36 replies to this topic

[Capn Jack]

Remember your Instructor's admonition? "These are FINS, not flippers. This is your MASK, not your goggles."

What was this Instructor's problem? Who cares? So what?

Well, the fact is terminology is important. It may be fun, it may cost you a beer when you're at the lake on your checkout dives, but what happens later?

It is important to continuously learn in diving, and one of the ways is to demonstrate your attention to the details. Your peers and the professionals around you will be assessing you based on many factors, but if you're asking your buddy to turn on your "oxygen", the chances of being brought into a discussion about planned run time, bottom time and gas management for the dive may be nil.

One of the first things new divers start working on is improving their air consumption. The fundamental terminology here revolves around SAC - Surface Air Consumption, and RMV - Respiratory Minute Volume. It is important to not only know the acronyms, but to understand what they mean.

There is a good discussion of SAC and RMV here: What's the difference between SAC & RMV?

So, what would your dive friends be talking about if they were discussing soft bottom and hard bottom? (and no, it's not how Angelina is getting back to form after childbirth)

What other terms are puzzling you?
Or what terms did you find puzzling when you first started that you can share and clarify here?

No term will be considered too simple.

[6Gill]

Of course there are sometimes regional differnces....spanner=wrench,G-clamp=C-clamp and I sure the same thing exsist in diving.

[annasea]

What "other" terms? Hell, I'm still puzzled by hard bottom, soft bottom and RMV! (This thread is the first exposure I've had to these terms.)

I learned a bit about SAC though... And apparently mine's not too bad for a newbie!

[ScubaDadMiami]

What "other" terms? Hell, I'm still puzzled by hard bottom, soft bottom and RMV! (This thread is the first exposure I've had to these terms.)

I learned a bit about SAC though... And apparently mine's not too bad for a newbie!

SAC is what you are using on your current tank in psi. RMV is how many cubic feet per minute you use, and that can be converted into SAC for any size tank with any fill pressure.

Soft bottom = planned bottom. Hard bottom = absolute max bottom before your gas mix is dangerous. Some also use the term to indicate the physical bottom of the dive are (the sand bottom, etc.).

[annasea]

Thank you, Howard! You're the best!

[Dive_Girl]

What "other" terms? Hell, I'm still puzzled by hard bottom, soft bottom and RMV! (This thread is the first exposure I've had to these terms.)

And this is exactly why this topic has been brought up for discussion!

Terminology can be important in a number of respects, many of which Capn Jack touched upon above.

[WreckWench]

How about why and when you say 'gas' vs. 'air' such as in an OOA or OOG situation.

[Scubatooth]

air for means just that 21% o2

gas can be anything other then 21%(above or below)

mix to me means that there is helium in it as well.

Tomato, tomatoe, potato, patato ets all good, thats the problem with english so many different words have the same meaning

Tooth

Edited by Scubatooth, 17 August 2006 - 05:01 PM.

[PerroneFord]

Saying "air" is like saying "oxygen". It is a VERY specific term. Gas is the generic term. Just like most divers cringe when they read an accident report in the newspaper that says the divers oxygen tanks were emtpy, we cringe a bit when someone refers to air, because it carries certain connotations.

[PerroneFord]

What "other" terms? Hell, I'm still puzzled by hard bottom, soft bottom

Soft bottom = planned bottom. Hard bottom = absolute max bottom before your gas mix is dangerous. Some also use the term to indicate the physical bottom of the dive are (the sand bottom, etc.).

And even here there is discrepancy. When I refer to a soft-bottom, I am saying this is my intended dive depth. When I say "hard bottom" in relation to dive depth, I am saying I absolutely do NOT want to go below this depth. The ONLY term I use for when a mix might become toxic is MOD. It is an immistakable term with a clear and well understood definition.

So in my Oriskany post, my soft bottom was 100ft. That was the depth I wanted to stay around. 110 was my hard bottom, I told my buddy that I did not want to be below that depth for anything other than an emergency. However my MOD was 132ft. I knew that if the crap hit the fan, I had enough wiggle room to descend to the deck of the ship, sort out a problem, and ascend. Hard bottom can also mean a physical maximum depth available on the site. Hard Bottom can also be used to describe the nature of the site... sand, silt, rock, hard bottom, gravel, etc.

[Walter]

Remember your Instructor's admonition? "These are FINS, not flippers. This is your MASK, not your goggles."

I do remember that and with regard to mask/goggles there's actually a reason. A mask covers your nose, goggles don't. OTOH, there's no reason for the fins/flippers issue. I followed it strickly until I met guys who started diving about the time I was born. A very high percentage of them say, "flippers." If the old moss backs say flippers, who am I to say they're wrong?

Hard bottom can also mean a physical maximum depth available on the site. Hard Bottom can also be used to describe the nature of the site... sand, silt, rock, hard bottom, gravel, etc.

That's the way I use the term. Your MOD (Maximum Operating Depth) is not a hard bottom. There's nothing hard about it.

Just like most divers cringe when they read an accident report in the newspaper that says the divers oxygen tanks were emtpy, we cringe a bit when someone refers to air, because it carries certain connotations.

There's no reason to cringe if the diver is using air.

[CaptSaaz]

Saying "air" is like saying "oxygen". It is a VERY specific term. Gas is the generic term. Just like most divers cringe when they read an accident report in the newspaper that says the divers oxygen tanks were emtpy, we cringe a bit when someone refers to air, because it carries certain connotations.

If you don't read the newspaper, you're uninformed.
If you do read the newspaper, you're misinformed.
-Mark Twain-

[Dive_Girl]

Lets not get into that. I just don't use air.

Sounds like another good thread starter!

[PerroneFord]

Are you getting paid by the thread or something?

Sure, I'll be happy to post why I don't use air.

[hnladue]

::Miss Cranky Pants ON

You put AIR in your tanks... You put GAS in your car...You get GAS when you eat beans..... I don't care if it's 21% 32% 36% heilum, or whatever it's still AIR.....

In any definition of GAS I cannot find it talking about AIR we BREATHE.

gas n.
pl. gas·es or gas·ses

The state of matter distinguished from the solid and liquid states by relatively low density and viscosity, relatively great expansion and contraction with changes in pressure and temperature, the ability to diffuse readily, and the spontaneous tendency to become distributed uniformly throughout any container.
A substance in the gaseous state.
A gaseous fuel, such as natural gas.
Gasoline.
The speed control of a gasoline engine. Used with the: Step on the gas.
A gaseous asphyxiant, irritant, or poison.
A gaseous anesthetic, such as nitrous oxide.

Flatulence.
Flatus.
Slang. Idle or boastful talk.
Slang. Someone or something exceptionally exciting or entertaining: The party was a gas.

[source: Dictionary.com]

::Miss Cranky Pants OFF

Now I'm gonna put some bumpers on my boat.