Cutaneous Decompression Sickness

[Dive-aholic]

...The only other thing to watch is your oxygen exposure. You use a CNS chart to run your oxygen clock, and for extended exposure to high oxygen concentrations, such as in repetitive technical diving, you run an OTU table to check long term (i.e. whole body, or pulmonary) exposure.

In the normal run of the mill recreational diving, neither one is much of a problem...

Not to split hairs, but OTUs aren't even that great a concern in technical diving. Bill Hamilton noted in his REPEX paper that tracking OTUs was designed for saturation divers with no opportunity to return to the surface (normal O2 pressures). However, all scuba divers will eventually return to the surface and that time is enough to allow enough blow off time to set the pulmonary clock back to zero each day. It's pretty much impossible to accumulate 300 OTUs a day in normal recreational and technical diving. You'll hit your other limiits before you hit your OTU limit. Just stay within your 45 minute single dive exposure for O2 at 1.6ATA and you'll never come close to 300 OTUs.

I know this is out of the scope of the original thread, but I felt like stirring the pot a little tonight.

 

[wylerbear]

Did 2 dives today without incident. Whew!
First dive maximum depth was 61'. Dive time 58 min. Did very long, slow ascent and spent a good amount of time at 25-30' and a nice long safety stop.
Second dive maximum depth was 52'. Dive time 73 min. Again did long, slow ascent, extended time in shallow water, and long safety stop.
Both dives were awesome!
I hope others have benefited from the info on this thread.
Safe diving!

 

[MilitantMedic]

Sounds good!

 

[Dive-aholic]

Glad to hear things went well!

 

[wardric]

It was actually VPM-B (off the top of my head), but you are right the wheel doesn't let you do it. I used a bad example to highlight that.

The weel wont let you do that profile... but a computer like the Cobra/vyper or any other might let you, am I wrong?

 

[MilitantMedic]

You're right that's a no-go on the wheel. As far as computers go a computer "should let" you do it. But keep in mind a computer never "lets" you do anything and conversely it nevers stops you from doing anything not so bright. It's there for guidence.

Computers also IMO don't really have analyzable algorithms, so you never really know how or why they are coming up with the information they do. Some computers let you do some wacky stuff. Plus they break, like I "had" a 9 hour dive @ 17 feet. (I should probably log that one too)

Moral to my rant: Use the grey matter between your ears.

 

[wardric]

Right, your moral says it all.
In fact, I think the more sophisticated your dive planning equipement gets, the less security margin is left for the diver. The table's square dives is more conservative than the multilevel (wheel or other) which is more conservative than a computer because these take account for depth in smaller increments of time (dont know if I express myself correctly there (language barrier:05: ). It reminds me of hunting. Wether you are hunting with a bow or a rifle, you have the same chance of missing if you dont stay within the limits of your equipement. If you do, they are equally safe or effective.