Ronstan Series 75 Core Block - Single, 75mm

The Ronstan Series 75 Core Block is a high-performance single block engineered for reliability in both cruising and racing applications. It features a tuned two-stage bearing system that delivers low-friction performance across a wide working load range. Under moderate loads, Acetal ball bearings minimize friction, while under heavy loads, a sliding Acetal bearing on a stainless steel race engages to maintain smooth operation. Designed for durability, this block includes alloy cheek plates and forged grade 316 stainless steel components.

Key Features:

• Versatile universal head offers 3-axis articulation and can be locked at 0 or 90 degrees using a 2.5mm hex key.
• Central hub hole serves as a becket take-off or tie-up point.
• Designed for mainsheet, halyard, and spinnaker sheet applications on boats up to 14 meters (46 feet).
• Sheave diameter: 75mm (3 in.).
• Maximum rope diameter: 14mm (9/16 in.).
• Pin diameter: 8mm (5/16 in.).
• Maximum Working Load (M.W.L.): 1,500kg (3,300 lbs.).
• Breaking Load (B.L.): 3,000kg (6,600 lbs.).
• Weight: 354g (12.5 oz.).

Materials:

• Sheave: U.V. stabilized Acetal.
• Cheek body: Aluminium alloy.
• Ball bearings: Carbon black Acetal.
• Shackle, head post, and hub: Grade 316 stainless steel.

Manufacturer part number: RF74100.