How much risk was I at for DCS?

[halocline]

I do realize that the dive was multilevel, but the fact that I'm not trained in multilevel diving worried me. What worried me most however, was the depth.

The answer to the question "were you at risk for DCS?" depends on how aggressive your dive profile was with regards to NDL. Single "Trust me" dives are not dangerous with regards to DCS if the profile is very conservative and nowhere near NDL. In fact, I would happily do a single dive without a computer if I was diving a profile that I knew from experience (or planning) did not push NDLs at all. So, it's more like a "trust but verify" dive, to borrow a phrase from the cold war. There are plenty of profiles with a depth of 26.4 meters and 40 minutes bottom time that would fit that bill, but there are also profiles that would push or exceed NDL, so truthfully nobody can answer your question with the given information. Planning repetitive dives without accurate dive data is likely much riskier, but again, it depends on the profile.

But, certainly the best thing you could do at this point would be to learn something about basic decompression theory in recreational diving and maybe play around with some dive planning software. There's a very good chapter in the PADI encyclopedia of recreational diving on the basic deco models. Once you have an idea of how the models work, you can dive in a much more informed and confident manner.

Honestly, using your own dive computer but not having an idea of how aggressive your dive profile is based on basic deco theory is only marginally safer (in my opinion, anyway) than doing the same on someone else's computer, at least for a single dive. The computer only tracks your time, depth, and ascent rate. If you dive near NDLs, don't control your ascent rates well, etc...you're at greater risk for DCS than someone who dives conservatively, (all other factors equal) computer or not. The only way a computer adds to your dive safety is if it changes your dive behavior, based on the information it gives you.

 

[SCUBA_Phil]

Something is wrong here. You started the dive with 210 bar and completed it with 100 bar. Im assuming since your a new diver, you were using a 80 cuft (11 L) tank. In this case you went thru ~40 cuft. Assuming your SAC rate is 0.6 cuft/min (exceptional for a new diver), 40 mins at 10M would consume (0.6*40*2) 48 cuft. My best guess is that you did a bounce dive to 26.4M, averaged less than 10m and the 3 min safety stop was included in your bottom time. If this is true, you were never at risk of DCS. Anybody have a better explanation?

 

[supercritical]

I shouldn't have gone to 26 for very long. Also, I'm one of those people who exhales as slowly as possible (is that a good idea?).

---------- Post added April 8th, 2013 at 08:03 PM ----------

So, lessons learned:
- Learn the plan that's being dived
- Discuss the plan
- Stay within your limits
- Don't be a passive diver
- Carry a depth/timing device
- Keep track of dive conditions

 

[TSandM]

Sounds like a good set of lessons!

I want to thank you for coming here and telling your story, and asking your questions. Threads like this were incredibly educational for me, when I first found ScubaBoard, and without the people bringing up the issues, these lessons wouldn't get shared.

 

[themagni]

I am pretty darn sure that those DMs are indeed leading a multilevel dive within the computer's NDL. Why would they do otherwise? Why would they feel compelled to do otherwise and lie about it?

Money.

If you're making the choice between "feed my family" or "never put these rich tourists at a slight risk" you're going to choose option one, every time.

That does not make it right for the diver to follow the DM blindly. If you are going to use the RDP, then you simply should not be doing dives like that. If you are going to follow a computer-based multi-level dive, then you need to have your own computer. You should not be relying on someone else.

One may not understand the real danger of those risks until one is on the injured list. If someone's got 100 dives or so and the DM with 5000+ (and 1000+ on the site you're visiting) tells them it's fine, what is the inexperienced diver going to do? They're going to trust the local DM.

There's a huge swath of irony cutting through this board. The opinion is that inexperienced divers (let's say < 500 dives) should be completely responsible for their own health and safety and not listen to other divers -- yet they don't know anything about the risks behind diving and therefore should trust more experienced divers.

 

[Hatul]

your[/I] dive and dive your plan.
2. Dive within the limits of your comfort, training and experience.
3. Do not share dive computers.

I first learned this lesson in Cuba, before I was certified I took a resort course, and was told, don't worry about anything we take care of everything. After a pool session I jumped into the water from the dive boat and could not breathe-- they forgot to turn my air on.

 

[boulderjohn]

One may not understand the real danger of those risks until one is on the injured list. If someone's got 100 dives or so and the DM with 5000+ (and 1000+ on the site you're visiting) tells them it's fine, what is the inexperienced diver going to do? They're going to trust the local DM.

A diver with 100 dives or so should certainly know enough about diving to be able to ask the DM for the dive details and then make a rational and independent decision. It should not take anywhere near that many dives.Where a DM's judgment becomes a factor for such a diver is when the DM knows the conditions of a local site (such as strength of current), knows the diver's ability, and tells the diver it is within the diver's ability. telling me that a dive has a lot of current tells me very little, and I will have to trust the DM to some degree with that.

There's a huge swath of irony cutting through this board. The opinion is that inexperienced divers (let's say < 500 dives) should be completely responsible for their own health and safety and not listen to other divers -- yet they don't know anything about the risks behind diving and therefore should trust more experienced divers.

Who said they should not listen to other divers? If they took the PADI OW course, they were told several times in the instructional materials and on the exam that when they go to a new site and with new conditions they should seek out that expert advice.

You seem to be taking a specific set of skills (monitoring depth and time to stay within NDLs) for which people say the diver should be responsible and generalizing it to all diving skills. Nothing on this thread has suggested that.

 

[openmindOW]

Forget the DM's computer. If you can't afford one at this time get a dive watch, a depth guage, and use your dive tables. Trust me dives have the very real potential to kill people.

My thoughts exactly.

I know of one DM led dive that did for sure and have proof that it did.

This is interesting, Jim. Please run a Thread on it.

 

[Jim Lapenta]

It's already on here from a few years ago. The death in grand cayman thread by fosterboxermom that inspired my who is responsible essay. DM/guide led seven divers on a planned by the DM 100 ft wall dive. Two of the divers were on their second dive post OW check out dives on a referral. And also included a seventeen yr old that had not been in the water for nearly a year. The one OW diver hit 342 ft before he bounced somehow and did a 302 ft ascent in two minutes. I had the op of that thread and her husband come seven hundred miles to take my AOW class after that happened. They brought the deceased computer profile and copy of the autopsy report. I use the profile in my planning and buddy failure presentations.
That is event is why I drill my students to never trust a DM led dive. They must always have a plan of their own.

Sent from my DROID X2 using Tapatalk 2

 

[supercritical]

...And also included a seventeen yr old that had not been in the water for nearly a year. The one OW diver hit 342 ft before he bounced somehow...

104 metres! Any idea how he fell that far?