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Harken Single Swivel Carbo 57mm Ratchamatic

Harken Single Swivel Carbo 57mm Ratchamatic

Ratchamatic load sensing mechanism

Free rolling both ways under low load

Automatic ratchet activation

Select by sheave diameter:
57mm or 75mm

10:1 holding power

Central hole forms a becket point


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Harken Ratchamatic Blocks help the crew to seamlessly shift between ratchet and light air modes, providing load sensitive handling for mainsheet and spinnaker systems on beachcats, dinghies and sportsboats.

Harken Sheaves:
Harken standard ratchamatic sheaves maintain a secure grip on the line by means of eight specially designed facets.
Facets are the angled concave shapes formed specifically to grip the line under load.
They act a bit like the pockets in a chain gypsy (although far less pronounced).
The faceted sheave allows a loaded sheet to be hand-held, yet still allow instant easing with control.
The crew can hand-hold main, jib, and spinnaker sheets with only a faction of the effort that a regular block requires.

Standard Holding Power - 10:1
Standard Holding Power sheaves are black anodised for identification:

Holding power varies according to sheave size and type.
40mm and 57 mm Ratchamatic blocks with eight-sided faceted sheaves can provide up to 10:1 holding power.

You can look at this in two different ways:

  • The crew can withstand 10 times more load than on a normal block without the sail winning :-)
  • The crew will only need 10% of the effort to withstand the same load on a normal block (10kg of force requires only 1kg holding power)

Harken Ratchamatic Block Design and Construction features:

  • Super lightweight parts
  • Composite fibre-reinforced sideplates
  • Hardcoat anodised aluminium sheave
  • Lightweight soft-attach method
  • Minimal moving parts in the ratcheting mechanism
  • Sheets can run out freely during mark roundings and asymmetric spinnaker sheets are freed instantly during gybes
  • Ratchet engagement is adjustable to a higher or lower load according to crew strength and sailing style
  • Approximately 10:1 holding power
  • The central hole in the sheave is ideal for dead-ending (tying on) a line to simulate a becket point

For the ultimate system, mount a ratchamatic on the boom above a cockpit mounted switchable ratchet for double holding power.

HarkenBlockMaximum Break loadSafe Working LoadMaximum Line DiameterWeight
2625 57mm Single Swivel 907kg 227kg 10mm 104g
2680 75mm Single Swivel 1361kg 341kg 12mm 238g