Metric or Imperial?

[Bennno]

Whenever the needle gets to "E", you just conveniently find a gas station to fill-up.

No, I start looking when it gets close to 'E'. My car doesn't tell me how many miles I have left on the tank.

 

[JohnN]

BAUE Z Factor Table

Oops, I was think 300 oK and looking at the 400 oK line

so @ 300 oK and 3500 PSI 6.6% which is ~ 8 cuft Still not insignificant

 

[agilis]

So by analogy, this is like qualitatively watching the "gas gauge" on a car: Whenever the needle gets to "E", you just conveniently find a gas station to fill-up.

Breathing Gas Consumption on Scuba at depth is a lot more vital quantitatively than your rhetorical trivialization above. . .

Read and Learn.

So by analogy, this is like qualitatively watching the "gas gauge" on a car: Whenever the needle gets to "E", you just conveniently find a gas station to fill-up.

.

Not if you're attempting a transect of the great western desert.

I'm aware that gas management is a very different thing. That's completely obvious and requires no elaboration. In any case it has nothing whatever to do with metric vs imperial, and very little to do with math calculations while submerged.

 

[Kevrumbo]

Not if you're attempting a transect of the great western desert.

I'm aware that gas management is a very different thing. That's completely obvious and requires no elaboration. In any case it has nothing whatever to do with metric vs imperial, and very little to do with math calculations while submerged.

So in any case then, explain objectively your opinion how "it has nothing to do" with math application of a depth gauge, timer and SPG: Basic Tools in either metric or imperial that we were all fundamentally taught to use from basic open water course, and learn how to use smartly as we progressed with experience and advanced courses.

 

[Kevrumbo]

So in any case then, explain objectively your opinion how "it has nothing to do" with math application of a depth gauge, timer and SPG: Basic Tools in either metric or imperial that we were all fundamentally taught to use from basic open water course, and learn how to use smartly as we progressed with experience and advanced courses.

Again, the motivation to dive smartly, be safe (and have some fun too) is here:

http://api.ning.com/files/KHeKOD-fw...pVsh/BattlefieldCalculationsDeliaMilliron.pdf

 

[Patoux01]

Oops, I was think 300 oK and looking at the 400 oK line

so @ 300 oK and 3500 PSI 6.6% which is ~ 8 cuft Still not insignificant

The usual dive shop (here) fills to ~230b, so you'll be somewhere between 1.03 and 1.07, most likely around 1.045, big deal if you ask me.

 

[Freak*Flag*Flyer]

what AJ said. Metric is better, it makes more sense, tanks are measured directly instead of indirectly, depth is easier to think about because of atmospheres which makes all the calculations easier. My gear is in metric, but only because my two primary dive buddies are engineers and think in metric, so it works for us, we also dive with "same ocean" principals, so there isn't much communication going on with regards to those units. Their pressure gauges are in imperial because they haven't had a need to change them.

Imperial is certainly easier if you dive with varied buddies, or dive in a team, it is best to stay on the local system, which is imperial on this side of the pond unfortunately.

I too, just lean more towards metric. I've been looking at dive computers and at least the ones I'm reading about, will calculate both in metric and imperial. My big issue is I suck at math, and I understand the metric way a bit easier than the other.
Thanks AJ and Tbone for the advice!

D

 

[Freak*Flag*Flyer]

Anyone who has a little scientific education immediately realizes how much easier metric is than Imperial. If you plan to mostly dive solo, then it wouldn't be unreasonable to buck the US system and do your own calculations in metric. But when you have to plan a dive with a buddy who prefers Imperial, you will find that using metric for your numbers and Imperial for your buddy's, is inconvenient and has the potential to introduce errors and result in miscommunications.

From looking at the different dive computers, at least the ones I'm reading about calculate in both. My big issue is I am not too good with math, but doing calculations in metric I feel a lot less dumb. lol

D

 

[BoltSnap]

Quite literally none of that is true. Tank capacity is ALWAYS dependent on tank pressure. Guess what, an AL80 at 200PSI certainly doesn't have 80 cuft of gas in it. Seriously, some of the things you've said on this forum are just plain wrong. About the ONLY thing that imperial has ANY advantage is is if you have a 3000psi fill and you're diving 1/3rds with no consideration for actual gas volume.

In the US, we use ft3 to denote the cylinder’s total capacity of how much air it can hold, you don’t need to know the pressure in the cylinder. In the metric diving world, they give you the internal size/volume of the cylinder but they don’t give you its total capacity of how much air/gas it can hold. You’ll need to know the service pressure of the cylinder in this case and multiply this pressure times the internal volume of the cylinder to get the actual total capacity of how much gas this cylinder can hold. For example, when I tell you that I am using a “steel 12L” Tank, you have no idea much gas it will actually hold until I give you the service pressure. I have several older 15L tanks that have 200Bar service pressure and I also have newer 15L tanks with service pressure 232Bar. There are also cylinders (12L, 10L, 6L) that can be filled to 300Bar yet their internal volume is exactly the same as the 12L, 10L, 6L that are rated with lower/other service pressures). If I didn’t specify the pressure, in Bar, for each type of tank, you would think that they hold the same amount/capacity of gas as most people do when they don’t know any better (they don’t know that same size tanks can be rated to different service pressures). In contrast, in the US, you are told the total capacity of the Tank (how much volume of gas it will hold), i.e. 130ft3, 100ft3, 40ft3, etc. The point here, for ME, it is easier and makes more sense to me to just tell me the TOTAL cylinder capacity of how much gas it will hold without me having to sort out the multiplication and having to inquire about the service pressure.



As for the pressure gauge, the Metric gauge has a range between 0 – 400 Bar (or close to this number) when the gauge using imperial units, or PSI, is has a reading range of 0 – 5000 PSI (or close to this range. Both types have “notches” that represent 10 of each unit. For a standard AL80 in the US with a service pressure of 3000PSI, a gauge with imperial units would show the pressure of this cylinder when full to its services pressure as having 3000PSI but a gauge with metric units would show 207Bar. For me, the gauge with imperial units, PSI, has a finer granularity/resolution in terms of its pressure reading and each notch will have a smaller pressure jump from/to previous/next notch than in the metric, Bar, gauge.



The same explanation applies to the depth readings for computers where the in the imperial system, each whole number represents a smaller/finer reading of depth (1 foot = 0.3048 meter) than in the metric computer. It is easier for me to keep track of depth and gives me better control when I use the imperial system with WHOLE numbers and with finer granularity than it is for me to use the metric system even if the computer would show depth in decimals. For ME, I like whole numbers that represent finer scale; it is more convenient and easier to track.



The Fahrenheit scale, again, has more numbers in its temperature range and, in this context, easier to follow.



I am talking here within the context of diving and reading gauges/computers at a glance not about making calculations. When I am making engineering calculations (not while diving), the metric system is far superior in this context

BTW, at the end, it depends on who you are diving with and what system they are using. I had to switch to metric where I live now because everyone else around me including my dive buddy uses the metric system. For me to be "conversant" with the rest of the dive team, I had to use the same units/language they are using. My preference is still the imperial system in this context.

 

[agilis]

So in any case then, explain objectively your opinion how "it has nothing to do" with math application of a depth gauge, timer and SPG: Basic Tools in either metric or imperial that we were all fundamentally taught to use from basic open water course, and learn how to use smartly as we progressed with experience and advanced courses.

You regard the use of a watch, a depth gauge and an SPG while submerged during a dive as a math application? Using the tables is basic and simple, more application, not really calculation.

Serious calculation belongs in pre-dive planning. Most contingencies should be covered by substantial safety margins and common sense.