Where does the valve of a slung cylinder sit in relation to your body?

[4sak3n]

I have recently purchased a 40cf cylinder for use as a pony bottle and rigged it as you would a stage or deco bottle so I can sling it.

I chose the 40cf because I wanted to sling it due to the fact that I believe that this is a better way than mounting it to the side of one's tank. This left me with the choice of either a 40cf or 30cf and since the shop only had a 40cf, I had my answer!

Anyway, on to the question. When in the water, how low should the valve hang below your body when it is clipped off to the upper d-ring?

I did a nice shallow easy dive in order to start getting used to the pony. Practiced deploying and stowing the reg (and found out that bungees are a pain! Must get inner tube as soon as possible) and removing and replacing it. But I noticed whilst I was swimming that although the butt floated nicely up out of the way, the valve was quite low beneath my body.

It was about 4 or 5 inches below the horizontal plane that my chest and (upper) legs were in. Is this normal? I know that correctly rigged a slung cylinder should not form a wedge in the water but should instead fit into the slipstream that your head and shoulders create. But I'm not certain what this translates to. Should the valve hang so very low beneath my body?

I had my buddy take some pictures to show how the slung 40 sat on me but unfortunately I'll only be able to get them on Sunday evening.

So, anyway, any help you could give on how a slung cylinder is supposed to sit relative to your properly trimmed body would be very much appreciated.

Many thanks!

P.S. I asked the question here in the tech section not because a pony bottle is tech but instead because mine is side slung and is thus rigged as you would a stage or deco cylinder.

 

[foles1972]

I also use a 40 as a pony bottle, slung on my right side. I bought an OMS pony bottle sling for about $50 US (but you could easily make one yourself). It attaches to the upper D-ring using a large swivel snap, and basically is no further away from my body than the length of the swivel. It is so close and comfortable that I hardly notice it is there while diving.

As far as the positioning of the valve goes, I have mine set up so the knob is pointing straight out in front of my body. It seems to be the most accessible position. Just a quick glance down and the valve is right there in front of you.

I know OMS and Dive Rite make the slings (as well as others I'm sure). Check their websites to see how they're made and you could make your own easily enough.

These are just my opinions, but I hope they help!

Sincerely,
Dave

 

[AndrewJD]

These two videos show divers with properly slung Al40s.

Jonathan

 

[4sak3n]

Thanks for the videos Jonathan, they definitely helped. Looking at them it appears that the valve is supposed to be below the plane of your body however I still feel that mine was a bit too low.

I managed to get hold of some photos to show you. Its hard to see in the front view but I circled my d-ring to give you a clearer picture. The side view shows much more clearly just how much my bottle drooped.

Yeah, the viz on this dive was HORRIBLE. Ah well ... at least my trim seems to have improved.

Thanks for the buying tips Dave. Those were exactly what I would be looking for because those kits were exactly the same as I set my bottle up.

I think part of the reason my bottle droops so low is because I have my shoulder straps on the harness quite loose (and the crotch strap shortened) in order to stop the first stage hitting my head and the negative buoyancy of the cylinder uses this slack to pull the d-ring down. I have moved the d-ring up a few centimetres along the harness to compensate.

Will dive it again this weekend and see how it goes. Thanks for the help guys. :14:

P.S. My 6" HP hose hasn't arrived yet so I'm having to make do with a normal one.

 

[Flightlead]

your chest d ring appears to be way low to me. should sit around your collar bone. I would move the attachment point for the bolt snap higher on the bottle. at or even slightly above the break, right now it appears to be an inch or so lower. that should snug that bottle up good.

I went through this early this year, ultimately found that tighter is better than looser on the harness and bottle. to keep my 80's snugged up well I also shortened the distance between the attachment points of the two bolt snaps by moving the bottom one upwards until there was about 13" between them.

 

[rjack321]

Yes, the harness D-ring is really low. Snug up the straps on the harness too. Your back tank reg seems to stick out from the valve alot. Looks like a 200bar valve with a "600bar" DIN connector (i.e. very long)

 

[Standingbear56]

Hi Everyone,
Just my .02 worth. I side mount mine so they don't hang below me in any way. Less chance of entanglement or getting damaged. You can still use your waist D ring, but use a bungee (or clip off to one) instead of your chest D ring. It also keeps the pony out of the way when it's not being used.
This has worked well for me.
Safe Diving,
George

 

[mr.rongilbert]

I like the side mounts right up under my arms where I can see the valve which is facing away from my body. I place my regs on the opposite side as well so I can see them and they are in reach. It works for me. I have a 4" piece of string on the valve side of the tank that is attached to my chest D-ring (OMS) the rear is attached to the bottom of my back gas via a brass butterfly clip and more string with the thought that if I get hung up I can cut the string away. I can reach it if I reach back just above my hip.

 

[mr.rongilbert]

Hey Bear - where do you bungee yours? is it a short piece attached to the chest d ring?

Andrew - those vids kick butt! Nice work!

 

[Standingbear56]

Hey Bear - where do you bungee yours? is it a short piece attached to the chest d ring?

Andrew - those vids kick butt! Nice work!

Hi Andrew,
I actually have done it several ways. I've had looped bungees that attatch to a strap that goes through the upper cam band slot on the back of my BCD. The loop can either go around the valve assembly, or the valve assembly can be clipped off to the bungee. The other is using bungees from Dive Rite. They attatch from the side "D" rings on the BCD back plate (or you can use one of the accessory holes on a steel plate) and run to the chest D ring. They can also either loop around the tank valve, or have the tank valve clipped off to the bungee. Advanced Diver Magazine's armadillo sidemount manual gives a lot of info on how to do this. Same with Dive Rites Nomad manual, plus the sidemount videos on Dive Rites site.
Sidemounting was designed to allow a cave diver to penetrate smaller places not accessable with back mount. However it's clean and streamlined configuration also works great with deco/sling tanks by holding them in tight until you need them. No valves or anything else hanging below you to get snared.
Hope this helps,
George