Wire to dyneema mainsail halyard

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melvynpatrick

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My boat has a wire mainsail halyard which has a rope attached for ease of handling to pull it up and down. This is done at the mast. I want to be able to feed it back to the cockpit but the rope isn’t long enough. I’ve been thinking of changing the wire for 6mm dyneema (which should run through the sheeve). The splicing on some thicker rope which runs back to the cockpit. Is this a good idea or a bad one?
 
melvynpatrick said:
My boat has a wire mainsail halyard which has a rope attached for ease of handling to pull it up and down. This is done at the mast. I want to be able to feed it back to the cockpit but the rope isn’t long enough. I’ve been thinking of changing the wire for 6mm dyneema (which should run through the sheeve). The splicing on some thicker rope which runs back to the cockpit. Is this a good idea or a bad one?
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The usual way is to use a single dyneema line, but remove the cover as required.
 
Chiara’s slave said:
The usual way is to use a single dyneema line, but remove the cover as required.
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Ah. Ok. I’m very new to dyneema. Find it a bit mysterious to be honest. So, use the core for the wire and leave the outer for ease of handling. I’m a bit concerned that the sheaves on the mast are for wire. Which is why I thought thin strong rope for that bit.
 
melvynpatrick said:
Ah. Ok. I’m very new to dyneema. Find it a bit mysterious to be honest. So, use the core for the wire and leave the outer for ease of handling. I’m a bit concerned that the sheaves on the mast are for wire. Which is why I thought thin strong rope for that bit.
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You seem to have seen through the mystery. The core might be 6mm, with a kind of ‘fat 8mm’ covered size. The cover removal needs to be finished properly, you’ll find a how to vid on youtube I am sure. But basically you end up with a 6mm rope for the wire part, and a conventional braid for ypu and your rope clutch to deal with. My boat started like yours, and now has a tapered, cover removed in part, jib halyard.
 
As he said

You might find that a chandler like Jimmy Green can make up the new Dyneema halyard for you and they will taper the cover into the core dyneema for you. If not a chandler then any decent rigger in the yacht club will be able to do it for you.

However splicing the cover into the core is a skill worth learning and practising - and then you can do the same for your headsail. Or if your headsail is not wire and rope - then you can replace the old headsail halyard with new dyneema, no taper needed.

Jonathan
 
a. The sheave will need to be taken off and polished. If wire has run over it for years, it is burred. The side plates at the masthead are probably also damaged and sharp. Check and polish as needed. These can really chew up rope, based on expereince. The sheave can be polished by chucking on a bolt in a drill or drill press. The masthead with a combination of a fine file and then fine sandpaper.

b. You can get rope and strip the cover. Alternatively, you can buy Dyneema and cover the tail with cover from other polyester rope. I have done this using good cover recycled from halyards, and even buying Samson XL (a good inexpensive rope) and using only the cover (the core is used to pull the Amsteel into place). Also stripped cover from other sailors, but feeding that over the Amsteel is a bit troublesome. Fishing a smaller pull cord through first works.
 
I replaced my wire and polyester main halyard last winter. My first idea was to get someone to splice new polyester onto the wire. No one was interested. I found a tutorial on Utube. It requires the opening up of strands of the 3/16 inch 7x19 wire. I found that impossible for me. So I got some 4mm dyneema and spliced it onto the end of the polyester tail. Again a Utube tutorial proved not as easy as it looked. The inner core of the polyester was easily spliced to the dyneema. The outer sheath not so easy. I just thinned the poly and tucked strands inside the dyneema and whipped the whole end with lots of stitches through dyneema in a taper. I confess i am not totally confident of the splice but so far 2 sails it seems OK. The splice emerges from mast when main sail is up.
Now in hind sight I should have done dyneema 4mm full length. Then cut off a outer braid of 10mm poly and spliced that in to the dyneema with whipping at the tail end with stiches through dyneema. I have no real concerns re top pulley of main halyard going from wire to dyneema. NB all this on a 21ft TS fractional rig.
Interesting it all did stretch on first serious race I hope that was a one off stretch.
I use covered 8mm dyneema for jib halyard seems ok but does also stretch a bit each time jib is raised. ol'will
 
If the sheaves are worn to much you might want to consider replacement. They are commonly held into the mast with simple pop rivets with the slot itself taking most of the load, and not the rivets. Sometimes the pop rivet is seriously big and is impossible to replace with a normal Stanley type rivet gun. Leave well alone if big - its a task when the mast is out or for a rigger. When you are up the mast measure the size of the slot and you might be lucky and be able to source drop in replacements. The other thing to do when up there - take your phone and take some pictures - you never know when they might be useful.

You don't say what model is your yacht - you might get focussed and quantitative replies if you mention the model name (and maybe year).

Dyneema can stretch, but its the lay that is stretching, not the rope. Once you tighten a dyneema halyard - it should be stable. All our halyards were marked with marks on the ropes and marks on the mast or clutch (or both).

Jonathan
 
Dyneema is used quite liberally here. Bear in mind it’s not all made the same way and covers vary. Cruising dyneema has double covers to make it more rope like and easy to splice and so may not be the same as others are talking about so it might be worth being more specific about which rope is being discussed.
 
Yes. I do find it confusing. I think the idea of dyneema and the thicker core is the way by the looks of it. I think I’ll probably get it made up by jimmy green or some such. I should be more practical though I do accept.
 
melvynpatrick said:
My boat is a 42ft wooden ketch. She is a one off designed by Alan Hill. Built in 1976
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Lucky man :)

I believe you can source Dyneema with a braided pale yellow colour so that it looks like hemp. Its used on historic vessels but has the disadvantage all your running rigging is the same colour.

For the different types of Dyneema check the various rope makers, like Marlow, or Liros, websites
melvynpatrick said:
Yes. I do find it confusing. I think the idea of dyneema and the thicker core is the way by the looks of it. I think I’ll probably get it made up by jimmy green or some such. I should be more practical though I do accept.
Click to expand...

One step at a time. I am sure there are many, if not the majority, here who could not splice dyneema core to a braid on brain tail. Dyneema was introduced, I think in the late 70s. As new applications have developed and issues with the new fibre identified (its excessive slipperiness for one) the construction of the rope has changed.

Jonathan
 
Here is what youtube has to offer.
4mm would be too fiddly. I would go for 6 mm.
Practice twice and as mentioned you will have a new skill (and halyard) under your belt.
Gary
 
I did my splice 10mm poly to 4mm dyneema as per the Utube. No problem with the core of poly. Could not get the sheath of poly in to dyneema (6MM would have been easier) I ended up tapering sheath getting some strands of sheath into dyneema then whipping using stitches through sheath and dyneema. Seems ok so far. Dyneema splicing is a real pleasure. ol'will
 
melvynpatrick said:
Ah. Ok. I’m very new to dyneema. Find it a bit mysterious to be honest. So, use the core for the wire and leave the outer for ease of handling. I’m a bit concerned that the sheaves on the mast are for wire. Which is why I thought thin strong rope for that bit.
Click to expand...
got rid of the wire on my present boat which had been there since build. Used 10mm dynema without problem.. didnt bother removing the outer
 
Lots of new boats from 2000 odd had wire and rope halyards and since replaced with dyneema -the dyneema on the main can be more inclined to kink so if dropping you might need to watch more than the old rope but otherwise (subject to rigger checking the blocks) an exchange when you come to replace halyard is fairly standard I suspect. We replaced our main halyard due to stretching but kept original (all rope) after about 5 years use. Never replaced the wire/rope though on last boat .
 
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