Lewmar 29927201BK 72mm Synchro Single Block with Swivel Shackle

The Lewmar 29927201BK Synchro Single Block is a plain bearing sailing block engineered to deliver racing-level performance at a cruising-friendly price point. Featuring a 72mm sheave diameter, this block is a versatile workhorse well-suited for a wide range of running rigging applications aboard cruising and performance sailboats.

Lewmar's Synchro design combines scientifically optimized block geometry, a high-density Free-Spin bearing, and a self-aligning swivel head to reduce friction and boost efficiency by up to 40% compared to standard budget blocks on mainsheet systems. Every component is synchronized with rope movement to deliver a smoother, easier transfer of power from deck to sail while minimizing line wear.

Key Features:

• 72mm (2-13/16") sheave diameter — accommodates 3/8" to 1/2" (max) lines
• Safe Working Load (SWL): 2,420 lbs (1,100 kg)
• Stainless steel strap for improved strength and extended service life
• Glass fiber reinforced cheeks prevent lines from wedging
• Tool-free sliding swivel locking mechanism — instantly switch between full 360° free rotation or fixed positions (0° or 90° to sheave axle)
• Fixed positions include 30° of rotational float for automatic self-alignment
• Compatible with Lewmar travelers via precision-engineered shackle post
• Weight: 6.7 oz (190g)

Common Applications:

• Halyard tuning and turning blocks
• Mainsheet systems
• Mast foot and mast head blocks
• Boom vang systems

The Lewmar Synchro Single Block (29927201BK) offers the kind of smooth, reliable performance demanded by both dedicated racers and serious cruisers, backed by Lewmar's reputation as a world-leading marine hardware manufacturer.