lightweight aluminium construction houses a precision-engineered bearing system: Torlon® roller bearings ride on a central cage that keeps them aligned and separated, minimising friction and maximising efficiency even under constant load. The result is a block that spins freely and holds strong during aggressive trimming and frequent manoeuvres.
The versatile shackle head can swivel freely or be locked in two positions to accommodate complex lead angles and prevent line twist. Whether on deck or aloft, the 3217 delivers uncompromising reliability in the most demanding applications.
Specifications
| Length (mm) | 132 |
| Recommended line - Max Ø (mm) | 12 |
| Sheave Ø (mm) | 57 |
| SWL (kg) | 1633 |
| NBL (kg) | 3267 |
| Weight (g) | 336 |
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