Tips for Installing Dyneema Rigging

[alanfw]

I need to replace the outhaul on my 31 footer. It is wire with a poly (I'm guessing) tail spliced to it. I want to replace it AND the two reef lines with sheathed dyneema, but I'm concerned about slippage of the core through the sheath. Should the sheath/core be sewed at the cleat position or am I being overly paranoid? Also, as an old dinghy racer who is new to cruising yachts, I'm used to only using bowlines to attach lines to sails. Is this still OK for cruising yachts? If not, can you augment my google skills with suggestions please! (Soft shackles? This is a term I'd never heard of before - been out of the sailing game for over 20 years)
Cheers
Alan

[ItDepends]

On a cruising boat it is easy to go crazy with dyneema. It has its place, but I would suggest that reefing lines are not one of them. When actually in use, the loaded parts are quite short, and the residual stretch is not critical. Dyneema also does NOT like the kind of tight bends under load that a reefing line has to make. It's the wrong application.

My boat has several control lines that are covered dyneema. In each case they are used where low stretch is critical, like it is for your outhaul (my outhauls are one of the places I DO use dyneema). In every case, I whip the end of the line, and nothing else. The dacron cover works like a Chinese finger trap. If it slips at all, it just grips the core tighter.

For attaching dyneema core line, I do something even simpler than a bowline. I tie a half hitch, and then seize the tail to the standing part. Neat, clean, easy. Never had one fail.

Last thing. Do not use cored dyneema in ANY application where failure would put a life at risk. Since the load is all taken by the core, you can not inspect it in any way. Dyneema bend around sheaves or in clutches is subject to crushing damage that is invisible--until it fails. It that was to happen while you were hanging from a dyneema cored halyard that might ruin your day.

[fxykty]

Dyneema lines prefer splicing, but with covered lines knots are not much of an issue as the cover prevents slipping. Bowlines are fine for the end of a reefing line where you lead the line around the boom, through the eye of the bowline, then up to the reefing cringle and back down to the turning sheave on the boom and forward to a cleat or winch or whatever.

For the outhaul connection to the sail a splice would be better - you can do it yourself (see instructions from Samson or Premium Ropes - they have apps) or have a sailmaker or rigging specialist make it for you.

Bends tighter than the line’s diameter are hard on Dyneema so you if you have stainless steel rings in your reef clews those may be too tight a turn. Do a search in here for Bullseye Soft Shackle for instructions to hang a LFR with proper radius from a regular clew ring.

Both outhauls and reefs are good places for low stretch lines. For reefs especially, they will stop the chafe and noise of the reef line squalling through the clew ring and the end boom sheave.

[alanfw]

Originally Posted by ItDepends

...

Last thing. Do not use cored dyneema in ANY application where failure would put a life at risk. Since the load is all taken by the core, you can not inspect it in any way. Dyneema bend around sheaves or in clutches is subject to crushing damage that is invisible--until it fails. It that was to happen while you were hanging from a dyneema cored halyard that might ruin your day.

THAT'S an understatement!

Thanks for the tips. I'm contemplating trying to rig a single line reefing set-up so low stretch will be useful. Plus, the reef lines lead back to the cockpit so there is considerable length for stretch.

[AKA-None]

I’m not using dyne na for reefing lines not sure anyone else is for this type of application

[Benz]

Originally Posted by AKA-None

I’m not using dyne na for reefing lines not sure anyone else is for this type of application

Dear me, there are hundreds of boats using dyneema for reefing lines--I've spliced scores of them myself. Because Dyneema is so much stronger than polyester, you can get by with a thinner line, thus reducing friction in blocks and around bends. And because it stretches less, the reefed sail retains its shape better.
For the poster who wouldn't go aloft with a core-dependent rope because the core can't be inspected: no more can the core of a cover/core dependant rope be inspected, but both ropes have the same cover!--one just has a far stronger core. If either uninspectable core fails, you're still hanging on the same cover.