PSI and BAR Buddies

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mmcdanie

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Location
Southern Calif.
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Has anyone had a situation where their SPG is PSI and the insta buddy is BAR? I'm curious how you agreed on presure signaling before a dive in this senario. I've not done a dive trip yet but I'm hoping to soon and this situatuion came to mind.
Thanks
 
Yep! I was on my honeymoon in Bonaire, and regrettably, my wife fell ill to a sinus infection. I spent a day diving with insta-buddies on the hotel's boat while she dealt with the interesting pharmaceutical products not available in the US (she recovered in less than 24 hours!). I ended up partnering with a diver from Italy. He spoke little English and I an not versed in Italian. We managed to define the limitations to the dive, and had a really nice time. We ended up showing the gauge to each other during the dive rather than signals, though 1/2 and 1/3 and/or turn pressure are simple to establish.
 
Diving in one hour with a semi-regular dive buddy, I am PSI, she is BAR. No big deal. You just understand that 50 BAR is about 700 PSI. From that you can compute a reasonable turn around BAR/PSI pressure keeping in mind the desire to keep 50 BAR in the thank for emergency.

I don't try to do fancy conversions during the dive. I signal my remaining air in PSI and she signals her air in BAR, no problem.
 
you can incorporate this quite easily into your gas planning.

Each diver is responsible for their own gas, you have a starting pressure, turn pressure and rock bottom pressure, and each diver calculates turn and rock bottom in units that make sense to them. During the dive, before it is turned you respond to gas questions with an OK signal as long as your gas is above the turn pressure. At the turn pressure, you give a signal to turn the dive. After the turn, you respond with OK if you are above rock bottom. Once you hit rock bottom, the thumbs up signal is given and the dive has ended.
 
Yep! I was on my honeymoon in Bonaire, and regrettably, my wife fell ill to a sinus infection. I spent a day diving with insta-buddies on the hotel's boat while she dealt with the interesting pharmaceutical products not available in the US (she recovered in less than 24 hours!). I ended up partnering with a diver from Italy. He spoke little English and I an not versed in Italian. We managed to define the limitations to the dive, and had a really nice time. We ended up showing the gauge to each other during the dive rather than signals, though 1/2 and 1/3 and/or turn pressure are simple to establish.

Being in Italy I can understand, however most of my stuff is in BAR. I can't understand personally why the metric system isn't used for diving over here. But what we typically do when diving with a mixed crowd here is to remember that 50 BAR is just about 750 PSI (actually around 725ish, but 750 is easy on the fly calculation). Most of the time it makes it relatively easy to set up a system for one diver to 'translate' his/her pressure to the buddy.
 
Happened to me a couple of times. In both cases I was serving as lead. So they just reported to me in Bar and I multiplied by 15 and had the PSI.

With any buddy PSI or BAR we go over this carefully ahead of time and I tell them to show it to me real slow. If they do it fast, I just ask for the gauge.
 
Everytime I dive. I live in the UK, but I have a psi gauge. It never creates issues, I just convert to bar
 
Vital conversions that you should know & can do on-the-fly:
Easy imperial US/metric conversions for depth & pressure, that you can do in your head:


Depth in meters multiplied by 10/3 gives depth in feet;
Feet multiplied by 3/10 gives meters.
Example: 18m(10/3) = 60' ; 60'(3/10) = 18m


Pressure bar multiplied by 3/2, and multiplied again by 10 gives pressure psi;
Pressure psi multiplied by 2/3, and divided by 10 gives pressure bar.
Ex): 200bar(3/2)(10) = 3000psi ; 3000psi(2/3)/10 = 200bar.


___
Your common counting numbers, or reference cardinal numbers, for depth in scuba are:


Imperial US (feet) by 10's:
Ex): 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 etc


Metric system goes by 3's:
Ex): 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33 etc


Practice the depth conversion factors above between the two number sequences. . .
The best compromise is an SPG with both bar & PSI units with clear precision; the best Practice for a Unified Dive Team is one system of measurement and only one --and that system must be Metric.

(Don"t be a stupid "national-USA-Centric Diver": learn & conform to the World Standard for Scuba, especially traveling overseas outside the US. . .)
 
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Have family in Europe that comes over to dive....I switch my SPG to the OMS ones that show both PSI & BAR...Also carry two computers, one is set to PSI the other to BAR....Any thing happens I'm covered.........
 
I've been diving here in Chile (where everything's metric) for several years now, but all my training was in the US as are my gear purchases. Sorry old dog here, and as much as I love the metric system, PSI just "makes more sense" to me for diving, probably because of all the years using it.

Anyway, the BAR folk signal tank pressure using one finger for every 10 bar just like the psi folk do for every 100 psi. In other words, five fingers means 50 bar, 10 fingers (or five twice) means 100 bar etc.

As a rule of thumb I generally use the following bar to PSI approximations:
200 bar ~= 3000 psi (full tank)
100 bar ~= 1500 psi (half tank)
50 bar ~= 750 psi (quarter tank)
30 bar ~= 500 psi (should be at the surface)

Everything in between is just that: in between. Remember, you don't need to know the exact conversions all the time, just how close you are to the next "milestone" that fits your dive plan.

Also, make sure to agree before hand who's signaling what. As soon as you start comparing gauges and talking about bar and psi, without knowing it you might have a mathematically gifted person that can do the conversions in their head and, in trying to make things easier on you, signals to you in PSI what they read in bar. If you don't know that they're doing that, it could lead to trouble.

EDIT: that just got me thinking. With the simplification of scuba certifications to make the sport more accessible to the masses, I wonder how long it's going to take for SPG's that read like the gas gauges in cars (i.e. no numbers just indicators for quarters of a tank) to appear.
 

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