Units of Measure in Diving?

[=C=]

I use metres, bar and pounds. Most of my weights are in pounds so I tend to use that instead of kg when writing down my weight.

I have no problems switching to imperial though (even though metric is superior), and would depending on who I was diving with. In Fiji me and my buddy were the only non Americans on our boat most of the time and they gave dive briefings using imperial.

HOLD ON THERE!!!

Meters and Bar represent a lower level of accuracy in our sport. How can you call that superior?

 

[Sas]

. OK, OK, I guess were all bozos on this bus, or at least geeks!

You're also a Star Wars apologist I think he said that because Lucas didn't know what a parsec was!

HOLD ON THERE!!!

Meters and Bar represent a lower level of accuracy in our sport. How can you call that superior?

Please explain how metres and bars are less accurate.

 

[Walter]

Why are the poll choices "inside the US" and "outside the US?"

 

[Akimbo]

Meters, Celcious degrees, Bars and grams.

Thermal units… hmmm. OMG, you must be more obsessive than me if you apply thermal compensation in your gas management calculations!

Seriously, I stand corrected.

 

[Akimbo]

Why are the poll choices "inside the US" and "outside the US?"

From my experience in the US, the vast majority of divers use Imperial units. I was curious how many used them where their official national units are SI. Other countries in the Americas because of proximity to the US, and the British Common Wealth countries for example. Then there are also US ex-patriots who may or may not have made the transition.

 

[gsk3]

Holding your depth to 1 meter is a lot easier than holding it to one foot. On the other hand, if your depth gauge/computer shows you fractional meters, then you'd be better off for mid-water ascents, since you could more finely see when you're deviating up/down and correct sooner. Not sure if any computers do that.

As a side note, while we're being all technical, kilograms technically measure mass, not weight. Hardly makes any sense when you're talking about lift. So who measures their lift in Newtons?

 

[Akimbo]

I use metres, bar and pounds. Most of my weights are in pounds so I tend to use that instead of kg when writing down my weight...

To be fair, accuracy is a measure of the instrument's precision. Units the instrument displays is irrelevant. I believe resolution betters describes your point.

Some units are courser in some base units such as meters and decrees Celsius, but are much finer in others like Grams and Pascals. That is what decimal points and prefixes like Kilo and Mega accomplish. In Scuba diving we rarely measure mass much closer than a pound. Half a Kg is 1.1 pound and is the smallest common diving weight in Europe as well.

Meters may seam a little course to people used to Feet, but given the accuracy of our depth gauges and computers; it is in the margin or error. Since Mechanical depth gauges read in 5 or 10 FSW increments at best, is it any different if the gauge displays units with hash marks at 1 MSW and numbers in multiples of 3 (at the shallow end anyway)?

However, many units are very convenient in diving. Notice how close all the SI units are to multiples of 10.

For those unfamiliar with SI (Système International d'unités), commonly called the Metric System, here are some conversion factors:

One Standard Atmosphere equals:

SI Units
101,325 Pascals
101.325 KPa or Kilo Pascals or 1000x
0.101325 MPa or Mega Pascals or 1 Million x
1.01325 Bar
10.0627586096078 Meters of Sea Water
Imperial Units
14.695948775 PSI
33.899524252 Feet of Fresh Water at 4° C
33.014299900156 Feet of Seawater based on a density of 64.1 Lbs/Ft³​

 

[captndale]

Safety and practicality are what is important. It really does not make any difference what set of units are used as long as they are used consistently. All team members must be using the same units for optimal communications and optimal safety. Remember NASA and the Mars probe. Different contractors using different units of measure led to the lander's failure.

 

[bracko]

From my experience in the US, the vast majority of divers use Imperial units. I was curious how many used them where their official national units are SI. Other countries in the Americas because of proximity to the US, and the British Common Wealth countries for example. Then there are also US ex-patriots who may or may not have made the transition.

Australia, Canada (from what I've seen) NZ, India (i believe), Hong Kong... all use SI units.

the UK now actually use SI except for mph which is most likely a cost varient of changing street signs than anything.

 

[ditch-diver]

Australia, Canada (from what I've seen) NZ, India (i believe), Hong Kong... all use SI units.

Actually in Canada, while being a metric country the vast majority dive imperial units at the recreational level. Not sure about the techies...

We'll drive 5km to the 100' dive, and fill our log books with the air temp being 24C and the water temp 57F