Ronstan Series 40 Triple Swivel Sailing Block

The Ronstan Series 40 Triple Swivel Sailing Block brings three sheaves into one compact all-purpose block for mainsheets, halyards, vangs, and spinnaker-control systems. A swiveling head allows the block to follow the tackle as the load direction changes, which helps the rope stay centered through all three sheaves. The triple arrangement is useful when a purchase needs additional mechanical advantage but deck space does not favor several individual blocks. Ronstan's all-purpose design is aimed at durable day-to-day use on dinghies, one-design boats, catamarans, and small sportboats.

Each sheave is made from UV-stabilized Acetal and is self-lubricating for low-maintenance service. Impact-resistant fiber-reinforced nylon cheeks protect the sheaves, while corrosion-resistant stainless hardware carries the working load. The design is intentionally simpler than a full race-only ball-bearing assembly, which makes it a practical choice for boats that value durability and easy care. A slotted-pin shackle also helps keep the attachment secure without leaving excess hardware around the line path.

• Three sheaves in one compact purchase block
• Swivel head helps the block align under load
• Self-lubricating UV-stabilized Acetal sheaves
• Impact-resistant fiber-reinforced nylon cheeks

Before installation, confirm the line diameter, shackle orientation, and purchase geometry match the existing rig. All three rope runs should stay parallel enough to share the load without rubbing the cheek plates. Rinse the block after saltwater use and inspect the swivel and sheaves for free movement as part of routine rig maintenance. For additional triple blocks and sail-control hardware, browse more Sailing Hardware.