"Riding your Computer Up" vs. "Lite Deco"

[scubadada]

...BTW, you did not mention that they considered using the 40 minute compartment because that was what their research indicated made sense, but they decided to use the 60 minute compartment to be more conservative...

Actually, Dr Rogers discovered that some series of long, shallow dives required a slower tissue than 40 minutes, and, consequently, chose 60 minutes on which to base the repetitive system of the RDP. The best description I've read is in Deeper into Diving, Lippmann and Mitchell, Second Edition, 2005, pp 283-306.

 

[boulderjohn]

Actually, Dr Rogers discovered that some series of long, shallow dives required a slower tissue than 40 minutes, and, consequently, chose 60 minutes on which to base the repetitive system of the RDP. The best description I've read is in Deeper into Diving, Lippmann and Mitchell, Second Edition, 2005, pp 283-306.

Hence the WX and YZZ rules.

 

[redacted]

If your breathing compressed gas while underwater. Do you really believe you only risk DCS when close to an NDL?

I believe there is a range well short of NDLs where the risk is zero. I also believe that the array of current acceptable recreational computers and tables provide for risk levels well under 1% for most healthy divers.

 

[lermontov]

at the risk of another run of threads let me see if ive got this right regarding views on NDL
written tables e.g. PADI etc have a definite red line -recommendations = do not exceed NDL without training
DC have a definite red line ( as it pertains to itself) -recommendations =follow your DC
multiple divers using different DC and settings, red line varies depending on which DC your looking at -recommendations = follow the most conservative
seems pretty simple or am i missing something

 

[redacted]

Why do you think this?

I have met several divers who were bent on no stop dives. One turned out to have a PFO, but had been diving, including substantial deco dives, for many years. One had got bent on a OW course in Egypt and another on a 15m dive.

If you read the BSAC incident reports you will find about 70 or 80 DCI incidents each year. Obviously some of those will involve proper deco dives, bad ascents or some obvious reason, but there are some which happen on simple NDL dives.

I have also, but all were doing fairly agressive recreational (no deco) diving.

The 15 meter dive is just a bit surprising but those tend to be strongly influenced by the series of dives. I have done 15 meter dives where I never exceeded 50% loading on my lead compartment (for a week of diving) and others (preceeded by deeper dives) where I had to manage my depths to avoid exceeding my NDL.

Linked article is still downloading.

 

[lermontov]

I have also, but all were doing fairly agressive recreational (no deco) diving.

.

what would you class as a fairly aggressive rec dive

 

[Basking Ridge Diver]

multiple divers using different DC and settings, red line varies depending on which DC your looking at -recommendations = follow the most conservative
seems pretty simple or am i missing something

Since this is the Advanced - Why follow the most conservative? I'll help get you to the anchor line - you get yourself up the line and back on the boat.
This is big boy diving - at least in the NorthEast. We dive same ocean - this is not a warm water 100 foot viz vacation dive. If you carry a pony - that is your business - if you don't I will help you if you come find me but I am not following you to make sure you are safe.

 

[redacted]

what would you class as a fairly aggressive rec dive

Typical Cozumel trip doing 3 or 4 recreational dives a day.

Flower Gardens live-a-board doing 12 NDL dives in 2.5 days all in the 80 to 100 ft range.

Bonaire doing 4 or 5 dives per day with an averagee depth of 30 ft is not aggressive.

For me, I feel I am diving fairly aggressively when my lead compartment loading is above 85% on my Oceanic computer. Such dives are not doable on PADI tables.

 

[KenGordon]

I have also, but all were doing fairly agressive recreational (no deco) diving.

The 15 meter dive is just a bit surprising but those tend to be strongly influenced by the series of dives. I have done 15 meter dives where I never exceeded 50% loading on my lead compartment (for a week of diving) and others (preceeded by deeper dives) where I had to manage my depths to avoid exceeding my NDL.

Linked article is still downloading.

Here is one from 2007 (the first one I have on my iPad) 07/032

A diver was involved in refresher training in a swimming pool. She dived to a maximum depth of 4m. Some time into the dive she experienced severe ear pain, she was instructed to clear her ears but was unsuccessful. She came to the surface, still in pain, and the lesson was aborted. The following day she awoke with a severe pain in her ears and face. She saw her doctor and was advised to rest. The pain got worse and she went to her local casualty department. She was diagnosed with a pressure related injury and possible mild DCI. She was sent home with pain killers. She then contacted a recompression facility for advice and attended for examination. She was diagnosed with sinus damage and was advised that her symptoms would resolve in two days. Two days later the symptoms persisted and the pain was getting worse. She contacted the recompression facility again, DCI was diagnosed and she was given a number of recompression treatments which resolved her symptoms.

Even I was surprised by this one, I had to read this one a few times to convince myself it was not just a barotrauma.

This is an extreme example, plenty are in the 10 to 20m range, a couple of dives with reasonable SI. There might be a handful of these recorded each year so the probability is probably lower that 0.01 percent, but if an average diver does 100 lifetime dives then one in a hundred can be expected to get injured. That seem so like a significant risk, even if it looks like a small number.

 

[lermontov]

Since this is the Advanced - Why follow the most conservative? I'll help get you to the anchor line - you get yourself up the line and back on the boat.
This is big boy diving - at least in the NorthEast. We dive same ocean - this is not a warm water 100 foot viz vacation dive. If you carry a pony - that is your business - if you don't I will help you if you come find me but I am not following you to make sure you are safe.

well arent you a fun guy to dive with