Unit compatibility (DIR practitioners invited)

[NudeDiver]

So, no one around here understands me when I talk in meters and bars. I don't understand them when they talk in feet and PSI. Not that I really care - but it seems like it could be an issue. On one dive, I was with an instructor for a drysuit course, and she looked at my computer at some point early in the dive, saw that it read 200 on the pressure, and thumbed me to the surface. She thought I was low on air, because she didn't know it was 200 BAR not PSI. No problem - I explained, and back down we went.

So - now I am wondering, what the usual is. Obviously, in the ideal world, buddy teams would be using bars and meters - eh, I mean - the same units. Equally obviously, there are situations where this isn't going to happen. When diving, I think in certain units, and someone else thinks in other units. I imagine that MOST people are not comfortable switching units and adjusting thought processes, and many of those people are not going to be willing to do so. I know I'm not.

So - now the questions:

a). Is it typical for buddy teams of "different units" to buddy together (think charter or something) and each dive in their own units?

b). Is it more typical for someone to adjust to the other person's units?

c). What if they have gauges that are not bi-calibrated?

d). Is it DIR for buddy teams to be using different units? Do you mandate everyone be on the same units?

e). Will you refuse to dive with a buddy who uses different units and refuses to switch to yours?

f). Is this just a ridiculous issue that I shouldn't even consider?

I'm just curious - mostly because of the incident I described in the opening paragraph.

 

[wedivebc]

I find a couple of minutes discussing dive issues with new buddies aleviates all sorts of problems underwater.

So, no one around here understands me when I talk in meters and bars. I don't understand them when they talk in feet and PSI. Not that I really care - but it seems like it could be an issue. On one dive, I was with an instructor for a drysuit course, and she looked at my computer at some point early in the dive, saw that it read 200 on the pressure, and thumbed me to the surface. She thought I was low on air, because she didn't know it was 200 BAR not PSI. No problem - I explained, and back down we went.

So - now I am wondering, what the usual is. Obviously, in the ideal world, buddy teams would be using bars and meters - eh, I mean - the same units. Equally obviously, there are situations where this isn't going to happen. When diving, I think in certain units, and someone else thinks in other units. I imagine that MOST people are not comfortable switching units and adjusting thought processes, and many of those people are not going to be willing to do so. I know I'm not.

So - now the questions:

a). Is it typical for buddy teams of "different units" to buddy together (think charter or something) and each dive in their own units?

b). Is it more typical for someone to adjust to the other person's units?

c). What if they have gauges that are not bi-calibrated?

d). Is it DIR for buddy teams to be using different units? Do you mandate everyone be on the same units?

e). Will you refuse to dive with a buddy who uses different units and refuses to switch to yours?

f). Is this just a ridiculous issue that I shouldn't even consider?

I'm just curious - mostly because of the incident I described in the opening paragraph.

 

[pwl]

i think the real lesson here is to understand what equipment your buddy is using before starting the dive; presumably there will also be some discussion of times, depths & air pressures during the pre-dive plan, where it will become very apparent who is talking in metric & who in imperial.

i'm also surprised your instructor didn't see that your gauge needle was pointing straight up (or thereabouts) & use that as the measure (rather than whatever number was written on the dial).

having said all that, since i've only dived in australia it's been very uncommon to come across anyone diving in imperial.

 

[Melicertes]

I'm not commenting on DIR practices here as I am not qualified to do so quite frankly, but my wife and I dive metric gauges and whenever we do have buddies with imperial gauges we make sure that we discuss this with them during the dive briefing. We've both grown accustomed to switching between both metric and imperial units for most diving related issues so it's no problem for us; just don't ask me about drill bit sizes in inches .

 

[NudeDiver]

i'm also surprised your instructor didn't see that your gauge needle was pointing straight up (or thereabouts) & use that as the measure (rather than whatever number was written on the dial).

Well, like I said, "looked at my computer." No gauge, needle or dial was involved

 

[Cabbie]

if the DM is speaking in tounges (e.g. PSI and feet) during the dive brief, I explain afterwards that my guages are in bar and I dive in metres and then ask for a rough estimation so I know how deep the dive is going to be and when we should be back on the surface etc (although I have a pretty good idea, I think the DM should too). Only happens when I'm visiting the other side of the world which is not very often !

 

[Deep-Thief]

I would not refuse to dive with you just because you are using different units than I. Some one should be able to convert relativly easily. At least the meters part. The bar might be a little harder. I would want to go over a few conversions with you first before we dive. That way if I should have to look at you guages, I have some idea of what is going on. I would want to know your turn pressure and what is 500psi equal to. This is all for recreational, reef diving, by the way. For doing technical dives, then there would be a whole lot more discussions and conversions so I knew what was going on with your stuff. Its a shame the US didn't force everyone to convert in the 70's when they talked about it. The world would be a lot easier now if they had.

 

[PfcAJ]

I'll comment on the DIR part.

I'm not going to check your guage during the dive in a DIR team. If we plan minimum gas for 700psi or 50 bar, its settled. If we're doing a minimum deco ascent, we both know where those stops are at, call it 20ft or 9m, we're still at 1.6ata.

However, the issue comes with gas switching (I know, not basic scuba). My 70 bottle looks real different than a 21m, but means the same thing. This needs to be discussed and understood PRE-DIVE. Add in a few more gasses, and this can get a bit confusing if you aren't versed in metric.

It helps to have the MOD markings conform to the local standard (if I was in Europe I'd have my bottles in metric, but Emperial in the US), but some prefer not to do so. Just keep on top of it and its a non-issue.

 

[b1gcountry]

In general, I would say you should adapt to whatever the standard is in the country you are diving in. If you come to the US, and plan on diving with the locals, then I think you should be prepared to do as the local culture requires. It's pretty useful to be able to communicate depth with your buddy, so I would say the two of you need to be on the same page. The Divemaster shouldn't matter though.

I will say that it is easier to convert from feet to metric for me. Metric is really nice because 10m = 2ata; 20m = 3ata; etc. I can get a pretty good measure on the depths by just thinking about how many atas it is I'm diving at, and then subtract one to get the meters (x10). For some reason, I just have a harder time doing it the other way...

Tom

 

[NudeDiver]

In general, I would say you should adapt to whatever the standard is in the country you are diving in.

So people in the U.S. should force themselves to use a screwy measurement system just because the country is backward, relative to the rest of the planet? Screw that