Metric vs Imperial

[Oldbear]

The maths aren't so hard once you objectively understand the units you are trying to derive. . .

IMO Kevrumbo is correct! :cool3:

I have had a fair amount of diving experience and training with both systems, and while imperial is easier for me to think about (native system), the metric is overall a better system. Besides Pig Latin, the metric system is probably the most easily foreign language for Americans to Learn (if they would try). :bonk:


I did my PADI OW and AOW with the imperial system.
I did my PDAI Rescue with the metric system.
I did my BSAC Dive Leader with the metric system.
I did my PADI Divemaster with both (my choice).

Now I own two analog SPGs; one for each system and my Atomic Cobalt is easily switched between metric and imperial. I carry in my kit both imperial and metric PADI Dive Planners and BSAC 88 dive tables. Regardless where in the world I dive or which system I use, I feel confident in my pre-dive planning abilities and after dive each dive compare the plan to the actual dive profiles.
:work:


Being verse in both systems has greatly enhances my diving experience. It is quite similar to fish identification. When I first dived I saw pretty yellow fishes and vibrant blue fishes. Now I enjoy observing Rock Beauties (Holacanthus tricolor), Spotfin Butterflyfish (Chaetodon ocellatus), Yellowhead Wrasses (Halichoeres garnoti), Blue Chromis(Chromis cyanea) and Queen Angelfish (Holacanthus ciliaris).
:fish::goldfish::fish::goldfish::fish::goldfish:


~Oldbear~

 

[pedo]

In general I would prefer if we moved to metric but metric is arbitrary as well. I actually prefer Fahrenheit to Celsius for everyday use. Rarely do temps go outside 0 to 100 F avoiding the need for negative numbers. I find that the Celsius scale is just to course, a change of one degree C represents too large a change.

[h=2]Celsius and Fahrenheit[/h]

 

[Tigerman]

For what purpose exactly is 1 degree celcius change too large of a change?
And.. you always have decimals..

 

[Akimbo]

In general I would prefer if we moved to metric but metric is arbitrary as well…

Are you kidding? What is arbitrary about the metric system?
SI base unit - Wikipedia, the free encyclopedia

Granted, the base units have been periodically redefined for greater precision, but all are based on the natural world.

 

[Kevrumbo]

The instruction that motivated me, an American Diver originally trained in Imperial US, to finally go all metric in Scuba is attached below. . ..

It talks about gas planning & management both pre-dive and during the dive, and how to do the calculations -with a lot of intermediate conversions between metric & imperial US. After a while I just simply decided to go completely with metric units instead.

 

[Hatul]

My iPod is not waterproof

Under water I don't do much calculating. The Remaining Bottom Air time calculation is done by my computer, and for Rock Bottom I use simply formulas that anyone can use regardless of units. One should be familiar with tank pressures in Bar or Psi.

Mostly the issue is on land when another diver uses a different system.

 

[nimoh]

I am going diving on Saturday and this thread has inspired me to (during the pre-dive briefing) give my starting pressure in bar and my MOD in meters just to see what kind of response I get.

Seriously, I would love to switch to metric, but unfortunately I would just end up having to do conversions for the people I dive with.

 

[boulderjohn]

The problem with converting a population from imperial to metric is that eventually you have to stop thinking in terms of converting from one to the other and just start thinking in terms of the new units. We have succeeded in doing that wherever we have just made the change and left no option. Soft drinks come in 1 liter and 2 liter bottles, and nobody seems concerned. Liquor is sold in metric units as well. Nobody seems to have a problem with that.

When America tried to convert, where I lived all of the highway MPH signs were printed with two numbers: MPH and KPH. Of course, everyone just looked at the MPH number and ignored the KPH number, making that transition worthless. In nearby Canada, they were making the transition, and they just put the signs in KPH. Everyone seemed to adjust pretty quickly, because they had no choice.

 

[Akimbo]

The problem with converting a population from imperial to metric is that eventually you have to stop thinking in terms of converting from one to the other and just start thinking in terms of the new units...

Personally, I found that thinking in Metric to be the easiest of all, to my great surprise. The hard part is being surrounded by 50-100 years’ worth of Imperial-based stuff. At what point does a minor design revision become a hard-metric redesign?

A hard metric redesign not only involves changing threads, but also all the other purchased components. It also means, where possible, to change to “hard” numbers like 25mm instead of just converting an inch to 25.4mm. Now you are changing tooling… like hardened steel injection mold$.

We are changing, slowly. More and more industries are designing new products in Millimeters for many reasons. Many components are actually designed and made elsewhere, international markets demand it, and ever-shorter product cycles create more opportunities to "bite the bullet".

The worst thing to do is make a half-way conversion. Mistakes go up tenfold, everyone hates it, and it takes longer. The most successful company-level conversions I have seen involves an over-night shift. The company literally confiscates and replaces all dual and Imperial-dimension instruments with Metric-only. It basically comes down to a “numbers is numbers” issue and they realize how easy it is. Once you are over that “hump” people start to think in Metric. Best of all, people quickly become Metric evangelists.

Sure you need to keep Imperial sockets, taps, and fasteners around to keep your infrastructure running, but most companies have to keep the Metric sets around now for the same reason.

 

[tridacna]

Here's what I find most annoying. When the US does support a metric measurement, they bung it up by changing the base units.

Example: Blood Glucose levels are measured in mmol/L in all countries except the USA where they use mg/dL.
Same for cholesterol and many others. And conversions are a giant pain in the ass because the conversions are not uniform. You have to factor in the molecular weight of each substance in each conversion..

I personally prefer furlongs per fortnight as a measure of velocity.