Metric or Imperial?

[Kevrumbo]

I am not sure what we are arguing about here or if we are on the same channel. At the end, it is really up to where you are and what your dive buddies are using. You are controlled to a great extent by local culture and standards.

In regards to learning by "rote," I am not sure that I'd agree here. We are talking about recreational diving within recreational diving limits here. One needs to plan their dives on the surface and accounting for emergencies during the dive plan on the surface not U/W. If I have an "emergency" U/W, I'd go up and not wait at depth (in most circumstances). I'd activate my contingency plans I prepared on the surface.

BTW, it is very difficult to understand what you are getting at here to justify having to do "back of the envelope" calculations underwater. Perhaps you can provide a real life experience you have had so that we can have a more focused discussion.

BTW, when doing the same profile and with lots of experience, I can "guesstimate" how long my air is going to last me at a certain depth at a certain effort without having to do any calculations. It is a guesstimate based on decades of experience and thousands of dives where one develops "feeling" for their limits and performance U/W. For "ME," the imperial system gauges/units provide me with better "feeling" and much higher resolution for the data I need for my equipment. It is no big deal however and the controlling factor here will be the locale and dive buddies and what they use.

Of course you Pre-plan, but the simple point is you should also actively know time and pressure remaining "check point intervals" as well, leading to your turn-around and/or surfacing minimum remaining pressure value (also known as bingo or Rock Bottom Minimum Reserve).

By rote practice & experience -and as a professional NAUI Instructor- you should be able to derive, figure and quantify these "guesstimates" realtime during the dive . . . (And If you been reading and comprehending what's been posted in this thread).

So calculate -or at least elaborate- on these "guesstimates" for a common dive plan that you do.

 

[BoltSnap]

Ok, you got me. An LP72 has 72cuft of gas in it at 3psi. Right? Because sure the pressure of the vessel doesn't make any difference.

The LP72 will have 72ft3 of gas when it is filled to its service pressure, what is so difficult to understand here please?

How would you know how much gas a 12L tank steel tank will hold if I don't tell you its service pressure? Are all 12L steel tanks created equal if you don't specify their service pressure??

And your imperial spg faceplate, that's moving the same degree of swing as my metric faceplate spg is totally more accurate. Right? I mean, I guess I could paint individual bar marks on my SPG's and have higher resolution, after all, despite the fact they move the same distance and display the same volume of gas, it's all about what you think is correct right?

Doesn't the imperial gauge have more marks than the bar one?

Not to mention metric depth gauges display in tenths of meters, which is higher resolution than your imperial depth gauge if you want to make the argument that resolution of display convention makes any amount of difference.

You still use an actual mechanical depth gauge? Not a computer? I haven't used one since circa 87 when I bought my first dive computer.

As I have said, I prefer to read in whole numbers and not fractions especially when I am glancing at my computer while taking photos or shooting a fish or taking a lobster.

You like metric and have a better feeling using fractions, go ahead and be happy. Don't let the imperials system get you so grumpy.

the fact that if you're planning gas down to the psi you're and idiot who shouldn't be diving because you've decided red c*nt hair margins for safety are ok.

Why do you have to be so vulgar? Is it your inability to understand and communicate getting in the way for you to stoop so low? Perhaps you need outside help.

You don't have to like chocolate if you love vanilla, I don't care

 

[JohnnyC]

The LP72 will have 72ft3 of gas when it is filled to its service pressure, what is so difficult to understand here please?

How would you know how much gas a 12L tank steel tank will hold if I don't tell you its service pressure? Are all 12L steel tanks created equal if you don't specify their service pressure??

How much gas volume is contained in an AL80 at service pressure? Guess what, it's not 80 cuft. You HAVE to know the service pressure to know the available volume of gas. How hard is that to understand? LP72 means absolutely nothing unless you know the pressure to which it has been filled. How much gas is in an LP85 at 500psi? That doesn't change whether it's metric or imperial. Regardless of the convention you are using for measurement, you have to know the service pressure of the tank in order to calculate the available volume of gas. The fact that it's easier in metric is a bonus.

Look dude, I can explain it to you, but I can't understand it for you. Just because you're incapable of understanding it, doesn't mean you are correct.

 

[BoltSnap]

How much gas volume is contained in an AL80 at service pressure? Guess what, it's not 80 cuft. You HAVE to know the service pressure to know the available volume of gas. How hard is that to understand? LP72 means absolutely nothing unless you know the pressure to which it has been filled. How much gas is in an LP85 at 500psi? That doesn't change whether it's metric or imperial. Regardless of the convention you are using for measurement, you have to know the service pressure of the tank in order to calculate the available volume of gas. The fact that it's easier in metric is a bonus.

Look dude, I can explain it to you, but I can't understand it for you. Just because you're incapable of understanding it, doesn't mean you are correct.

When I am choosing between tanks based on their capacity, if you tell me their total capacity (how much gas they would hold when filled to their rated pressure), I will know immediately what they can hold and compare between them. In the US, you know this without needing any further information since we use their total capacity in ft3 to differentiate between them. In Europe, they say: "12L, 15L, 10L, etc." but don't tell you the service pressure so you have no idea which tank holds more (or less) gas until they tell you their service pressure. If you wanted to buy the 12L tank that would hold most gas, you will need to know its service pressure since you can have the choice between 12L/200B, 12L/232B, 12L/300B. You will also need to multiply internal volume (12L, 15L, etc.) with the service pressure for you to figure out which tank will hold more gas when all you know is their internal volume. A 10L/300B will hold more gas (106 ft3) than a 12L/232B (98ft3) but you wouldn't know that if I just told you 10L and 12L without their service pressure.

 

[The Laconic]

I'm not going to read the whole thread. But I know you've all concluded the answer is "metric". Faith in humanity restored!

 

[DevonDiver]

The fact that people need to argue/educate about 'service pressure'...and there is confusion over tank volumes and capacities with the imperial system is a good hint at which system is superior IMHO.

11.3L (AL80 metric) x 200 bar = 2260L

Anyone need night school for that? LOL

 

[Kevrumbo]

When I am choosing between tanks based on their capacity, if you tell me their total capacity (how much gas they would hold when filled to their rated pressure), I will know immediately what they can hold and compare between them. In the US, you know this without needing any further information since we use their total capacity in ft3 to differentiate between them. In Europe, they say: "12L, 15L, 10L, etc." but don't tell you the service pressure so you have no idea which tank holds more (or less) gas until they tell you their service pressure. If you wanted to buy the 12L tank that would hold most gas, you will need to know its service pressure since you can have the choice between 12L/200B, 12L/232B, 12L/300B. You will also need to multiply internal volume (12L, 15L, etc.) with the service pressure for you to figure out which tank will hold more gas when all you know is their internal volume. A 10L/300B will hold more gas (106 ft3) than a 12L/232B (98ft3) but you wouldn't know that if I just told you 10L and 12L without their service pressure.

Is it too hard to look up as well as do the calculation?
http://www.xsscuba.com/downloads/Worthington-Steel-Specs.pdf

 

[BoltSnap]

Is it too hard to look up as well as do the calculation?
http://www.xsscuba.com/downloads/Worthington-Steel-Specs.pdf

You are assuming that the whole world is using these cylinders and buy them from this same vendor in the US AND all of them will have access to the internet?

 

[DevonDiver]

You are assuming that the whole world is using these cylinders and buy them from this same vendor in the US AND all of them will have access to the internet?

Most manufacturers publish the specs for their tanks... it's a simple matter of Google.

If someone knew the specs for Faber and Catalina AL80s, they'd be prepared for diving in the vast majority of vacation spots in the world.

 

[BoltSnap]

Most manufacturers publish the specs for their tanks... it's a simple matter of Google.

If someone knew the specs for Faber and Catalina AL80s, they'd be prepared for diving in the vast majority of vacation spots in the world.

And why would one need to do this instead of just giving the tank capacity as they do in the US by its ft3, a one step process that doesn't need looking up or making any calculations? It isn't a big deal to look up the specs or do the multiplications and convert to ft3 from L (if need be) but if the capacity were available as it is in the US market (you noticed that the vendors readily have the capacity in ft3 in the US even for European made cylinders?), it would be more convenient.

Faber isn't the only mfg . in Europe, there at least two or more mfg. of steel tanks there. Faber may not be the largest one but I am not sure.