We’ve all tensioned a halyard thinking it looks plenty tight to then round the leeward mark and sheet on to find the luff is so creased you have to luff up to put more halyard on. This is the age-old problem of stretch or elongation in rope. Even the best materials like Dyneema SK99 will elongate as much as 1% at working load due to the construction of the rope. Over the length of a mast on a 50-footer this could be as much as 200mm. The answer…. shorten the halyard. That is really what a lock does. It means you remove the stretchy bit of the system which is the rope. Locks come in all sorts of varieties. Manual bullet locks, auto locks, internal locks, external locks, swivel locks and even mainsail locks. Most mast manufacturers have designed their own locks for their masts which fit neatly inside the mast or on to the associated fittings externally. There are also a number of off the shelf varieties designed to be able to be retrofitted externally to an existing mast. These allow any yacht owner the ability to upgrade their yacht and take advantage of the benefits of locks.
The benefits can be grouped a 2 ways, performance and reliability. Performance gains come from the zero halyard stretch primarily. Combined with modern sail making materials your sails set with the intended shape and hold the shape as the wind increases. This all adds to improved angles and the ability to control the power in the sail more easily. Coupled with less weight aloft which is a combination of lighter halyards but also the overall rig weight. When a mast is designed with halyard locks the overall compression of the mast is reduced due to removing the halyard force from inside the mast. Along with the reduction in weight of the fittings and sheaves that now only need to lift the sail up to the lock, the effect is a reduction in heeling moment. When added to the improved sail shapes this means a big gain in performance especially upwind. In terms of reliability the benefits are more relevant for boats doing longer passages where chafe and fatigue are more of an issue. By not having the halyard loaded in the rig chafe is almost non-existent. This also represents a safer option too then having the loaded halyard in the cockpit where at night it could very easily be released by mistake which could result in boat breakages or worse crew injury.
Advantages · No loss of luff tension · Lighter halyard especially if using a 2:1 previously · Less weight aloft · No risk of halyard chafe and failure
· Lower mast compression · No loaded halyards on the deck · No need for expensive clutches and jammers Disadvantages · Expensive · May require some mast hardware changes · Adjustable tack required · Maintenance required otherwise they can malfunction
Obviously, these benefits come at a cost. But for a larger yacht where you are investing a lot of money in the sails already it is worth considering the change to locks to make sure you are getting the most performance for your money. Equally for a yacht planning a world cruise or even just a long passage the inconvenience of having to repair or replace halyards at great cost in remote parts of the world should be enough to consider using locks which provided they are serviced regularly in same way you service your winches they will last the same amount of time.
These locks do come in all shapes and sizes just like the boats that they go on and there are lots of different options. The best thing to do if you are considering fitting locks is to discuss it with a rigger who can advise the best system for you and let you know all the associated costs which may include hardware changes on the mast and deck or additional components.
For advise and pricing get in touch with us or alternatively check out www.upffront.com where you will find a range of products along with useful guides. Join their Foredeck Club and receive a 10% discount.