Cover for dyneema

[mrybas]

Hi,
I have a bunch uncovered dyneema that I would like to add a cover to just the part that gets used on the winch/clutch.
I’m assuming a polyester cover would be better than than a dyneema cover as it’s a bit grippier. I can not seem to find anywhere that sells polyester cover. Can anyone help?

[Benz]

Call Dynamic Yacht Rigging in Portsmouth. There's lots of empty cover there, though mostly it's polyester/technora blend. Grippy, though, for sure.

[thinwater]

Often the cheapest source is an inexpensive polyester line, like Samson XLS. Just pitch the core. You won't need much.



In fact, cover-only a pain in the ass to get over the line anyway; you use core to pull it over.

[Breaking Waves]

in quite a number of applications with clutches it is nicer/better to insert cord inside the center of the dyneema, to bulk it up, to give it more to crush on, which gives it enough grip to hold.

This is smoother than putting on a short external cover, and also easier to do.

With a cover, under high load, a dacron cover can part because it is a lot weaker than the dyneema - that is the common failure mode with knots in highly loaded dacron-covered dyneema core.

For very highly loaded lines, right at the clutch limit, the cord insert approach can slip, and then a cover or a stronger clutch will be needed.

We used a lot of bare dyneema thru clutchs and around winches, using the cord insert approach. We did also need to use a couple more wraps on the winches.

[Matt Johnson]

Originally Posted by Breaking Waves

We used a lot of bare dyneema thru clutchs and around winches, using the cord insert approach. We did also need to use a couple more wraps on the winches.

Would you only have the insert within the range of the clutch or anywhere the winch is used?

[Breaking Waves]

Originally Posted by Matt Johnson

Would you only have the insert within the range of the clutch or anywhere the winch is used?

Generally only within clutch range.

However, it depended on specifics of self-tailing jaws. Inserts worked/helped on some, with strong spring loads, but not so much on some others.

[Seaworthy Lass]

Originally Posted by Breaking Waves

in quite a number of applications with clutches it is nicer/better to insert cord inside the center of the dyneema, to bulk it up, to give it more to crush on, which gives it enough grip to hold.

This is smoother than putting on a short external cover, and also easier to do.

With a cover, under high load, a dacron cover can part because it is a lot weaker than the dyneema - that is the common failure mode with knots in highly loaded dacron-covered dyneema core.

For very highly loaded lines, right at the clutch limit, the cord insert approach can slip, and then a cover or a stronger clutch will be needed.

We used a lot of bare dyneema thru clutchs and around winches, using the cord insert approach. We did also need to use a couple more wraps on the winches.

Could you elaborate please?
eg Is polyester double braid or just the core inserted? (I have core leftover from other projects). Typically what diameter insert is used for 6 or 8 mm UHPWPE? Is it just beefed up enough to fit within the diameters specified for the clutch? Is it necessary to stitch the core to secure it? I can’t imagine it moving anywhere.

SWL

[fxykty]

I wouldn’t like to use bare Dyneema in a clutch that has any sort of teeth or relatively sharp gripping edges, even if it has been bulked up with an insert.

Dyneema covers with or without Technora are available and if sewn on (twice at 90* angles) provide good wear resistance. This is what we did with our 8mm bare Acera UHMWPE reef lines have and they stand up well to the gooseneck-end boom jam cleats, which do have pretty sharp teeth. On my next set of reef lines I will add inserts in addition to the cover to provide more grip area for the jam cleats.

Regarding bare Dyneema on a winch, no problem, just use more turns (instead of 4 for covered line use 7 or 8 turns for bare Dyneema). No need to add cover if that’s all you need. If you want the line to be held by a self tailer then add an insert to that section of the line.

I don’t think the insert needs to be stitched in place if it is reasonably long (200mm +). But if short then probably yes. And if it needs to be held in a clutch then probably yes. Try without and see what happens.

I’ve used inserts the same diameter as the line. I would use just polyester core as it is softer and won’t damage the Dyneema.

[Benz]

Originally Posted by Seaworthy Lass

Could you elaborate please?
eg Is polyester double braid or just the core inserted? (I have core leftover from other projects). Typically what diameter insert is used for 6 or 8 mm UHPWPE? Is it just beefed up enough to fit within the diameters specified for the clutch? Is it necessary to stitch the core to secure it? I can’t imagine it moving anywhere.

SWL

Usually a core insert is far smaller diameter than the line. For 6mm core, I've used a 2.5mm insert. Doesn't have to be fancy: any poly twine will do. Normally the line is beefed up only in the zone of the clutch. I've never stitched an insert, but I always put them into the cores of covered rope. It's a bit complicated to do, since you have to dig the cover apart at the center of the target area, pull out a loop of core, install insert, then milk the cover back over everything. The local fleet of IC37 race boats all have main halyards with core inserts installed by me, and they're working fine.

As for dyneema cover on a winch, well, dyneema, while abrasion resistant, is slippery, and has a low melting point which makes it unsuitable for winching, since one slip around the drum will smoke it. Better to use technora, PBO, or a blend. Poly/technora blends are common for covers, and give good longevity for price.

[Matt Johnson]

Do inserts make sense on main halyard if you plan on using an electric winch to raise the sail? We have a P dimensions of 65' and are a 2:1 halyard. 130' of insert seems like a lot

Reef lines and furling seem like a no brainer, but I'm not sure if removing a cover on double braid; adding cover to single; or adding inserts to a single is the best choice for a halyard. By best choice, I mean cost/vs effort.

[Breaking Waves]

Originally Posted by Seaworthy Lass

eg Is polyester double braid or just the core inserted?


I never did any testing to determine what was optimal. That would not be too hard to test if anyone wanted to - get a bare dyneema line which slips under a known load in a clutch and then try various cores.

in my experience, pretty much anything at all will do the job, whatever is at hand and easiest and cheapest. I used quite a bit of polypro cord I happened to have around - worked fine, easy to pull thru the center and made a good compressable core'. French rigger I know uses small polyester double braid, also works just fine.

Typically what diameter insert is used for 6 or 8 mm UHPWPE? Is it just beefed up enough to fit within the diameters specified for the clutch?

My theory was to size the core to try to reach the maximum diameter spec for the clutch. As Benz suggested, often that was smaller dia than the original line, but ofc depends on your hardware set-up.

Is it necessary to stitch the core to secure it?

I never stitched and never had one move. I think stitching would actually be somewhat undesirable unless done super carefully - could either create 'harder spots' or if done loosely to avoid the harder spots potentially creating snag points - doubt this is a big issue but feels to me like more negatives than positives.
SWL

........

[Breaking Waves]

Originally Posted by Benz

As for dyneema cover on a winch, well, dyneema, while abrasion resistant, is slippery, and has a low melting point which makes it unsuitable for winching, since one slip around the drum will smoke it.

I've smoked line around winch drums on big racing boats with big sheet eases, but I don't think I have ever even come close to this on a cruising boat, not even 'superyacht' cruising boats.

So, I think perhaps you are overstating your 'unsuitable for winching', at least in a cruising context.

As you say, there are covers designed specifically for winching, which are probably 'optimal' . . . but at least in my experience are unnecessary for cruising applications and in racing even only necessary for very specific large load applications.

I've never heard on someone putting an insert in an already covered double braid - that sounds like the clutch is specced too big diameter? Or do they need that bigger size clutch for its working load, and using the small line for weight aloft and there is no good 'standard' fit between the clutch and the rope? Seems odd.

btw . . . . . related but off on a tangent - textile clutches are pretty neat, & soft on the lines with excellent grip, and also (for the racers) very light weight.

[Breaking Waves]

Originally Posted by Matt Johnson

Do inserts make sense on main halyard if you plan on using an electric winch to raise the sail? We have a P dimensions of 65' and are a 2:1 halyard. 130' of insert seems like a lot

Reef lines and furling seem like a no brainer, but I'm not sure if removing a cover on double braid; adding cover to single; or adding inserts to a single is the best choice for a halyard. By best choice, I mean cost/vs effort.

If you can have a hand on the tail, helping it self-tail, while running the electric winch I have never seen any absolute need for core or cover added on winch (I am talking typical cruising application, not racing application). Just put an extra wrap on and it (almost certainly) go fine.

The question with bare dyneema is if it will slip/drop out of the self-tailing if you do it entirely hands-off. If you do it hands-off and it does have a tendency to drop out then either a core insert or cover could help - personally, in that case, If I wanted the top tip part stripped/bare, I would probably get a double braid and strip the tip cover off and leave the cover on for the winch and clutch... easier than doing the insert.

[Benz]

Originally Posted by Breaking Waves

I've smoked line around winch drums on big racing boats with big sheet eases, but I don't think I have ever even come close to this on a cruising boat, not even 'superyacht' cruising boats.

So, I think perhaps you are overstating your 'unsuitable for winching', at least in a cruising context.

As you say, there are covers designed specifically for winching, which are probably 'optimal' . . . but at least in my experience are unnecessary for cruising applications and in racing even only necessary for very specific large load applications.

I've never heard on someone putting an insert in an already covered double braid - that sounds like the clutch is specced too big diameter? Or do they need that bigger size clutch for its working load, and using the small line for weight aloft and there is no good 'standard' fit between the clutch and the rope? Seems odd.

btw . . . . . related but off on a tangent - textile clutches are pretty neat, & soft on the lines with excellent grip, and also (for the racers) very light weight.

You're right--unsuitable for winching only applies to the racing boats I've been servicing, which also have a tendency to smoke brand-new PBO covers. It's good for job security, but painful to see nonetheless.
As for the raceboat halyards, it's a mix between trying to keep the cost/weight down on a club fleet, and getting maximum retention out of a clutch in the middle of it's range. One of the reasons I hate clutches is because in order to work with a big load they need to be almost maxed out for size, and they still chew up the rope pretty bad.
Soft clutches are nice, but they need more room to install, and they have a little take-up distance that gung-ho racers find unacceptable.

However, because cruisers aren't doing mega sheet-easings, I don't see why they'd want dyneema cover at all on the winch. Why not simply dyneema-cored, polyester covered line? It's cheaper in the long run.

[Matt Johnson]

Do the textile clutches work well on bare dyneema? I've read that the textile clutches are very sensitive to line size, so wasn't sure if the large weave and slipperiness of the dyneema would work with them without a cover.

Our deck hardware plan calls for textile on the reef lines and main halyard (I forgot the halyard called for this). But I've only used them on boats that had double braid lines.

Matt