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Ronstan SHOCK Blocks - Simple Efficient Low Friction Rings

by Phil Anniss 22 Jan 09:00 PST
Ronstan SHOCK Blocks - simple efficient low friction rings © Kohlhoff Stuhlemmer Sailing

The name of the Ronstan SHOCK Block is derived from SHeaveless blOCK and reflects the growing trend for replacing ball bearing blocks, with "low friction rings", in a whole range of sailing system applications. Lightweight, high-load with no moving parts, Shock blocks are perfect for control lines and small purchase systems.

Made of anodised aluminium, Ronstan Shocks are available in two sizes (for lines up to 5mm and 10mm max diameters) and 3 colour options (Blue, Red and Grey). They are specifically designed for soft attachment; either spliced directly onto the end of a line, lashed or fixed in place with webbing.

The elongated attachment aperture has been designed to ensure correct alignment of the Shock to the line load, whilst the gentle overall 3D geometry is kind on the running line and forgiving to lead-angle variations.

Tech Specs

Line Min (mm)Line Max (mm)Height (mm)Width (mm)Length (mm)BL (kg)Weight (g)
Shock 5mm1.558.514.922.93502.5
Shock 10mm31014.524.836100012

Key Benefits

  • Lightweight
  • Compact
  • Cost effective
  • NO moving parts - maintenance free
  • Durable
  • Colour coded
  • Impact resistant
  • Strength to weight ratio
  • Soft attachment


  • Line deflectors
  • Purchase systems
  • In-hauls / Out-hauls / Tweakers
  • Lazy jacks
  • Dinghy Vang
  • Cunningham


It is obvious that a lot of thought and engineering has gone into creating such a simple product. If you have a dinghy, sportsboat or any yacht with small diameter control lines; armed with a handful of Ronstan Shocks, some single braid Dyneema® and bungy cord, you can transform your onboard systems!

You can view Ronstan Shocks online or if you have any questions about any deck hardware issues, please feel free to contact us at or via the Deck Hardware enquiry form.

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