Thursday, March 15, 2012

Climbing gear for tethers

There is a lot of crossover between rock climbing and sailing.  Because he is deep into both sports, Drew over at Sail Delmarva serves as a good resource for crossover opportunities.  Carabiners (climbers call them 'biners) are one such item:
I've always used locking carabiners on the jack line end; non-locking biners can lever off a fixed point or tight rope in any number of ways, and the jack line end gets dragged all over all sorts of edges and fittings. Ice climbers, wearing heavy winter gloves, take advantage of this very mechanism to clip gear in and out without fumbling with the gate. We generally leave the tethers attached to the jackline anyway, so a screw-lock biner is safe, dependable, and snag-free. We use climbing biners rather than "marine" biners; their clunky stainless designs bang on the gel coat and their weight makes them more snag-prone, and to me, snags present a safety hazard.
I'm not a fan of snap shackles on the harness end of  a tether. I've seen them break FAR below their rated strength and I've seen them open easily when not closed just right. Can you see or feel that they are fully closed , in the dark, with gloves on? Ask a climber--or a rigger or anyone with an ounce of common sense--to hang from one up the mast and they will look at you as though you have none. Use one in the mountains and no climber would join you again, convinced you are a complete safety menace and an idiot as well. Yet we're supposed to trust them in a storm, with the boat leaping about. No thanks.

I'm not a fan of the current crop of locking "marine" biners; the webbing loves to catch in the grove at the gate, they don't slide over obstructions well when used on jacklines, and they're difficult to open when wet. I don't need difficulty when things are going badly. The Kong biner does not have the grove (it's a key-lock style biner), it's lighter and smother (not cut from plate), and has a much smoother action.

Wire gate biners are easy to use and unhooking at the harness end is very, very unlikely. The attachment isn't rigid isn't being dragged up and down the deck. But it could happen, and I think about that when working down the sugar scoops, landing a fish or fooling with the tender while underway, often single handed.

The Kong Trango seems to be the best of both worlds. Opening is effortless and instinctive; the same light squeeze that opens the gate releases the lock. It's heavier and bulkier than climbing biners, but it's aluminum and 1/2 the weight of the stainless alternatives. Some have expressed concern over corrosion, but Practical Sailor left one in saltwater until it grew a reef and it still worked, and I treat my safety gear a bit better than that. As usual, I will keep the pivots greased.

Why do I use knotted tethers, in preference to sewn?
  • Because climbing slings never break at the knot, they cut over an edge.   
  • Because tethers clipped to a jack line with appropriate stretch and impact absorption characteristics will never see a force over 500-600 pounds. 
  • Because because knotted slings encourages replacement of warn parts. Cost and time are no object.
  • Because I like to change things from time-to-time. Lengths. Biners. Mid-tie locations. We currently have 2 styles: fixed at 7 feet long, and 11 feet long with a tie-in 4 feet from the harness end. The longer one reaches the transom, where landing fish presents a significant risk.
  • Because they cost $2.00 at REI. Far less, for me, since I bought a spool of webbing years ago at wholesale, but that's cheating.


     Notes on lubrication:
    • Waterproof grease is best on screw gates. very dependable.
    • A good corrosion blocking spray should be applied to all pivots, and critically, to the spring inside the base of the gate. Be liberal there.
    • Cor-Block and Bo-Shield did very well in Practical Sailor wire corrosion testing in a salt environment chamber/accelerated aging test. Many others, like WD-40, are basically useless. 
    Rock climbers are generally advised not to lube biners. Lubricants attract grit when biners are thrown on the ground in dusty crag-side environment. Additionally and very importantly, there is a risk a climber will try to revive a bent carabiner with lubrication, which is an obvious risk; the biner may be weakened and there is a risk that the gate could hang open at a critical moment. These are good reasons, but they are not too relevant in the marine environment. However, if a biner or other piece of climbing equipment does stick because it is bent or burred, discard it. Though I am a dedicated fix-it guy, I don't repair damaged biners.


    I have several other posts on jacklines, climbing gear for sailors, and the stresses involved. As a life-long sailor, rock climber, and engineer, it's a favorite topic.

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