Line Marking

[JD]

Craig, you have put more clearly what I am trying to find out. Seems that the placement of the NDM is very dependent on the end purpose use. If it is for intra team then the placement may be different than if it is for indicating to other teams than you are on jumps etc.

No. The placement is always the same. For a jump installed by others, assume the jump as part of the main line and peg accordingly. See the diagram for a better explanation.
The idea of marking the reel end is a) it creates an intersection, so must be marked and b) when the owner of the jump returns ahead of you, they realise there are still divers using the jump and leave it in situ. The last diver out who can see there is no pegs on it pulls the jump. As you can see, at any marked jump there are 2 line arrows indicating the jump. The reel is put in between these, so even though the direction of the exit is still known, you MUST put a personal marker here!
In a particular section of Tank this is the actual arrangement of the lines, however we get here from the other direction. When we mark this jump, we place personal markers on the WRONG side of the arrows. Both ways actually lead to the exit (it is a circuit), but we exit against the arrows. See the need for personal markers?
Yellow=Main line
Blck= Jump
Orange= Secondary line
Pink= diver path into the cave
Blue= Markers
Red= Line arrows

JD

PS RB + IT: I know I put the arrows the wrong way, but it still serves the purpose. I realised how much this looks like the B14-H1 jump afterwards, and thought I would use that as an example. I am not going mad!

[PMH]

have you boys covered leaving a NDM at the cave entrance..this enables other divers to know who is still in the cave...In tank I leave one at A1 or A2 (close enough to the entrance)

[JD]

have you boys covered leaving a NDM at the cave entrance..this enables other divers to know who is still in the cave...In tank I leave one at A1 or A2 (close enough to the entrance)

And F5, C7, A8, S4, H2,..........
Harvs, are you ever coming out!

JD

[PMH]

have you boys covered leaving a NDM at the cave entrance..this enables other divers to know who is still in the cave...In tank I leave one at A1 or A2 (close enough to the entrance)

And F5, C7, A8, S4, H2,..........
Harvs, are you ever coming out!

JD

what?

[onwardsupwards]

QUOTE JD
 
The exit side of ANY intersection.
If you get to a 4 way intersection, you mark the line on which you entered the junction (ie, the way OUT), same with T's or an 8 way junction.

This is much easier to explain using a pad and pencil! Damn Internerd! Angry Roll Eyes

JD

QUOTE IAN

The NDM MUST be placed on the exit side of the line. No if's or buts. I agree with your diagram, you would know which was is out by placing a NDM on the way you're going in, and an arrow pointing out, though why bother. Just place the NDM on the exit side, make the turn, and you know WHAT DIRECTION IS OUT (ie: turn around, follow back to the NDM, then take it )

QUOTE JD

Craig, you have put more clearly what I am trying to find out. Seems that the placement of the NDM is very dependent on the end purpose use. If it is for intra team then the placement may be different than if it is for indicating to other teams than you are on jumps etc.

No. The placement is always the same. For a jump installed by others, assume the jump as part of the main line and peg accordingly. See the diagram for a better explanation.
The idea of marking the reel end is a) it creates an intersection, so must be marked and b) when the owner of the jump returns ahead of you, they realise there are still divers using the jump and leave it in situ. The last diver out who can see there is no pegs on it pulls the jump. As you can see, at any marked jump there are 2 line arrows indicating the jump. The reel is put in between these, so even though the direction of the exit is still known, you MUST put a personal marker here!
In a particular section of Tank this is the actual arrangement of the lines, however we get here from the other direction. When we mark this jump, we place personal markers on the WRONG side of the arrows. Both ways actually lead to the exit (it is a circuit), but we exit against the arrows. See the need for personal markers?

Which is it guys?  Seems that in the last quoted scenario by JD that the NDM could be put in two places.

[JD]

Yes it could. In that particular route, either way is an exit, however we mark the way WE came in and the way WE want to exit the cave. This MAY be in the opposite direction to the arrows, so we ALWAYS follow our own markers, arrows are secondary. See how you can get into trouble?
Just remember to always mark the exit line and you will not get into trouble.

JD

[Craig]

<<edit>>

BTW, dont panic too much, this is all covered in the course.

JD

No panic Pookie, just came up as a topic of discussion on the weekend & thought we'd seek counsel from divers more knowledgable than us.

Couldn't find any so thought may as well ask here anyway 

[Ian T]

RN,

I was only saying CL was correct when placing a NDM on the direction taken line, was if you ALSO had the arrow pointing out, placed on the exit side of the Tee. If only one marker is placed, the NDM is placed on the exit side of the intersection. JD and I have said this all along. The only reason I agreed to CL's description, was that he had placed an arrow on the exit side of the Tee, then ALSO the NDM on direction he took. I can't see the reason for placing two markers. You always know where you are, only need to mark where you've been, ie: which was is OUT.

[Craig]

So on that basis if you're jumping between two line arrows as a marked jump there's no need to put an NDM/PM at that intersection as the line arrows already show the way out?

You would still however put an NDM/PM at the reel end of your jump at the intersection you've created to indicate the way out.

Do you use many line arrows or mainly PM's?

C

[JD]

Correct Craig. A marked jump has 2 line arrows about 6" apart. Place the jump line in between these. As the jump reel creates a T, you must peg it both ends. As I stated earlier, in a circuit situation, we sometimes go the wrong way to get out, ie against the arrows. In this case, the half way point of the circuit is marked with back to back arrows, so either way is out. The intersection I am referring to is very close to the turning point of the circuit. One way is large tunnel and an easy swim, the other has a few restrictions. This is why we choose to go against the arrows.
Pegs are great. Use good quality ones with a coated 'spring' section, ie anodised, as they last longer. They will eventually rust, but the good ones I have last for years. Putting in a cookie or line arrow takes time, where pegs do not. I have placed line arrows on a line to mark a spot where I want to have a look on the way back or on a subsequent dive, but only on an intersection when I have run out of pegs!
There is a special arrow in Tank however with JD on one side and IT on the other which is to be left there..... If you find it, please place yours next to it, but remember to put it on the exit side! I think it is safe for a few more years!