Info The Rule of 120

[EFX]

But what I do know is that I've only ever been bent twice (both semi-deserved...

Ummm......this does not give us any confidence for your average depth and/or modified rule of 130. I simply don't understand why anyone would bother with any of this while diving, and unless you don't have access to your computer or tables to do some pre-dive planning, what's the point?

 

[boulderjohn]

Ummm......this does not give us any confidence for your average depth and/or modified rule of 130. I simply don't understand why anyone would bother with any of this while diving, and unless you don't have access to your computer or tables to do some pre-dive planning, what's the point?

This reminds me of a similar debate about a dozen years ago, with John Chatterton taking the side of the computer users. He asked much the same question, and the reply was that doing all the calculations gives the diver something to think about during the dive. Chatterton replied that he had plenty to think about on his dives and didn't want to be distracted from that. He said that if you need something to think about during your dives, you need to start doing more interesting dives.

 

[Bob DBF]

Having used the Navy Dive Tables for decades, I didn't use the rule of 120 because it would cheat me out of bottom time, easier to remember the table, or read it. The rule won't give you 5 min at 190'.

 

[Manatee Diver]

The rule won't give you 5 min at 190'.

The people that designed it would call that a feature not a bug as they don't believe you should be at that depth without helium.

 

[tursiops]

The people that designed it would call that a feature not a bug as they don't believe you should be at that depth without helium.

The rule appeared long before helium was popular. Diving to 200 ft on air was common in the US and Europe.

 

[Manatee Diver]

The rule appeared long before helium was popular. Diving to 200 ft on air was common in the US and Europe.

I stole it from the GUE.

 

[tursiops]

I stole it from the GUE.

Late comers to the game.

 

[oya]

Ummm......this does not give us any confidence for your average depth and/or modified rule of 130. I simply don't understand why anyone would bother with any of this while diving, and unless you don't have access to your computer or tables to do some pre-dive planning, what's the point?

Two points here:

The no-confidence vote-
Way to maintain the stigma of DCS. The truth of it is that you either know divers who have been bent, but won’t talk about it because of the stigma, or you haven’t been diving long enough. (Or neither you or anyone in your sphere dive anywhere near inert gas levels like that).

DCS needs to be destigmatized so that when someone on the boat thinks they might have some symptoms they feel comfortable speaking up rather than being thought of as unclean or whatever so they suffer in silence, praying to god it just goes away.

Why I bother-
Many are the dives I look down at my computer, when I’m at, say, 30 feet, which says “NDL 99” and I am still miles away from my turn pressure.
BUT
My average depth + time (1/2 my time, anyway… because I have to swim back along the symmetrical exit) = 130

If I’m guiding someone who is not deco trained… time to go. Because I know that if I don’t, even though my computer is currently telling me that I am no-deco diving… by the time we get to the exit we will have a deco obligation.

I just deleted “PM me for more info.” Because talking to some dude on the internet isn’t really a good replacement for deco training.

 

[oya]

Late comers to the game.

As far as bronze-age Persians who were diving using a waxed goat stomach we a breathy bag, Aqualung was a latecomer.

“Recent” doesn’t equal “wrong.”

Message sent on an iPhone using cell towers and satellites that are in space., all all of which get firmware updates every fifteen minutes.

 

[oya]

The people that designed it would call that a feature not a bug as they don't believe you should be at that depth without helium.

Everyone knows that if you breath nitrox as deep as 101 feet you catch fire.