Using a Climbing Rope as an Anchor Line?

[Young]

Hi, I'm an experienced rock climber with many climbing ropes that have reached climbing retirement age (~5 years. Climbers periodically retire them to prevent potential failure in an extreme dynamic fall, but for all practical applications they are still 100%.) I have several 60m (~200')+ lengths in various diameters from ~8-11mm (~5/16-7/16") in excellent condition.

I've already been using them with great success as dock springer lines and spinnaker sheets. I'm wondering if anyone has experience using climbing rope as the primary anchor line all the way down to the chain, or if anyone has insight into the safety of doing so.

Thoughts:

-Climbing rope stretches more. I raise my 10kg (22lb) Rocna by hand, so no problem with windlass twisting or storing the rope under tension. If anything, the stretch might make for a softer ride.

-Climbing ropes are a kernmantle weave, not braided. I know they lose a fair bit of their strength when wet (but I believe all ropes are weaker when wet.) The weave might also allow bottom sediment to work through the sheath, become trapped and slowly wear at the inner strands (a concern for climbers in very dirty/dusty conditions.) If I change them every season, not so bad.

-Climbing ropes might take longer to dry, but I don't see it being a real concern when stored in a cool, dark place.

Any constructive insight would be appreciated.

Thanks!

[mrm]

Originally Posted by Young

I've already been using them with great success as dock springer lines and spinnaker sheets. I'm wondering if anyone has experience using climbing rope as the primary anchor line all the way down to the chain, or if anyone has insight into the safety of doing so.

This (rope vs chain anchor rode) has been discussed here in many threads. The most obvious problem with all rope anchor rode is sharp objects (coral, rocks) at the bottom. I would suggest using a climbing rope as a snubber to an all chain anchor rode. More experienced folks will surely chime in..

[Cheechako]

Nylon rode stretches quite a bit at anchor. If the climbing rope stretches even more it could be a little problematic at times. I imagine it's pretty abrasion resistant though? Maybe if it's fairly oversize it would be worth a shot. I looked into it years ago for kicks... cant remember why I ruled it out. I think it may be the " doesnt play well with water" thing...

[sailorboy1]

So you're asking whether a rope that isn't good enough to risk your life with is good enough to risk your boat with? Only you can answer that for yourself since it is your boat, but my boat is worth more to me than the cost of a rope.

[Tia Bu]

I see no reason not to use it. At the risk of getting into yet another endless anchoring debate, I'm very sceptical of the all-chain rode approach and, having used both types of arrangements, suspect the only real advantage of the all-chain rode is psychological. You can find tests and papers on the Internet that discuss that at length.

The extra stretch of the climbing rope might cause more tacking back and forth at anchor?? What the heck. The rope is essentially free at this point. Try it out and see.

[Steve Bean]

A lot of people use three-strand nylon as part of their anchor rode. It is very stretchy, depending on size and loading.

[Palarran]

Guys, he has a Macgreger 26. Let's not over think this. Nothing against your boat but it's light and fairly small. Your probably not going to be anchoring over South Pacific atolls. Your climbing rope will work GREAT. Just put about 15' of chain between the anchor and the rope. I'd probably use the smallest you have.

[Ukeluthier]

A 26' inland cruiser in BC waters? What is this silliness about all-chain rode and ultimate breaking strength?

Using the 11 mm stuff for easy handing renders the breaking strength question moot for a lightweight 26' boat, and just sufficient chain for a decent catenary allows you to thumb your nose at those treacherous British Columbia coral heads.

Go for it.

[Young]

A couple quick thoughts-

mrm- I'm not debating chain vs. line (that debate will rage until the sun burns out.) I'm using a chain/line combo, and was asking if anyone has any specific experience using climbing line as their primary anchor line down to the chain (not just as a snub.)

sailorboy1- climbers taking dynamic falls generate fantastic forces (more than 10x the initial mass) in factor 2 falls. Because of this, ropes are often retired as a cautionary measure because they lose their ability to absolutely guarantee a catch in an extreme dynamic loading situation, but their maximum load strength is not decreased. Gusting at anchor doesn't generate 10x the initial strain in less than a third of a second. So yes, I absolutely trust my life to these ropes in a non extreme dynamic loading situation.

Palarran- Yes, this is just for a small, light 26' boat (though nice cat photo! I spent several years sailing around the south pacific on a 54' Wharram.) I will be gunk-holing while I sail around Vancouver Island for a couple of months this summer, so although I will be on and off blue water down the west side for a month, I can hide when things kick up.

Thanks for all the varied and immediate input!

[mrm]

Originally Posted by Young

mrm- I'm not debating chain vs. line (that debate will rage until the sun burns out.) I'm using a chain/line combo, and was asking if anyone has any specific experience using climbing line as their primary anchor line down to the chain (not just as a snub.)

My apologies then, I read a title of your post "Using a Climbing Rope as an Anchor Line?" and went from there. I must have missed the part about chain/line combo.

We use high stretch lines as snubbers only, but the boat is slightly larger/heavier, and Baltic is cold, often murky (does not exactly invite to dive to check on anchor), and has a lot of post war crap at the bottom, so we are in 'all chain' camp. Having said that, your boat is smaller and lighter, and your cruising area is definitely different so, as with many things sailing related 'it all depends'.

Please let us know how it works out for you and if the rope is not too springy.

[David M]

For your running rigging you want to use rope that stretches as little as possible. Traditionally Dacron has been used for this but more recently many are using other exotic low stretch synthetics. Nylon does not qualify as low stretch.

As far as an anchor rode, if you want to splice your climbing line then go for it. Knots are weaker than splicing, effectively lowering the breaking strength of a line. Knots also do not run easily over bow rollers and sometimes not at all through blocks or over sheaves.

Three strand nylon works great for anchoring because it is so easy to splice, helping to retain its strength.

[evm1024]

Of course a factor 2 fall is extremely severe (most severe you can get) and is not often encountered.

Kernmantle ropes are exactly that. A kern (core) covered by a mantle (cover). The key point here is that a climbing rope is constructed typically of 60,000 to 90,000 individual strands in the core.

By design the peak loading force experienced by the climber in a fall is limited to around 1400 pounds regardless of the distance fallen. In a factor 2 fall 10 feet of rope has to absorb the energy created by a 20 foot fall (20/10=2). This is worst case and the rope limits the force experienced by having the individual strands elongate and then break at one or more places along its length. Generally speaking climbing ropes are designed to not be elastic (who wants to rebound back up into a roof after a fall?)

Climbing ropes are rated in number of falls and this reflects the number of strands in the core. And the loss in ability to limit impact loads.

If you were to use a climbing rope as an anchor rode you would have no problems outside of the usual for a fiber rode. As time goes on the "shock" loads to teh rope would break more and more fibers at more and more places along its length. This would elongate the rope and reduce its diameter as well as tensile strength eventually leading to a failure of the rope.

Bigger boat, bigger shock loads, sooner to failure.

Sure you could use an 11mm perlon rope for an anchor rode. Just keep in mind its design goals....

[Chrisc]

Sorry to go off topic, but I have a question for Young. : with the forces that you allude to on a climbing rope in the event of a fall, how does the body withstand that sort of sudden shock loading? I am thinking of safety harnesses where the attachment point is meant to be able to withstand tons of force in the event of violent loading. I have often thought that whereas my safety harness would keep me from going overboard, it may well kill me in the process. Perhaps a good application for climbing rope?

[Young]

Hi Chrisc- no problem (but if we get too carried away let's pm instead of clogging up the thread.) I have a bit of qualification to answer that- I'm a certified industrial rope access technician as well as a professional climbing instructor.

You've hit the nail on the head- climbing ropes are creating to be stretchy precisely to mitigate gear placement strain and personal injury. Short falls in climbing are often more jarring to the body than large ones because there is less rope out, giving less stretch to slow the deceleration (just like bringing your car to a slow stop instead of jamming on the brakes.) I've taken 50 foot+ falls on climbing rope, and other than having to change my pants afterwards, it was actually quite soft. Some early climbers did indeed get hip dislocations and the like with static systems.

I think you are also right on the money when you question if your boat safety harness should be soft or rigid. If it stops you from falling over the edge (i.e.- you can't ever reach the side of your boat) then I'd want rigid for sure, because your whole body weight won't load it and you don't want to get nearer to the edge.

It also depends what you clip yourself onto. If you clip to a running rope that goes down the centre of your boat, then there will be inherent "give" in the system for sure. But if you fall several feet with full body weight onto a static system that is clipped straight to your mast- ouch! I've seen someone get seriously injured from slipping 3 feet and dynamically loading a static system when on the rock.

To get around that concern when climbing, I use a Purcell Prusik (the knot slides a little when loaded-

https://www.youtube.com/watch?v=vng4NVYhL90

)
To get around it when working on an industry job, we use adjustable ~4ft lengths of climbing rope called cowtails. Both work. Hope that helps!

[Hydra]

Last week, I used a retired 11mm climbing rope as the warp on my FX-23 Fortress anchor, with a few meters of chain. I was anchored in a 30m-wide crack in the cliff in 8m of water at high tide, with 2 anchors to keep me in the middle of the crack, head to the swell: 10kg Rocna at the bow with 30m/100' of chain and the Fortress at the stern.

The climbing rope was perfect in this use: stretchy to compensate for the tide, plenty strong to resist a Beaufort 3 wind coming from astern, and light and easy to retrieve in the morning.

Of course, with a 3.5-ton boat, I wouldn't use this rope on the bower anchor.

Alain