[Brion Toss]

[quote=Mark Johnson;5430]#637


I need some feedback... You especially could help Jack.
I am considering using Dux rigging for my running backs for starters, but have a couple of reservations. One is the lifespan. They claim 5 years, as compaired to 8 for 316 SS. This confuses me... As a boatbuilder/cruiser, I don't have many racing friends, or for that matter friends with million dollar mega yachts. But none of the thousands of people I have known over 40 years of doing this, has changed out their SS rig @ 8 years old, just because! Mine, (316 1X19 wire), is 14 years old, and technically due for replacement, yet it looks perfect.[/html]

First, the 5-year number is arbitrary, and deeply conservative (unlike the 8-year number for wire, but more on that in a moment). Actual testing in tropical conditions shows Dynex, at least, being in better relative shape than stainless in the same conditions. Some forms of Spectra are less UV-resistant than Dynex; that and the engineering tendency to err on the conservative side with new stuff accounts for the 5 number. In Northern climates, the lifespan of Spectra is much, much longer.
8 years, on the other hand, is a good number for stainless in the tropics, and this is based on many years of experience. Older than that, and the effects of fatigue, chloride corrosion, and crevice corrosion tend to result in wire failures. Yes, hardly anybody replaces their rigging after 8 years, even in the tropics, but it's a good recommendation. Again, in the North, with lower temperatures, lower salinity, and often lower average windspeed and boat usage, wire can last much longer; here in the Northwest, a rig can be in fair condition after up to 20 years, for example.

(I use properly installed Sta Locs).

Probably not, if you followed Sta-Lok's instructions. They specify too little of the wrong kind of sealant. Corrosion can kill "properly installed Sta-Lok's."

In all of these years, and tens of thousands of miles, I have re-tuned only once. (almost no creep) In fact, as I replace my wires, I'd gladly have them destruction tested, and bet $1,000 that they would test out at 90% of their origional strength. At least I'd do it once. I can't afford to be wrong more than that!

You'd probably win that bet. In fact, if the wires have lived North, you might find that their break numbers exceeded 100%, as stainless gets stronger (work-hardens) as it cycles. The problem is that it also gets more brittle, leading to sudden failures. Young wire is reliable wire. Oh, and regarding the "almost no creep" reference, actually you have had absolutely no creep; creep is not a characteristic of steel. If you had to retune, it was because your hull had deformed, or you moved to a higher windspeed area, or your hull loading changed, or, gods forbid, you exceeded the wire's elastic limit.

With synthetics exposed to UVs, If & when it is determined that 5 years is the safe replacement interval, that's when I'd replace it! So this issue of having from half to one third the lifespan, makes the Dux look quite expensive by comparison to SS. Time will tell?

Time has told, and Dux appears to hold up at least as well as stainless at a given level of safety.

I have re-read Jack Molan's impressive volume of information on Dux and gather that replacing my too stretchy 1/4" wires with 7MM Dux would result in "creep" that would require regular Re-tuneing. However if I go with 9MM, I have VASTLY more strength at less stretch, and almost no "creep" issues. This is a plus, so I'd oversize to minimize "creep".

It depends. Creep is time-dependent, so for your runners, you might not leave them up long enough (100 hours or so) for the effect to occur.

Also I see that there is a UV cover available with slightly more windage. (double the lifespan)?

Covered Spectra is basically immortal.

I assume that the splice over the terminator is left bare? Is this the case? If so, is it assumed that the line being thicker at the splice/terminator, makes it enough stronger here that the UVs don't make this area the stay's weak link.

Think this through. All the extra mass is inside the rope, and it is held in place by the outside. We serve the portions we can't get the cover over.

Then there is windage... I know that due to the vortices created, things like a wire have far more wind resistance than their windage alone would indicate. This creates parasitic drag. (especially with our 12 wires) Has it been determined that the undeniably "lighter on her feet" motion of a lighter rig, is a bigger plus than a rig with less windage. I would assume that a fatter but way lighter rig wins out, but wonder if it is a fact?

I don't have numbers for this, but my experience says yes, lightness winds out over windage, at least at this scale.

Then there is one more concern. The terminators being of aluminum, and attched to the SS mast fork tangs by a SS clevis pin, (with the cheeks chaffing the anodizing), or my runner's SS pin attched snapshackle, makes for a corrosion potential. This may be purely cosmetic, or it may eat away enough material to make the terminators expendable, just like the line, in 5 or 6 years. (even more expensive)

A little Tef-Gel where the tangs meet the terminals will prevent corrosion. The pin holes are bushed with a non-reactive material. Don't use thimbles, or snapshackles, on your runners.

Fair leads,
Brion Toss