Ronstan Series 55 Ratchet Orbit Block - Single - Swivel Head - Auto & Manual

The Series 55 Ratchet Orbit Block by Ronstan is engineered for the discerning boater seeking unparalleled performance and versatility. Featuring a robust swivel head and dual engagement modes, this single block seamlessly integrates into your sailing setup, ensuring smooth sheet handling and exceptional holding power for a range of marine applications.

Exceptional Ratchet Mechanism

Experience the ultimate in control and flexibility with Ronstan's exclusive automatic and manual ratchet engagement modes. In automatic mode, the ratchet engages effortlessly when load is applied and disengages upon release, allowing sheets to run out smoothly—ideal for rapid easing and managing asymmetric spinnakers. Switch to manual mode to control the engagement as needed, a preferred setup for many seasoned sailors. Test both modes to find the perfect fit for your sailing style.

Unmatched Holding Power

Ronstan's Ratchet Orbit Blocks boast the highest holding power in the market, thanks to the advanced NC-machined sheave with Generation 2 cross-hole geometry. Offering up to 21:1 holding power, nearly double that of competitors, these blocks feature 12 gripping faces that provide straight resistance to line movement. This design not only distributes the load efficiently but also minimizes rope wear, ensuring longevity and reliability in demanding conditions.

Key Features

• Up to 20:1 holding power for superior load management
• Seamless easing of sheets for smooth sail adjustments
• High-performance cleating ensures secure sheet handling
• Swivel shackle head allows unlimited block rotation for optimal positioning
• Stainless steel shackle head ensures durability and compatibility with harsh marine environments
• Dual automatic and manual ratchet engagement modes for versatile use

Ideal Applications

• Mainsheet systems and spinnaker sheets on dinghies, sportsboats, and small keelboats up to 8 meters (26 feet)
• Halyard, vang, and backstay setups on boats up to 8 meters (26 feet)
• Spinnaker sheets on sportsboats and small keelboats utilizing lateral lead blocks

Premium Materials

• Sheave: Hard anodised Aluminium for durability and smooth operation
• Ball Bearings: High compression strength carbon black Aceetal for reliable performance
• Frame/Cheeks: Toughened, glass fiber reinforced Nylon for enhanced strength
• Rope Link: UV stabilized, multi-strand impregnated SK75 Dyneema® for superior line handling
• Head Fitting: Grade 316 stainless steel to resist corrosion in harsh marine conditions

Product Specifications

Specification	Details
Sheave Diameter	55mm (2")
Maximum Rope Diameter	10mm (1/2")
Minimum Working Load (M.W.L.)	250kg (550lbs)
Breaking Load (B.L.)	650kg (1,430lbs)
Weight	82g (2.9oz)

See It in Action

Orders of physical products placed by 3 PM EST M-F typically ships the same day, if all requested items are in stock. Weekend orders will typically ship on Monday.

Shipping takes 2-7 days.

We currently ship to the Contiguous 48 States.

Life of Sailing merch is custom made for the customer after an order is placed. Total turnaround is typically 7-14 days from order to doorstep.