Ronstan Series 50 Double All-Purpose Sailing Block

The Ronstan Series 50 Double All-Purpose Sailing Block is a straightforward two-sheave block for mainsheets, halyards, vangs, and spinnaker-control systems on larger dinghies and sailboats. Its double layout lets a rigger build useful mechanical advantage without using two separate single blocks at the same attachment point. Ronstan lists the Series 50 all-purpose range for sail-control work on boats up to roughly 10m (33 ft), with selected applications extending to about 12m (40 ft). That broad application range makes this version a practical choice for both replacement rigging and new purchase systems.

The block uses self-lubricating Acetal sheaves with a Grade 316 stainless-steel load strap. Fiber-reinforced nylon cheeks resist impact and UV exposure while keeping the housing lighter than an all-metal block. A slotted-pin shackle helps keep the attachment hardware compact and reduces the chance of loose pieces around the rope path. Because the sheaves do not rely on a delicate exposed ball race, routine maintenance is mainly inspection and fresh-water rinsing.

• Double-sheave all-purpose configuration
• Self-lubricating Acetal sheaves
• Grade 316 stainless load strap
• Slotted-pin shackle for a tidy attachment

Ronstan specifies line up to 12mm (1/2 in), with a maximum working load of 2,200 lb and a 4,410 lb breaking load. Both rope runs should enter the block cleanly so one sheave is not forced to carry more side load than the other. Check the shackle, cheeks, and rope grooves when servicing the rest of the running rigging. For more double blocks and all-purpose sailing hardware, browse more Sailing Hardware.