Questions regarding backplate and doubles

[Colliam7]

Are there reasons why I shouldn't start with a backplate and wing when I'm ready to move on from rental gear?

None. A good diver can use a jacket or a back-inflation BCD, it really doesn't matter. A negatively buoyant, metal backplate, with a simply web harness, offers some advantages, in terms of simplicity / flexibility / modularity / buoyancy & trim characteristics. I encourage you to pursue that approach.

double tanks seem to have clear safety advantages and no disadvantages except cost.

I think some of the potential disadvantages have been covered, and I would agree with them. There is no reason why a new diver cannot move to back-mount, manifolded doubles, or sidemounted doubles, at the very beginning of the process of learning to dive (i.e. what you do AFTER your initial certification). The disadvantages - weight, availability, transport, cost, etc. - to me, at least, argue for a more deliberate approach, beginning with developing good buoyancy and trim, and general dive skills, with a single cylinder. But, that is a slight personal preference. I dove doubles exclusively for ~ 5 years, and found they were fairly easy to use for recreational diving. I still dive doubles more than singles. But, I also thoroughly enjoy single cylinder diving and I actually find the logistics to be just a little 'easier'.

One other comment in your post caught my attention.

Plenty of personal accounts out there of freeflowing regulators, runaway BCs, and clogged dip tubes, all easier to handle with doubles. . . . What am I missing

Here is where I may show some personal bias: there may be plenty of accounts but there seem to be two frequent themes, and one common denominator, across the vast majority of them. Regulators seldom freeflow unless they are poorly maintained, or poorly used (e.g. being dragged through sand, being dropped on the hard tarmac, being damaged by having tanks dropped on them, etc. That is really a skills problem. Dip tubes seldom become clogged without debris , and that debris is most likely to come from particulate matter such as rust or al oxides accumulating in a cylinder. And, that is unlikely to happen unless you get bad (moist) airfills (poorly used), and don't have your cylinders VIP'd (or personally inspected), regularly (poorly maintained). And, those situations, again, reflect a skills problem. Dip tubes do not just spontaneously 'clog'. And, runaway BCDs do occur. I have seen it happen to two divers (fortunately, in both cases in shallow water), and in both cases the divers readily acknowledged afterward that the problem was their fault - they failed to do what they were trained (in one case, by me) to do: get initial control of the situation with their purge button, then disconnect the LP inflator hose. A LP hose can be disconnected, even with heavy gloves (irrespective of whether the design is good or bad, modern or antiquated). BUT, like everything else, practice makes perfect. If you practice the skill regularly, it becomes easy. If you don't, it isn't. And, in both of the cases I mentioned above, the divers also admitted afterward that they hadn't practiced the skills they learned in OW, SINCE OW. So, once more, the common denominator is a skills problem. Not only that, in both cases, I rebuilt the offending inflator for the divers afterward, and guess what - there was significant (salt water) corrosion evident, which suggested poor maintenance / rinsing (poorly maintained), which is - a skills problem. Take care of your gear, and it is more likely to take care of you. Gear can fail. But, scuba equipment, when properly maintained, is remarkably reliable. (I could even argue that the primary 'life support equipment' in use by divers is NOT the rig on their back, it is what is between their ears. But, that is another topic, altogether.) That does not mean that doubles don't provide a valuable level of redundancy. They do - of a) equipment (a second first stage) and b) air supply. But, don't go with doubles just because of 'plenty of personal accounts out there of freeflowing regulators, runaway BCs, and clogged dip tubes'.

I would do two things. Pick up the phone and call Tobin. He has posted on here and is one of the leading experts on bp/w design. He makes some seriously nice stuff and is incredibly helpful. If that hasn't convinced you, then I would find a reason to go to Chicago and swing by Dive Right in Scuba and talk to the guys there since you can see stuff in person.

VERY good advice!

 

[2airishuman]

Oh yeah.. and if you are worried about safety, then you need to change the gear in your avatar. Having a mask on your forehead AND a snorkel with a purge valve will surely cause your death, before any freeflow or stuck inflator.

Wow.

IIRC the water was 4' deep when the photo was taken. I had taken off the mask for the camera's sake.

As for the snorkel, I bought it before I had any interest in scuba; it was recommended to me by the instructor at a dive shop. Do tell me how its replacement should be seen as a priority.

 

[tbone1004]

he was making a snide remark. Don't worry about it. There is a great preference on this board for black skirted mask, which should be on the back of your head when not on your face, and not using snorkels unless needed for extended time at the surface, and if so, it should be a simple J-snorkel. Don't worry about it.

 

[dumpsterDiver]

Wow.

IIRC the water was 4' deep when the photo was taken. I had taken off the mask for the camera's sake.

As for the snorkel, I bought it before I had any interest in scuba; it was recommended to me by the instructor at a dive shop. Do tell me how its replacement should be seen as a priority.

It's all a joke. People here go crazy about snorkels and MOF.. Actually that is the snorkel I prefer.

 

[2airishuman]

...Regulators seldom freeflow unless they are poorly maintained, or poorly used (e.g. being dragged through sand, being dropped on the hard tarmac, being damaged by having tanks dropped on them, etc. That is really a skills problem. Dip tubes seldom become clogged without debris , and that debris is most likely to come from particulate matter such as rust or al oxides accumulating in a cylinder. And, that is unlikely to happen unless you get bad (moist) airfills (poorly used), and don't have your cylinders VIP'd (or personally inspected), regularly (poorly maintained). And, those situations, again, reflect a skills problem. Dip tubes do not just spontaneously 'clog'. And, runaway BCDs do occur. I have seen it happen to two divers (fortunately, in both cases in shallow water), and in both cases the divers readily acknowledged afterward that the problem was their fault - they failed to do what they were trained (in one case, by me) to do: get initial control of the situation with their purge button, then disconnect the LP inflator hose. A LP hose can be disconnected, even with heavy gloves (irrespective of whether the design is good or bad, modern or antiquated). BUT, like everything else, practice makes perfect. If you practice the skill regularly, it becomes easy. If you don't, it isn't. And, in both of the cases I mentioned above, the divers also admitted afterward that they hadn't practiced the skills they learned in OW, SINCE OW. So, once more, the common denominator is a skills problem. Not only that, in both cases, I rebuilt the offending inflator for the divers afterward, and guess what - there was significant (salt water) corrosion evident, which suggested poor maintenance / rinsing (poorly maintained), which is - a skills problem.

Colliam, I get that, and I appreciate your reply. Something troubled me a little about it though, and I think I can articulate my thoughts better now having thought about it overnight.

In aviation, Piper aircraft changed from a rectangular ("Hershey bar") to a tapered wing profile in the early 1970s. The new wing had marginally worse performance, manifested through about a 5% reduction in maximum cruise speed and fuel economy, but had much more forgiving handling characteristics at low speeds where the wing loses its lift (called a stall, a term of art in that it's the wing that stalls not the engine). Back in the day, I flew aircraft with both wing profiles, and practiced low speed flight, and never felt unsafe with the "Hershey bar" wing. Widely derided at the time as an "equipment solution to a skills problem," the tapered wing resulted in a drastic reduction in stall/spin accidents, which is clearly visible in the actuarial data since large numbers of these aircraft were produced both before and after the change.

I no longer participate in sport aviation for reasons that are many and complex, but at the time I first quit flying I did so because I believed I was no longer doing it enough to keep my skills sharp. A transition that many people do not make with grace, whether in aviation or other activities.

One question to ponder is whether sufficient skills and training completely remediate the potential risks, to the point that the "equipment solution" provides no additional safety. The answer may be different for one particular individual diver than it is for the diving community as a whole. I don't presume to have any idea what the answer is.

 

[cool_hardware52]

Colliam, I get that, and I appreciate your reply. Something troubled me a little about it though, and I think I can articulate my thoughts better now having thought about it overnight.

In aviation, Piper aircraft changed from a rectangular ("Hershey bar") to a tapered wing profile in the early 1970s. The new wing had marginally worse performance, manifested through about a 5% reduction in maximum cruise speed and fuel economy, but had much more forgiving handling characteristics at low speeds where the wing loses its lift (called a stall, a term of art in that it's the wing that stalls not the engine). Back in the day, I flew aircraft with both wing profiles, and practiced low speed flight, and never felt unsafe with the "Hershey bar" wing. Widely derided at the time as an "equipment solution to a skills problem," the tapered wing resulted in a drastic reduction in stall/spin accidents, which is clearly visible in the actuarial data since large numbers of these aircraft were produced both before and after the change.

I no longer participate in sport aviation for reasons that are many and complex, but at the time I first quit flying I did so because I believed I was no longer doing it enough to keep my skills sharp. A transition that many people do not make with grace, whether in aviation or other activities.

One question to ponder is whether sufficient skills and training completely remediate the potential risks, to the point that the "equipment solution" provides no additional safety. The answer may be different for one particular individual diver than it is for the diving community as a whole. I don't presume to have any idea what the answer is.

In scuba (most of the time) when people raise the "equipment solution to a skills problem" the argument is against *more* equipment, more tanks, more BC dumps, more inline shut offs, more bladders in your wing, more buckles on your harness etc.

(If you haven't yet you will eventually hear some refer to the diver that looked like drenched themselves in aquaseal and rolled though a dive shop on the way to the water. )

Your General Aviation example is not more about more vs less, it's about a different performance envelope for the same piece of equipment.

Tobin

 

[hroark2112]

If you want to avoid the standard crotch strap, as I do, both Zeagle and OxyCheq make a saddle strap. Instead of a single strap between the franks & beans, you've got 2 straps that wrap around the thighs. Much more comfortable IMO for high giant stride entries.