SMB as backup lift source.

[PfcAJ]

I kinda suspect that, I just chose that depth range to be sure the diver was carrying hypoxic backgas. I know that 60m is Not being tech trained, I don't know where in that depth range it'd be smart to use a hypoxic backgas


D'oh. I forgot to take that into my calculation. So, roughly how much would that affect the weight of the backgas if the twinset was filled with 18/45 or 15/55? A twin 12x232 holds some 5500 surface liters or nearly 200 cu.ft.


You won't see me argue against that

Deeper than about 200ft/ 60m starts requiring hypoxic gases if you want to keep your po2 at 1.2 or less.

15/55 is a reasonable gas choice for dives in to 200-250’ range.

A cubic foot of air is about .08lbs. A cubic foot of helium is about .01lbs.

So in your example, you’d have 110cuft of helium weighing 1.1lbs, plus 90cuft of air (close enough for scuba math) weighing in at 7.2lbs. Total is 8lbs of back gas, vs 16lbs if it was all air.

So half the weight. That’s a big deal.

 

[CaveSloth]

Alright, I have decided I will go ahead and get a drysuit. What is the best value model? Also, I plan to lose 50 pounds of body weight over the next 6 months. Is there a drysuit which will fit me both now and after the weight loss?

I have a single bladder wing. I am debating adding a second bladder to it. The only thing giving me pause is the GUE website saying not to dive double bladder wings.

 

[Storker]

half the weight.

Nitpick: half the backgas weight

 

[Graeme Fraser]

It's quite a big ask to expect a drysuit to accommodate 50lbs difference in body mass and still fit well, particularly the neck and wrist seals. Fair play to you for setting a challenging goal though. Maybe wait till you're the weight you want and then treat yourself to a nice new drysuit.

Regarding the wing, you can't just add a second bladder to a single bladder system, but a new wing isn't that expensive. Remember the BPH is transferable. Also with your drysuit a) your much more balanced (weight and trim) and b) you have your buoyancy redundancy right their. In other words, if you get the drysuit, forget the new wing.

Just one other thing, when you get the drysuit get trained and comfortable in it before going open water especially tech.

Good luck. G

 

[CaveSloth]

BPH?

I am being told that my Dive Rite Rec XT wing can be upgraded to dual bladder. Somehow the shop can open the wing, insert the second bladder, add the inflator hose, etc...

 

[doctormike]

BPH?

I am being told that my Dive Rite Rec XT wing can be upgraded to dual bladder. Somehow the shop can open the wing, insert the second bladder, add the inflator hose, etc...

Hey, if it's good enough for John Chatterton...

 

[Graeme Fraser]

BPH?

I am being told that my Dive Rite Rec XT wing can be upgraded to dual bladder. Somehow the shop can open the wing, insert the second bladder, add the inflator hose, etc...

Back plate and harness. Fair enough if they can alter your existing wing.

 

[CaveSloth]

I called Dive Rite and they said it is an approved upgrade to add a second bladder to the wing. All other considerations aside, any reason for me NOT to add a second bladder to my wing? Yes I know it means one more thing dangling from my rig but any other reason not to add it?

 

[Storker]

Nitpick: half the backgas weight

However, in my hypothetical example, the gas weight would still be some 7kg/16# (quick and dirty, assuming the backgas has half the density of air). That's still quite a bit to swim up. Maybe doable, but gorram, I wouldn't like to have to swim up that kind of weight to avoid drowning. Notwithstanding the issue of what can happen on the surface, after surfacing.

 

[PfcAJ]

However, in my hypothetical example, the gas weight would still be some 7kg/16# (quick and dirty, assuming the backgas has half the density of air). That's still quite a bit to swim up. Maybe doable, but gorram, I wouldn't like to have to swim up that kind of weight to avoid drowning. Notwithstanding the issue of what can happen on the surface, after surfacing.

I wouldn’t want to swim that up either.

Hence the drysuit