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Ronstan Soft Attachment Snatch Blocks

Designed from the outset to deliver outstanding performance, these blocks come in three sizes and 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 high strength aluminium dog bone.

Ultimate dynamic and static load performance
SA Blocks incorporate a full contact, self-lubricating 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.

Attach, detach and open
The soft shackle provides a simple means of attachment, secured with the high strength aluminium dog bone but easily opened when necessary to detach the block. With the shackle open a gentle 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.

Soft shackle with high strength aluminium dog bone
Drawing on the expertise of Nodus Factory, many design iterations were tested before finalising specifications of the Dyneema® SK99 cord shackle and high strength aluminium dog bone. Proprietary Nodus Factory splicing techniques and fibre surface coating ensure secure load transfer from the block and maximum durability.

Aluminium alloy cheek plates & sheaves
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.

A multitude of applications
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

RF47109 42mm, RF47109NS 42mm no soft shackle, RF67109 60mm, RF67109NS 60mm no soft shackle, RF77109 75mm.

For more information on Ronstan, please contact Sales here.