Ok guys, mooring question

[Izikalvo]

Use an elastic climbing (snepling) rope for dock mooring instead of using Snubber or mooring spring, your thoughts?

[rslifkin]

As long as they're routed in a way that chafe isn't an issue, stretchy dock lines are a good thing.

In the US, dock lines are typically nylon for that reason. Most of the time I see people using those rubber snubber things is when a line isn't long enough to provide useful stretch and there's no better way to route it.

[Benz]

The same diameter 3-strand nylon will stretch about the same. But if you have some retired climbing line lying around, go right ahead. I wouldn't buy new climbing line to use as docklines.
As the above poster noted, a little length in rowdy water is good. Doesn't matter at a dock where the water's not being agitated.

[SailingHarmonie]

If you have a tiny little boat and 10 mm line is good enough as a dock line, sure have at it. It is a more efficient way of emptying your wallet than using standard 3 strand nylon.

But for anything larger than a big dinghy, you'll need lines with higher ultimate strengths than climbing ropes can supply, unless you can find 16 mm climbing ropes made for mountain-climbing elephants.

NB: Although that response had a higher level of sarcasm that maybe it should have, the fact is "climbing rope" is typically not strong enough to tie up even medium sized sailboats. Climbing ropes are made to hold people off the ground. Dock lines are made to hold surging boats that can weigh many tons. They are different problems, and should have different solutions.

[Hartleyg]

To echo others, climbing rope may not be large enough for vessels over 30 feet or so. When sizing docklines, ultimate strength is less of an issue than chafe - for our boat, 3/8" nylon would be strong enough - until it started to chafe, then things could go sideways quickly! for that reason, we use 3/4" nylon, and pay close attention to wear - some wear is inevitable, the trick is figuring out when it's time to replace BEFORE it fails!
One aside - many folks do the "clove hitch over the piling" with their docklines, and this works well - UNTIL the line gets highly loaded! I've had to cut two nylon docklines that had pulled that clove hitch so tight it was impossible to loosen them up. I now tie knots instead.


Hartley
S/V Atsa

[Izikalvo]

I am using a 12mm climbing rope as a snubber for a while now, with no signs of fatigue as a result of UV or salt exposure, time will tell.

The question is different, did you try using this kind of rope as a snubber, connected to the dock cleat? meaning double rope, to and from the dock, will it give you enough elasticity? don't forget that this rope cannot be spliced so the knot is the weakest point.

[thinwater]

Originally Posted by Izikalvo

I am using a 12mm climbing rope as a snubber for a while now, with no signs of fatigue as a result of UV or salt exposure, time will tell.

The question is different, did you try using this kind of rope as a snubber, connected to the dock cleat? meaning double rope, to and from the dock, will it give you enough elasticity? don't forget that this rope cannot be spliced so the knot is the weakest point.

It's going to boil down to chafe gear. The only failures of any dock line I have seen were either chafe/friction-heating/UV/age or the hitch pulling off the boat or dock. The only reason I have not used climbing rope is that I've used my old ropes for other things and docklines are cheap.



They will be more elastic and less fatigue prone than any equivalent rope. The knots won't be either, because the rope will fail from chafe. Also, the dockline is always knotted somewhere, if only through a chock and to a cleat hitch, which is a weak spot.



Trivia: Climbing ropes are drop tested using a figure 8 knot, not a drum wrap or a splice. They take knots rather well.

[Shrew]

You need to look at the 'Dynamic Elogation' of the rope being used. (Yes, I said rope. It's not attached to a vessel yet )

Climbing rope is going to limited in diameter and have a huge percentage of dynamic elongation. The working load limit (WLL) on climbing rope are fairly low (as compared to boat/dock/anchor line), even with several climbers and gear. Due to weight and loads, climbing rope will only come in limited diameters.

Dock Line/Anchor Line will have a much lower percentage of dynamic elongation, but will have much higher working load limits. It will come in diameters able to scale to the demands almost any sized vessel.

In heavy winds climbing rope could potentially have you bumping docks and pilings if it stretches too much. In an anchor line, it will have you slingshotting on the rebound of being loaded.

[leecea]

Along with all the good information above, I'd add that you will have to be making assumptions about the life of your climbing rope for completely different uses than it was design for and how climbers judge their ropes lifespan.

Ropes are tested to hold a small number of worst case falls. Climbers understand the different types of leader falls and top-rope style falls and judge when to replace ropes accordingly. Replacement times can vary enormously based on the fall types experienced.

Boats are completely different - they could be pulling against the ropes for days at a time, exerting a repeated, unknown load on the rope based on wind and waves. How would you know when to replace it?

[SailingHarmonie]

Originally Posted by leecea

Boats are completely different - they could be pulling against the ropes for days at a time, exerting a repeated, unknown load on the rope based on wind and waves. How would you know when to replace it?

You’d do it the way most people maintain their boats: You replace it after it breaks.

[AndersO]

I tested dynamic climbing rope and 3-strand nylon rope - they have almost the same elasticity when they have same diameter 10-11 MM

They both strech ~10% with a load of 200 kg (which is 10% of the breaking strength of the ropes I tested).

So you can directly compare climbing ropes with 3-strand nylon with same diameter.

Dynamic Climbing ropes are made with nylonfibres in the entire core, so they ARE nylon ropes - only with a cover.

I also tested several other ropes - and there is huge difference in elasticity, so you have to chose carefully.