How long does YOUR tank last?

[BLoaf]

A few weeks ago I did a dive that is close... tank was single HP100. Found one iPhone 4s and 12pr sunglasses or maybe 13, I forget..anyway:
max depth 41
avg depth 36
dive time 79min
psi start 3480
psi end 1677

Thanks for the info. Nice signature also.

 

[DivemasterDennis]

I have never intentionally (or unintentionally) breathed a tank dry. (Came close once, but that's a different thread) Log book review shows Debbie and I have dozens of dives in the 40 to 49 foot range of over 60 minutes, and I had the lowest end-of-dive air left, one one occasion, about 550 psi from a 3100 starting pressure. I also noted that in my first 20 dives, (almost a900 dives ago) dives in that depth range averaged under 40 minutes, with "leftover" air of from 700 to 850 psi. My wife Debbie is a curve breaker here. After 60 to 70 minutes in the 40 to 49 foot maximum depth range, her "left over" air has never been under 1000 psi, and is usually in the 1200-1300 psi range. She is my dive buddy AND my "spare air!"
DivemasterDennis

 

[freewillie]

For California cold water, did a 40 ft night dive with AL 80. We were in the water over an hour, and when we finished I was still at 1100 psi.

Then again, cold water temp at 50 degrees and dive to 100 ft, same tank lasted only 40 minutes with 700 psi surfacing.

 

[t-mac]

70 minutes or so with 500-700 psi left. My sac is typically .4 ish and this is consistent with the dives I've logged in this range.

 

[NE_SSI_Diver]

It would depend on the water temp, but if I stayed at 40 ft I could make an aluminum 80 last 1 1/2 hours at least. However, due to dive boat rules/ limitations of the group I have never dove more than an hour, so I do not know for sure.

 

[mselenaous]

Last weekend I dove on four two-tank dive trips (water temp 83-84).

104 ft 23 min used 1163 psi AL80 (SAC =0.32) lots of current on the Duane with 2 students
35 ft, 57 mins used 1271 psi AL80 (SAC=0.28)
27 ft, 58 mins used 1326 psi (SAC= 0.29) and then 32 ft, 52 mins used same HP 80 tank (SAC = 0.26)
29 ft 43 min & 27 ft 50 mins, 1900 psi on same AL80 (I had 4 OW students in tow on these dives) (SAC= 0.28)
29 ft 58 mins 1282 psi HP80 (SAC=0.31) lots of current on this dive
20 ft 64 mins 1250 psi AL80 (SAC = 0.32) lots of current on this dive

So with an average rate is 0.300 cu.ft/min, an AL 80, leaving 500 psi (using 2500 psi) at 40 ft, I can presumably stay about 100 mins.
(Thanks for keeping my brain from rusting, it's been a while since I'd done these calculations)

 

[golfette44]

I can easily dive 60 mins, but at 40 ft I could probably dive 75 mins. or longer.

 

[mathauck0814]

AL80 at a constant 40 feet? Somewhere between 1:15-1:30 I'd guess to still come out with a reasonable reserve. Maybe 1:45 hours if I pushed all the way to 500psi

 

[ChrisMan]

Don't worry about it! As long as you stay within the limits of your experience, capability, boat rules etc. All that matters is you get back to the surface in a safe manner. Just enjoy your diving and your breathing will get better. (My first AOW wreck dive was to the Hardeep wreck in Thailand (in a dropping 40 current) . When I got down the 30m line near the wreck, I signalled I was at 70 bar, so my instructor thumbed us back to the surface. All in all a 5 or 6 min dive on an AL80!!) I laugh about it now as normally spend about 30-40 mins on the wreck, in the same currents and worse!

 

[Scuba_Noob]

Last dive, 50fsw avg, cold water, drysuit - 70 minutes with a steel 100 with 700psi left.

If it were at 40fsw avg, with an Al80, relaxed dive, I would probably be able to get 60 minutes at least.

More than enough for me, 'cause I start getting chilly anyway. I think 45-60 minutes is my ideal length of time for a dive.