Can you monitor your tank pressure mentally?

[cadiver67]

I have heard that some divers automatically know from experience how much air is left in their tanks and in their buddy's tank without checking their gauges.

One persons post says that at any given point in the dive he knows what his pressure is and what his buddy's pressure is to within 100 PSI -/+ without checking his gauges.

Anyone else?

 

[mania]

Well
As a matter of fact you should. Because you should know your SAC, monitor your time and so on.
during Adv. Nitrox this was one of the thing during dives. We had to be able to say how much gas we have without looking. 10 - 20 bars was acceptable margin.

Mania

 

[3-Ring Octopus]

I have a rough idea....MOST of the time. Of course, there are those little "oh, there's a cool ____!" excursions mid-dive that can throw you off. And the good/bad bouyancy control days (the ones where you feel you nail it every time or just can't quite get it right). And the new buddy vs. old buddy anxiety. (In case you haven't noted where this is going....lol)

If it's a dive that person has made several times and doesn't have any new distractions...then I'd buy it. If it's a completely unfamiliar dive, with a new buddy, in a new locale, with some stressors thrown in....then I don't buy it.

Bottom line...dive with your gauges...check them early and often so you know what's going on.

Cheers,
Austin

 

[Charlie99]

The basic rule is that you shouldn't be surprised when you look at your gauges, whether it is depth, time, deco, or air pressure. If you are getting surprised, then either your overall awareness is lacking, or there is an error in the gauge.

I don't figure on doing a complete dive without looking at my SPG, but I do have a good enough mental clock combined with knowledge of how fast my air is going that when I do look at the gauge I rarely see something more than a couple hundred psi away from what I expect.

I may be looking at the gauge only every 20 or 30 minutes if it's a shallow dive, or looking every 5 minutes if its a 100+' dive.

In much the same way as I mentally guess what I'll see before looking at the SPG, I also make a guess as to what my computer is going to be saying (depth, runtime, and N2 loading) before looking at it. Big discrepancies alert me that either my mental computer or my dive computer are having problems.

Charlie Allen

 

[fweber]

You can't know your tank pressure without looking at a gauge. But, you should be able to predict what your gauge will tell you. Once you know your SAC it doesn't take much gas planning to get a grasp of the rate you will use gas for a give depth. I've found all of this to be considerably easier if approached in metric or SI units (BAR, Atmosphere, meters).

 

[ClayJar]

I check my gauges often, but I can indeed predict what my gauge will say this check based on what it said the previous check (and whatever factors my mind has been trained to include).

With my regular buddy, my SPG may as well have a scale for their tank, as I can read off precisely what theirs will show just by looking at mine. Any discrepancy would indicate an issue to be addressed. (We do signal pressures and NDLs back and forth quite often.) For an unknown buddy, after a couple pressure checks, I have a good first-order approximation of their usage on which to base my signaling rate.

 

[ReefGuy]

Whenever we're training we call in our pressures every 15 minutes. Also, when I'm diving for shark teeth, I tell myself how much gas I've got before I look at my gauges.

I can usually hit mine and come close on my buddy's pressure. With a new buddy, it usually takes a couple of attempts, but once I've got an idea of their SAC vs mine, I can pretty much peg theirs.

 

[Web Monkey]

I have heard that some divers automatically know from experience how much air is left in their tanks and in their buddy's tank without checking their gauges.

One persons post says that at any given point in the dive he knows what his pressure is and what his buddy's pressure is to within 100 PSI -/+ without checking his gauges.

Anyone else?

With enough experience you can have a good idea of what your tank pressure or your buddy's tank pressure should be (and probably is).

But nobody can "know" what it is without checking the SPG/computer.

Not checking your pressure because you "know" what it is is a Bad Idea.

Terry

 

[fairybasslet]

What kind of sentence is "I can't need to check gauges."? What does this mean?

I can't answer the poll because to me, the answers provided don't make any sense. How would I know an instabuddy's SAC? And for me it actually depends upon the dive. If I see a whale shark or manta and I am trying to get a photo against the current, well, I might check my pressure a little more often than if I was floating along on a drift dive. My guesses might be totally off. Who knows?

 

[SparticleBrane]

I was the poster in question.
Perhaps "know" was too strong, and "good estimate" a better description? Obviously I don't have a pressure transducer connected from the tank to my head so I don't "know" the pressure in the tank.

I can, however, make a good estimate based off of knowing my normal air consumption and then factoring in what's happening on the dive.

As to fairybasslet's comment about instabuddies--the simple answer is to avoid them and dive with regular dive buddies. However, if you're going to dive with someone new, ask them what their air consumption is. If they give you a number, at least you know they're halfway thinking. If they look at you with a question mark on their face...:11:
If an instabuddy gives you a number, when you check your own gauge during the dive run a quick calculation based on the number they gave you and the current dive conditions, and ask them what their pressure is. If it's off by a good amount, either they were lying or perhaps they're not as comfortable as normal. Either way if I'm diving with someone new, I'd rather dive with an instabuddy who gives me a number rather than one who doesn't.

As I said in the original thread, I have less than 100 dives. I have a long way to go in knowing my air consumption in different conditions (that's why I'm OCD about keeping track of it in my dive log). I'd say I'm within +/- 100psi at least 80% of the time. Other times I don't get it quite right.
For the diving I'm doing right now, that's fine. Later on that accuracy will increase with experience and knowledge.