Diving Line

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davepinch

Guest
Hi All,

Can anyone recommend any good line for use in sumps, I currently use the blue poly stuff, but it has a tendency to float and can sometimes be difficult when using it off a reel.

Any advice / recommendations would be greatly appreciated.

Regards

Dave
 

Pitlamp

Well-known member
Dave - try the paper by Yeadon from the early 1980s called "Line Laying And Following" published by the CDG. This was written as a direct result of the loss of Ian Plant in Bull Pot Of The Witches - an accident which was line related. It was written in the pre snoopy loop and ziptie days but is still largely relevant. The chapter on line laying in the 1990 CDG Manual was largely based on it.

Your caving club library may have it or if not it'll be in the BCRA librbary which all members have free access to. (Or is it now called the BCA library??)
 

Marcus

New member
Depending how much line you need to take, a 2 litre pop bottle can hold a fair bit of 4mm polyprop. Knot the tail end through a hole in the bottom of the bottle and run the line out through the neck of the bottle between your finger and thumb. A few snoopys around the bottle can be a good idea. When 'reeling back in' just wrap the line around the outside of the bottle. Job done.

Marcus
 
D

davepinch

Guest
Thanks for your advice Gents.

I don't have a problem with using the poly line, it's a bit fiddly but nice and 'feelable' in our nice warm waters...

I have found a good nylon line supplier but it's £30 for 200m :shock:

Thanks again

Dave
 

Stu

Active member
OT sorry...

do you cave divers ever use a reflective line?

Asked by someone who nows now't!
 
D

davepinch

Guest
I've never seen reflective line Stu.. but then again I haven't been cave diving that long. It's not a bad idea though.. I was using white nylon line a few weeks ago and that did show up very well.. can't imagine the cost of reflective though :wink:
 

Stu

Active member
davepinch said:
I've never seen reflective line Stu.. but then again I haven't been cave diving that long. It's not a bad idea though.. I was using white nylon line a few weeks ago and that did show up very well.. can't imagine the cost of reflective though :wink:

I expect you could do a DIY job. Blobs of reflective paint on polyprop. Only curious.
 
M

MSD

Guest
Usually when reeling out line, problems usually occur because of the line reel, the way the line has been loaded onto the reel or the way the line has been laid. I used a lot of polyprop line in my day and properly handled it works fine. Some tips:

a) Have a line reel with a BIG hub. Polypropylene line can't be bent through a small radius without a semi-permanent effect. If the middle of the reel is too small, the last bit of line acts like an enormous slinky toy and is completely impossible to use or even downright dangerous. You actually lose very little capacity by making the middle bigger, because the first couple of wraps only hold a few metres if the reel is too small in the middle.

b) don't be tempted to load absolutely as much line as you can onto the reel. 90% of dives you don't come back with an empty reel anyway and if you need to reel back in, the line always takes up more space. A overloaded line reel that bursts apart mid-sump is obviously a potential nightmare. In particular, don't load try to load the reel really neatly (as a machine would). If the line is in a seemingly neat order, this means a strand can easliy dig down and jam the reel. If the reel is a bit less "well ordered" this doesn't tend to happen. Capcity is a bit less, but if that can save problems handling the line underwater it's usually worth it.

c) Always reel in as soon as you go back or otherwise make the line slack. Imagine that your last line belay is a fish you are trying to land and you get the idea. A small tension keeping the line taught solves a lot of the problems. If the line begins to pull around corners etc..... then it's maybe time you thought about another belay.

d) Remember that you are working in three dimensions. There are aften just as many line belaying possibilities in the roof as the floor, but you are maybe not seeing them (a cave diver swimming along looks naturally down at the floor). A line which sinks is convenient for belays in the floor, but a line that floats is just the thing for belays in the roof. A line off the floor doesn't get stuck in silt, but a lead weight can be used even if there is nothing else available and necessarily belays the line on the floor. Basically what I'm saying is that there is no "optimum" solution, you have to try a few different ideas and see which works best for you in a particular circumstance.

An advantage of the typical 4 or 6mm polyprop line is that it is hawser laid and therefore easy to feel underwater. Most nylon line I have seen is braided and doesn't give anything like the feedback through a wetsuit glove. Another advantage is that it is cheap. But come on, cave diving is a dangerous and relatively expensive game - dying because you were too cheapskate to buy the right line seems a silly way to go. So if you just don't get on with the cheap stuff, spend the extra money and get something you are comfortable with.

Reflective lines.....when the sump is liquid shit, you are navigating by feel, not with your eyes. Rule number one in any sump with less than perfect visibility is KEEP HOLD OF THE LINE.

Safe diving,

Mark
 
M

Mike W

Guest
What an excellent post Mark !

Just for completeness, polythene line is less 'floaty' than polyprop, and you used to be able to get a lead-cored version ( braided though ) which was quite well behaved. Regarding laid ( twisted ) rope, an added advantage is being able to tuck the tail of a knot thru' the lay for security.
 

Pitlamp

Well-known member
. . . then again poly(ethy)lene line can have lower friction but a significant elastic memory, meaning that knots might undo themselves (so are best secured by adding zipties). Hawser laid line also has the advantage that plastic sticky tape distance tags can be attached through the lay and are less likely to migrate along the line over time - also information tags (such as "out" or "airbell" markers) can be ziptied through the lay for the same reason.

I dislike the pop bottle approach - a proper reel is best for large amounts of line and for anticipated small advances (e.g. in underwater digs) it's probably better to have a few metres of line secured concertina style under inner tube loops on a lead block. You can then feed out just the right amount as your dig progresses and the device stays in control on the sump floor because of the lead block.

Reflective line? H'm, I wonder. Of course anything you can see at all is "reflective", since it reflects light from a light source into your eye. However if a line is available which has enhanced reflectivity or fluorescence it could be very useful. The idea would work best in water which absorbs light because of dissolved substances (e.g. the typical brown peat stained water of the Dales). The most conspicuous line I've seen was fluorescent yellow nylon (which I think is used by some "technical" divers). Anything which can be done to enhance line conspicuity must be good for safer diving. Does anyone know a source of such line?
 

Johnny

New member
Thanks MSD, very thorough.

stu said:
OT sorry...

do you cave divers ever use a reflective line?

Asked by someone who nows now't!

Sounds interesting do you know where to get some?
 

bubba

Administrator
I remember reading about some dive line with fibre optic technology so it would actually emit light along it's length - can't remember anything more than that though and not sure how useful it'd be in murky UK sumps anyway.
 
M

MSD

Guest
bubba said:
I remember reading about some dive line with fibre optic technology so it would actually emit light along it's length - can't remember anything more than that though and not sure how useful it'd be in murky UK sumps anyway.

This idea would only work for a single continuous line, so it would have extremely limited application - any line junction or join would cut the light path.

I feel that joining the fibre optics underwater would be a bit of a technological overkill :)

Mark
 

Stu

Active member
Johnny said:
Thanks MSD, very thorough.

stu said:
OT sorry...

do you cave divers ever use a reflective line?

Asked by someone who nows now't!

Sounds interesting do you know where to get some?

God know. I stumbled onto thinking about this whilst bored! I'm not a diver. Sorry. Just seemed one of those things that get asked many times by numptys (ME) but will have many reasons why not.
 

Pitlamp

Well-known member
Stu - it was a very good point you made. Sometimes the best suggestions come from people not directly involved as they are perhaps more easily capable of lateral thinking. So don't describe yourself as a "numpty".
 
M

Mike W

Guest
Pitlamp - zip-ties are brilliant ( for all sorts of things ), but a long tail and several tucks are quicker and easier with numb fingers. That said, the last line I joined was double knotted, zip-tied and tucked twice through the lay !! It's kind of important, isn't it !
 

bubba

Administrator
MSD said:
This idea would only work for a single continuous line, so it would have extremely limited application - any line junction or join would cut the light path.

I feel that joining the fibre optics underwater would be a bit of a technological overkill :)

Mark

Good point - shows you what I know about diving ;)
 
D

davepinch

Guest
I certainly think mr pitlamp knows how to run a line or two :wink:

Thank you all for the advice, I have just managed to read the line laying paper by Yeadon and been through the CDG manual section a few times... I will stick with the poly line I currently use and with better handling it will do all the jobs that I require it for.

Thanks again and safe diving.

Dave
 

Marcus

New member
pitlamp said:
I dislike the pop bottle approach - a proper reel is best for large amounts of line and for anticipated small advances (e.g. in underwater digs) it's probably better to have a few metres of line secured concertina style under inner tube loops on a lead block. You can then feed out just the right amount as your dig progresses and the device stays in control on the sump floor because of the lead block.

Each to their own, but this has worked very well for me in body sized tubes where handling a reel would have been somewhat more difficult.

As for fibre optic type materials, these are designed to keep the light in, and so no benefit for keeping an eye on the line in any but the clearest of sumps (oh yes, we were talking about the UK....).

Reflective line will again only have any benefit, and I believe it would be slight, in very good vis. Suspended particulate matter will reduce any benefit rapidly. Glow sticks can be useful for marking stages / airbells, but plan for one dive only!

Any line with wire incorporated should be treated with great respect, and not laid in sumps where much traffic is expected without very careful consideration.

Polyprop is the best way to go for most situations, and confidence / competance at using your preffered method of distribution in low / zero vis.

Stay safe,

Marcus
 

Brains

Well-known member
Last night (Thur 15 Dec) on Channel 5 there was a bit about some bloke wanting to swim with manatees in Florida. To pad it out they went diving in the blue holes - excellent vis, and no problem with the line, it stayed nice and safe on a dinky little reel on the mans harness, or in the dive boat, but I suppose they are whole different ball game...
 
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