Series 30 Orbit Single Block with Slotted Headpost
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RONSTANSeries 30 Orbit Single Block with Slotted Headpost


In stock online.
Model # 10468536 | Mfg # RF35100AUPC # 9316800415052


Series 30 Orbit Single Block with Slotted Headpost

Name Value
Becket No Becket
Diameter 5/16 Inch or 8 mm
Direction Any
Integral Cleat No Integral Cleat
Mount Type Swivel Shackle
Ratchet Non Ratcheting
Safe Working Load 661 Pounds
Sheave Diameter 1 3/16 Inches or 30 mm
Type Single
Weight 1.1 Ounces

Product Overview

Lightweight and strong blocks for modern rigging systems.

The 30mm single block slotted head post is a true workhorse and is suitable for use in most dinghy control line systems. The slotted post allows the block to be secured using an eye strap, bow shackle (included) or bail. Great for boom vangs, sheets, backstays, halyard tuning systems and more.

Ronstan’s goal for the Orbit Blocks™ was to produce a block with the highest strength to weight ratio—and they nailed it. Through extensive computer modeling unnecessary metal components were replaced by engineered light-weight composites without compromising strength. The unique glass fiber reinforced nylon cheeks and head design can be secured using the supplied loop or converted to a soft attachment using a Dyneema® link to further reduce weight. The hollow bearing at the center of single sheave serves as a becket to further reduce weight while adding versatility.

Performance was not lost with the weight savings. In fact the Orbit Blocks™ have the highest working loads in their class and feature an improved two-stage bearing system that efficiently handles static and dynamic forces throughout the load range. High compression grade acetal orbital ball bearings migrate to the loaded area of the sheave to handle light to moderate loads; larger loads are shouldered by the full-contact PTFE impregnated nylon bearing with carbon fiber reinforcement. Conventional and high-tech lines run smoothly over the UV resistant acetal sheave

Sailors can have the best of both worlds with Ronstan Orbit Blocks™. These lightweight and compact bocks are smooth, efficient even under larger loads and are an ideal solution for modern control line systems on dinghies up to larger yachts.

Key Features

  • Excellent strength to weight ratio
  • Improved two-stage bearing system for efficiency for static and dynamic loads
    • Acetal ball bearings migrate to load areas of the sheave for light to moderate loads
    • PTFE impregnated nylon bearing with carbon fiber reinforcement supports higher static loads
  • Hollow bearing at center of sheave serves as a becket to reduce weight and offer additional versatility
  • UV resistant Aceal high compression sheave that is compatible with conventional doublebraid and high-tech 12 stand lines
  • Ideal for
    • Boom vangs
    • Backstays
    • Halyard tuning systems
    • General dinghy control lines 

Orbit Blocks™ User Instructions

Ronstan Orbit Blocks™ Selection Guide

Sheave DiameterLine CompatibilityShackle Pin Diameter (if applicable)
20mm1/4" (6mm)1/8"
30mm5/16" (8mm)5/32"
40mm5/16" (9mm)5/32"
50mm3/8" (10mm)3/16"
55mm3/8" (10mm)3/16"
70mm1/2" (12mm)Only available with Dyneema® link


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