Ronstan S100 Core Block Mast Base

A balanced design approach incorporating functionality, performance and style makes the Series 100 Core Blocks the right choice for performance cruising or racing applications. A full contact bearing 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. Glass Fibre reinforced nylon sheave, alloy cheeks and stainless fixings complete the durable package.

Dynamic and high static load performance
Core Blocks incorporate a full contact acetal bearing on a polished stainless steel race to maintain low friction performance under heavy loads.Ball bearings are configured to act as a thrust bearing between the sheave and checks, 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 foot blocks.

Universal head
The head assembly incorporates a brass bearing washer to provide smooth 360 degrees rotation of the post and shackle. A set screw arrangement allows the head to be locked at 0 degrees or 90 degrees. Shackles are high quality forged grade 17-4PH stainless steel.

Aluminium alloy cheek plates
Block cheeks are manufactured from the highest quality aluminium alloy for maximum strength and hard anodised for durability and corrosion resistance. Material optimisation and the cut-away design minimises weight and allows easy fresh water rinsing of salt and debris from the bearings. The hollow hub can be used as a becket take-off or tie-up point.

Suit 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 mainsheet, spinnaker sheet, vang, halyard and backstay applications on boats to 16m (53ft).
• General applications on larger yachts.

• High dynamic and static load capacity
• High load bearing system
• Ball bearings to counteract side thrust loads
• Class leading performance and sleek, contemporary styling
• Durable aluminium alloy cheek plates
• Central hub hole can be used as a becket take-off or tie-up point
• Also available in Series 45, 60 and 75
• 22mm (7/8') inside cheeks at head
• Mount with 2 x 12mm (7/16') fasteners (not supplied)
• Full block rated load can only be achieved with uniformly distributed load across full length of clevis pin. ie. 22mm (7/8') diameter mast collar post or 22mm (7/8') wide mast collar plate/tang.