Earned, Un-earned or Predisposed?

[DandyDon]

I don't have the training of all the doctors and DMs on this thread, so I've always gone by the limits I learned on the mike ball + peter hughes boats - which is 5 dives/day max. I'm wondering if a lot you on this board exceed that, and if you do, is it because you use nitrox?

I haven't tried nitrox since I usually have air leftover when everyone is getting back in the boat, and I'd rather have the leeway on my depth.

If it isn't because of the nitrox, are you just cowboys?

Using Nitrox has nothing to do with air consumption, nada, zilch - at least not directly. Indirectly, the divers with better air consumption like you suggest you are are the ones who benefit more as it's all about Nitrogen loading - so the longer you can stay down the more loading you are capable therefore more likely to get hit on Air vs less likely on Nitrox. Since you seem to have no knowledge of Nitrox, then the preceding discussion with regard to the lack of its use probly wasn't understandable. I hope that very brief explanation helps.

Do you dive a computer or tables? What has been your highest reading?

While there has been some discussion here about the diver pushing himself too hard, Scubaboard does not condone unsafe diving practices or suggestions of such. I was born and raised a cattleman, saving herds from blizzards and plagues for decades so it always seems funny to me for someone to use the word cowboy as an attempted insult rather than a honor, but I suppose we do the same about bareheaded city people.

 

[SC_Hoaty]

Ok I just got permission and picked up a copy of the dive profiles;
Water temp 61 degrees, no thermocline.
Rainy cold weather for most of the day. Clear cool evening around 45 degrees.

Dive1: Max depth 69 feet. Elapsed dive time 31 minutes. 4 minute safety stop.
Dive2: 25 minute SI. Max depth 38 feet. 25 minutes. Most of dive at a suspended platform at 20 feet. 5 full minutes ascending from 20 feet to surface.
Dive3: 1:39 SI. Max depth 54 feet. Elapsed time 34 minutes. 3 min safety stop.
Dive4: 28 minute SI. Max depth 34 feet. Dive time 27 minutes. Alternate air ascent drill with students from 20 feet at 20 minutes. CESA1 from 20 feet @ 26 minutes with ascent violation corrected at 5 feet. CESA2 to end Dive.
Dive5: Rescue Dive. 2:16 SI. 39 feet. 4 minutes and 30 seconds.
Dive6: Rescue Dive. 21 minute SI. 29 feet. 9 minutes. Rescuer ascended too fast but no violations show on printout.
Dive7: 29 minute SI. Max depth 35 feet. Elapsed dive time 20 minutes. 5 minute ascent from 25 feet to surface.
Dive8: 3:03 SI. Night Dive. Max depth 70 feet. Elapsed dive time 38 minutes. 4 minute stop at 20 feet. 3 minutes @ 15 feet. Slow ascent to surface during which he claims to have felt what he thought was a spasm in his upper back and shoulders and which grew more intense after surfacing and exiting the water.

I'm aware that almost everyone dives computers these days - I rely on mine. The dive tables are quite conservative, and don't give "credit" for things like spending time on a platform at 20 feet. All that being said, pull out a table and start working through the repetitive dives. With my SSI table I show a G diver after #1 (and also beginning #2 due to short SI), Dive 2 with 73 RNT and 25 BT yielding a Group I diver, down to F after the SI, with dive #3 going over the NDL.

BTW - this does not even consider the altitude factor.

I mention this since the tech at the hyperbaric facility I toured used dive tables to explain a recent DCS hit he had treated. The computer said the diver was within its limits, but he was still in the chamber being treated.

 

[Jax]

May I ask a noob question?

The instructor was diving an Oceanic VT Pro. I seem to remember this as an aggressive computer.

Added to the aggressive computer was an aggressive dive schedule. Could the computer's aggressive algorithm have allowed this diver to push the envelope to the very edge?

 

[boulderjohn]

OK, I am coming at this with fresh eyes now that I have myself returned from Santa Rosa having dived similar profiles and having some health problems myself. It did not turn out to be DCI, but some of the symptoms were the same, and I was, frankly. very concerned when they appeared. I did fewer dives total on the first day in question than the person studied in this thread (only 5) but since one was to 150 feet with a bottom time of 30 minutes (+ 40 minute ascent), it was arguably more aggressive.

Reflecting back on my days, I tried to recall the times I had had water, and I realized those times were way too few, and the volume way too low. Ironically, on one of those few times I drank, I emphasized to my students knew how important it was to stay hydrated.

Working frantically to keep up a schedule (I finished packing my gear at 7:30 PM), I sacrificed my own need for hydration in order to keep up a hectic pace and finish on time. It was a mistake I will not make again.

 

[fdog]

Regardless of what the final diagnosis and mechanism may have been:

When reading the OP this came across to me as a "how to get bent" guidebook.

...as an aside, when conducting similar training, I breathe as rich of a mix as I can blend; spread the ascent training over several dives; spread them out on each dive; don't schlep anyone's gear except my own.


All the best, James

 

[TSandM]

Wow . . . 10 ascents in one day, with several of them too fast, and then a deep last dive. If there is anything to the idea of bubble-pumping (diving with bubbles causing them to crush and pass the pulmonary filter, and then expand on the arterial side) this would be a setup for it.

 

[Divedoggie]

Regardless of what the final diagnosis and mechanism may have been:

When reading the OP this came across to me as a "how to get bent" guidebook.

...as an aside, when conducting similar training, I breathe as rich of a mix as I can blend; spread the ascent training over several dives; spread them out on each dive; don't schlep anyone's gear except my own.


All the best, James

Yes, it was an aggressive schedule. The dives were not aggressive. 8 dives are too many...even in a pool! Factor in tempurature changes, not enough food, not enough water, etc., and its a bad idea.

My friend was wearing 3 computers and none of them were ever in the yellow/caution area. My computers were never in the yellow either.

As Boulderjohn stated above, he recently returned from Santa Rosa and experienced some ill effects. Its easy for an Instructor or DM to over-do it in order to help students. A couple of DMs and I all dove the same profiles that day.

The final diagnosis was an electrolyte imbalance and vit B12 deficiency along with dehydration and exhaustion causing a shutdown to extremities. He never showed any signs or symptoms after the first hour in ER on fluids and O2.
It turns out that the victim never felt any paralysis in his chest, abdomen, back, or rear end. He is perfectly fine, active and diving again with no problems.

None of us who were on the trip that weekend will ever work that hard and conduct a training weekend in the manner again!

 

[boulderjohn]

The final diagnosis was an electrolyte imbalance a... along with dehydration and exhaustion

I am pretty sure that was my issue as well.

There is one other part of that description that piqued my interest, although it did not appear to have been a factor, and that was the rapid ascent in the rescue scenario described.

I once played a rescue victim during a scenario in which the diver was supposed to bring an unconscious diver to the surface. This was being done at nearby Rock Lake, where I could settle down in a weedy area and appear to be unconscious. As I lay there with my eyes closed, I felt the rescuer get on my back and lift my inflator hose. Then I heard the rush of air as he pushed the button for all he was worth.

I knew what was going to happen next, so I immediately began a full force exhale that lasted all the (very brief) time it took to get me to the surface, where I broke through like the submarine in Hunt for Red October. It was scary, frankly. The instructor conducting the class and I later discussed the need for an emphasis on safe ascent rates in the pre-dive briefing in the future. (The student had done it correctly in the pool, but...)

A lot of people don't realize that, according to Boyle's Law, air expands more during an ascent at altitude than at sea level. I calculate that at Santa Rosa, air expands more than 10% more going from 34 feet to the surface than it does at sea level.

 

[DandyDon]

The instructor was diving an Oceanic VT Pro. I seem to remember this as an aggressive computer.

Aggressive computer? No more than Padi tables. The "conservative" do give you less dive time than Padi or Oceanic if that's what you want.

Yes, it was an aggressive schedule. The dives were not aggressive. 8 dives are too many...even in a pool! Factor in tempurature changes, not enough food, not enough water, etc., and its a bad idea.

My friend was wearing 3 computers and none of them were ever in the yellow/caution area. My computers were never in the yellow either.

As Boulderjohn stated above, he recently returned from Santa Rosa and experienced some ill effects. Its easy for an Instructor or DM to over-do it in order to help students. A couple of DMs and I all dove the same profiles that day.

The final diagnosis was an electrolyte imbalance and vit B12 deficiency along with dehydration and exhaustion causing a shutdown to extremities. He never showed any signs or symptoms after the first hour in ER on fluids and O2.
It turns out that the victim never felt any paralysis in his chest, abdomen, back, or rear end. He is perfectly fine, active and diving again with no problems.

None of us who were on the trip that weekend will ever work that hard and conduct a training weekend in the manner again!

Glad it was nothing more than that. I screw up a lot, but I work at hydration - which is probly what saves my butt at times.

 

[ianr33]

Aggressive computer? No more than Padi tables.

But tables are inherently conservative unless you dive a perfect square profile at a depth exactly divisible by 10 e.g. 80 feet or 100 feet.

Drop down one extra foot to 101 for 30 seconds and it makes very little difference on the computer,but following tables by the book that has just become a 110 foot dive,which will significantly reduce NDL.