Past NDL. And then this???

[tursiops]

It would be interesting to hear the official reason for the 6 hour rule, but I always assumed it was because the surface intervals on the table are governed by the 60 minute compartment, which is why the table clears out in exactly 6 hours; that is, a diver finishing a dive at the Z level will be totally off the table--done with the A group--in 6 hours.

But that is really off topic. This dive was governed by a computer, not the tables.

The table may clear, but the body doesn't. Thus the various 12, 18, 24h rules for FAD.

 

[boulderjohn]

Thus the various 12, 18, 24h rules for FAD.

...rules made many years after the PADI tables were created.

 

[tursiops]

...rules made many years after the PADI tables were created.

That's the point! If the PADI tables (c.1994) say you are clear after 6h, then why did the DAN FAD workshop in 2002 say at least 12h, 18h if you've done multiple dives/days, and "substantially longer than 18 hours" for deco dives? And 24h is commonly advised by operators after intense liveaboard trips. I think it is unwise to argue the tissues are clear after 6h, no matter what the RDP says. In any case, 6h only gets you to 98.5% clear; 12h would be 99.98% clean, which is more like the stats on unexpected hits.

 

[sea_otter]

Guys I think the procedures, need for communicaiton etc have been discussed over and over again and are now very clear. I am now discussing two other important (according to me) things:

A) Once in emergency deco, calling the dive and going up to deco depth FAST is so important step but it is not mentioned anywhere in the manuals, and
B) Cressi (and hence Subsurface) marks any ascent faster than 4m/min as a warning

This summary scares me a lot. It's never a good idea to ascend FAST. I'm also not so sure the word "emergency" is truly appropriate. You're in a place you shouldn't be without training and pre-planning - we've already established that. There's no immediate emergency, but your risk of encountering one just jumped way up. Have you planned enough gas to complete your stop? What would happen in the event of an equipment failure? What is your plan if you can't find your buddy? Are you near the anchor line, or do you need to shoot a SMB and have someone on the boat spot you? How far will you drift in current? Lots of potential for an emergency (unmitigated).

I once read a story on this board about someone whose buddy saw DECO on his computer and shot up to 10 ft, because that's what his computer said to do. You overreacted in the opposite direction, taking 30 minutes to ascend 70 feet. The right answer is to abort the dive and ascend at a safe speed.

As to classes not teaching it, I guess it's comparable to teaching sex ed to pre-teens. Some might argue that teaching abstinence only is appropriate, while others would make the case that it's important to teach ways to do it safely, even if it shouldn't be done in the first place.

 

[doctormike]

If your training agency, computer manual or instructor gave you advice on what to do in a NDL situation they could be held liable for having trained you to do that type of diving. Therefore, they don't cover the situation at all. A consequence of a litigation society.

I don't understand this.

They are teaching you how to deal with a problem that you might encounter. Would teaching an open water diver how to CESA imply that they were being trained to run out of gas? I don't think so.

So why would teaching an open water diver how to deal with unplanned deco cause any sort of liability? Apart from the usual "anyone can get sued for anything" observation.

 

[Centrals]

Here is what your computer manual says about exceeding decompression limits on page 50:

In the event that you have exceeded the no decompression limits, Leonardo will assist with specific information related to surfacing and related decompression information. Upon violating the no decompression limits, the computer will issue a sound alarm, and the display changes as in the figure 22, providing the diver with the following information: 1) Stop icon with the writing DECO, showing that the no decompression limits have been violated and that decompression stops must be performed. The arrow indicating UP flashes. 2) Depth of first decompression stage (the deepest), given in meters (m) or feet (ft.). It may vary from a maximum of 78 ft. to a minimum of 10 ft., by steps of 10 ft.. 3) Time in minutes for the first decompression stage (the deepest). 4) TOTAL icon, indicating the total ascent time, that is the time required to ascend to the deepest stage, respecting the ascent rate, PLUS the stop time at that depth and at any other subsequent stop (including the deep stop if necessary), PLUS the safety stop time, PLUS the time required to reach the surface after completing the decompression stages. 5) “DIVE. T” icon giving the total time spent while diving.​

​

Thank you for posting it.
All the info were there for the OP to follow but he chose to pay no notice to them.
i. Alarm
ii. Change of display
iii. DECO icon
iv. Flashing arrow(UP). No meaning to the OP!!
v. TOTAL icon + the rest. I believe he misunderstood the meaning of TOTAL. But whose fault is it?

The OP is still trying to justify his action on that eventful dive. It was NOT his fault for not understanding the severity of the display that was shown into his face.

 

[DevonDiver]

Uwatec Aladins.

They're calling g themselves "sophisticated technical diving computers"????

 

[DevonDiver]

If your training agency, computer manual or instructor gave you advice on what to do in a NDL situation they could be held liable for having trained you to do that type of diving. Therefore, they don't cover the situation at all. A consequence of a litigation society.

Emergency Decompression is covered practically on the PADI Deep Diver course.

Students have to complete a simulated 8-min emergency decompression stop and also breath from a reserve/redundant gas source.

I personally think it should be moved forward to dive #1 of that course... so that it also featured in AOW.

It's often done as an arbitrary 8min @ 5m stop (as per RDP) and with a hanging tank.

I prefer to do it with a dive computer and the student uses a pony cylinder.

 

[KevinNM]

This summary scares me a lot. It's never a good idea to ascend FAST. I'm also not so sure the word "emergency" is truly appropriate.

Iirc, DAN sponsored research that showed 60 ft per minute was the optimal rate in NDL diving. I stick to 30 ft per minute, but I don't think that is what research showed was the best, but it isn't bad.

And once you have left the area where you have rules for conducting a dive safely it's pretty much an emergency. If you understand what you are doing it's not a big deal to drift into light deco, but if you don't it's a bad thing to do.

 

[joe10540]

They're calling g themselves "sophisticated technical diving computers"????

I wouldn't say sophisticated or technical but they are running straight buhlman and that shouldn't result in ludicrous deco times however blowing those off could get you hurt too. That was my first computer and I still use it occasionally to the dismay of my dive buddies (too many audible alarms) I can also clear deco with a reasonable ascent profile and have yet to get out of the water with less than 30min NDL remaining even after being "in deco" at 110'