coliseum:
I think they call it a backpack? its basically a BCD without the inflatable part... its great... he doesnt even wear weights!
Ah, I gotcha. I know those things well. They're pretty neat... Kinda like a backplate made of ABS - it even has a harness made of 2" webbing. They sell around $50.
There was a time when that was standard scuba gear - divers weighted themselves correctly (using weights if they had to, different tanks, or "backpacks" made of different materials - often allowing them to negate the need for weights at all) and simply dove.
The only issue was that the tank changed weight as it emptied - air (or whatever gas you're breathing - it was always air at the time) does have weight to it. An example would be an AL80 - from full to empty, the tank gets lighter by six pounds... And that, of course, can't be compensated for on a "backpack" rig because you can't add a little gas in the beginning of the dive, ending neutral with an empty bladder.
...Not that it was a really big issue... A good diver could easily just swim a little up or down, or use his/her lungs to compensate, and for the most part stay relatively neutral.
Later, a device was invented that helped the diver to compensate for the emptying tank... And the "buoyancy compensator" was born. Early designs had the diver wearing a collar that compensated, and in the early '70's Scubapro invented the "Stability Jacket" - the first jacket-style BC. Fast forward to today, and the backpack has made somewhat of a comeback, for it's simplicity and streamlinedness. If you were to make it out of aluminum or stainless, they'd call it a backplate. And it'd be very DIR.
...It's pretty much exactly what your buddy is wearing - except that we choose metal because we've seen it last longer, it doesn't crush when someone drops a tank on it, and there's a little weight to it - good, because we have to compensate for today's wetsuits and drysuits, which weren't worn originally, or were made of less buoyant materials.
The "wing" part of a DIR rig is interesting in that it folds the "compensator" part around the tank - exactly where it's needed.
Effectively, everything that your buddy is doing is exactly what GUE is teaching - except that we also add the bladder to compensate for the loss of gas as you empty the tank. It's also nice at the surface - you can just float in it.
Like Rich said (sorry if this is reiterating you, Rich... I thought I'd expand), there's also a backup second stage in case something goes wrong with the regulator (a "folded" diaphragm or sand/foreign body comes to mind here) or your buddy needs gas... Although you didn't say whether or not your buddy had a backup.
...Of course, you probably already know all of this - I guess I'm just pointing it out for the anonymous reader.
...But it's easy, then, to see why DIR preaches "correct" weighting so much... It's a wonderful thing not to have to use your bladder, and/or only use it to compensate a little. It also explains why a DIR diver's wing is surprisingly small... It's really only used to compensate for the change in weight as the gas is emptied from the tank.
Now we can all scratch our heads and wonder why so many BC's can't hold doubles or stage bottles (they can only handle one tank), but have 50 pounds of lift or more.
Anyways... everyone has their thing and DIR is not mine... its a matter of choice and I respect yours ofcourse!
...As I respect yours. I know a lot of great divers - and only a small percentage of them are DIR... I just found something that works for me, and am probably a little too boisterous about telling people. It's just hard not to get excited about
that feeling of perfect weightlessness and utter control.
NWGratefulDiver:
Well, actually there is (a secret handshake). I started noticing that all my DIR buddies were doing it while diving ... hands extended forward, holding left fingers with right fingers.
Lol... Ah, yes... I didn't realize that was the secret handshake.
Yeah, holding your hands like that promotes the correct arch in the back, keeping the body prone and streamlined. It's also a nice place to have them, since your instruments are on your wrists and therefore right in front of you.
