Anchoring - static or dynamic rope?

[jimi]

I've got loads of old climbing rope, is that any use as anchor warp or is the stretch contracting going to act as a powerband to rip out the anchor?

 

[fireball]

I can just see you ... elastic anchor rode ... being flung about the anchorage

 

[prv]

People generally use nylon for anchor warps, which is stretchy. I have seen one article which talked about the spring effect as a possible issue, but generally there doesn't seem to be a problem.

Pete

 

[jdc]

Stretch is good, but climbing rope dubious

I think stretch in an anchor warp is pretty much always a good thing in that it minimises peak force on the anchor. Indeed this is the argument in favor of mixed rode (ie chain + warp) over all-chain.

However I'm very skeptical that climbing ropes are at all suitable for anchoring.

1. Breaking strain. The breaking strain of dynamic climbing ropes is usually in the region 7 - 10kN (see for instance mammut 10mm 'super-dry'). Compare this to 10mm anchor plait from English Braids which is 24kN, and the more usual 14mm dia is 38kN. I think you need > 10kN for anything over 24' or so.

2. Longevity. Climbing ropes are tested for a little greater than 10 falls (eg 13) and you are recommended to replace them after 7 or so. These are your old ones I guess, so already past the point at which they have guaranteed tensile strength. In contrast the design life of an anchor plait rope is probably 1000+ deployments.

3. Resistance to immersion. I don't know about your climbing ropes, but they are frequently hybrid construction with a sheath of polypropylene or polyester or at least some fibre sailors are used to - but an inner core of a latex or synthetic stretchy material. This inner core has no established reliability when continuously submerged, let alone in salt water.

 

[sarabande]

shock absorbing is what counts, and it's the boat which will benefit from the surge, since the anchor should be relatively static.

I used climbing ropes in recovery of LandRovers before kinetic recovery systems came in. One negative feature is that sand and mud can work their way into the insides of a climbing rope, and potentially cause abrasive damage.


http://www.youtube.com/watch?v=wuBkxUP2Aho&feature=related for a look at the newer systems.

 

[jimi]

Thanks all. I'll keep 'em for something else other than anchor warp!

 

[fireball]

Should be alright for a halyard?!

 

[fireball]

actually - better idea would be for cruising chute sheets - when a gust hits it automatically eases the sail ... cool !

 

[jimi]

actually I tried that with a sheet with 15 foot of bungee on it.. worked well until it broke ..

 

[AngusMcDoon]

I've got loads of old climbing rope, is that any use as anchor warp or is the stretch contracting going to act as a powerband to rip out the anchor?

I've used an old climbing rope for anchoring with my smaller anchor for years. No problem so far.

 

[davidej]

Should be alright for a halyard?!

Only if you want you sails to hang down when you sheet in

 

[fireball]

Only if you want you sails to hang down when you sheet in

yer - but it makes reefing easier ... no need to let the halyard out ...

 

[jimi]

I think stretch in an anchor warp is pretty much always a good thing in that it minimises peak force on the anchor. Indeed this is the argument in favor of mixed rode (ie chain + warp) over all-chain.

However I'm very skeptical that climbing ropes are at all suitable for anchoring.

1. Breaking strain. The breaking strain of dynamic climbing ropes is usually in the region 7 - 10kN (see for instance mammut 10mm 'super-dry'). Compare this to 10mm anchor plait from English Braids which is 24kN, and the more usual 14mm dia is 38kN. I think you need > 10kN for anything over 24' or so.

Hi, I've been informed that the "breaking strain" is different from the "impact force" of a rope. The impact force is the figure listed on the rope package and is in the range you quoted. They is very different to "breaking strain" however. It is the max force which is transfered to gear/climber after the rope has done its job, not the force required to break the rope. The breaking load of a 10.5mm static rope would be around 2700KG (27kn) so i suspect a dynamic rope would be very similar

 

[jwilson]

I've got loads of old climbing rope, is that any use as anchor warp or is the stretch contracting going to act as a powerband to rip out the anchor?

It should certainly be strong enough for anchor warp for small yachts: you are probably looking at breaking strains of a couple of tons when new, and even allowing only 25% remaining strength for age and wear it should be more than half a ton. Most anchors will break out of the bottom well before that strain. I'm also sure the elasticity will be good.

 

[Ubergeekian]

shock absorbing is what counts, and it's the boat which will benefit from the surge, since the anchor should be relatively static.

Climbing ropes are designed to absorb energy by irrecoverable extension, on the grounds that wheeeeoooop (descending note on slide whistle is better than wheeeeboingboingboingboing. There are therefore very good at shock absorbing ... but not very often!

 

[electrosys]

I wouldn't have any problem using 'em on a small boat - say up to a couple of tons - use a rubber or nylon snubber if you're worried about excessive loads.

Sarabande's comments re: abrasion are valid, but also true for ropes of any similar construction. I'd also add that salt crystals don't do synthetic ropes any good, either.

 

[Sybarite]

I've got loads of old climbing rope, is that any use as anchor warp or is the stretch contracting going to act as a powerband to rip out the anchor?

I would have thought that it has just the opposite effect. The elastic amortizes the snatch loads on the anchor.

 

[Sybarite]

Thanks all. I'll keep 'em for something else other than anchor warp!

You could attach it to your main rode as a shock absorber.