Dive metric

[Zept]

Originally posted by Shaun
Is there a world beyond metric?

'Fraid so. It's full of annoying imperial divers who use stupid big numbers for everything and then stay down until they reach 500psi, which is a miserable 35bar. Makes it hard to match the air consumption of an imperial diver... mutter, grumble, moan .

Useful things to know:

• 3 metres = 10 feet
• 1 bar = 15 psi (approx)

Dea, the more recent Suunto computers (Mosquito, Vyper, Stinger, Cobra and probably the Vytec) can be switched between metric and imperial units. Most of the people I've dived with in Asia used metric gear, although I've dived with a couple of North Americans who wear using imperial gauges. It's worth knowing how to convert from one to the other so you can tell whether your buddy is running out of air.

Example: An imperial diver might hold up one finger to indicate 1,000psi (70bar). To a metric diver, one finger means 10bar (150psi). Yikes! It isn't so bad if both divers are using analogue pressure gauges -- you can see where the needle is relative to the red zone -- but if you have an air-integrated computer with a digital readout, it can look as if the imperial diver has loads of air (b/c the computer is still showing a big number) even when their tank is practically empty.

Zept

 

[budgy]

In Scotland, as well as a finger for 10 bar we use a fist for fifty bar and the time out sign for 100 bar.
I suppose its always easier using what your used to. I use the metric system and I am quite lost when you quote imperial figures.

 

[Rick Murchison]

Ah, life is just full of those pesky numbers, ain't it? I mean, why do we have 60 seconds in a minute? Why not 100... it'd be so much easier to deal with. But then we really should revise to 10 hour days, 100 minute hours and 100 second minutes don'tchathink? And Latitude/Longitude, with degrees, minutes and seconds... and then suddenly tenths and hundredths of seconds... 60/60/100??? Who thought that up?
And aviation is forever mired in feet for altitude and knots (an inexact speed depending on which nautical mile you choose) of all things for speed... except when they use mach number, where your speed varies with temperature!
And international businesses deal in 42 gallon barrels (158.98l) of oil...
And 365.24219 days in a year... but that's increased by a full second in the last 180 years, so what's a fellow to do?
What a mess... how inconvenient...
I dive with both metric and imperial instruments, but I find my little pea brain converting everything to imperial for understanding. Imagine that.
Rick

 

[caymaniac]

I like your answers Rick, with all the different ideas on how much is how much you might say that someone is using one finger to point out differences in measurement ( mainly the middle finger):boom: .

Dive Safe,
Caymaniac

 

[miked]

Hi Rick,
Good post. I think you said it all.
As a Math teacher, I get frequent "doses" (a great, specific amount) of trying to sort out that confusion.
BTW, I followed the link in your post in in the "hoods and hair" thread. Nice site, great pictures!!
Good luck,
Mike

 

[padudle]

Hello All,

My wife is getting her first equipment setup and she decided to get a bar-meter analog spg. This seems wise to me. Besides the local certification hole (Santa Rosa Blue Hole) we have only seen bar-meter SPG's. This includes Mexico and Australia. I think the same would hold true for Canada, Europe and Asia.

During our last trip to Mexico I was the odd man out with psi-feet on my guage. The other divers were using the equipment supplied by the shops that were in bar-meters.

I suggest that we all stop buying psi-feet SPG's and put an end to this issue.