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Ronstan Series 75 Core Double Foot Block

Original price was: $371.45.Current price is: $334.95. incl GST

SKU: RF74251 Categories: , , , ,


Ronstan Series 75 Core Double Foot Block – RF74251:


  • Class leading performance and sleek, contemporary styling.
  • Excellent dynamic and high static load performance.
  • Less than half the friction of the nearest competitor.
  • Durable aluminium alloy cheek plates.
  • Central hub hole can be used as a becket take-off or tie-up point.
  • Universal head with full 3-axis articulation.
  • Shackle head lockable at 0 or 90 degrees.
  • Alloy Rope/Wire sheave version also available.
  • Fastening hole dimensions: 62mm Centre to Centre, with 10mm CSK Fastenings.

Single Core Blocks™ are a true all-round solution. A tuned 2-stage bearing system provides excellent performance across the full working load range with an integrated thrust bearing feature and the resilience to handle high dynamic or static loads. Acetal sheave, alloy cheeks and stainless fixings complete the durable package. For reliability and a long service life, these blocks are the right choice for sheets, halyards and control line applications for cruising and racing.

Universal Bearing Dynamic and high static load performance:

The Ronstan Universal Bearing incorporates our proven 2-stage bearing system:

  • Stage 1 – Under moderate loads, Acetal ball bearings ensure minimum friction.
  • Stage 2 – Under heavy loads, where deformation of ball bearings alone would result in increased friction, a sliding Acetal bearing on a polished stainless steel race takes over, maintaining low friction performance.

Additionally, the ball bearings are configured to act as a thrust bearing between the sheave and cheeks, preventing the sheave from rubbing on the cheeks and causing friction when the line lead in and out of the block isn’t perfect. Particularly important for cheek blocks.

Alloy cheek plates:

Block cheeks are manufactured from the highest quality alloy for maximum strength. Material optimisation and the cut-away design minimises weight and allows easy fresh water rinsing of salt and debris from the bearings. Cheek design has been further styled with flaring at the block throat and reduced gap between the cheek and sheave, minimising rope wear.

Universal head:

The head assembly incorporates a brass bearing washer to provide smooth 360° rotation of the post and shackle. A set screw arrangement allows the head to be locked at 0° or 90°.

Shackles are high quality forged grade 316 stainless steel.


  • Ideal for use on mainsheet, spinnaker sheet, vang, halyard and backstay applications on boats up to 14m (46ft).
  • General applications on larger yachts.
  • Alloy sheave models are available for use with wire.


  • Sheave: U.V. stabilised acetal or anodised aluminium (AW models).
  • Cheek plates: Aluminium alloy.
  • Ball Bearings: High compression strength carbon black acetal.
  • Shackle, post & hub: Grade 316 stainless steel.


Product NoSheave Dia mm (in)Max Working Load kg (lb)Break Load kg (lb)Weight g (oz)Pin Dia mm (in)Max Rope Dia mm (in)Max Wire Dia mm (in)
RF7410075 (3)1500 (3300)3000 (6600)354 (12.5)8 (5/16)14 (9/16)-
RF74100AW75 (3)1500 (3300)3000 (6600)432 (15.3)8 (5/16)14 (9/16)8 (5/16)
RF7410875 (3)1500 (3300)3000 (6600)234 (8.6)8 (5/16)14 (9/16)-
RF7420275 (3)1500 (3300)3000 (6600)506 (17.9)-14 (9/16)-
RF7411075 (3)1500 (3300)3000 (6600)428 (15.1)8 (5/16)14 (9/16)-
RF7415175 (3)1500 (3300)3000 (6600)259 (9.2)-14 (9/16)-
RF7414075 (3)1500 (3300)3000 (6600)468 (16.5)-14 (9/16)-
RF74108A75 (3)1500 (3300)3000 (6600)230 (8.1)8 (5/16)14 (9/16)-
RF7425175 (3)1500 (3300)3000 (6600)530 (18.7)--

Additional information

Weight .75 kg