on the boat w/500 psi

[Crush]

It is always better to be back on board a little sooner as 500psi can sometimes mean 300-400psi.

I know that my gauge was (and probably still is) good to about +/- 50psi. I learned this because my regs were still delivering air when I broke the surface with 50psi on the gauge. Not a brilliant day, but it could have been worse.

 

[Darnold9999]

Never learned it. Not fond of rules of thumbs like this. 500psi may be significant over kill or not enough. Not a bad starting point however.

Have had some operators ask for it but normally I plan my own reserve which will depend on the dive, conditions and the tank I am diving. I have surfaced once with an empty tank - had to burn through my reserve and was very glad I had it. The operator quite happily filled my tank - I did explain what happened and that the tank was empty so he could deal with that. Surfaced another time with 50 psi - burned through the reserve at 15 feet watching fish. Ornate Ghost Pipefish so I deemed it worth it.

Mostly I like to have 300 - 600 psi left on a normal dive in a steel HP 100. 300 in very benign conditions, up to 600 in heavy current, boat traffic, bad weather, long surface swim, etc....

 

[TSandM]

Surfaced another time with 50 psi - burned through the reserve at 15 feet watching fish.

I've just about done that . . . had a truly extraordinary day in our local mudhole, with unbelievable viz (maybe 70 feet or even better) and tons of marine life. My great buddy and I just kept working our way shallower, and burned the last couple hundred psi in 6 feet of water, photographing a beautiful jellyfish. I won't say what my ending pressure was, except to state that I could NOT remove my reg without purging it

 

[FireInMyBones]

I know that my gauge was (and probably still is) good to about +/- 50psi. I learned this because my regs were still delivering air when I broke the surface with 50psi on the gauge. Not a brilliant day, but it could have been worse.

That's why I have the nice gauges I do too. I think my instructor was using it as a little more of a scare tactic. Nevertheless, it worked. I went home and learned gas management as soon as I could.

I wish more was covered in class though.

 

[The Chairman]

This reminds of a dive long ago. My buddy and I got to our safety stop and he freaked out. He showed me his SPG and before I could focus on it, he bolted for the surface. I watched him from below as I finished my 3 minutes (it was before I went to 5) and when I surfaced I asked him about it. The boat was SOOOOO adamant that we had 500 PSI in our tank that he completely blew off his safety stop. :shocked2:

I tried to explain how stupid it was to blow off the safety stop, but it was lost on him. On the next dive, I kept track of his pressure since he wasn't doing a good job. I haven't stopped doing that.

As for 500 PSI... I rarely surface with less than 1000 PSI and often double that for an OW dive. I'm a bit more conservative on cave or tech dives.

 

[eponym]

I liked NetDoc's reply above. Ditto. On non-deco boat dives with a boat-issued buddy I typically have 1000 to 800 back aboard except when I've had to contribute gas to my new buddy, which happens more often than I expect. Maybe I can't read people so well.

-Bryan

 

[MXGratefulDiver]

I was picking up a bunch of tanks at the shop one day and commented to the shop owner that all my HP119's and 130's were a bit short ... 3200 to 3300 psi. So he looks at me and says "Bob, how much gas do you usually have left at the end of a dive?" I shrugged and said, "Usually somewhere between 1000 and 1500 psi". He looks at me and said "So what was it you were complaining about?"



... Bob (Grateful Diver)

 

[SandyRobinson]

I know a dive op who tells their clients if they come back with an empty tank, they're done diving for the day. The reasonable assumption is that if your tank's empty, you ended up making a CESA ...

... Bob (Grateful Diver)

I witnessed this in the Keys 1.5 years ago. Even after the briefing, a diver surfaced from a dive on the Speigel Grove with no air and without his buddies (they were finishing their safety stop) They surfaced shortly with very little air. The captain told them they were done for the day but the three argued with him for 20 minutes or so. We also heard from the divers, "this is how we dive at home (Brazil) They never understood what was wrong. There was other stuff that happened that I can not remember but the other divers were glad these three were finished for the day.

I think I heard about the 500psi (or maybe 300psi) during my OW class. But that was in 1981. But, I have heard 500psi on about every boat where we were making recreational dives.

 

[Bubbletrubble]

Voted just now, but noticed poll's math is off by an extra 15%. Maybe that's a one-sixth reserve?

-Bryan

Multiple votes are allowed as one person may have had the opportunity to learn these concepts in different places.

@Bryan St.Germain: If you sum the percentages, it adds up to more than 100% because the survey allows people to vote more than once.
In your attached image, it displays 15 tallied votes yet reports that 13 people answered. 2 people voted twice.

 

[Buadhai]

NWGratefulDiver's article is definitely worth reading. Here's a link:
.
Understanding Gas Management