How to hang a deco cylinder?

[stuartv]

In a month or so, I will be going out as the support diver for 2 teams diving the Monitor.

One of my jobs will be to hang a cylinder of EAN80 at 30' for backup/contingency use.

I have a couple of ideas on how that would best be done. But, I don't want to prejudice this conversation by trying to describe them. Also, the teams or the boat captain may already have a method for doing this that they want to use. Probably do. I haven't gotten a response from the teams yet on that and I won't get to ask the boat captain until the weekend of.

So, in the meantime, can y'all tell me how you would normally do this? It seems like a very simple task with a hundred different ways to mess it up. Assume the cylinder has normal stage rigging on it.

 

[Doby45]

I have seen where they have a line they drop from the boat with a buoy on it that has loops tied into the rope at the predetermined depths and you just clip it to the loop with a bolt snap.

 

[stuartv]

Okay. But, the hung tank needs to be where somebody that is hanging on the anchor line can easily access it. For planning purposes, I have to assume there is a stiff current. As in, the stiffest that could be and them still do the dive. Maybe worse if the current picks up while they're on the bottom.

If the tank is hanging down from a buoy, I think it would be nowhere near the anchor line.

 

[Doby45]

The one I saw was hanging from a buoy and that line was connected to the anchor line with a "jon line" type connection. We stayed on the anchor line but the deco weasels moved across the "jon line" to their own line/buoy that had the tanks hanging.

 

[Vicko]

If it's off a anchor line make loops out of bungee cord and pas it trough itself around the anchor line 2 times and tighten, clip off the tank to that. Presurize the system and close the valve.

 

[PfcAJ]

Wouldn't it be simpler to meet the teams on deco and see if they actually need anything?

 

[stuartv]

The one I saw was hanging from a buoy and that line was connected to the anchor line with a "jon line" type connection. We stayed on the anchor line but the deco weasels moved across the "jon line" to their own line/buoy that had the tanks hanging.

"deco weasels"!

If it's off a anchor line make loops out of bungee cord and pas it trough itself around the anchor line 2 times and tighten, clip off the tank to that. Presurize the system and close the valve.

Making some loops and doing a double or triple Prussik around the anchor line to clip the tank(s) to was one of my ideas.

If the surface action is rough and the anchor line is pounding up and down, will the tank getting dragged up and down a lot, and violently, not result in it moving up or down the line?

Have you actually seen this technique used (in rough conditions, near the surface)?


However the tank is secured, should I clip off the upper and lower clips, thus holding the cylinder perpendicular to the current? Or just clip it off with the top clip only, letting the butt end float out and keep the tank more streamline to the current?

 

[Vicko]

"deco weasels"!



Making some loops and doing a double or triple Prussik around the anchor line to clip the tank(s) to was one of my ideas.

If the surface action is rough and the anchor line is pounding up and down, will the tank getting dragged up and down a lot, and violently, not result in it moving up or down the line?

Have you actually seen this technique used (in rough conditions, near the surface)?


However the tank is secured, should I clip off the upper and lower clips, thus holding the cylinder perpendicular to the current? Or just clip it off with the top clip only, letting the butt end float out and keep the tank more streamline to the current?

I cliped of both ends in about 1.5 meter waves at 6 meters depth, 15L aluminium stage stayed in place, here we don't dive if the waves are any bigger then that.

You could also attach a loop to the line with something like a constrictor knot, nothing is moving that I guess.

 

[Killerflyingbugs]

If you use line for the Prussik and a piece of bungee between the tank and the knot it may hold better than just using bungee.

 

[stuartv]

If you use line for the Prussik and a piece of bungee between the tank and the knot it may hold better than just using bungee.

I've been cipherin' on it. I was thinking:

A piece of line in a loop for a triple Prussik around the anchor line.

Have a line with loops in it that is tied off on the boat, with the tank clipped to it.

Clip the tank to the line using top and bottom clips, to 2 different loops in the line.

Use a loop higher up the line to clip to the loop that is on the anchor line.

The line would then be like a leash holding the tank, which the current could have "blowing" off to one side. The leash would be like a Jon line from the anchor line to the tank, keeping the tank from experiencing so much of the up and down jerking that happens to the anchor line.

Summary: Tank line tied to boat, goes to loop that is clipped to Prussik loop on anchor line. Then tank line goes another 10 feet or so to where the tank is clipped on using both clips.

So, maybe 50' of line, total. 3 loops tied into the line at the bottom end with a bolt snap on the loop that clips to the anchor line, plus a loop or two and a quick link at the top, to secure it to the boat. Or just tie it off to a deck cleat.

I like all the redundancy. If the line somehow comes loose from the boat, the clip to the Prussik loop keeps the tank line from being lost and the Prussik loop keeps it from sliding down the anchor line. If the clip to the Prussik loop somehow is compromised, the end tied to the boat keeps it from being lost.

If one bolt snap on the tank comes unclipped or breaks or the loop comes apart, the other clip and loop keep the tank attached to the line.

Or maybe it's all overkill....