Check this out. We spliced up two new halyard lock strops using FSE Robline’s new Ocean 5000 STS, which is a pre-stretched heat-set Dyneema. The Tylaska snap shackle is clipped to the sail and the stainless bullet locks into place inside the mast. On large race boats the load on the halyard is so great that it can actually compress and misshape the mast. Also, on longer halyards the small percentage of stretching seen under load can translate into a few inches, and in extreme cases, the load can pull the turning block at the base of the mast out of the deck! Lock strops are used to distribute high halyard loads to the 2-3 feet of halyard strop rather than through the length of the mast.