UKH

At a kids party today we used my climbing rope for a tug-o-war. 

To avoid rope burn on the kids' hands I tied double overhand stopper knots every metre for about 15m of rope. The problem is that all the adults joined in heaving on the rope and now I have about 8 knots that I cannot get a start on untieing.

Any tips for undoing extremely tight knots in a climbing rope - or is it now destined to become two ropes - one for the kids and one for short crags!?

Thanks

Hazarding a guess... pliers?

Take a short loop of rope in your hand, with the knot in the centre of the loop, then swing it hard at something very solid. The impact will help loosen the knot. You may need to do this quite a few times, and to avoid abrading the rope at the impact point it's better to bash it at something less abrasive, such as a wooden post or smooth limestone, rather than against rough rock.

Works a treat for untying knotted slings too.

Marlin spike

Or a knitting  needle, bit like a marlinspike but more readily available. 

Just spoke with my dad who insisted that a marlin spike was the answer, but that I would also need it removing from my hand at some point based on his own personal experience of using this tool!

I gave one knot a light mauling with the needle-nose pliers but wasn't gaining any ground.

Thanks John. That's my next approach. Right now I'll be quite happy to bash the knots on something, it will be therapeutic. Perhaps on my own thick skull...

A relative of mine provided a climbing rope for a tug of war in the Queen’s Silver Jubilee Celebrations.

The rope snapped. Not surprising really with 10 people either end. One participant had a heart attack and died.

Must have been a simond rope That wouldn't have happened with a Beal rope.

I'd recommend similar... medium strength raps on a flat surface with a wooden or plastic mallet. I must have strong fingers as I've needed to do this. In contrast quite a few sling knots needed stomping after aid weighting.

Soak the knots in WD40 overnight

then tomorrow morning throw the lot into the bin 

Put the knot on a hard surface like concrete and roll it under your shoe. Normally loosens things up.

There was a recent post in Mountain Project about tug of war and dynamic rope. I googled and found: "During a typical tug of war match, a tremendous amount of tension (or elastic recoil) builds up. When improper rope is used (i.e. nylon), the chances of a snap exponentially increase. When this does happen, the stored tension in the rope can easily tear through tendon and bone. Similarly, the broken ends of an elastic polymer (again, nylon) can recoil like a rubber band if released, and reach speeds high enough to sever appendages."

Apparently in recent times there have been many second degree burns, severed digits, a hand, an arm and two boys were killed in 1995 when hundreds took part(whiplash and one crushed). Apparently its depends on the tensile strength of the rope and unlikely to happen with small numbers of people.

Bloody hell!  No deaths or missing limbs here, just a few very tight knots.

I'm down to olny the middle 5 knots now.  Have been having success by "gnawing" at each knot from different angles with a mole-wrench - with the jaws wrapped in tape to avoid sharp edges.

I don't have enough knowledge to venture an opinion, but will the use for tug of war have affected the properties of the rope? Probably not as nobody, including the usual technically knowledgeable suspects, has made any comment. Two opposing groups of children and adults might put quite a strain of some duration on the rope. There has been a recent thread of possible relevance: " Using climbing rope as tow rope ".

I'm surprised that no-one has yet suggested that the rope might be trashed.  I would be very wary.

It's pretty easy for a person to pull with a force of about their own bodyweight - the ever-useful XKCD suggests that 1.5 times body weight is a reasonable estimate: https://what-if.xkcd.com/127/

You don't say how many adults, but if we were talking 15 big-ish men on each end then that is around 18kN - that's three times the rated breaking strain of a small nut, and approaching that of a sling.  This will have been applied for a significant length of time and, because of the knots, it will not have been applied evenly over the whole core.  

If you can ever get the knots undone, I would advocate checking the core extremely carefully for bulges and soft spots!  Even if it had none, I'm not sure if I'd be happy about continuing to use it.