How close did I come to getting bent?

[joed]

I learned a lesson in my 2nd year of diving in 1974. Here are the details and I always wondered how close I came to DCS or the bends or anything else... I just moved to CA and joined a club in Oakland. I was very impressed by one of the divers in the club. He worked at an old estlabished dive shop and he was experienced, I thought. In the meantime he was 18 and I was 24 years old. He took me down to 70' at Monterey, Point Lobos, the deepest I had ever gone. So this kid was my pied piper..
So we dive at Carmel Meadows in Monterey, a deep dive accessible from shore. I remember the bottom as a steep slope. Carmel Meadows was always rough so on a calm day you always went for it. So we did a bounce dive to 125'. Than we came up had lunch, rested for 2 hours and did another bounce dive to 150'
Actual bottom time at depth on each dive was approx. 1 minute. Total dive time from the surface dive to the accent dive was maybe 5-10 minutes per dive. I know I had nitrogen narcosis. Once we got dry, I began to think about what we did. How close did I come to disaster?

 

[daylight]

Joed,
You didn't mention anything about ascent rates or stops.
If they were nominal you shouldn't have had a problem.
Why do you think you had a problem? When you are that age you're invincible anyway.
Larry

 

[Dr Deco]

Dear joed:

How Close?

The long and short answer is “I do not know.” As has been mentioned on several occasions on this BOARD, decompression tables are made such that the most sensitive diver will not get DCS. That means if the table has a 1% “hit rate,” then 99% of the divers could perform the same dive without problems. AND these divers are not clustered together in their sensitivity to DCS. The risk is spread out , although it naturally increases as bottom time increases.

Where you were in the spectrum of sensitivity cannot be told by this dive since it was not particularly “aggressive.” If you had monitored yourself with a Doppler bubble detection device, you could have gotten a better idea.

Except for exposing yourself to increasingly greater does of nitrogen and watching what happens, one would not know if they were sensitive or resistant to DCS. This is definitely only a laboratory test, and it is not without risk of neurological decompression sickness. :boom:

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[raviepoo]

It is only possible to determine how close you were to being outside the no decompression limits of a number of different dive tables. Look at your dive tables. It is possible to dive to 150 ft for a VERY short time without a deco obligation.

DCS is kind of like magic. It's not predictable. Staying within the no decompression parameters of a dive table is not fool proof protection from DCS. Going beyond those parameters does not guarantee a hit, either.

This stuff is taught in basic open water classes, isn't it.

 

[joed]

It looks like I fabricated something to worry about that day that did not exist. Our ascent rate was normal, following our slowest bubble. The ascent was up a slope until the final 25' so it was a slow ascent. I was mad at myself because we made the deeper dive second. If we did a 150' dive and than a 125' dive that makes more sense than the way we did it.We did a 125' dive and then a 150' dive. But both divers were fine in the end. I learned on that day to be in charge of myself, and not to follow someone who I figure knows more than me.

 

[Braunbehrens]

joed once bubbled...
I learned a lesson in my 2nd year of diving in 1974. Here are the details and I always wondered how close I came to DCS or the bends or anything else... I just moved to CA and joined a club in Oakland. I was very impressed by one of the divers in the club. He worked at an old estlabished dive shop and he was experienced, I thought. In the meantime he was 18 and I was 24 years old. He took me down to 70' at Monterey, Point Lobos, the deepest I had ever gone. So this kid was my pied piper..
So we dive at Carmel Meadows in Monterey, a deep dive accessible from shore. I remember the bottom as a steep slope. Carmel Meadows was always rough so on a calm day you always went for it. So we did a bounce dive to 125'. Than we came up had lunch, rested for 2 hours and did another bounce dive to 150'
Actual bottom time at depth on each dive was approx. 1 minute. Total dive time from the surface dive to the accent dive was maybe 5-10 minutes per dive. I know I had nitrogen narcosis. Once we got dry, I began to think about what we did. How close did I come to disaster?

I don't think you came close at all. You probably went straight down to depth, and then worked your way back up the slope. If I remember the site right, it's a fairly shallow slope at the beginning and then gets steeper and steeper. So coming up, you had a naturally correct "curve" to your deco. I assume you came up nice and slow.

Couple of interesting facts about that dive...one, there isn't that much to see, do you remember what you saw? Two, you can go prettty much as deep as you want. The middle of that bay goes WAY down.

 

[Braunbehrens]

latest research shows that deepest first doesn't matter...check with DAN. In any case, 125 and 150 are pretty close, and you had a 2 hr surface interval which is plenty.

 

[joed]

You are correct. I dove there about 5 times and there was nothing ever to see. On the 125' and 150' dives I made ,there was a sandy bottom all the way with some broken shells, broken coral and broken sea urchins. I guess the only reason we dove it because it was forbidden territory, it was rare to have no big surf. But you had to dive that site early morning, by noon the surf would roll in. One day I drove by the site around mid morning and it was flat calm. I saw a guy gearing up in a red uni suit, the popular dry suit of the day made by Parkway in New Jersey. He said I could join him on the dive so I geared up in record time. He went in first and as I got my fins on and I was stepping into the water this huge monster wave appears out of nowhere. When it
hit the beach it knocked me down and I looked up and I saw this uni suit on top of a wave that looked 10-15' high. He was cool, he waved me to stay in and he played the waves until he could ride
one in. There was no body to help you out if you needed it that day. Another crazy place was Chase Reef in Monterey Bay. Ed Brawley School of Skin Diving used to run a barge to that reef. Current was savage. Jumped off the barge one time and aborted the dive immediately, used all my power to climb back into the barge, there were ropes hanging off the sides. One diver was new and we saw jump into the water and float rapidly down the bay, had to be brought back an hour later up by a passing boat. He had no buddy, just zoom-gone.
But some of the guys from the shop could fight that current and dive the reef. I was amazed how they could swim against that current.

 

[joed]

I think Carmel Meadows is the slope that heads into Carmel Canyon. Carmel Canyon may go down to 3,000 feet. Also the waves are huge because they are deep water waves that come out of the Pacific and nothing stops them until they break on this site. This may not be accurate information, if anyone can correct me please do.

 

[Arnaud]

Braunbehrens once bubbled...
latest research shows that deepest first doesn't matter...check with DAN.

The argument has been made several times on the board. I've been browsing DAN's website, but couldn't find anything. Is there any in-depth articles available on line about this, besides GI's literature?