If there are any on here  :-\ 

https://youtu.be/cwLtDQybHhU

Saw it when posted yesterday.. greatly enjoyed watching, the vis is amazing. Also learned stuff.. for example wondering why a clothes peg on line at start, but at end when removed could see your name written on it (penny dropped!)

Cantclimbtom said:

Saw it when posted yesterday.. greatly enjoyed watching, the vis is amazing. Also learned stuff.. for example wondering why a clothes peg on line at start, but at end when removed could see your name written on it (penny dropped!)

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Its simply to know which line takes you out Tom sometimes a junction can get really complicated , I also use what I call comfort markers when down a long line , some people think its stupid I don't and was taught by one of the best in the game .

ahhh.. I thought that was at the start and you were clocking in and clocking out.

So that's marking the exit route at a junction?  What on earth is stupid about that (even in perfect vis). It's simple and fool proof. I'm a devout believer in not just Murphy's law... but Finagle's law (which I always thought was termed Sod's law, but apparently not??).

It's a hardly complex and expensive system you have there, seems a brilliant idea to me.

Cantclimbtom said:

ahhh.. I thought that was at the start and you were clocking in and clocking out.

So that's marking the exit route at a junction?  What on earth is stupid about that (even in perfect vis). It's simple and fool proof. I'm a devout believer in not just Murphy's law... but Finagle's law (which I always thought was termed Sod's law, but apparently not??).

It's a hardly complex and expensive system you have there, seems a brilliant idea to me.

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The comfort markers down a long line are what some divers think ore over excessive , ALL divers mark the exit at a junction , well nearly all some get a bit complacent if they are very familiar with a place , I even put another arms length up the line in case that one gets kicked of by a fin. The lines in Dinas are so done as well as to not get mixed up, the main exit line is blue and the branches are orange . We put a mini snoopy loop as we call it round and round the peg so its really stiff to open usually some cycle inner tube as you can see on mine but some of Sues on that dive have a rubber band,  rubber bands only usually last for one dive . Hope that helps you Tom. 

Cantclimbtom said:

So that's marking the exit route at a junction?  What on earth is stupid about that (even in perfect vis). It's simple and fool proof.

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It would be brilliant if it was totally foolproof system. However, you can :

a. Swim over a junction without seeing the T ( / branch line) on the way in.  Then on the way out, you reach a junction with no cookie/peg/arrow and (in theory) have no indication of which way to exit. This can happen if the T line is hidden behind/over a rock or immediately around a corner. There's a prime example in Cunhac/Ressel 2 in France. The 2nd T in Ressel itself is pretty bad for this too.

b. Put the cookie/peg/arrow on the wrong line at a junction. I wouldn't have thought this was possible, but I've seen it done in person by one of the most diligent and careful divers I know. It was a slightly unusual jump from one line, followed by an immediate jump to another, after a long swim against the current at 30m with some narc involved, but an inexcusable mistake that was very worrying to witness.

The lines and markers are primary navigation, but there's a lot of general awareness needed too. Personally, I always take an extra set of eyes & brain, but understand this isn't always practical in uk conditions.

Steve Clark made a good point when he wrote: "The lines and markers are primary navigation, but there's a lot of general awareness needed too.". Rick Stanton (whom I've known for many years and who knows a thing or two about cave diving) has always advocated "Follow the cave, not just the line".

The potential for confusion / unintended interference is one reason (of many) why opting for a solo dive may well be safer than being in a sump at the same time as others, particularly in the challenging conditions of many British underwater caves (as Steve alluded).