Ronstan Series 40 Ball Bearing Upright Lead Block

The Ronstan Series 40 Ball Bearing Upright Lead Block is intended for halyards and other frequently handled lines that turn at the mast base. Its upright layout keeps the rope close to the deck while the ball-bearing sheave reduces the effort needed to hoist, ease, or tension the line. Compared with a plain-bearing lead, this version is a better fit where the line moves often and friction is noticeable to the crew. The fixed format also keeps the exit angle predictable when the halyard is led toward a clutch, jammer, or winch.

Acetal ball bearings carry the sheave and reduce rolling resistance through repeated adjustment. Corrosion-resistant load hardware supports the bearing assembly and provides the strength needed for a mast-base turning point. Because the block is fixed rather than self-aligning, the sheave works best when it is mounted square to the incoming and outgoing rope. The compact housing keeps the line turn tidy without placing a large fitting in an already crowded mast-base area.

• Ball-bearing sheave for frequently adjusted halyards
• Upright low-profile mounting
• Acetal bearings for reduced friction
• Fixed lead keeps the exit direction consistent

Install the block where the rope can make its turn without dragging on the deck, mast collar, or neighboring hardware. The mounting structure and fasteners should be sized for the complete halyard load, including shock and dynamic loading. Rinse the sheave after saltwater use and check that it still spins freely when the halyard is inspected. For more halyard leads and mast-base rigging components, browse more Sailing Hardware.