Ronstan Series 50 All Purpose Block - Double - RF51200
Manufacturer Part #: RF51200
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Ronstan Series 50 All Purpose Double Block – RF51200
The Ronstan Series 50 All Purpose Double Block (RF51200) is a strong, lightweight, and versatile pulley designed for high-load sail control systems on cruising and performance sailboats. Built to handle demanding applications, this double block delivers smooth, efficient line handling with minimal friction.
Featuring two 50mm sheaves, the RF51200 is ideal for use in mainsheets, vang systems, traveler controls, halyards, and control line purchases. Ronstan’s precision-molded UV-stabilized composite cheeks provide excellent strength-to-weight performance while resisting corrosion in harsh marine environments.
The self-lubricating acetal sheaves rotate freely under load, reducing wear on both the block and line. A stainless steel load-bearing axle ensures long-term durability and reliable performance under continuous use, whether racing or cruising.
Compact yet powerful, the Series 50 double block is a trusted choice for sailors who demand efficiency, durability, and proven engineering from their deck hardware.
Key Performance Features
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Universal Head Design: The head features a "three-way" shackle system that can be locked at 0° or 90°, or left to swivel freely, preventing line twists and tangles.
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Stainless Steel Load Frame: A robust internal stainless steel frame carries the primary structural load, ensuring the block won't fail even if the UV-stabilized plastic cheeks are damaged.
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High-Grade Acetal Sheave: The sheave is made from self-lubricating acetal, which provides low friction and excellent wear resistance against both braided and traditional ropes.
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Versatile Application: Ideal for 4:1 or 6:1 mainsheet systems when paired with a single or triple block, as well as vang and cunningham systems.
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Composite Cheeks: Fiber-reinforced nylon cheeks provide impact resistance and protect the boat’s deck and spars from scratches.
Technical Specifications
| Feature | Details |
| Model Number | RF51200 |
| Sheave Diameter | 50mm (2") |
| Max Rope Diameter | 10mm (3/8") |
| Max Working Load (MWL) | 1000 kg (2,200 lbs) |
| Breaking Load | 2000 kg (4,410 lbs) |
| Weight | 196g (6.9 oz) |
| Shackle Pin Diameter | 6mm (1/4") |
Comparison: AP vs. Ball Bearing
When choosing between the AP (All Purpose) and Orbit (Ball Bearing) blocks:
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Choose AP (RF51200): For high-load, static applications like halyards, backstays, or mainsheet systems where the line stays under high tension for long periods.
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Choose Orbit: For high-speed, low-load applications like spinnaker sheets where "free-running" speed is more important than raw breaking strength.
Renowned for precision engineering and reliability, Ronstan deck hardware is trusted by sailors worldwide. The Series 50 All Purpose Double Block – RF51200 delivers dependable performance for a wide range of onboard rigging and sail control applications.
Ronstan Series 50 All Purpose Block - Double - RF51200 is backordered and will ship as soon as it is back in stock.
Ronstan Series 50 All Purpose Block - Double - RF51200
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