Voluntary Conversion - Imperial to Metric

[tkdgodess]

I buy gas in litres, buy meat by the KG, run by the KM - but think 8 blocks is a mile, 1.6 K = 1 mile, drive in KM, height in feet, weight in pounds...

I was in elementary school when the "conversion happened"

I dive PSI and Feet. Anyone converted to meters and bar? I'm thinking about just doing it!

 

[Pullmyfinger]

I'm switching over also. I just ordered SPG's in BAR, my Nitek Duo is switchable to metric. I have a Uwatec bottom timer that Imperial, I'll use it in addition to my Nitek in gauge mode until I get used to thinking in metric.
I have a bunch of tables I made up for gas consumption calculations, I'll have to re calculate these in metric units.
I've been using NOAA dive tables, these are already in Imperial and Metric.
Eventually I'll get another Uwatec backup bottom timer in Metric, once I get used to dealing with metric.
In the meantime, it's nice to have an Imperial reference to compare with.
Now it's just a matter of getting over the confusion from thinking of my aluminum 80's as 11 litre tanks, and a 40 as a 5.6 litre tank.. I'm still getting my mind wrapped around that idea
I should probably quit Imperial cold turkey, though. ;-)


-Mitch

 

[Kevrumbo]

Discovered an interesting one-to-one correspondence between depth and my physiological gas consumption rate in bar/min, while diving with double AL80's (and why I now prefer using the Metric System even in the US). An example:

18m depth, same as 2.8 ATA -->translates directly to 2.8 bar/min
21m depth, same as 3.1 ATA -->translates directly to 3.1 bar/min
24m depth, same as 3.4 ATA -->translates directly to 3.4 bar/min
27m depth, same as 3.7 ATA -->translates directly to 3.7 bar/min
30m depth, same as 4.0 ATA -->translates directly to 4.0 bar/min

So for an arbitrary & convenient time period of say, for example 10 minutes, at a particular depth above, I would expect to consume:

2.8 bar/min(10min) = 28 bar
3.1 bar/min(10min) = 31 bar
3.4 bar/min(10min) = 34 bar
3.7 bar/min(10min) = 37 bar
4.0 bar/min(10min) = 40 bar

Essentially then, all I need to know is depth in ATA and time at that depth, and I'll know instantly how much gas I've consumed --even before looking at the SPG!

Parameters:
Surface Consumption Rate (SCR): 22 litres/min*ATA [My physiological gas consumption rate]
Twin 11 litre tanks (double AL80's): 22 litres/bar total tank rating.

Now dividing SCR by total tank rating (22 divided by 22) yields: 1 bar/min*ATA (and that's the secret easy math trick discovered --the unity conversion ratio of 1 bar/min*ATA which lets me transform directly from depth to a delta bar per minute rate, and the resulting SPG bar consumed).

For a Single 11 litre tank:
Surface Consumption Rate (SCR): 22 litres/min*ATA
11 litre tank (single AL80): 11 litres/bar total tank rating.
Dividing SCR by total tank rating (22 divided by 11) and I get 2bar/min*ATA rate for single tank diving.

The point of all the above is, I'd rather work with easier unit chunks such as 1bar/min*ATA in metric, rather than 14.5psi/min*ATA in imperial units --especially doing on-the-fly, during the dive gas calculations & remaining estimations.

 

[Pullmyfinger]

I've read one of your earlier posts where you mentioned this. I still have to convert my surface and depth consumption rate calculations to metric and see if I end up with something similar. Your consumption rate works out great for 11 litre tanks.

I dive aluminum 80's for doubles, an 80 for single tank diving, and a 40 for a deco tank. I also have a 100 that I sometimes dive.

80's are 11 litres, a 40 is 5.6 litres, and a 100 is 13 litres. I'm still working on this aspect of converting to metric.

I already know the answer...but, how is Palau? ;-)

-Mitch

 

[DiveNav]

I actually went the other way around .... almost.

I am a metric guy (Italian) so all my math / formulas / algorithms are in metric system, but .... to test our simulator / classes for US customers I HAD to convert / adapt myself to Imperial ... and now I am super confused .... my car shows miles/hour, but I check the temperature in Celsius

Alberto (aka eDiver)

 

[Kevrumbo]

I've read one of your earlier posts where you mentioned this. I still have to convert my surface and depth consumption rate calculations to metric and see if I end up with something similar. Your consumption rate works out great for 11 litre tanks.

I dive aluminum 80's for doubles, an 80 for single tank diving, and a 40 for a deco tank. I also have a 100 that I sometimes dive.

80's are 11 litres, a 40 is 5.6 litres, and a 100 is 13 litres. I'm still working on this aspect of converting to metric.

I already know the answer...but, how is Palau? ;-)

-Mitch

Palau is fantastic. . . ! (Saw my first Bull Shark:shocked2: --scary big & "girthy", built like a dump truck!). But just like anywhere I dive overseas, I get paired with an Asian or European, so I have to be comfortable communicating in the metric system.

Mitch, just use my figures above as a reference baseline. So if you end up with a better nominal Surface Consumption Rate (SCR) --for example 30% less than my rate of 22L/min*ATA-- just for starters take roughly 30% less of my Depth Consumption Rate (DCR) numbers above. . .

 

[Pullmyfinger]

Kev,

Thanks for posting your numbers. It will give me some great reference points as I complile my own numbers.
Enjoy the rest of your trip.

-Mitch