Halyard sheathing question

[TomK]

Question for knowledgable riggers on the forum:

I’m on a boat in Italy (grand soleil 46). The owner/skipper had a new main halyard from a rigger in Sicily, as the previous one become worn and chafed the outer. The rigger also replaced the sheave at the top of the mast (as this was what was causing the wear on the rope).

The rigger has spliced what appears to be a dyneema outer over the last 6 or so metres of the halyard at the shackle /mast head end. So far so good.

The interesting part is that when we took the sail down yesterday we noticed that the middle part of the last 6 metres has become much thinner (7mm on verniers) and is bar tight like a cable. So the core has clearly come apart at some point.

My question: is this a normal / standard way of doing the sheathing? Or has the core broken where it shouldn’t have?

We are waiting for the rigger to get back to us now, but we are on passage now (under motor.)

Not inclined to raise the main without a second opinion….

 

[roaringgirl]

Splicing a length of braid on braid to another involves pulling the sheath down off the core, tapering the core and threading the sheath through the core, before pulling the sheath back over the core again. It is not as strong as leaving it alone in the first place. If it has thinned, then something is wrong. Since the whole of the halyard is under the same tension, what is the advantage of splicing 6m of dyneema to the end of it?

 

[Roberto]

Being an additional cover, possibly with different material/weave geometry --> different elongation characteristics, it might be that when the rope is under tension the original rope and cover stretch more or less uniformly, but once the tension is released the friction between the added cover and rope prevents or delays their recovering of the original dimensions.
The 6m might be to get to the second/third reef.
Funny things may happen, these are an Imoca used shrouds, once the mast has been laid horizontally.

 

[PaulRainbow]

Splicing a length of braid on braid to another involves pulling the sheath down off the core, tapering the core and threading the sheath through the core, before pulling the sheath back over the core again. It is not as strong as leaving it alone in the first place. If it has thinned, then something is wrong. Since the whole of the halyard is under the same tension, what is the advantage of splicing 6m of dyneema to the end of it?

You have misread the OP, 6m has not been spliced to the end, the last 6m has had an additional cover fitted, possibly for some additional chafe resistance ?

 

[TomK]

You have misread the OP, 6m has not been spliced to the end, the last 6m has had an additional cover fitted, possibly for some additional chafe resistance ?

Think we’ve got to the bottom of it. Turns out the rope has a dymeema core, which has made it behave as per Roberto’s picture. The sheathing on the outside was to REPLACE the polyester outer with a dyneema outer, not go over the top of it. With the purpose of reducing friction, and chafe resistance - hence the change in widths.

I’m used to smaller boats, so I’ve never seen this done - and it felt a bit alarming. The rigger has assured us it’s fine, and having a look at the inner stripped back from the other end it makes sense.

Found an article here explaining it pretty well: Stripping and recovering yacht ropes - when, where and why?

 

[roaringgirl]

Think we’ve got to the bottom of it. Turns out the rope has a dymeema core, which has made it behave as per Roberto’s picture. The sheathing on the outside was to REPLACE the polyester outer with a dyneema outer, not go over the top of it. With the purpose of reducing friction, and chafe resistance - hence the change in widths.

I’m used to smaller boats, so I’ve never seen this done - and it felt a bit alarming. The rigger has assured us it’s fine, and having a look at the inner stripped back from the other end it makes sense.

Found an article here explaining it pretty well: Stripping and recovering yacht ropes - when, where and why?

Ahhh yes, this makes sense, I think dyneema is more chafe resistant than polyester.

So now a further question - why is chafe such a problem here?

 

[dunedin]

Ahhh yes, this makes sense, I think dyneema is more chafe resistant than polyester.

So now a further question - why is chafe such a problem here?

See post #1 again - sounds like a damaged or sharp sheave, which has now been replaced

 

[roaringgirl]

See post #1 again - sounds like a damaged or sharp sheave, which has now been replaced

Then the re-sheathing is unneccessary now the sheave has been replaced?

 

[TomK]

Then the re-sheathing is unneccessary now the sheave has been replaced?

In theory I suppose it should prolong the life of this new halyard, and also make it more manageable when reefing as the halyard will have a lot of friction on it at that point. It’s a bloody tall fractional rig with big old sail on it!

also it’s a way for the rigger to charge for a bit more work ;-)

 

[r_h]

I use Dyneema chafe jacket a lot - it's impressive stuff and in my experience shows next to no wear even after many thousands of ocean miles.
I've always applied it over the top of the existing outer cover of dyneema halyards, where it then also acts as an extra layer...
...but in this case the set up (whether at the masthead, or at a lower level) may not have been able to cope with the extra thickness.