Question Rec cold water diver: Single, Double or Sidemount? (focus on safety)

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Are you still going to tell the captain to eff off and dive SM off his boat if he forbids it? We’ll see how well your “don’t care what others think” attitude works in that situation.
No, but I'll find another boat or shore.

edit: I may ask why. If it is a matter of boat-space, you can SM single-tank or with a pony-bottle, and there are ways to work around that.
 
No, but I'll find another boat or shore.

edit: I may ask why. If it is a matter of boat-space, you can SM single-tank or with a pony-bottle, and there are ways to work around that.

There are some boat captains who don’t like SM at all and refuse to allow it. Reasons range from taking up too much space, too slow to get back on board or gear up, etc.
 
re: H & Y-valves.

I'll first state I think H and Y valves are great, and I don't wish to tell anyone to NOT use them.

There are some drawbacks though, compared to a independent redundant-air supply. (ex: Pony bottle with regs).
  • It's usually only available on cylinders you own. Therefore, not available on rentals or travel (except in RARE circumstances).
  • Every time you buy another tank, it's time to buy another valve.
  • It's not a redundancy in some scenarios, such as an unnoticed leak or failure to monitor air-consumption.
I've never come close to unexpectedly running out of air, and after my experience consider it highly unlikely, but I do occasionally hear about it happening to experienced divers for one reason or another.

The way I look at my pony bottle (or SideMount) is that I always have 2 completely separate air-sources, which either always has enough air to safely bring me to the surface without any rush. The pony-bottle in particular is seen and treated similar to a "backup parachute", whereby it's only real purpose is to handle an emergency. I do always leave the pony on, and do take a few practice-breaths each dive, but otherwise I look at it as a sort of "life insurance."

Again, not trying to put down H or Y valves, I'm just pointing out they're not exactly identical to a pony. The one thing I'll say in their favor, is it's one less tank to manage.
 
Another question regarding SM: Would you say this is as good as BM in a current in a river or is maneuverability limited with SM? (I don't think so)

Sidemount not firmly affixed bottles in this situation will have the propensity to kill you before any other system

SlugMug gets his info from reading, from popular ScubaBoard culture, and from SlugMug? not from real diving
 
Wow, thanks again for so many replies :)
Let me answer some questions or reply to assumptions or suggestions.

It's kind of "strange" to read about the preference of pony bottles in the US in contrast to using an H or V valve in Europe. To be honest, I've never seen a pony bottle used in local rivers/lakes or when browsing pictures of divers in my region. But it seems that most people who started with a single tank with an H valve switched to a double tank configuration and are more happy with that. That's the input I was looking for, opinions from experienced divers.

Charging for refills: At my place, you can either pay for individual fills based on tank capacity and air pressure or pay a yearly fee and have unlimited refills. Roughly, if you need >25 fills at the same location, go for the flatrate.

Safety with buddy: I absolutely agree with you @SlugMug. I will always strive to be able to rely on myself (such as 2x tanks, 2x first/second stages or similar); I think I wanted to say that in addition to run out of air (for whatever reason) I hope that a buddy would help me at other unexpected circumstances (getting trapped underwater / losing consciousness / rapture of the deep / ...).

@Lorenzoid What I usually see are divers with one tank w/ one set of 1st/2nd stage OR one tank w/ two sets of 1st/2nd OR two tanks w/ two sets of 1st/2nd. Sometimes I see SM. I never saw a pony bottle anywhere.

Regarding the SM on boats: I will not do boat diving at my place. On vacation, I will rent BM equipment. In Maldives, there was one guy with SM on our dive boat. Everyone was interested in his equipment and I did not have the feeling that he used more space than others. Admittedly, he needed more time to get into water safely, but hey, we're on vacation. It doesn't matter if you wait another minute or two to get everyone into water and be ready to dive. Just relax. Talk with others. (Yes, I also know from experience that some people are not able to just wait in the water for everyone to be ready. I don't want to dive with those people.)

Out of curiosity: How does a decent Pony bottle configuration looks like?
One tank with one 1st and one 2nd stage & Pony with one 1st and one 2nd stage, OR
one tank with one 1st and two 2nd stages (main and octo) & Pony with one 1st and one 2nd stage (in total three 2nd stages)?
 
Sidemount not firmly affixed bottles in this situation will have the propensity to kill you
I would assume that in this situation (strong current) you may also use bolt snaps to secure your tanks at the top instead of only using bungees?
 
Wow, thanks again for so many replies :)
Let me answer some questions or reply to assumptions or suggestions.

It's kind of "strange" to read about the preference of pony bottles in the US in contrast to using an H or V valve in Europe. To be honest, I've never seen a pony bottle used in local rivers/lakes or when browsing pictures of divers in my region. But it seems that most people who started with a single tank with an H valve switched to a double tank configuration and are more happy with that. That's the input I was looking for, opinions from experienced divers.

Charging for refills: At my place, you can either pay for individual fills based on tank capacity and air pressure or pay a yearly fee and have unlimited refills. Roughly, if you need >25 fills at the same location, go for the flatrate.

Safety with buddy: I absolutely agree with you @SlugMug. I will always strive to be able to rely on myself (such as 2x tanks, 2x first/second stages or similar); I think I wanted to say that in addition to run out of air (for whatever reason) I hope that a buddy would help me at other unexpected circumstances (getting trapped underwater / losing consciousness / rapture of the deep / ...).

@Lorenzoid What I usually see are divers with one tank w/ one set of 1st/2nd stage OR one tank w/ two sets of 1st/2nd OR two tanks w/ two sets of 1st/2nd. Sometimes I see SM. I never saw a pony bottle anywhere.

Regarding the SM on boats: I will not do boat diving at my place. On vacation, I will rent BM equipment. In Maldives, there was one guy with SM on our dive boat. Everyone was interested in his equipment and I did not have the feeling that he used more space than others. Admittedly, he needed more time to get into water safely, but hey, we're on vacation. It doesn't matter if you wait another minute or two to get everyone into water and be ready to dive. Just relax. Talk with others. (Yes, I also know from experience that some people are not able to just wait in the water for everyone to be ready. I don't want to dive with those people.)

Out of curiosity: How does a decent Pony bottle configuration looks like?
One tank with one 1st and one 2nd stage & Pony with one 1st and one 2nd stage, OR
one tank with one 1st and two 2nd stages (main and octo) & Pony with one 1st and one 2nd stage (in total three 2nd stages)?
Pursue SM when you're ready and motivated, but not before then. You can even SM with a pony on one side, if you ever want to do effectively 1-tank. A pony-bottle is something you can do TODAY, whereas SM might be months or years down the road, depending on when you have the time, budget, and motivation to pursue SM.

Regarding seeing pony-bottles, I rarely see them either. But who cares? If safety is #1, where does popularity rank? I carry a pony-bottle (or 2nd tank) no matter the dive, even 30ft dives. There's never second-guessing, "do I need to bring it?"

However, NO OCTO on your pony bottle! In fact, just any working regulators will do. Grab something off the used market, it doesn't have to be high-qualit, just work. 1st stage, 2nd stage, hoses, and SPG (or button SPG). I prefer slinging the pony, or even side-mounting the pony. Personally, I also ditch the octo on my primary. The point of an octo is redundancy, which you already have on your pony-bottle. The octo just becomes an entanglement hazard.

I'll share pictures of my pony-bottles in a little bit, with rigging and regulators.
 
I use a Y valve on a single 130 and sling a 40cf pony. Three first stages, three second stages. I dive the same configuration whether diving in 30 feet of water or 130.
 
https://www.shearwater.com/products/perdix-ai/

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