Allen 50mm Blocks

Allen 50mm blocks are the largest in the dynamic range and are built for high load sheet systems. They are most often used for mainsheets on dinghies and sports catamarans, and for fast running sheets on keelboats. The large sheave reduces friction and suits thicker rope, which makes long sheets easier to trim and quicker to ease.

Choose a 50mm Allen block for mainsheets and other high load systems, especially on catamarans, larger dinghies and keelboats. Choose a 40mm block for jib sheets, spinnaker sheets and the mainsheet on a smaller dinghy. The bigger sheave on the 50mm runs more freely, which you will notice most when easing the sheet in light winds.

A ratchet block is worth fitting on almost any dinghy or catamaran mainsheet. It grips the sheet under load, so you hold far less of the strain in your hands, and it still lets the rope run out when you ease. The Allen 50mm Pro Ratchet is normally fitted as the last block in the system, the one the sheet leads from to your hand.

A mainsheet system is built by pairing blocks on the boom and the boat to create purchase. An Allen 50mm double swivel block paired with a double swivel block with becket gives a 4:1 or 5:1 purchase, depending on which block is fitted to the boom. Add a Pro Ratchet block as the final lead to make the sheet easier to hold.

Allen 50mm blocks are designed for the thicker ropes used in sheet systems, and are a good match for 8mm to 10mm mainsheets. Always check the maximum rope diameter and working load on the individual product page before you buy, as a rope that is too thick will add friction and wear.