Ronstan Series 55 Ball Bearing Orbit Block - Single - Becket - Swivel Head

The Series 55 Ball Bearing Orbit Block™ is engineered for marine enthusiasts seeking unparalleled performance and lightweight efficiency. Whether you're managing mainsheets, spinnaker sheets, or control lines, this orbit block delivers exceptional strength and durability tailored for dinghies, sportsboats, and small keelboats.

Ultra Lightweight Construction

Designed to offer maximum working load capacity while minimizing weight, the Series 55 Ball Bearing Orbit Block™ stands out as the world's lightest in its class. Its unique orbital design ensures that bearings operate only in the active areas of the floating sheave, significantly reducing the mass of inactive components. This innovative approach not only lowers the overall weight but also enhances maneuverability and ease of handling on the water.

Exceptional Load Performance

The orbital ball-bearing system features the largest possible bearing race diameter, optimizing load distribution and performance. Equipped with Ronstan's proven 2-stage bearing system, it incorporates high compression grade acetal ball bearings and a secondary full-contact bearing. This combination ensures minimal friction across the entire working load range, providing reliable performance even under demanding conditions.

The floating sheave is supported by a fiber-reinforced load frame, meticulously stress-optimized through computer modeling. The Dyneema® Link, crafted from FSE Robline SK75 fiber, offers a connection that is ten times stronger and lighter than steel, ensuring robust and dependable attachment to your boat's load points.

Key Features

• Ultra lightweight design for enhanced performance
• Low friction 2-stage orbital ball bearing system
• Highest working load capacity in its class
• Low profile and compact for easy installation
• High-performance cleating for secure rope management
• Swivel shackle head allowing unlimited block rotation
• Durable stainless steel shackle head compatible with harsh marine environments
• Integrated ultra-low profile becket for streamlined operation

Ideal Applications

• Mainsheet systems on dinghies, sportsboats, and small keelboats up to 9M (30')
• Spinnaker sheets on dinghies, sportsboats, and small keelboats up to 9M (30')
• Halyard, vang, and backstay applications on boats up to 8M (26')
• Control line setups on larger yachts
• Lateral lead blocks for spinnaker sheets on sportsboats and small keelboats

Premium Materials

• Ball Bearings: High compression strength carbon black acetal
• Stage 2 Bearing: Carbon fiber reinforced, PTFE impregnated nylon
• Frame/Cheeks: Toughened, glass fiber reinforced nylon
• Rope Link: UV stabilized, multi-strand impregnated SK75 Dyneema®
• Sheave: Carbon fiber reinforced, PTFE impregnated nylon
• Head Fitting: Grade 316 stainless steel for ultimate durability

Technical Specifications

Specification	Details
Sheave Diameter:	55mm (2-5/32")
Maximum Rope Diameter:	10mm (3/8")
Maximum Working Load (M.W.L.):	500kg (1,100lbs)
Breaking Load (B.L.):	1,000kg (2,200lbs)
Weight:	88g (3.1oz)

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.