Ronstan RF56100 Series 55 Ratchet Orbit Block Single Swivel Head Auto/Manual

The Ronstan RF56100 Series 55 Ratchet Orbit Block offers unprecedented versatility with both automatic and manual ratchet engagement modes. In auto mode, the ratchet engages under load but releases when tension is removed, allowing sheets to run out smoothly—ideal for rapid easing and gybing asymmetric spinnakers. In manual mode, sailors can switch the ratchet on or off as needed, the preferred setup for many competitive mainsheet applications.

Industry-Leading Holding Power:

• Up to 21:1 holding power, nearly double the nearest competitor
• CNC-machined sheave with Generation 2 cross-hole geometry
• 12 gripping faces with straight resistance for optimal load distribution
• Offset faces draw rope into gripping area under load
• Minimizes rope wear while maximizing holding performance

Construction & Materials:

• Hard anodized aluminum sheave with ball bearings
• Toughened glass fiber reinforced nylon frame and cheeks
• 316 stainless steel swivel shackle head for unlimited rotation
• High compression strength carbon black acetal bearings
• UV stabilized multi-strand SK75 Dyneema rope link

Specifications:

• Sheave diameter: 55mm (2 inches)
• Maximum rope diameter: 10mm (1/2 inch)
• Maximum working load: 250kg (550 lbs)
• Breaking load: 650kg (1,430 lbs)
• Weight: 82g (2.9 oz)

Applications: Ideal for mainsheet systems and spinnaker sheets on dinghies, sportsboats, and small keelboats to 8M (26 feet). Also suitable for halyard, vang, and backstay applications, as well as lateral lead blocks for spinnaker sheets.