Padi Tables and Cold Water

[pcarlson1911]

SO here is the scenario:

32 minutes, max depth of 60' (for 5 minutes) the rest of the dive at 40'. Should I add 10' to the maximum depth to find my pressure group, or, should I simply use 60' since so little of the dive was at that depth.

What would you do, (other than consult your computer)

 

[Ber Rabbit]

The way we train and dive, I'm NAUI, you use the deepest depth reached no matter how little time you spent there. When diving in cold water or doing strenuous dives after we determine our ending group letter we round to the next group letter (ex: if you are a D diver you round to E) as a safety measure.
Ber :lilbunny:

 

[pcarlson1911]

I forgot to ask part of my question. What is "cold water"

so, what would the comparison be? Is rounding up a group equivalent to adding ten feet to depth on the NAUI table? PADI teaches to add ten feet. Adding ten feet is a strong "penalty" on the PADI Table, and it actually takes us pretty close to the NDL.

I have no desire to endanger our safety whle diving, while at the same time, we would like to maximize our bottom time.

We did figure our dives according to PADI directions, and with 1.5 hrs as a SI it was a non issue, I am just curious how others handle cold water.

 

[Jake]

Similar to what Ber Rabbit stated, my PADI training says use the maximum depth as the depth for the whole dive when using the Recreational Dive Planner. If you're using PADI's multi-level planner or the wheel, adding 10 feet isn't a bad idea. It's probably overly conservative if you're *only* diving cold water (and not, say, cold water AND surge AND bad viz AND big waves, etc), or if you're diving in comfortable, familiar conditions.

 

[Jake]

I forgot to ask part of my question. What is "cold water"

Here in SoCal, I've been taught that cold is generally less than about 60 degrees F. Above that, you have moderate, and then warm.

We did figure our dives according to PADI directions, and with 1.5 hrs as a SI it was a non issue, I am just curious how others handle cold water.

I've never found cold to have an adverse physiological effect on me in and of itself that would require me to be as conservative as the 10 foot rule. However, yesterday I was working on my Search and Recovery certification in heavy surge, poor viz, and generally tough conditions, and in that case I did add 10. You never know how your body will act to physical *and* mental stress. Better safe than sorry in that case.

Where I find the need to be most conservative is on air--surface with more than you might in great conditions, on ascent--slower than 1 foot/2 seconds if possible, and take a slightly longer SI.

 

[moneysavr]

Cold water to be is any temp were you have the chance with thermal protection to loose body heat,
so you could in theory be a cold water diver in the Florida Keys in lets say 72 water temps but with high winds top side as you dri off you will loose your core temp and have seen many divers loose so much body heat they call the second dive.

To be safe,
1. Run your table to max depth as you said 60 FSW
2. Add 10' as its a cold water dive and this is a great Conservative factor-i.e. safety net!
3. use your computer,but know your tables-a diver that uses tables is a safe diver,computers die= Table divers don't!! even if you run the no#s at home prior to the dive,Macho factor.
Dive safe,
Brad

 

[Ber Rabbit]

Yes, rounding up a group letter is equivalent to adding 10 feet.

Cold is a bit subjective as the others said, we usually call 55 degrees and under cold in a 7mm suit but I freeze in 72 degree water in a 1/4 inch suit so I take my slowed off-gassing ability into account then too.
Ber :lilbunny:

 

[Eeyore48104]

I'm with Ber. Anything less than 55* is cold. (Except with my body fat - then, cold is when there's ice on the top! )
Then you take the other conditions into account.

 

[pickens_46929]

Yes, rounding up a group letter is equivalent to adding 10 feet.

Cold is a bit subjective as the others said, we usually call 55 degrees and under cold in a 7mm suit but I freeze in 72 degree water in a 1/4 inch suit so I take my slowed off-gassing ability into account then too.
Ber :lilbunny:

Actually round up a letter will always be more conservative to adding 10 ft.

There are cases when you can add 10 ft. to max. depth and still be in the same letter group as you would have been with the actual depth. PADI does it one way... NAUI does it another way. Both have the same goals of factoring in an additional safety margin.

Generally anything under 60 F is considered cold for me...

 

[Charlie99]

Actually round up a letter will always be more conservative to adding 10 ft.

Assuming your statement is in regards to the USN table, it is only true for depths of 60' and deeper.

A typical example of where rounding up one repetitive group is NOT more conservative than adding 10 feet is a 40', 70 minute dive. letter group G. H, the next letter group is reached after only 60 minutes at 50'. A 50', 70 minute dive would be group I -- an increase of 2 letter groups over a 40', 70 minute dive.

It is "usually" more conservative to add a letter than to add 10', at least at deeper depths, but it isn't "always".

On the PADI RDP, with more letter groups, adding 10' is generally more conservative.