Splice 4mm dyneema double braid to 8mm polyester

[MikadoII]

For reefing lines I am using small blocks at the cringles and 4mm dyneema as the line. For handling and the line clutches I want to use 8mm double braid polyester. I have trawled the web but cannot find a splice for such an extreme transition. Can anyone advise please?

[Benz]

What's usually done in this case is the whole length of the line is dyneema, and a cover is added over it where it engages the clutch or gets pulled on. Or if bought with cover on, the unwanted cover is stripped off.
A transition as you describe is not often done and nowhere near full strength: you'd have to bury the polyester core of the 8mm into the center of the dyneema, tapering both, then milk the 8mm cover back over and bury the end of that into the dyneema, probably in 2 bundles of 11 strands and 1 of 10 (assuming the cover is 32-pick).

[chrisr]

i agree with ben

what we have always done in this sort of application is use dyneema for the full length, and then strip the cover off the section needed bare (obviously for less friction)

an extra cover to protect in the jammer can be useful too

cheers,

[tenchiki]

I have successfully used the following instructions to splice 1/8" dyneema to 1/4" sta-set. https://l-36.com/halyard_splice.php. I expect that the same directions, scaling length by diameter, would work for any size, as long as the double-braid was 2x the diameter of the dyneema. Note that a couple of the steps are really tough, at least in the smaller sizes...

[fxykty]

No need to splice.

We use bare UHMWPE (Acera Admunsen - no need to pay extra cost for Dyneema in this application) for our outhaul and reefing lines (8mm replacing the 14mm double braid polyester the boat came with).

For the first 1.5m off the boom we sew on a Dyneema chafe cover - sufficient length to go from the boom, through the reefing LFR, down and around the boom-end sheave). For the locations where we need to jam the line cover sewn on alone is not enough - you need to add an insert first, then a cover over top, for it to hold in the jammer. We use 4mm para cord inside 8mm UHMWPE, then a 14mm braided polyester cover. The cover needs to be sewn, not just whipped at the ends, as it will slip on the slippery UHMWPE.

Make sure that your line is UV protected. Generally quality Dyneema/UHMWPE that is 12 strand will be. However, a line with Dyneema core may not necessarily have UV protected the core - ask the manufacturer (not the dealer/distributor).

[thinwater]

And you don't need 8m for handling. 6mm is plenty for lazy jacks. Plenty of people use smaller than that on a 30-foot boat. You don't need a jammer; a cleat will do fine.

[Cwens]

Originally Posted by thinwater

And you don't need 8m for handling. 6mm is plenty for lazy jacks. Plenty of people use smaller than that on a 30-foot boat. You don't need a jammer; a cleat will do fine.

I believe the OP was asking about reefing lines, not lazy jacks. I can't speak for anyone else, but I would find hauling in a 6mm reefing line on a 30' boat, even with decent gloves on, hard on my hands.

[fxykty]

Originally Posted by ChrisOwens

I believe the OP was asking about reefing lines, not lazy jacks. I can't speak for anyone else, but I would find hauling in a 6mm reefing line on a 30' boat, even with decent gloves on, hard on my hands.

8mm uncovered UHMWPE on a 55’ cat’s reefing lines is just fine to hand handle. You do need a lot more turns on the winch however.

[MikadoII]

Thanks everyone for your suggestions. I will probably go with a full length 4mm dyneema and a cover.

[thinwater]

Originally Posted by ChrisOwens

I believe the OP was asking about reefing lines, not lazy jacks. I can't speak for anyone else, but I would find hauling in a 6mm reefing line on a 30' boat, even with decent gloves on, hard on my hands.

Oops.



I'd go 6mm on the Dyneema. Cover the tails 8mm as suggested. Problem solved.