Questions regarding backplate and doubles

[cool_hardware52]

Hmm. Yep, I'm willing to pay for safety and deal with the rental hassles (or dive with a single in those instances when no practicable alternative exists), if that's the tradeoff

*Much* harder to rent doubles. Nearly impossible to rent small doubles.

A pair of LP50 steel cylinders is around 10 pounds heavier than an AL-80, right? And you carry a few pounds less lead.

True, the aluminum 30's I doubled up for my daughter are lighter than an al 63, but they are the only pair on the planet I know of. Good luck find any small dubs to rent. Oh and you will need different reg / hose configs for singles vs doubles. That either means swapping hoses / plugs when moving from singles to doubles or have 3 regs, 1 for singles and a set of two for doubles.

I read the reports and am not entirely convinced that the isolator valve provides any net safety benefit because the incidence of tank, valve, and burst disk failures is vanishingly low.

True, but "cheater bar" i.e. non isolated doubles, are much less common today than isolated doubles. Again good luck renting any.

Qualified instruction is a good thing with any equipment, I'll give you that, yes, emphasis on qualified. My (inexperienced) point of view is that regulator free flows and runaway BCD inflators are both a significant contributor to accidents, and the statistics, the anecdotal reports, and the near-miss narratives all bear this out. With doubles, not hard, just close the valve on the offending side and switch to the working reg.

"unfixable" reg free flows are pretty rare and for recreational diving, i.e. free ascent to surface, a free flow is only a nuisance. One can always unplug a runaway BC inflator.

If you really want two first stages and two dip tubes buy a Y valve. An H valve will get you two orifices but only one dip tube. Be careful about European Y valves as tank neck threads are metric, not 3/4 as here in the states. You can take it with you when you travel.

If you decide to go with doubles be sure to practice those valve drills………..

Appreciate your words, wisdom, and perspective

2air

Thank you.

Tobin

 

[NAM001]

For the most part a BPW is not newby gear. (newby in knowledge, not time) As said with proper instruction your bpw is a farraii compared to the VW jackets. Doubles many will say is no biggy, the construction of doubles is done to enable valve usage and that takes some instruction and practice to master. My advise get a BPW get it to fit right. get a no STA wing and do single tank diving for a while. Then and noly then if you think that doubles may be for you then go for it. Tobin hit most everything on the head. The idea of diving double 45's is a good one, if you can find them. great stepping stone into back packing 100# of tank and gas plus gear.

 

[2airishuman]

dumpsterDiver,

I realize that the customary means of resolving a runaway BC is to disconnect the hose. Then again, I have read reports of people having difficulty disconnecting the BCD hose in an emergency, particularly with heavy gloves. I don't believe that the disconnect fitting was designed/chosen for ease of disconnect during an emergency. My experience with similar fittings in other environments is that they are prone to jams.

 

[dumpsterDiver]

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.

 

[NAM001]

get tobin to send you some lp hose hats

dumpsterDiver,

I realize that the customary means of resolving a runaway BC is to disconnect the hose. Then again, I have read reports of people having difficulty disconnecting the BCD hose in an emergency, particularly with heavy gloves. I don't believe that the disconnect fitting was designed/chosen for ease of disconnect during an emergency. My experience with similar fittings in other environments is that they are prone to jams.

 

[dumpsterDiver]

dumpsterDiver,

I realize that the customary means of resolving a runaway BC is to disconnect the hose. Then again, I have read reports of people having difficulty disconnecting the BCD hose in an emergency, particularly with heavy gloves. I don't believe that the disconnect fitting was designed/chosen for ease of disconnect during an emergency. My experience with similar fittings in other environments is that they are prone to jams.

Yeah the fittings used on standard inflators are archaic, stupid, poorly designed, prone to corrosion (and have been pretty much universal for over 30 years now). One solution to this potential problem (which the people here will love) is to use an entirely different type of hose and inflator... one which CAN be easily disconnected with thick gloves and is more robust and less prone to jamming from corrosion... get an Air 2 inflator/regulator. That is what I use on most all my Bc's and BP/W's.

 

[Roman_66]

Double tanks are horribly heavy, cumbersome, expensive,

- Yes, yes, of cause as they are two tanks + manifold.

will slow you down in the water.

- During a dive water resistance B/P with doubles should be not bigger than BCD with single tank.

If you need more air, you can buy a single big steel tank

- which will be horribly heavy and cumbersome , additional water resistance. I own HP120 steel.

They will probably cost you double to fill every time you use them.

Usually yes, why not ? You fill two times more air. The same some fill station asks for 1.5 price when they see my HP120.

Less comfortable on the boat

- why ? B/P set takes the same or less space than regular BCD.

much less comfort and support on the surface - since all the lift is in the back they tend to put you face down while diving and while on the surface

- yes, BUT 1. B/P idea to provide benefits in water, not on surface. and 2. It is matter of training : release little bit air from wing and you will see how simple to be on surface lie on your back.

much more prone to failure due to pinch flats from the plate cutting the internal bladder

- Probbaly I didn't understand which part do you mean (picture?), but B/P with one piece harness has mostly zero breaking points, than BCD has many.

they pretty much REQUIRE you to use an extra strap that goes over your nuts and is a pain to locate and connect on a pitching boat, and the most commonly recommended one piece harness is much harder and slower to get into, than say, a typical BC with adjustable straps.

- fully agree.

The crotch strap also significantly impedes the instant release of a weight belt in an emergency

- I never see people with B/P wearing weight belt. I have pockets on harness belt and trim pockets on single tank or weights between tanks on doubles.

They do have some advantages. One might be better trim while diving, but the vast majority of recreational divers do NOT use BP/W configuration.

- I believe that it is only because all training agencies, exept DIRs, uses BCD on open water training.

Wanna buy my used wing? It is in great shape.

- it may be good idea to buy used for start set and see later where you will go. At least you will not lose much money, as B/P set always possible to sell and size is fully adjustable.
IMHO : If you ready to buy B/P - take it. Pay attention on first two - three dive, as you will feel different in the water.
If you would like to go for doubles (B/P mostly must in this case, only few BCD allow you to connect doubles) - go, BUT take 2-3 dives training before with instructor.
You need to know how to handle doubles and manifold.
P.S. I have one set of regulators with long hose, which I change from single to double depends how I dive.

 

[pedro_rj]

With all due respect for the far more experienced divers who posted before, I don't see the point of discussing the tools without knowing the job. Is a hammer "clearly" better than a phillips?

Who cares, the real question is "better at what"? What kind of dive do you see yourself doing? It could be bp/w, it could be jacket, it could be sidemount. Without defining the mission you just can't determine which is better suited.

 

[tbone1004]

little recap.

Why are stab jackets the norm? They are cheaper to make and dive shops make more profit on them. Seriously, that's the only reason. BP/W's are actually cheaper for the shops to use as rental and training rigs in the long run because they need less of them, but there is a stigma around them.

Face forward. We train all of our students from day one in bp/w's. They are appropriately fitted, and there have never been issues of face forward. That happens when you crowd all of the lead on the front of a weight belt and put more air in the wing than is needed, usually with a wing too large for what you're doing. With proper weighting and technique it is a nonissue. With doubles you are usually being pulled backwards at the surface because all of the weight is behind you. This again is easily remedied by proper technique with your fins at the surface. You can rotate 180*, lean back, forwards, you name it with very easy fin motions and remain stable in the water without moving. Do it all the time.

Crotch strap-there are multiple variants, yes the stiff unpadded 2" crotch straps can be uncomfortable especially if in a bathing suit, but if you're in a 5mm or thicker there are no issues. Dive Rite makes a padded 2" strap that is quite nice, and I use a 1" strap with a buckle on it if I'm in a bathing suit. Been diving this way for almost a decade with no issues.

If you want to be in doubles, get into doubles. I'd recommend looking for a set of old steel 72's, but you'll probably have to scout outside of the twin cities. Doubles are difficult to find when travelling, so I would recommend starting with a single tank and an H valve if you want the redundancy for local diving. Only places I know that you can easily rent doubles are in cave country, some Great Lake charters, and NJ *required for most of their legit charters*. Coast of NC has some, but you have to look for them.

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.

 

[Scubatude]

.....or come to So Cal. We rent doubles and bp/w