Spreader tip modification for synthetic
 

I want to convert the #10 discontinuous rod rigging (double spreader config) of my 1978 Crown 34 to 9mm continuous Dux, as I do not know it's age and have already had a turnbuckle screw fail. However, my understanding is that Dux is rather slippery. My spreaders are all attached to the mast by two small brackets, fore and aft, which do not limit up and down movement significantly, so I am afraid the spreaders will walk up or down.

To further complicate things, the end of the lower spreaders are built for the "cups" of rod rigging, like this:


Take out the "cup" and you have a nice ring not suited for continuous rigging at all. I have a rough design for an aluminum puck sized to fit in the ring which can "squeeze" down on the Dux. But that assumes that squeezing is the right way to hold on to Dux.

Therefore: What is the best way to attach spreader tips to the Dux to keep the spreaders from walking up or down?

Don't squeeze the Dux
 

I don't think you can squeeze the Dux hard enough to make it not slip. And if you could, it would be unwise to. Easiest thing to do is terminate and re-start at the first spreader. I'd be surprised if Colligo Marine doesn't have a neat way to do that already.
Ben

Lashings?
 

I'm feeling a little sheepish 'cus now I see another thread where it was suggested to use delrin and lashings. Do you think this is application is very different? I only ask because in all my internet wanderings I can't remember seeing dux rigged discontinuously (though I am certain somebody's done it) and Colligo doesn't have anything for spreader tips as far as I can tell - I asked John a couple weeks ago about this.

Assuming lashings would work, is there a particular flavor of lashings that works best?

Lots different
 

Are you thinking about having two runs of Dux begin at the chainplate, one of which bends inboard at the first spreader and the other which carries on past the second spreader to the cap? Because in that case you could do it--just lash very firmly with fine twine. you could even run a thin piece of Dyneema from spreader tip to shroud tang to prevent the spreader tip from sliding down.
But you can't have the same setup as now, with one lower wire and two that carry on from the first spreader with Dux unless you terminated at the spreader. The force on that leg that goes from spreader end up to under the second spreader would overcome any lashing and pull the spreader up.
I would splice the Dux around a Colligo thimble so that it stuck just past the spreader, then splice the two diverging legs to the thimble. Not very low-profile, but without having a custom-designed fitting specially machined for you, this might the only option.