Series 55 Ratchet

 Orbit Block™


  •  Up to 20:1 holding power
  •  Smooth easing of sheets
  •  High performance cleating

  Product No. Desc. Sheave ØMax. Rope ØMax. Cable ØPin ØM.W.L.B. L.Weight
 RF56100 RF56100 Single, swivel head, auto & manual 5510525065082
 RF56101 RF56101 Single, auto & manual 5510--25075078
 RF56110 RF56110 Single, Becket, Swivel Head, auto & manual* 5510525075086
 RF56120 RF56120 Single, Cleat, Swivel Head, auto* 55 + 35105250*2750204
 RF56130 RF56130 Single Becket Cleat, Swivel Head, auto* 55105250*750209
 RF56151 RF56151 Cheek Block, clockwise, auto & manual 5510--25070076
 RF56151A RF56151A Cheek Block, anti-clockwise, auto & manual 5510--25070076
 RF56330B RF56330B Triple, underhung becket, adjustable cleat, auto, swivel* 5510750*1500392
 RF56510 RF56510 Single, Fiddle*, Becket, Swivel Head 55 + 353/85250750112
 RF56530 RF56530 Single, Fiddle*, Becket Cleat, Swivel Head 55 + 35105250750235
These blocks have been specifically designed and optimised for use on racing sailboats and the conditions encountered in this unique application. They should not be assumed suitable for other non-marine or industrial applications. For further details on associated risks see Orbit Block Usage and Considerations
**  This block has full Automatic ratchet engagement only.  ie. No On/Off manual mode operation


Automatic ratchet block

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. This lets the sheet run out smoothly and freely-great for rapid easing of the sheet and for gybing asymmetric spinnakers. In manual mode, the ratchet mechanism can be switched on or off as required. This is the preferred mainsheet set-up for may top sailors. Try the block in both modes and see which you prefer - you really can't go wrong.

* Selected Series 55 models.

Awesome ratchet block holding power

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 21:1, almost double that of our nearest competitior. The unique sheave design has 12 gripping faces which directly resist loaded line movement. Traditional designes 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. 

Click to view full Practical Sailor's Ratchet Click-off article 


  • Sheave: 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®


  Range aaDescription
  Standard D Shackles Standard D Shackles