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Why are my halyards fraying?

2016 July 1

Dear Boat Doctor,

My Tayana 48 came with wire and rope halyards and as part of my refitting efforts I replaced them with high-quality Dyneema double braid last summer. After wintering in the Caribbean on the boat and bringing the boat back this spring, I found that the cover on a couple halyards and the topping lift has worn through. I bought what I thought was good cordage, so why did this happen? I also broke the block on the mainsheet. It was an older block, but appears to have been made of plastic with metal strapping. I’d like to replace it with an all-metal block so I don’t risk breaking it again, but I’m not sure what kind I should look for.

Jim McCarthy

Wilmington, North Carolina

Dear Jim,

When multiple halyards show signs of wear, especially when they are new and made of high-quality line, the first place to look for the culprit is at the top of the mast. Something is chafing the cover away and, even though you got rid of them, your wire halyards may be to blame. 

Wire halyards will sometimes use a special sheave with a little slot in the rounded profile of the sheave for the wire to run free. This slot is great for wire, but it will tear up the cover on a rope halyard. If this is the case, you have no option but to replace the sheaves. Zephyrwerks (www.zephyrwerks.com, 360-385-2720), in Washington, makes nice custom sheaves at a good price. 

Even if your sheaves don’t have that little slot, be sure to check the condition, as wire halyards can make rough spots on the sheaves. If the damage is not too bad, you can just file, sand and polish the sheaves back to smooth. 

Take a look at the sheave box too, the wire could have roughed up the sides of the box, which in turn would chafe the covers. A little filing and sanding should fix things up for you. Just make sure you check this sooner rather than later. You have a lot invested in nice Dyneema halyards and every time they run over a damaged or improper sheave takes time off their life.

As for your mainsheet block, you’re right to suspect that the plastic was to blame. Keep in mind, though, that plastic from 20 years ago is much different from the material used on hardware today. Still, it is susceptible to damage from ultraviolet light. A good place to start is Harken’s Black Magic line, which are extremely high quality, good looking and will serve you well for many years. For a bit less, you may want to also consider Lewmar’s HTX line of blocks, which aren’t as slick looking as the Black Magic blocks, but will also serve you well.