Question about using a lift bag for redundant buoancy

[Makhno]

I just put it into deco planner for you.

Buhlmann 20/85
150ft, 30mins, 21/00 (air) = 26mins deco time with o2 and 50%
150ft, 30min, 21/00 (air) = 36mins deco time with just 50%

10mins difference. 7mins difference if the back gas is 21/35. 10mins is not worth the effort (and even risk) of dragging a 2nd bottle, and its certainly not worth diving 2 al80s filled to 3000psi.

Thanks for running the numbers. . . . (Either VPM differs a lot at 50m for air from 20/85 GF, or I'm having a "senior moment," but 10 minutes seems like a lot less difference than I recall.)

Anyway, as I said -- whether ideal or not, that's how a lot of folks are actually diving.

Trimix at 40 meters, or a drysuit in 26C waters: now that is fantasy land for most divers.

However, I do appreciate your dedication to striving toward the Platonic ideal, and as Reg pointed out, a lot of folks other than the OP will read this thread, and I bet you've done some of them some good.

Anyway, as Reg implied, we're probably beating a dead horse at this point. Cheers and good night from Asia.

 

[boulderjohn]

In the last month, I have done several deco dives to the 150-170 foot range, with bottom times similar to those posted by PfcAJ and with total run times about 70-75 minutes.

I did use trimix (21/35) on those dives. I also used two deco gases--50% and 100%--in Al 40s. I did not need them. I used two gases because I don't get to do as much deco diving as I would like, and I like to keep the skills required for those dives fresh.

I was not alone on those dives, and just about everyone else was doing them with only one O2 bottle.

 

[teknitroxdiver]

Thanks for running the numbers. . . . (Either VPM differs a lot at 50m for air from 20/85 GF, or I'm having a "senior moment," but 10 minutes seems like a lot less difference than I recall.)

Anyway, as I said -- whether ideal or not, that's how a lot of folks are actually diving. Trimix at 40 meters, or a drysuit in 26C waters: now that is fantasy land for most divers.

However, I do appreciate your dedication to striving toward the Platonic ideal, and as Reg pointed out, a lot of folks other than the OP will read this thread, and I bet you've done some of them some good.

Anyway, as Reg implied, we're probably beating a dead horse at this point. Cheers and good night from Asia.

Vplanner (vpm-b) on +2 gives a 9-minute difference between both 100% and 50% and 50% only. 14-minute difference between both and 100% only.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

[mod8521]

Past all that, the lift bag thing is beyond silly. Jumping in the water, weighted like a boat anchor, and thinking you're going to get out a lift bag and inflate it while plummeting to Davy Jones's Locker is ridiculous. Stop being a nickel rocket, get the right gear (either light tanks or a drysuit) and enjoy your scuba dive. Bandaid 'solutions' give nothing but false peace of mind and don't fix the real problem

And if people would stop giving out crappy advice, OP probably wouldn't have bought gargantuan cylinders (which cost like a thousand dollars new) in the first place. OP could have bought a proper set of doubles an used the rest for training or diving.

I already had the tanks. Was diving them as singles. Got a second hand set of bands and manifold. More like 300 assembled valves rebuilt and o2 cleaned.

Reg Braithwaite yes I did get the a answer to my question. I understood before I posted this diving heavy steels wet is not a good idea. That is why there are specific details in my first post. ie not planning on diving where a hard bottom exceeds 130' I agree a drysuit is the best answer but I don't feel it is the only answer. That is why I asked the question here.

Who makes a quality made to size drysuit for under 1000?

 

[decompression]

Easy to find good drysuits second hand for under $1000 and whites drysuits are new at $1000.

Here is a video that shows the importance of a balanced rig....
NOWDIVE TV Balanced rig on film - Unified Team Diving

 

[boulderjohn]

Who makes a quality made to size drysuit for under 1000?

Is "made to size" the issue? Lots of good used dry suits are available for sale for those with relatively normal sizing.

 

[teknitroxdiver]

And a few new ones in that range.

 

[MXGratefulDiver]

You can get the back-zip version of the White's Fusion for around $1000, and it doesn't require a custom fit.

... Bob (Grateful Diver)

 

[mod8521]

I need a custom fit. Off the shelf sizes dont fit.

 

[teknitroxdiver]

I need a custom fit. Off the shelf sizes dont fit.

Can you post your dimensions?