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Ronstan S55 RT Orbit Block,Single Swivel Head (RF56100)

SKU:  RF56100

Brief Description:

Now you can enjoy the flexibility of setting up your ratchet blocks to suit yourself. Ronstan is the only company that offers a ratchet block with both auto and manual engagement modes*. In the auto mode of the ratchet mechanism engages when load is applied, but switches off when it's released.

In manual mode, the ratchet mechanism can be switched on or off as required.

* Selected Series 55 models.


Quite simply, Ronstan Ratchet Orbit Blocks™ have the highest holding power available.Its holding power is up to 21:1, almost double that of our nearest competitior.



  • Automatic and Manual ratchet in one block
  • Up to 20:1 holding power
  • Smooth easing of sheets
  • High performance cleating
  • Swivel shackle head for unlimited block rotation.
  • Stainless steel shackle head for ultimate durability and compatibility with harsh fixing points.


  Sheave Ø 55 mm
  Max. Rope Ø 10 mm
  Max. Cable Ø mm
  Pin Ø mm
  M.W.L. 250 kg
  B. L. 650 kg
  Weight 82 g



  • Mainsheet systems and spinnaker sheets on dinghies, sportsboats and small keel boats to 8m(26ft).
  • Halyard, vang and backstay applications on boats to 8m (26ft).
  • Spinnaker sheets on sportsboats and small keel boats (lateral lead blocks)



  • Sheave: Hard anodised Aluminium
  • Ball Bearings: High compression strength carbon black Aceetal
  • Frame/Cheeks: Toughened, glass fibre reinforced Nylon
  • Rope Link: UV stabilised, multi-strand impregnated SK75 Dyneema®
  • Head fitting: grade 316 stainless steel.
  • Ball Bearings: High compression strength carbon black Acetal.
  • Sheave : Hard anodised aluminium.