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Snusmumrik
Contributor
7l 200 bar steel tank that is positively buoyant when empty, and neutral with 50 bar.
DPV, rebreather and stages drag
- Thread starter Snusmumrik
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That's virtually the same as an LP50, when you add a regulator it's rather negative through most of the dive and will tend to hang.
You can try a bungee loop to tuck it up behind your armpit like sidemount.
You can try a bungee loop to tuck it up behind your armpit like sidemount.
Agreed. I think the stages when near empty just sorta find the turbulent space behind you and effectively streamline themselves by finding the point of least resistance.
mr_v
Contributor
@Snusmumrik, so we are dealing with a bailout bottle, not stage. Bailouts usually stay on you through the dive, so make it tight. Some divers sidemount their bailout stages so that the profile is streamlined.
If you have a bottle that you drop off, figure out how to mount that bottle so that it is easy to take off and then clip it back on. My stages have a tiny bit movement freedom compared to the bailouts that are essentially glued to the body.
@Nick_Radov spills the truth - a lightly positive bottle clipped to the butt or to the side may minimize the drag while scootering. The bottle is light enough for water push it down as you scooter along, so the bottle lines up with your body. A heavy bottle will hang perpendicular to your body generating drag.
@Garth explained it well a few weekends ago and I had a chance to test the setup with a 30/30 AL80 (11L) tank. I did not notice the bottle or its effects. Actually, I thought I lost the bottle because Garth pranked me and took it off while I was dealing with other gear.
If you have a bottle that you drop off, figure out how to mount that bottle so that it is easy to take off and then clip it back on. My stages have a tiny bit movement freedom compared to the bailouts that are essentially glued to the body.
@Nick_Radov spills the truth - a lightly positive bottle clipped to the butt or to the side may minimize the drag while scootering. The bottle is light enough for water push it down as you scooter along, so the bottle lines up with your body. A heavy bottle will hang perpendicular to your body generating drag.
@Garth explained it well a few weekends ago and I had a chance to test the setup with a 30/30 AL80 (11L) tank. I did not notice the bottle or its effects. Actually, I thought I lost the bottle because Garth pranked me and took it off while I was dealing with other gear.
justinthedeeps
Contributor
I am confused how people think steel stages/bailouts are "neutral." Which cylinders, filled to what pressures?
Rigged steel Faber LP50 stages (~7L, "180" bar fills) are definitely not neutral, and they aren't trim either, without something to snug up the heavier valve side (a must for efficient DPV-ing, but should still be deployable)
Forget mfg/DGX charts and let a rigged/filled stage go underwater. It will almost certainly sink if it is steel--it is not neutral--and it will still sink even if it is aluminium, unless it is lean trimix or mostly empty. All of them will sink (or rare cases, float) valve-down, because that's where most of gravity is pulling on.
If instead we are talking about stage trim(?)
Shock cord loops or "shocker" around the tank valve/neck to get the cylinder neck right up into the armpit area, and custom-fit stage rigging lengths (loops, snaps and the length along cylinder axis). Good (or DIY) rigging kits can be untied, trimmed and re-tied to remove slack. The position of D rings matter too, standard hip D ring should be no further than a few fingers off the backplate. I believe perfectionist sidemounters are even re-adjusting where rear rigging band sits on the cylinder during dives as the cylinder buoyancies change.
I guess some people just get bigger DPVs... perhaps there is a also secret to mitigating the asymmetric drag of having a bunch of cylinders on one side only, if that secret is not just to man up and hang on (orthodox OC tech bottom times aren't that long, eh
)
Rigged steel Faber LP50 stages (~7L, "180" bar fills) are definitely not neutral, and they aren't trim either, without something to snug up the heavier valve side (a must for efficient DPV-ing, but should still be deployable)
Forget mfg/DGX charts and let a rigged/filled stage go underwater. It will almost certainly sink if it is steel--it is not neutral--and it will still sink even if it is aluminium, unless it is lean trimix or mostly empty. All of them will sink (or rare cases, float) valve-down, because that's where most of gravity is pulling on.
If instead we are talking about stage trim(?)
Shock cord loops or "shocker" around the tank valve/neck to get the cylinder neck right up into the armpit area, and custom-fit stage rigging lengths (loops, snaps and the length along cylinder axis). Good (or DIY) rigging kits can be untied, trimmed and re-tied to remove slack. The position of D rings matter too, standard hip D ring should be no further than a few fingers off the backplate. I believe perfectionist sidemounters are even re-adjusting where rear rigging band sits on the cylinder during dives as the cylinder buoyancies change.
I guess some people just get bigger DPVs... perhaps there is a also secret to mitigating the asymmetric drag of having a bunch of cylinders on one side only, if that secret is not just to man up and hang on (orthodox OC tech bottom times aren't that long, eh
)
Lower the fin on the opposite side, now it is symmetric drag.
justinthedeeps
Contributor
I think we need a cool name for this pose, like the steel glute (unless that is already a GUE trademark?)
InWay2Deep
Contributor
I clip mine to my butt/crotch D-ring and let it ride between my legs (if using the crotch D-ring you need a slightly longer neck leash), it basically disappears there, similar to a tow scooter. I did 2 that way this past weekend and stayed pretty well balanced.
I don't see how using the crotch D-ring could work when the stage is full and still slightly negative. Even with a longer leash it's going to hang down.
The butt D-ring can work but we usually find it's easier to clip a loop leash to the left waist D-ring, clip the extra stages to the leash, and then push the stages back between your legs. Having the separate loop leash makes it easier to do bottle rotations during ascent. The butt D-ring might also be occupied with a camera rig as that seems to be the best place to stow it during long scooter runs when you're not shooting pictures.
InWay2Deep
Contributor
Oh yea, you come off the trigger and a heavy bottle drops, best when just staging lots of bottles and you are running the same route back and forth, go fast enough and the prop wash keeps them up!
In my current config I can't reach my butt D-ring so I have to use the crotch one. Working on modifying my rig so I can regain the use of it as the bottles do float better attached back there, I had someone else hook it to the butt D-ring for a couple of runs and it was much better.
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