The Offshore Voyaging Reference Site

The Unknown Unknowns

unknown

Andy’s recent two posts on Dux high modulus rope rigging were fascinating. He did a great job of communicating his enthusiasm, without being a fanboy blindly extolling the virtues and ignoring the drawbacks of a product, as you see so often on the Internet.

He also wrote that he would explain:

why [Dux] can be considered to have already passed John’s 20-year field test.

And that’s what I want to explore in this post. But first, understand I’m not writing this to set some young whippersnapper straight. In fact, I have huge respect for Andy’s opinions.

That said, my rule in question is probably the one that has contributed most to our track record of successful voyaging—in 25 years we have only altered, or even delayed, our plans once due to a gear failure*.

Here’s my rule:

If your primary goal is to get out there and stay out there voyaging, don’t install any gear on your boat, at least if it’s mission critical, that has not been in common use for at least ten years and preferably twenty.

As you have probably guessed by now, I believe that high modulus rope standing rigging (Dux or otherwise) does not pass this test. Read on for why.


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Drew Frye

I built chemical plants for many year. Unreliable = unprofitable, but 50 year old tech also = unprofitable. So every time I was trying something new. Perhaps it been used somewhere else and adapted. Perhaps I’d run a pilot plant. Perhaps the engineering was well understood and it just wasn’t really much of an unknown, just a change. Mostly I was right, and a few times I was not. But I always left myself a way back. Some reasonable way it could be fixed during a scheduled shut down. A little “hidden” capacity or some manner of adjusting the process later. And you can bet that anything mission critical got special attention; not just discussion, but real testing and real contingency planning. Over engineering is traditional!

I think the same applies here. In the case of Dyneema, it’s generally practical to go way over strength and flog chafe to death. Inspections increase with new gear; that is part of the science. With some gear you will always carry a spare anyway. Sometimes traditional gear is really pretty poor even after 20 years. Safety gear, for example, is so seldom really tested that some stupid designs became traditional. Certain inflatable PFD and jacklines designs come to mind. So we inovate when the status quo is unimpressive.

But yeah. I just finished an article on repairing sails with adhesives, which included a good bit of lab testing. The a few days later I hauled my genoa down and spent 4 hours on hand-stitched repairs. Yeah, I just trusted it more.

Stein Varjord

Hi John and Drew

I think you have very good points, of course. I like to go properly into the experimental zone of new solutions, often trying to develop new ideas. Working on racing boats that’s necessary. But most ideas don’t live long, even in the mind. I assume one of a thousand “good ideas” prove to actually be good, and mostly are quite small steps. And I’m quite proud of my creative thinking ability. 🙂

Without actually using it here, you both point to an English word I’m fond of: Redundancy. Preferably all critical elements of a boat should have a backup. If something fails, it will not make significant other damage and it will be easy to get up and running again. On racing boats, which are still my measure for optimum functionality, one always try to apply Johns “both belt and braces” rule unless that’s gonna slow the boat significantly.

Look at the Vendee Globe Race going on right now. Solo, nonstop, round the world, no assistance, 60 foot extreme boats cruising steady over 20 knots. Now close to Cape Good Hope. Fascinating! The leaders have lifting hydrofoil wings. “Rock star” sailor Alex Thompson on Hugo Boss has been leading for about ten days. Some days ago his sb wing hit something in the water and broke off. Very bad, but the boat also has the normal daggerboards, so he’s now not loosing ground. Redundancy. Soon he can gybe and fly on the port wing.

The main reason i prefer rope rigging is exactly the possibility to have more redundancy. It is more vulnerable to chafe, etc, but also shows any such problem clearly before it fails. (Steel doesn’t). It’s light and affordable enough to have more spares. It’s very much easier and quicker to exchange worn elements. Many key spots will allow doubling up without much penalty. For me, a complete sailing nerd, rope rigging is way more reliable than a steel version. For sailors who are not into inspecting the boat continuously, i think steel rigging is more reliable and will remain so for some time…

Ted

Good post. On the subject of synthetic rigging we recently chatted with a rigger in New Zaealand where we currently have the boat. He mentioned that he had recently resigned two boats that had tried synthetic rigging and had suffered an unacceptable degree of deterioration from chafe and perhaps UV. Our wire rigging is still going strong after 17000 ocean crossing miles and 7 years use.

Eric Klem

Hi John,

Well said. I worked on the other end of what Drew discusses when I was designing industrial machinery and it was really interesting to see how plant managers viewed our stuff. We could develop a new model that would save them 10’s of thousands of dollars a year in energy costs with extensive reliability testing and they had no interest in installing it unless we installed an old proven model right alongside ready to start up if the new one had any issue. Understanding their thinking has been very helpful to me and has helped a lot with knowing what to buy and what spares to own.

On the other hand, I think that sailors can get too obsessed with tradition or what the local chandler is selling and end up with a far from great solution. I fabricate a lot of my own stuff because I can’t bear to buy something which I know is flawed and will likely break at a bad time. I do my best to fully understand the requirements of what I am building but sometimes the flaws don’t show up for quite a while and they are not at all what I would expect.

Eric