cover for dyneema

[Malaya 18]

I need to put a polyester cover on about 5 feet of 4mm dyneema. Can't seem to find polyester covers as a stand alone product, so I would like to strip the cover off some poly double braid, what diameter double braid would I strip?

[Alex W 230]

5/16" / 8mm

[Malaya 18]

Thanks Alex

[mgs 96]

I’d look for a cover with 24 carriers or greater. Avoid 16

[Haligonian Winterr 29]

+1 the above, also remember it is easier to get cover to match slightly larger core than to go smaller.

 

HW

[Alex W 230]

Also ask your small keelboat friends (like J/24 or Moore 24 owners) to see if they've stripped Warpspeed or Endura Braid for lighter halyards recently.  They hopefully kept the extra cover and can pass some along to you.

[thinwater 40]

Is there a table of core vs. cover diameter? I know they are typically of equal strength and volume or a conventional eye splice would not work. Thus, the core is typically more like 2/3 of the total diameter, no?

rope image

Yes, an oversized cover is easier to work with than a tight cover.

[Haligonian Winterr 29]

15 hours ago, thinwater said:

Is there a table of core vs. cover diameter? I know they are typically of equal strength and volume or a conventional eye splice would not work. Thus, the core is typically more like 2/3 of the total diameter, no?

rope image

Yes, an oversized cover is easier to work with than a tight cover.

Unfortunately, all manufacturers are different, and within a manufacturer the ratios will differ between products. Which is why many shops will get one manufacturer and stick with them. Difficult to do repeatable precise splicing with many different manufacturers.

 

2/3-3/4 is a good ballpark. For instance Marlow MGP Tech 50/Race 100 in 12mm has a 9mm core.

 

With the cover, oversize is easier to splice, but I meant that slightly undersize is easier to milk tight.

 

HW

[JoeBleaux 45]

On 5/20/2020 at 3:37 PM, Alex W said:

5/16" / 8mm

I don't think this is right. If you need to cover 4mm dyneema, I would pull the core out of 6mm/ 1/4" double braid. Aps used to sell polyester cover only made by Yale, but they don't carry rigging stuff anymore. My local rigging shop will basically give me the leftover cover from when they strip halyards. If you're covering to avoid chafe, this dyneema cover is really good. You can tell them diameter of the rope and they'll give you the cover to fit. https://www.fisheriessupply.com/new-england-rope-dyneema-chafe-sleeve#AllProductBookMark

 

[sailorman44 60]

Be a little careful here. If the cover is a little loose it will be OK to go around a winch but If you are using the cover to get a better grip on the dyneema where it goes through a rope clutch, the clutch will chew up the cover to the point it will jam in the clutch. I use dyneema halyards and found that they would slip in the clutch. When I put on covers and the covers got chewed up. I inserted a piece of 1/4" double bread core into the 1/4" dynemma to thicken it up then installed a 5/16 cover over it. This arrangement lasted thru the season. Now I inspect the cover on the halyard before using it.

[F18 Sailor 285]

On 5/26/2020 at 2:48 PM, JoeBleaux said:

I don't think this is right. If you need to cover 4mm dyneema, I would pull the core out of 6mm/ 1/4" double braid. Aps used to sell polyester cover only made by Yale, but they don't carry rigging stuff anymore. My local rigging shop will basically give me the leftover cover from when they strip halyards. If you're covering to avoid chafe, this dyneema cover is really good. You can tell them diameter of the rope and they'll give you the cover to fit. https://www.fisheriessupply.com/new-england-rope-dyneema-chafe-sleeve#AllProductBookMark

 

Concur. 4mm Robline Dinghy Control has has 2mm core, 5mm is 2.5-3mm, 6mm is closer to 4mm etc. Each line is different, so best to check with the real thing. Unfortunately I don't stock things past about 8mm so can't help with the larger stuff.

My preferred approach to halyard building is to use a cored line and splice the dyneema into it...yes its a bit more expensive than using cover 'just where you need it', but my experience is the factory cover->core is going to be a lot tighter than you can get at home. Ideally you put the splice (thickest part of the line) right were the clutch is for maximum grip.

[thinwater 40]

On 5/21/2020 at 5:40 PM, Haligonian Winterr said:

Unfortunately, all manufacturers are different, and within a manufacturer the ratios will differ between products. Which is why many shops will get one manufacturer and stick with them. Difficult to do repeatable precise splicing with many different manufacturers.

2/3-3/4 is a good ballpark. For instance Marlow MGP Tech 50/Race 100 in 12mm has a 9mm core.

With the cover, oversize is easier to splice, but I meant that slightly undersize is easier to milk tight.

H

I was trying to be PC.

As you say, the problem with a loose cover is that it will slide and bunch up. If using PDB the 2/3 rules has worked for me every time... except for the fact that "true" line diameter varies a little bit!

[Amalfi 1]

On 5/29/2020 at 6:40 AM, samc99us said:

Concur. 4mm Robline Dinghy Control has has 2mm core, 5mm is 2.5-3mm, 6mm is closer to 4mm etc. Each line is different, so best to check with the real thing. Unfortunately I don't stock things past about 8mm so can't help with the larger stuff.

My preferred approach to halyard building is to use a cored line and splice the dyneema into it...yes its a bit more expensive than using cover 'just where you need it', but my experience is the factory cover->core is going to be a lot tighter than you can get at home. Ideally you put the splice (thickest part of the line) right were the clutch is for maximum grip.

You preferred approach--- checking, you mean something like:

Take a lower cost double braid, splice the core with the dyneema, and bury the cover into the dyneema,  and you  target the splice point to be in the clutch zone? I've done this successfully when I was given a bunch of bare dyneema, worked well, and you get your choice of favorite tail covers.