BCD-Bp/W----WHY?

[mrmonk7663]

Ok, I see many posts on bp/w vs. bcd etc etc. I have read that BP/W is better for Tech diving ie cave, wrecks and stuff of that nature. My question is this. What prevents one from diving wrecks and caves with a BCD? What makes this a bad thing? If down the road I start desiring to dive a little tech can I use my BCD and do it or will it not work? As of now I am just going to be diving for recreation and fun, but who knows what later will hold. I don't really understand this personally so if someone could explain it I would greatly appreciate it. Thanks.

 

[Kim]

The simplest explanation is to do with bouyancy and trim. Using a B/P and wing - or other kind of back inflate system helps to keep you more stable in the water. A wrap around BCD allows more roll as the air is all around your body. With back inflate it's all behind/above you - you 'hang' more below it. This is especially important in overhead environments where you need to be able to move through the environment in a very controlled way - sometimes with very little room for manouver.

 

[Albion]

Ok, I see many posts on bp/w vs. bcd etc etc. I have read that BP/W is better for Tech diving ie cave, wrecks and stuff of that nature. My question is this. What prevents one from diving wrecks and caves with a BCD? What makes this a bad thing? If down the road I start desiring to dive a little tech can I use my BCD and do it or will it not work? As of now I am just going to be diving for recreation and fun, but who knows what later will hold. I don't really understand this personally so if someone could explain it I would greatly appreciate it. Thanks.

The main issue is redundancy, although i have penetrated wrecks with a single tank, having now dived twins i see the foolishness of this, and a BCD with twin tanks and probably stage bottles will not work very well, it can but B/P wing is a far better solution.

Pockets go on your leg not on the jacket where they can stick out and get in the way, your whole frontal area is clean

 

[The Kraken]

Kim wrote:
"A wrap around BCD allows more roll as the air is all around your body. With back inflate it's all behind/above you - you 'hang' more below it. "

An observation if I may in re the jacket style BC -

When at depth and neutrally buoyant the BC/Wing is, for the most part, empty, correct? That would mean that both the BC and Wing, all other things being equal, would contain basically the same amount of air, if any.

Now, air in a water column rises to the highest point.

If the diver is in a normal diving, swimming position, would not the air in the BC rise to the top, ie toward the area along the sides and up to the area where the tank meets the BC. And in doing so, wouldn't the buoyancy characteristics of the two configurations be nearly equal?

 

[Kim]

Kim wrote:
"A wrap around BCD allows more roll as the air is all around your body. With back inflate it's all behind/above you - you 'hang' more below it. "

An observation if I may in re the jacket style BC -

When at depth and neutrally buoyant the BC/Wing is, for the most part, empty, correct? That would mean that both the BC and Wing, all other things being equal, would contain basically the same amount of air, if any.

Now, air in a water column rises to the highest point.

If the diver is in a normal diving, swimming position, would not the air in the BC rise to the top, ie toward the area along the sides and up to the area where the tank meets the BC. And in doing so, wouldn't the buoyancy characteristics of the two configurations be nearly equal?

Quite true. But if you then twist to the side the air in a BCD will flow to the new highest point - the side. Air in a back inflate will always bring you back to a level trim position - IMO not true with a BCD. In an overhead you sometimes have to twist and turn to negotiate obstacles, however you'll want to be in the correct attitude whenever possible, as it's the most stable position. A back inflated wing will automatically try to keep you there - without having to 'fight' the air moving around the bladder of a wrap-around BCD.
Also - if you are correctly weighted with a nearly empty tank in a wetsuit near the surface - you will need some air at depth with a full tank, and a less bouyant wetsuit.

 

[TX101]

Ok, I see many posts on bp/w vs. bcd etc etc. I have read that BP/W is better for Tech diving ie cave, wrecks and stuff of that nature. My question is this. What prevents one from diving wrecks and caves with a BCD? What makes this a bad thing? If down the road I start desiring to dive a little tech can I use my BCD and do it or will it not work? As of now I am just going to be diving for recreation and fun, but who knows what later will hold. I don't really understand this personally so if someone could explain it I would greatly appreciate it. Thanks.

scubaboard as a whole seem to have a rabid affection for the wing. When people ask "which bcd is better? A or B?" at LEAST 1 and usually many, many more people will reply "well, actually C, which is a bp/w. You should try this because ..." and they trot out the time-honored reasons why a wing is SO MUCH better. Usually the guy who asked the question dosent get an answer, because everybody is telling him how much better a wing is.

I dive a wing. When I switched to a wing, I never recieved the epiphany everybody else seems to get (and I'm sure now I'll recieve 100's of replies saying it's not setup right, I should get someone to help me set it up and that I should take DIR-F). I can quite easily switch back to my jacket BC and be just as horizontal, "trimmed out", whatever you want to call it.

For me, there are only two small advantages for my wing (which is a diverite classic, not that itr makes any difference). (1) On the surface it dosen't constrict my breathing when fully inflated. (2) On my jacket BC, I can't reposition any d-rings. But this is kinda made up by the fact that the jacket BC has pockets and the harness dosen't.

If I knew what I know now I wouldn't have bought a wing, since my jacket has enough lift for doubles.

So, to answer your question. Nothing except current convention stops you tech diving with a jacket BC. So long as you have enough lift, you can use your jacket BC for tech diving as much as you like.

 

[DA Aquamaster]

The BP wing is a sacred cow of sorts and believing in a BP/wing and exposing it's positive attributes while decrying the faults of everything else is a great way to sound like a real live technical diver. And that is before we even get into DIR's postion.

Often I suspect the opinions are honestly felt and given but are in some cases based on somewhat flawed experiences. Many new divers have problems in rental BC's due to poor fit and inexperience and then experience the aformentioned epiphany when they finally move to their own BP/wing. Divers with 10 years experience with a variety of BC's are less likely to decide a BP wing is the "only" solution. That in itself however does say a lot as it is easy to get a perfect fit with BP/wing where that can be a more elusive thing with some BC's.

The general arugument that a wing is more stable under water than a BC just does not hold watr however. As indicated above, the air in a BC will migrate to the highest point and give you the same stability in a normal swimming position as a wing. With a well designed BC like the Scubapro jackets, stability is actually much better than with the traditional u-shaped wing as the air is free to move through the jacket to rise to the high point, and back again, through almost any maneuver. In comparision, if I roll 90 degrees to the right or left with my wing, all the air goes to one side or the other and then much of it stays there. It takes a concious effort to lift the front of the BC to get it to equalize. A donut shaped wing resolves this but they don't come in sizes useful to cold water divers.

The advantage of a BP/wing is that it has a backplate which makes it more stable and more comfortable with doubles. They also tend to be very compact for packing purposes and make great travel BC's if using an AL or ABS plate.

I also think that a BP wing with either a one piece or pivot ring harness offers more security, a lower profile and better streamlining than most BC's.

But there are several back inflate cross over BC's out there that do tech well. The Genesis recon has a backplate and other than being a little bulky to pack and only having one size wing, I don't have any compaints about for technical diving. Dive-rite and OMS both sell crossover BC's that delete the backplate and use padded comfort harnesses that still retain a technical capability in terms of D-ring placement etc.

For that matter many jacket BC's now incorporate D-rings that are placed to enable the use of a slung pony bottle or deco bottle. Admittedly some of these are attached to the bag itself with not a lot of support and would not tolerate the weight of a large stage bottle. But if the jacket can also accomodate doubles, has adequate lift, and suitably placed dump valves this type of jacket would allow some degree of technical diving with short to moderate deco that could be accomplished with one or two 30-40 cu ft deco bottles.

 

[mrmonk7663]

Wow, thanks for the straight forward answers. Many responded in regards to a Jacket style BCD. FWIW, and I should have said this, I am going to be using a rear inflation style BCD if I do in fact go the BCD route. Does this make it somewhat better suited to the occassional tech aspect of the sport moreso than the jacket style? I appreciate the honesty in the responses and the seemingly lack of Bias Keep it coming.

Thanks.

PS One other thing. I checked out the Genesis unit that was mentioned above. This looks like an awesome BCD but i'm confused about the lift. It has 75lbs of lift on that sucker. I am going to assume that this is for doubles correct...but what if one were diving singles with this BCD, how would that work and would the very high lift affect this? Thanks.

 

[Kim]

The BP wing is a sacred cow of sorts and believing in a BP/wing and exposing it's positive attributes while decrying the faults of everything else is a great way to sound like a real live technical diver. And that is before we even get into DIR's postion.

Often I suspect the opinions are honestly felt and given but are in some cases based on somewhat flawed experiences. Many new divers have problems in rental BC's due to poor fit and inexperience and then experience the aformentioned epiphany when they finally move to their own BP/wing. Divers with 10 years experience with a variety of BC's are less likely to decide a BP wing is the "only" solution. That in itself however does say a lot as it is easy to get a perfect fit with BP/wing where that can be a more elusive thing with some BC's.

The general arugument that a wing is more stable under water than a BC just does not hold watr however. As indicated above, the air in a BC will migrate to the highest point and give you the same stability in a normal swimming position as a wing. With a well designed BC like the Scubapro jackets, stability is actually much better than with the traditional u-shaped wing as the air is free to move through the jacket to rise to the high point, and back again, through almost any maneuver. In comparision, if I roll 90 degrees to the right or left with my wing, all the air goes to one side or the other and then much of it stays there. It takes a concious effort to lift the front of the BC to get it to equalize. A donut shaped wing resolves this but they don't come in sizes useful to cold water divers.

The advantage of a BP/wing is that it has a backplate which makes it more stable and more comfortable with doubles. They also tend to be very compact for packing purposes and make great travel BC's if using an AL or ABS plate.

I also think that a BP wing with either a one piece or pivot ring harness offers more security, a lower profile and better streamlining than most BC's.

But there are several back inflate cross over BC's out there that do tech well. The Genesis recon has a backplate and other than being a little bulky to pack and only having one size wing, I don't have any compaints about for technical diving. Dive-rite and OMS both sell crossover BC's that delete the backplate and use padded comfort harnesses that still retain a technical capability in terms of D-ring placement etc.

For that matter many jacket BC's now incorporate D-rings that are placed to enable the use of a slung pony bottle or deco bottle. Admittedly some of these are attached to the bag itself with not a lot of support and would not tolerate the weight of a large stage bottle. But if the jacket can also accomodate doubles, has adequate lift, and suitably placed dump valves this type of jacket would allow some degree of technical diving with short to moderate deco that could be accomplished with one or two 30-40 cu ft deco bottles.

FWIW I don't hold a BP/Wing as any kind of sacred cow. I dive with a Transpac II and Travel wing - which is the donut shape mentioned above. Also as said above it's not suitable for doubles or cold water. I was simply trying to answer the question as to why back inflate is theoretically more suitable to tech diving than a wrap around BCD. I haven't dived any jacket style BCD's since 1999 and I'm quite sure that there have been many improvements in that time. Many of the currently available cross over styles would fulfill the criterion that I needed in 1999 - which is why I referred to - "or other kind of back inflate system". The main point for me is that the air cannot travel as far around your body - and is basically kept behind you all the time. I find that this gives less roll than with a jacket. I only dive recreationally - so within NDL limits. A single tank will take me to those limits but if I decided to go further into deco and needed doubles then I already know that I would have to rethink a bit as the U shaped Dive-Rite wings suitable for doubles have the disadvantage mentioned above that the air moves less freely than in the Travel wing. On the other hand the main advantage with the Transpac or BP is that you can easily swop just the wings if you want to change the configuration - and the rest of the harness stays the same. That's a lot cheaper than buying a whole new BCD!

 

[MechDiver]

So long as you have enough lift, you can use your jacket BC for tech diving as much as you like.

Horsepucky