Core Blocks™

Use them Anywhere

A balanced design approach incorporating functionality, performance and style makes our Core Blocks™ the right choice for performance cruising or racing applications. A tuned 2-stage bearing system provides excellent performance across the full working load range with an integrated thrust bearing feature and the resilience to handle high dynamic or static loads. Acetal & aluminium sheave options, alloy cheeks and stainless fixings complete the durable package.


The Ronstan Universal Bearing incorporates our proven 2-stage bearing system.
Stage 1 – Under moderate loads, acetal ball bearings ensure minimum friction.
Stage 2 – Under heavy loads, where deformation of ball bearings alone would result in increased friction, a sliding acetal bearing on a polished stainless steel race takes over, maintaining low friction performance.Additionally the ball bearings are configured to act as a thrust bearing between the sheave and cheeks, preventing the sheave from rubbing on the cheeks and causing friction when the line lead in and out of the block isn’t perfect. Particularly important for foot blocks.

Block cheeks are manufactured from the highest quality aluminium alloy for maximum strength. Material optimisation and the cut-away design minimises weight and allows easy fresh water rinsing of salt and debris from the bearings. Cheek design has been further styled with flaring at the block throat and reduced gap between the cheek and sheave, minimising rope wear, and the hollow hub can be used as a becket take-off or tie-up point.

Selected models are available with an aluminium sheave which has a deep groove profile specifically made for use with wire.

The head assembly incorporates a brass bearing washer to provide smooth 360° rotation of the post and shackle. A set screw arrangement allows the head to be locked at 0° or 90°. Shackles are high quality forged grade 316 stainless steel.

Removable becket pins allow fitting of pre-spliced lines. The flush fit becket pin head is kind on deck surfaces and won’t snag lines.

Stand-up models have a low profile linkage that provides full rotation and articulation. A high strength precision cast padeye minimises the footprint and a dedicated rubber boot ensures the block is held upright when not loaded.


Ball Bearing
Orbit Blocks™


Ball Bearing Orbit Blocks™ have been engineered to achieve the highest possible strength-to-weight ratio, using composite reinforced polymer materials and a Dyneema® link attachment instead of metal components. The unique orbital version of our 2-stage ball bearing system maximises the available bearing surface and positions recirculating ball bearings exclusively within the loaded area of the sheave. A secondary full-contact bearing maintains low friction across the full working load range. The Dyneema® link, realised in high-grade SK75 fibre, is easily fitted and retained securely by a moulded retainer clip. The flexible link allows limited articulation in a 0° or 90° orientation, while swivel head models with stainless steel shackles provide full rotation and ultimate durability. Orbit Blocks™ are fitted with our carbon-fibre reinforced C-Cleat™ for secure rope holding with low entry and exit efforts, and fairleads for fast action from any angle. Cleat arms have a wide range of adjustment and calibration marks for setting your preferred cleating angle.

Ball Bearing Orbit Blocks™ - FEATURES

Kilogram for kilogram of working load, BB and RT Orbit Blocks are the world’s lightest. To gain peak performance, we engineered out the heavy steel load straps, head post, shackle, full-length fasteners, and cleating accessories. Through extensive research and development, we replaced virtually all metal components with high-tech polymers and fibre equivalents. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimises the mass of the inactive return race and hub. Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block has a through-sheave becket arrangement. The result? The lowest weight possible. Multi-sheave blocks have only single intermediate cheeks and an ultra-light and efficient head arrangement. This gives a 30% weight saving advantage over the nearest competitor. Other brands just link together their single blocks. This results in unnecessary double cheeks between each sheave, held together by a heavy steel channel across the top of the block.

Block cheeks are manufactured from the highest quality aluminium alloy for maximum strength. Material optimisation and the cut-away design minimises weight and allows easy fresh water rinsing of salt and debris from the bearings. Cheek design has been further styled with flaring at the block throat and reduced gap between the cheek and sheave, minimising rope wear, and the hollow hub can be used as a becket take-off or tie-up point.

The orbital ball-bearing arrangement gives the largest possible bearing race diameter. This maximises load performance. The proven Ronstan 2-stage bearing system features high compression grade acetal ball bearings and a secondary full-contact bearing. This gives minimum friction across the full working load range. The floating sheave and bearing system is supported by a fibre-reinforced load frame. The design was computer modelled to be stress optimised. The Dyneema® Link is produced from FSE Robline SK75 fibre, which is 10 times h6er and lighter than steel, and provides the final connection from the block to the load point.
The flexible Dyneema® Link provides controlled rotation and 0° or 90° orientation. It connects directly to the head of the block rather than to an intermediate head post. This reduces weight and gives the lowest possible profile while allowing full articulation. Beckets have been carefully designed to minimise height.

Ball Bearing Orbit Blocks™ - PRODUCT RANGE

Ratchet Orbit Blocks™


Multiple gripping faces machined into our ratchet block sheaves work in conjunction with our unique cross-hole geometry, delivering up to 20:1 holding power to resist slipping of the loaded line while minimising rope wear. Ball bearings ensure minimum friction under load and a free running sheave when the ratchet is disengaged.

Control switches are located on both sides of the block to remain accessible wherever the block is fitted. In auto mode, the ratchet mechanism engages when load is applied but disengages when released to let the sheet run out freely – ideal for gybing asymmetric spinnakers. In manual mode, the switch is used to set up the block with ratchet either on or off as required.

It is essential equipment on racing dinghies and sports boats, and when you want the ultimate holding power.

Ratchet Orbit Blocks™ - FEATURES

Quite simply, Ronstan Ratchet Orbit Blocks™ have the highest holding power available. The sophisticated NC-machined sheave features Generation 2 of our patented sheave cross-hole geometry. Its holding power is up to 25:1, almost double that of our nearest competitor. The unique sheave design has 12 gripping faces which directly resist loaded line movement. Traditional designs have only 8 faces with an angled resistance to line movement. Our Generation 2 design has straight resistance faces which both distribute the load and minimise rope wear. These faces are offset from the radial line, to draw the rope down into the gripping area when under load.
The Dyneema® Link is easily fitted and is retained securely by a moulded retainer clip. The flexible link can be left with one end attached to the block when fitting – no more lost shackle pins. The system is compatible with Dyneema®/Spectra® strops, webbing and carbon connection points – much more so than steel loop tops or shackles.

Ratchet Orbit Blocks™ - PRODUCT RANGE

Soft Attachment Blocks


Designed from the outset to deliver outstanding performance, these blocks achieve the highest ratings for dynamic load vs sheave diameter in our keelboat block range. They are built to perform and built to last. Every SA Block features fully machined, anodised aluminium cheek plates. Sheaves run on duplex stainless steel hubs and incorporate precision composite journal bearings and thrust washers. The soft attachment is a purpose designed Dyneema® SK99 cord shackle with titanium dog bone.

Soft Attachment Blocks - FEATURES

SA Blocks incorporate a full contact, selflubricating composite journal bearing running on a polished duplex stainless steel hub, to maintain low friction performance under heavy dynamic and static loads. Thrust washers in the same composite material are positioned between the sheave and the cheek plates to handle the high side loads that can be generated when line entry and exit alignment is not ideal. Testing has shown reduced friction and greater durability than ball bearings in this application.
The soft shackle provides a simple means of attachment, secured with the titanium dog bone but easily opened when necessary to detach the block. With the shackle open a entle rotation of the cheek plates opens the head of the block so it can be fitted to a standing line. To close the block, rotate the cheeks back to the closed position until the spring loaded ball lock secures them in place. No additional external straps or bands required.
Drawing on the expertise of Nodus Factory, many design iterations were tested before finalising specifications of the Dyneema® SK99 cord shackle and titanium dog bone. Proprietary Nodus Factory splicing techniques and fibre surface coating ensure secure load transfer from the block and maximum durability.
Block cheeks and sheaves are precision machined from high strength aluminium alloy, then anodised for durability and corrosion resistance. The soft attachment through the hub provides a protective buffer between the block and boat surfaces. Retaining guides in soft elastomer ensure that the block remains aligned within the soft shackle.

Suited to temporary or permanent line deflection, load carrying and snatch block applications including:

  • 2:1 Main halyards
  • Headsail and spinnaker sheets
  • Mast base halyard deflection
  • Running backstays

Soft Attachment Blocks - PRODUCT RANGE

Orbit Blocks™


Orbit Blocks™ are a no-compromise product range developed to meet the demands and expectations of the very dedicated and increasingly professional racing sailor, with characteristics including:


The Orbit sheave has captive Acetal or Torlon® ball bearings for side thrust loads, eliminating the need for side retainer plates. This reduces weight and allows for a wider bearing surface that can accommodate longer Torlon® needles – achieving a substantially higher strength-to-weight ratio.

There are only 3 primary components to the block: the twin side pieces, sculptured from solid high grade alloy, and the one-piece sheave with its captive ball bearings. The Orbit sheave has captive acetal or Torlon® ball bearings for side thrust loads, maximising the available bearing surface for its Torlon® needle rollers to achieve a high strength-to-weight ratio.
Head posts of swivel blocks can be locked at 0° or 90°. The high resistance shackles are forged in grade 17-4PH stainless steel.
These blocks have been designed primarily for attachment around the mast collar to lead halyards aft from the mast base to winches. The head of the block has a removable pin which enables easy attachment to the deck padeye or mast collar. This method of attachment provides a low lead aft to organisers or winches.
These lightweight alternatives to traditional blocks are used where a rope lashing attachment is passed through the hub of the sheave to provide a failsafe feature. Lashing blocks have incredibly high breaking loads – up to 40,000kg. Their versatility makes them suitable for many applications, with four lashing guide holes to allow for multiple attachment options including single, parallel and split lashings. The central hole can also be used for a becket in 3:1 purchase systems. Every detail has been carefully executed to achieve the best optimisation of performance, size, weight and ultimate strength available today.
The bottom plate incorporating the hub section is machined from solid alloy for maximum integrity of the load bearing structure. The top cover plate protects the sheave against impact, prevents dirt and grit from entering the hub area, and can be removed for service without removing the mounting bolts that secure the block through the base plate to the deck.
A number of stand-up solutions are available for Orbit Blocks™. These include assemblies incorporating padeye and rubber boot, stand-up spring kits and blocks with special swivel-eye to suit non-tumble padeyes.

Ball Bearing Blocks


Ronstan’s Ball Bearing and High Load blocks, conceived and engineered for the demands of competitive sailing in skiff, Olympic and sports boats classes, have rapidly become the international choice for high performance hardware.


Meet the high performance demands of running sheet applications with a unique two-stage bearing system. Stage 1 – Under moderate loads, Acetal ball bearings ensure minimum friction. Stage 2 – Under heavy loads, where deformation of ball bearings alone would result in increased friction, a sliding Acetal bearing on a polished stainless steel race takes over, maintaining low friction performance. Regular flushing with fresh water to remove salt and sand will maintain optimum performance over a long service life. These blocks are an excellent choice for main and jib sheets, spinnaker sheets and control lines.

Ball Bearing Blocks™ - PRODUCT RANGE

Utility Blocks


Utility Blocks are an ideal match for the needs of everyday recreational sailing. They are designed for low-maintenance reliability and offer a choice of sheave/ bearing configurations depending on their intended use.


UV stabilised Acetal sheaves provide bearing performance on a polished stainless steel race that performs equally well with dynamic and static loads. Sheave design features side ribs to minimise weight and enhance strength. Self-lubricating Acetal polymer minimises friction and ensures dependable load bearing reliability.

Utility Blocks™ - PRODUCT RANGE

Special Purpose Blocks


Special Purpose Blocks are based upon the same race winning design concept as the Ronstan high performance Ball Bearing blocks, but utilise a full contact bearing for ultimate performance in high load or prolonged static load applications.


Wear resistant sheave materials, either in lightweight, self lubricating polymer or in alloy with special purpose bushes, are suitable for use with rope or wire. High Load blocks provide outstanding static load performance and are typically used for halyards, backstays, etc.


Ultimate Ratchet Blocks™


Our Alloy Ratchet blocks have been optimised to deliver maximum holding power and durability.


Quietly boasting an increased 20:1 holding power, the Ultimate Ratchet Block™ has a strong dinghy pedigree and has been at the top of the Olympic and World Championship podium, whilst also providing a touch of finesse to main and spinnaker sheet systems aboard sportsboats and small keelboats.
The Ultimate range features a patented extruded-hole ratchet sheave, hard anodised cheek plates and a low friction carbon black Acetal ball bearing system that also provides a premium control line solution for larger yachts.


Upright & Pivoting Low Lead Blocks

Upright & Pivoting Low Lead Blocks - PRODUCT RANGE

CONTATTI via Meucci, 3 – Z. I. Aussa Corno 33058 San Giorgio di Nogaro (Ud) – Italy
T +39 0431 65575 /

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