Ronstan 75mm Single Becket Core Block

Item #


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Product Description

Ronstan 75mm Single Becket Core Block


  • Class leading performance and sleek, contemporary styling

  • Excellent dynamic and high static load performance

  • Less than half the friction of the nearest competitor

  • Durable aluminum 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

  • Removable becket pin for fitting of pre-spliced lines


    Sheave Ø - 3 in. (75 mm)

    Max. Rope Ø - 9/16 in. (14 mm)

    Max. Cable Ø - in (mm)

    Pin Ø - 5/16 in. (8 mm)

    M.W.L. - 3300 lb. (1500 kg)

    B. L. - 6600 lb. (3000 kg)

    Weight - 15.1 oz. (428 g)

    Product Information

    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 optimization and the cut-away design minimizes 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, minimizing 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.

    Suits pre-spliced lines

    Removable becket pins allow fitting of pre-spliced lines. The flush fit becket pin head is kind on deck surfaces and won’t snag lines.


  • 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. stabilized acetal or anodized aluminum (AW models).

  • Cheek plates: Aluminum alloy

  • Ball Bearings: High compression strength carbon black acetal.

  • Shackle, post & hub: Grade 316 stainless steel.