Tips on starting diving doubles

[SouthernSharktoothDiver]

@grantmac I'm scratching my head why I would cut off a tank in the event of gas failures in independent doubles. Sure, it might be nice to keep water from getting into the tank, but in the unlikely event of gas failure behind the reg, either my valve, tank neck, or regulator first stage is busted, and all three of those necessitate a trip to the dive shop for repairs in any case. Simple enough to get the tank/reg dried and cleaned if necessary while I'm there, and while that does cost an extra $30 (assuming worst case and I need a tank tumbled and o2 cleaned), that is a risk I'm quite willing to take.

 

[old frogman]

Not pertinent to the subject of the thread and nobody cares.

USA is a democracy. Individuals will decide what is pertinent to them. They do not need you to dictate what is pertinent.

 

[Eric Sedletzky]

Post in thread 'Rules'

Aug 18, 2010

Also:

Rule No. 1: Don't dive with strokes.
Rule No. 2: Don't listen to strokes.
Rule No. 3: There is nothing underwater worth dying for.
Rule No. 4: Always analyze your gas.
Rule No. 5: Don't dive a rebreather unless you really need it.
Rule No. 6: Always look cool.

Option No. 1: Don't dive.

• lamont

• 

Get that cigarette out of your mouth.

 

[old frogman]

No, it’s a S-10, with sliding risers and the oval cutout. The canopy is the same as the Army T-10 except for those modifications for steering.

SeaRat

Cool rig. Noticed the quick release box at the chest. Reminds me of the Irvin GQ PX rig I initially trained on (static line, riser steered). Did you have steering toggles, or did you use the risers?

 

[old frogman]

Cool rig. Noticed the quick release box at the chest. Reminds me of the Irvin GQ PX rig I initially trained on (static line, riser steered). Did you have steering toggles, or did you use the risers?

For those who are criticizing SeaRat about the cheater bar should note that he is US Airforce Pararescue. In 2018 the Thailand cave rescue, US Airforce Pararescue (stationed in Okinawa, Japan), contributed significantly to the rescue of the 12 boys. Alongside the Thai Navy SEALS, international tech/cave divers and medical experts.

 

[Eric Sedletzky]

For those who are criticizing SeaRat about the cheater bar should note that he is US Airforce Pararescue. In 2018 the Thailand cave rescue, US Airforce Pararescue (stationed in Okinawa, Japan), contributed significantly to the rescue of the 12 boys. Alongside the Thai Navy SEALS, international tech/cave divers and medical experts.

Most of these clowns wouldn't make a pimple on SeaRats ass.

 

[James79]

Most of these clowns wouldn't make a pimple on SeaRats ass.

While I concur, I quit engaging a while back.

 

[SelfDiver]

@grantmac I'm scratching my head why I would cut off a tank in the event of gas failures in independent doubles. Sure, it might be nice to keep water from getting into the tank, but in the unlikely event of gas failure behind the reg, either my valve, tank neck, or regulator first stage is busted, and all three of those necessitate a trip to the dive shop for repairs in any case. Simple enough to get the tank/reg dried and cleaned if necessary while I'm there, and while that does cost an extra $30 (assuming worst case and I need a tank tumbled and o2 cleaned), that is a risk I'm quite willing to take.

OP,
I will answer this, While the usual Scubaboard targets are going on in the background.(free entertainment)

The reason to close a problematic tank comes from more technical diving and really does no belong in an "Advanced Scuba" discussion. However, you asked about diving doubles and it is relevant in that context.
When an unknown failure point is causing bubbles behind your head, the first priority is to stop the bubbles by closing the valve. If the bubbles continue, then the valve or tank neck Oring are the likely point of failure and there is nothing you can do.
Stopping the escaping gas makes sense in overhead environment where the ascending bubbles can severely disturb the ceiling and cause silt out or zero visibility conditions. The additional bubbles add chaos in a place where order is paramount. There is a more serious gas plan in deep diving and penetrative dives. The possibility of saving even some gas is worth the 7 seconds of turning off a valve.
In your diving:
-you are less than 50 feet from the surface
-there is no overhead
-there is no deco obligation
-the gas plan is simple
-the emergency procedure is "go up"
You will probably be fine to just ignore the freeflowing tank and end the dive safely from the other tank.

You might want to consider that the escaping gas has a cooling effect and might freeze the regulator in an expensive way. A leaky first stage can still be used by feathering the valve. A busted first stage can be replaced underwater with your working one. With some practice, you can even breathe directly from a tank valve.
All these are moot points if you don't want to learn a skill that takes 7 seconds.

In one of my previous posts, I asked why you don't just dive one tank as regular back mount like basic open water setup and just sidemount the second tank on the left like a deco/stage/pony tank.
This is an easier introduction to both sidemount and diving manifolded (or independent) doubles. It also looks like that is a cheaper option than buying manifolds and bands.

 

[old frogman]

OP,
I will answer this, While the usual Scubaboard targets are going on in the background.(free entertainment)

The reason to close a problematic tank comes from more technical diving and really does no belong in an "Advanced Scuba" discussion. However, you asked about diving doubles and it is relevant in that context.
When an unknown failure point is causing bubbles behind your head, the first priority is to stop the bubbles by closing the valve. If the bubbles continue, then the valve or tank neck Oring are the likely point of failure and there is nothing you can do.
Stopping the escaping gas makes sense in overhead environment where the ascending bubbles can severely disturb the ceiling and cause silt out or zero visibility conditions. The additional bubbles add chaos in a place where order is paramount. There is a more serious gas plan in deep diving and penetrative dives. The possibility of saving even some gas is worth the 7 seconds of turning off a valve.
In your diving:
-you are less than 50 feet from the surface
-there is no overhead
-there is no deco obligation
-the gas plan is simple
-the emergency procedure is "go up"
You will probably be fine to just ignore the freeflowing tank and end the dive safely from the other tank.

You might want to consider that the escaping gas has a cooling effect and might freeze the regulator in an expensive way. A leaky first stage can still be used by feathering the valve. A busted first stage can be replaced underwater with your working one. With some practice, you can even breathe directly from a tank valve.
All these are moot points if you don't want to learn a skill that takes 7 seconds.

In one of my previous posts, I asked why you don't just dive one tank as regular back mount like basic open water setup and just sidemount the second tank on the left like a deco/stage/pony tank.
This is an easier introduction to both sidemount and diving manifolded (or independent) doubles. It also looks like that is a cheaper option than buying manifolds and bands.

Brilliant. I agree.

You have made an accurate situation assessment. Identified the true risk in relation to the situation. Delivered a plausible contingency plan for the potential risk event.

In addition, you have offered (not enforced) the consumer alternate options to enhance the dive experience. In conclusion you have allowed the consumer the democratic right to make a choice without intimidation or coercion.

No dogma, no inflexible rules.

This is an example of risk management in practice.

 

[SouthernSharktoothDiver]

@SelfDiver This is a valid set of points I had not considered. As you've said, in the event I have a freeflow going on behind my head with my current dive conditions, I'd put even money that I could be at the surface before the tank ran dry, but your point about reg freezing is a good consideration. Something to chew on, as far as failure scenarios go, and something to plan for as I design my current setup.

As for your suggested sidemount idea...I just don't know. It feels (emphasis on feels, I have not attempted to sidemount a tank, and would very much defer to more experienced divers on the matter) that manage the relatively loose sidemounted tank in the heavy current would be an added struggle. Today, for example, the current was pushing us hard enough I often had to press flat against the riverbed and fin like crazy, plus digging in with my screwdrivers just to advance forward. I worry an added AL 80 would represent an encumbrance that I simply would not be able to easily manage in such a situation, though I acknowledge I might be wrong about that fact.

I like backmount, generally speaking, because tanks in backmount are in a known position barring some extreme failure. If I'm on the bottom, and I encounter a logjam or other obstacle, like I often do, I can more easily move past it because I know that my major snag points are on my back (the tank valves and regs) and running back and to the sides (my HP and LP hoses). Sidemount I feel like adds extra variability to that equation, something else I have to manage for, while also dealing with current. Again, this may well be far less of an issue that I feel like it would be, as I've never done sidemount before, but it definitely feels like more of an acquired skill to manage.

If you have some tips on trying it, I'd certainly be down to mount an AL 80 on the side and take it out in the nearby lake for a low-risk test, then work up to more challenging dive conditions with it. One question, to begin with, if I'm backmounting a single and sidemounting another single, would my 38 lb wing be sufficient for such a setup? Per my understanding, I'd need more lead to keep the AL 80 from getting floaty near the end of the dive. I also have a pair of LP 72's, if those would be preferred for such a setup.