Max Depth vs. Cylinder Capacity

[Akimbo]

I fear that there is a trend in diver training to depend too much on rules and technology to the detriment of understanding and skills. Unfortunately, rules of thumb like Lamont's are too often taken out of context and become the end of the story rather than just the beginning.

Anyone who has ever seen a large male wearing a set of doubles so they can match bottom time with their female buddy should understand that this rule is too general to be broadly applied.

 

[ianr33]

Anyone who has ever seen a large male wearing a set of doubles so they can match bottom time with their female buddy should understand that this rule is too general to be broadly applied.

Maybe. But its better than "be back on the boat with 500 psi"

 

[elmer fudd]

I fear that there is a trend in diver training to depend too much on rules and technology to the detriment of understanding and skills. Unfortunately, rules of thumb like Lamont's are too often taken out of context and become the end of the story rather than just the beginning.

Anyone who has ever seen a large male wearing a set of doubles so they can match bottom time with their female buddy should understand that this rule is too general to be broadly applied.

You're right of course, but the one thing I'd really be wondering about with the male/female team would be her ability to bail him out in an OOG situation. That 1/3 in reserve for emergency starts to look pretty meager when your buddy uses twice the air you do.

 

[Akimbo]

You're right of course, but the one thing I'd really be wondering about with the male/female team would be her ability to bail him out in an OOG situation. That 1/3 in reserve for emergency starts to look pretty meager when your buddy uses twice the air you do.

Good luck getting her to pack doubles

I also question the 1/3rd rule of thumb. It is excessive for a recreational dive in 30' and wholly inadequate for some restricted overhead profiles (cave, wreck, or decompression).

 

[Akimbo]

Maybe. But its better than "be back on the boat with 500 psi"

I am usually back on the boat with 2-300 PSI. 500 PSI is also a mindless rule.

 

[ianr33]

I also question the 1/3rd rule of thumb. It is excessive for a recreational dive in 30'

Now that is one of my pet peeves !!!! What the heck does the rule of 1/3 rds have to do with Open Water diving? Never have been able to figure that one out.

The way I plan dives is to allow for one catastrophic failure at the worst time. Gives me a warm fuzzy feeling

 

[D_B]

I'm sorry, but I cant do the math in my head, and trying to do SAC calculations and such just confuses the heck out of me ... I can understand that "ridiculous rule" and it works for me

( I do know what my average SAC rate is, but only from using online calculators based on total air consumption and also from downloading my dive computer )

 

[Akimbo]

I'm sorry, but I cant do the math in my head, and that "ridiculous rule" works for me

If you find it works for you, then it is not a ridiculous rule. I submit that "guideline" would be a better choice of words than "rule". It is when it is blindly followed as an unbending rule, without understanding the functional range it works within, that I question.

In the end, it is somewhat academic since plans are modified during the dive based on SPG readings anyway. The worst case for a recreational diver is they can’t see what they hoped and learn from the process.

 

[D_B]

Guideline, yes, that's a better description.

... the math part of my brain has never been good, and I think it's atrophied too

 

[elmer fudd]

I'm sorry, but I cant do the math in my head, and trying to do SAC calculations and such just confuses the heck out of me ... I can understand that "ridiculous rule" and it works for me

( I do know what my average SAC rate is, but only from using online calculators based on total air consumption and also from downloading my dive computer )

I took 2 years of post calculus, (decades ago), so I'm pretty good at math, but when I'm at 120' I'm hard pressed to add 4+4 much less multiply 10 x's my depth and add 300. What I can do though is remember, a maximum depth that we plan to go to and a turn around pressure.