Metric versus Imperial System for Diving?
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drrich2
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You know, the irony about diving metric vs. imperial is, the main advantage of metric is simpler calculations, yes?
Well, for someone who already has life-long intuitive familiarity with imperial, but who for whatever reason is not quick to obtain such with metric, if you give him depth in feet, or lead in lbs., he knows right off how far or heavy that is. But if you give him depth or weight in metric, he has to do a mental conversion, which for him is more work, not less. And most people won't be doing some of the on-the-fly calculations that Kevrumbo has discussed.
Same issue with U.S. 24 hour 'military time.' I know what it is. I know how it works. I've encountered it many times over the years. And if you tell me Eighteen twenty hours, I will (in addition to thinking you sound way too uptight) say, okay, 18 minus 12 is 6, it's over 12 so this is p.m., add the 20, we've got 6:20 p.m.
I will always convert 24 hour time to 12 hour a.m./p.m. time. I will probably always convert meters to feet and kilometers to miles.
Richard.
Well, for someone who already has life-long intuitive familiarity with imperial, but who for whatever reason is not quick to obtain such with metric, if you give him depth in feet, or lead in lbs., he knows right off how far or heavy that is. But if you give him depth or weight in metric, he has to do a mental conversion, which for him is more work, not less. And most people won't be doing some of the on-the-fly calculations that Kevrumbo has discussed.
Same issue with U.S. 24 hour 'military time.' I know what it is. I know how it works. I've encountered it many times over the years. And if you tell me Eighteen twenty hours, I will (in addition to thinking you sound way too uptight) say, okay, 18 minus 12 is 6, it's over 12 so this is p.m., add the 20, we've got 6:20 p.m.
I will always convert 24 hour time to 12 hour a.m./p.m. time. I will probably always convert meters to feet and kilometers to miles.
Richard.
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DaleC
Contributor
Dfx, regarding your last question....prove your point. Show me that metric is easier.
I really have to ask why it bothers anybody which set of units is used. It appears now that the only thing this thread is about is a European bitch fest of political nature. It belongs in the PUB.
From someone who used to use imperial for diving then about 4 years ago switched to metric I can indeed say metric is easier to calculate.
For the first 6 months it was harder as others pointed out as I switched back to feet in my head. After a while I started to get intuitively familiar with meters and no longer needed to convert. That's when it got better.
Admittedly, if you are not planning your dives for min gas and using SAC rate to estimate gas usage or doing gas tracking underwater ( something I advocate all divers do) you won't see the advantage. Also, for those that like to have precision control of their buoyancy, seeing 10cm increments is really nice as you can immediately see if you are going up or down and adjust as required.
I also find the bar SPGs cleaner and easier for calculating thirds on the fly when cave and overhead diving.
At the end of it, I paid a lot of money to convert all my SPGs over but I still have my PSI SPGs and will dive metric or imperial depending on the dive team I'm with. I do both but prefer metric now.
For the first 6 months it was harder as others pointed out as I switched back to feet in my head. After a while I started to get intuitively familiar with meters and no longer needed to convert. That's when it got better.
Admittedly, if you are not planning your dives for min gas and using SAC rate to estimate gas usage or doing gas tracking underwater ( something I advocate all divers do) you won't see the advantage. Also, for those that like to have precision control of their buoyancy, seeing 10cm increments is really nice as you can immediately see if you are going up or down and adjust as required.
I also find the bar SPGs cleaner and easier for calculating thirds on the fly when cave and overhead diving.
At the end of it, I paid a lot of money to convert all my SPGs over but I still have my PSI SPGs and will dive metric or imperial depending on the dive team I'm with. I do both but prefer metric now.
mrdre
Contributor
It's not a fair offer, because you might be very experienced diver. How about this offer? We take two new, fresh student divers: one metric (from Europe, Asia - wherever), and one imperial (American, I guess, or Liberian). Teach one metric, one imperial accordingly. Let them have same amount of dives. After 10-20 dives, I bet $1000 that the metric person will beat hands down the imperial person in all the calculations regarding diving in all the math involved. How about that? Would you be up to that kinda bet?
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It may well be a rhetorical question, but it's the whole point of the thread. Metric units make easier math.
Depth/10 + 1 = pressure
1 liter of air needs 1 kg of weight.
You don't have to jump through conversion factor hoops to do a rock bottom calculation.
You don't have to memorize tank factors, because the water volume and pressure rating is stamped on the tank.
And the 3, 6 etc. is just because you guys can't be arsed to adapt, and someone has to, otherwise we'll have complete chaos. The European counterparts to PADI OW certify you to 20m, since that's a nice round number just like 60ft, which is 18m, not quite that nice and round in metric.
Problem is, when some people start ranting about how y'all don't care 'bout the rest of the world because 'MURRICA!!! THE GREATEST!!!, it takes a stronger will than mine to resist sniping back...
EDIT: ...which is pretty darned ironic considering which thread this trainwreck was split off from. The stereotype of the loud, obnoxious, in-your-face "we're the best, f*** the rest" American is very much alive. And with a bit of selection bias that stereotype can be kept well fed for a long time, as demonstrated in this thread and - I guess - to the chagrin of the large number of polite, intelligent Americans.
---------- Post added October 31st, 2014 at 07:58 AM ----------
For anyone, the "best" system - at least in the short run - is the one we're used to. So the question of whether metric or US/Imperial units are "best" is really a pretty stupid question.
I'm brought up SI metric, with the exception of energy units, which still was calories at that time. I still count my food in calories (or, rather kcal), but any engineering calculation is done in J (or multiples or J), since it's obviously easier. I don't have to throw in the 4.19 conversion factor. When I lived in the US, I slowly got F temps, but I still thought in C. Distances, however, were in miles from the get-go, since the speedometers and maps all were in mph and miles. I never converted to km, I just related to the miles. Just as I still use nm at sea, since boat speeds are still in knots. The minute we change to km/h also on the water, that's when I'm switching to km distances. When I was a kid, my dad measured depth in fathoms and I related just fine to that. After I've grown up, I've always measured in meters. Another incongruity.
If you try to avoid the chest-thumping, we can try to avoid the sniping. If we concede that switching to another measuring system is a b*tch, will you admit that metric makes for easier math because metric - or rather SI - math doesn't need other conversion factors than powers of ten?
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Nothing easier for us humans to calculate than powers of 10 in a base 10 numbering system...there's a reason it's so intuitive for us too...just look at those two things in front of you on the keyboard to see why 
A long time ago I first learned to dive using cubic feet etc, however the majority of my diving has been in the new fangled metric system.
Mostly the units used diving have no dry land relationship that matters. The depth really could be in fathoms, you don't need to look up and estimate that you are at 10 fathoms or 5 fathoms. Thus once you get used to a particular number X meaning deep, Y meaning not especially deep etc you develop a feel for the numbers. Also with pressure, other than filling an SMB the actual physical volume of gas doesn't matter in relation to real, dry, experience. All that matters is that you use P at the surface and some multiple of P at depth and the cylinder contains some (hopefully bigger) multiple of P so you can do the dive.
They are all meaningless numbers really. I don't think it really matters what your local culture of measurement is. You will not have to fit a piece of wood bought in cubits or whatever against depth. (People doing shot lines excepted).
On the other hand teaching gas consumption etc to someone who cannot divide by 33 in their head is a bit more challenging than if they only need to divide by 10. Instead of concentrating on the ideas you have to get all bogged down in the difficult numbers.
By and large people are astonishingly bad at mental maths, often have not used it since leaving university or school. I think if the imperial people were taught diving entirely in metric they would never notice or care it wasn't the same as day to day measurements.
Mostly the units used diving have no dry land relationship that matters. The depth really could be in fathoms, you don't need to look up and estimate that you are at 10 fathoms or 5 fathoms. Thus once you get used to a particular number X meaning deep, Y meaning not especially deep etc you develop a feel for the numbers. Also with pressure, other than filling an SMB the actual physical volume of gas doesn't matter in relation to real, dry, experience. All that matters is that you use P at the surface and some multiple of P at depth and the cylinder contains some (hopefully bigger) multiple of P so you can do the dive.
They are all meaningless numbers really. I don't think it really matters what your local culture of measurement is. You will not have to fit a piece of wood bought in cubits or whatever against depth. (People doing shot lines excepted).
On the other hand teaching gas consumption etc to someone who cannot divide by 33 in their head is a bit more challenging than if they only need to divide by 10. Instead of concentrating on the ideas you have to get all bogged down in the difficult numbers.
By and large people are astonishingly bad at mental maths, often have not used it since leaving university or school. I think if the imperial people were taught diving entirely in metric they would never notice or care it wasn't the same as day to day measurements.
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