PSI or BAR in Tech diving?

[Ste Wart]

I decided to put this into the Advanced Scuba Discussions although it has probably more to do with Technical diving.

Back in October I was over in Utila doing a couple of Tech dives; nothing serious just some extended range. The depths were fairly average at 50m and fairly short with 20 minute bottom times.
However that's not the point. The thing was all the divers were using Imperial to plan their dives and I was not. All my training has been done in Europe and Egypt when it comes to tech, so therefore I'm Metric all the way. I looked at them as if they just suggested I kiss my sister when they asked me my SAC rate in Imperial. It's never really occurred to me to even know what it would be.

Now I know the formulas can quickly be found on the interwebs to do the conversion, but I feel personally that Metric and Tech go hand in hand, for several reasons.
1: Atmospheric pressure is easy to calculate. 10m = 2 atm and so on
1a: Because Atm Pressure is easier I find it quicker to calculate gas mixes (even trying to teach a student Nitrox in Roatan had me umming and erring, even though I could have the answer in seconds with Metric)
2: SAC rate easy to calculate.
3: 3 metre stops, compared to 10ft stops

How does everyone else feel on this subject?

 

[redacted]

What is the metric measure for SAC rate? That one would give me pause.

 

[mikemill]

I decided to put this into the Advanced Scuba Discussions although it has probably more to do with Technical diving.

Back in October I was over in Utila doing a couple of Tech dives; nothing serious just some extended range. The depths were fairly average at 50m and fairly short with 20 minute bottom times.
However that's not the point. The thing was all the divers were using Imperial to plan their dives and I was not. All my training has been done in Europe and Egypt when it comes to tech, so therefore I'm Metric all the way. I looked at them as if they just suggested I kiss my sister when they asked me my SAC rate in Imperial. It's never really occurred to me to even know what it would be.

Now I know the formulas can quickly be found on the interwebs to do the conversion, but I feel personally that Metric and Tech go hand in hand, for several reasons.
1: Atmospheric pressure is easy to calculate. 10m = 2 atm and so on
1a: Because Atm Pressure is easier I find it quicker to calculate gas mixes (even trying to teach a student Nitrox in Roatan had me umming and erring, even though I could have the answer in seconds with Metric)
2: SAC rate easy to calculate.
3: 3 metre stops, compared to 10ft stops

How does everyone else feel on this subject?

I think a person should use whatever system they are most familiar with. For someone who can do math well, both systems are easy.

BTW I'm not sure I understand how 3m stops are easier than 10' stops. I can count 10s a lot easier than I can count 3s. Kind of the same reason counting ata is easier in metric. BTW you might want to look at the difference between atm and ata on your point #1

What is the metric measure for SAC rate? That one would give me pause.

Liters/minute

 

[Skydiver1]

Liters/minute

delete

 

[BabyDuck]

it's totally how you *think*. i worked labor & delivery a lot of years, and it took forever before i could picture a 3356gm baby - though i could easily picture a 5lb baby or a 8lb baby. so while metric is probably an easier system, i can't think in bar and meters. i'd be converting in my head anyway (and me doing math in my head while diving is not a pretty sight), so i'll stick to how i can think.

i wish this wasn't true about me, but it is.

 

[Shcubasteve]

Liters/minute

liters/minute/atmosphere... Right?


As for planning dives, I would think that the only conversion would be max depth and depth of stops... Everything else would be the exact same.... If you plan using liters/min/atm and a buddy is planning in cubic feet/min/atm, the net result is the same- each of you would plan your gas requirements independently.
Metric prob. is better for most measurements and is more widely recognized throughout the world. All my science classes were in SI(metric)

 

[liuk3]

I believe metric would be better, and I've tried to convert, but at this point, I'm much more confident in my imperial calculations. Also, all my dive buddies are using imperial.

 

[DevonDiver]

I had the same issues for the first time when I moved to the Philippines. Until then, I'd never dived extensively (or tech) in a region that wasn't metric.

If there was one thing the scuba industry could do better... it would be to standardize this.

 

[mikemill]

liters/minute/atmosphere... Right?

Well SAC implies surface or 1 ata so really there isn't a need to write that part down (IMO).

 

[Blackwood]

It makes no difference to me. If my buddies want to start using metric gauges, that's fine.

BTW, as was said above (maybe by mike?), if the metric system is easier because of even 10s, then why are 3m ascents superior? If fact, isn't 3m simply a crude approximation of 10ft? I've often wondered why those doing stage deco diving with meter depth gauges haven't demanded software that delivers stops in 5m increments.