SRT connecting two ropes for bigger trees

[Joe Newton]

6 minutes ago, peds said:

 

Because it isn't complicated enough. Because humans are timid, flighty creatures who need to believe that there's as complex an answer as possible behind keeping them alive. Why settle for the quickest solution available when you could add a load of padding and window dressing and vajazzle to inflate our sense of value.

Of course, you have to have faith in a knot that's keeping you from hitting the ground, and it's just possible that it'll notice if you don't believe in it and come apart. You can't blame it, we all get like that sometimes. But I've spent enough time in my life dangling over hundreds of metres of cold air and jagged granite to learn to trust a simple overhand.

Fair enough. There's plenty to be said for experience. Do you climb trees? For the application originally mentioned as a base anchor there can be a lot of cyclic loading and unloading of the knot, with rubbing on the stem added into the mix.

 

I'm never under the gun to the extent that a few extra seconds for added redundancy matters.

 

Another consideration is the difference in climbing lines. With rock lines being dynamic it would aid the knot to grip, whereas arb climbing lines are more static and often tight braids to run through devices, they don't always have the same knot holding characteristics.

[peds]

I do climb trees, but only occasional cowboy weekend work. Nothing like the heavy hitters on here, and anyway, trees here on the west coast of Ireland are only about 4 metres tall. Sometimes even a ladder seems overkill. But most of my ropework I learned in the French Alps.

 

Static, semi-static, dynamic, it's all the same, your overhand will bite. It isn't a slipknot with a fiddlestick we are talking about here, like those weird canyoneers are fond of.

[waterbuoy]

I have just read through the thread coming from a range of backgrounds which do not include SRT/DRT but do include working with ropes for much of my life - both in the alps and back here in the UK. 

 

I have always been of the belief that, whilst convenient, the overhand knot has a significant impact on the strength of the rope.  I have therefore tended to use the double fishermam's knot (bend) wherever it was an issue.  As Joe has said, a few second extra doesn/'t make much difference so far as most situations are concerned - it is the end result that matters.

 

Thinking that my memory may be incorrect I have just checked a few online sources to see what effect different knots have.  Edelrid have the following to say on the matter:

 

When comparing knot types, the flat offset overhand and double flat overhand bends have the greatest strength reducing effect of -38% to -75%, with the offset overhand bend causing slightly greater strength reduction. The load type on the knot has a significant influence on the knot's strength reducing effect. If an offset overhand bend is subjected to load as a roping-up knot, the strength reduction is about 20% less than when the load is placed on the ring. The double fisherman's knot causes less strength reduction than the double flat overhand bend.

 

So, for planned and or routine work I will continue to use the double fisherman's.  If, however, I am half way up/down a pitch with frozen extremities and realise that my rope is too short then yes, a double overhand may be appropriate. 

[daltontrees]

On 15/01/2023 at 17:54, Carteeni said:

I have a 45m rope for SRT and i was looking advice as I haven’t seen this done before.

could you connect two ropes together spliced eye to spliced eye to give you a longer rope for’

 

 

base tie, could you use one rope say 25 for your Base tie and running up tie back side of tree connected to another 45m rope, splice to splice with a carabiner, as long as you keep the connection to the base anchored side of the tree?

 

canopy anchor, same thing but have the carabiner and 25m rope connected to the retrieval side when using a canopy anchor or even just a throw line? Just to retrieve the anchor from the ground as it wouldn’t be life support.

 

I am just asking in case I encounter a tree that I would need a 60m or more rope, could I connect a 45 and a 25 in the configurations above?

im new to SRT and Went for a 45 rather than a 60m as it will be used for DRT climbing too and I didn’t want to pull 60m through.

 

cheers guys any advice or if anyone has done anything like this let me know!

The answer is yes, but use a screwgate krab and just check that it isn't cross-loaded. This assumes both ropes have a spliced eye. In this configuration everything is being used exactly as designed and the strength limit is that of the weakest component. 3kN ropes and krabs  (i.e 3 tonnes) are standard and you'd need to eat a lot of pies before you would be worrying about strength limits.

 

 

[waterbuoy]

At the risk of being a smart arse/pedant - I think you may have meant 30kN ropes.  Otherwise totally agree.

[daltontrees]

26 minutes ago, waterbuoy said:

At the risk of being a smart arse/pedant - I think you may have meant 30kN ropes.  Otherwise totally agree.

Quitre right, I thought I had said that. 10kN=1 tonne.

[redmoosefaction]

Alpine to alpine..with a crab, do what you know... Keep it simple!