Doubles (Twin-Set) Removal & Replacement in Mid-Water

[rx7diver]

... Old scuba guys, and the scuba police instructors, want ...

@MidOH,

The incident I referred to above took place in 1993 or 1994, way before some people commenting here had drunk their particular flavor of Kool-Aid, maybe even before they had passed their OW cert. I'll look for my old SB posts discussing this incident, and lessons learned from it (IIRC), when I have time.

rx7diver

 

[steinbil]

To summarize, for the new scuba divers, since this is the basic scuba forum:

1. Don't solo dive. Your buddy is your redundant gas supply, and can help if you get entangled.
2. Make sure you can reach your valve(s)
3. There's no need to doff your gear underwater, even if you might have done it in class*
4. The risk of this maneuver goes up drastically the heavier your tanks and undergarments are

*Meaning: If you are in a situation where this is necessary, you have already broken many basic principles of diving, and it's much easier and more productive to avoid these situations before they materialize.

 

[MidOH]

Bwahaha. Nobody in basic single tank can reach their valve.


Check your guage and purge, inflate, before jumping. If you absolutely need to reach your valve, carry an Al40 pony or stage.

 

[rx7diver]

... Nobody in basic single tank can reach their valve. ...

No, this is not correct. I could reach my cylinder valve *easily* when I wore a U.S. Divers plastic blow-molded back pack, and when I wore my first SP SSJ (the 3rd gen, orange, taco-pocket model, purchased new in 1987).

I replaced that orange SSJ with a new Black Classic SSJ ca. 1993 (for a bit more room for my then-new drysuit). I can reach my valve only with a bit of "gymnastics" when I'm wearing this "new" SSJ (since it "registers" the cylinder a bit lower down my back than my orange SSJ did). These gymnastics make it difficult for me to reach over my shoulder and feather the cylinder valve, though.

I became the proud owner of a SS Freedom Plate in 2010 (which fits similar to the U.S. Divers back pack) and this Freedom Plate allows me to similarly *easily* reach my valve(s) when I'm wearing a standard-sized cylinder (e.g., a 25" old-school PST LP 72, my favorite single) either fitted with a K/Pro/DIN valve or a Y-valve (the latter I almost always wear when diving my Freedom Plate).

Being able to reach over one's shoulder to manipulate his/her cylinder valve was stressed in my YMCA/NAUI open water course (in 1986). Being able to doff and don one's kit under water was similarly stressed (although this was NOT performed in mid-water). I consider these two skills core skills--even for buddy diving-trained basic open water divers. If someone's kit prevents him/her from being able to reach his cylinder valve or doff and don his gear mid-water, I would urge him to take a critical eye to his kit.

CAVEAT: I am NOT a scuba instructor. And I've drunk nobody's Kool-Aid.

rx7diver

 

[MidOH]

That's good and all.

But 18/20 divers on my next boat ride can't reach their single tank valve.

 

[dlao]

To summarize, for the new scuba divers, since this is the basic scuba forum:

1. Don't solo dive. Your buddy is your redundant gas supply, and can help if you get entangled.
2. Make sure you can reach your valve(s)
3. There's no need to doff your gear underwater, even if you might have done it in class*
4. The risk of this maneuver goes up drastically the heavier your tanks and undergarments are

*Meaning: If you are in a situation where this is necessary, you have already broken many basic principles of diving, and it's much easier and more productive to avoid these situations before they materialize.

It reminds me of a GUE diver who suddenly took off his gear (single tank) in blue water during a dive with absolutely no apparent emergency. Back on the boat he says, he found he could not reach his valve so he could not do a V-drill, which made him [nervous], so he took off his gear to adjust the position of his tank.

No this is not a joke teasing GUE, it's a real story.

 

[dlao]

I remember doing this maneuver as part of the hypoxic trimix course, with al80 twinset and two deco stages, without a mask. The whole drill requires maintaining neutral buoyancy. It was difficult in tropical water and wetsuit, and I cannot think of doing it in a drysuit.

In real life, unless it is ABSOLUTELY the only way to stay alive, I would not do this maneuver. And if the dive is planned right, I cannot see any scenario in which this maneuver may be needed. The added complexity can easily turn a small solvable gear failure into a catastrophic one.

 

[crofrog]

A solo diver absolutely needs to be able to doff his/her rig (IMHO)--even if it's a doubles rig, and even if he/she is wearing a drysuit. (What's the alternative?)

rx7diver

Team diving