Please explain (teach me)

[ianr33]

Thank you all for your prompt replies. I think BoulderJohn explained it perfectly.

So as long as I follow my dive computer I should be safe right?

and to willembad: Yes the computer recommended a 5 minute deco stop. I did 10 to be safe.

Thank you all again for your reassurance.

What was your plan in the event you ran out of air during your deco stop?

(And yes, I'm just playing Devils Advocate to point out there is more to diving than just blindly following a computer)

 

[The Chairman]

Your second dive was a multilevel dive.

Your first dive was probably a multilevel one as well. PDCs (Personal Dive Computers) do a wonderful job of accurately tracking our depth and time in a way a human can not hope to keep up. As was previously pointed out, using a table for a multilevel dive is like using a hammer to set a wood screw. You can do it, but its the wrong tool for the job!

That being said, with the longer dive times, please consider increasing your safety stop from 3 to five minutes as well as doing a two minute "half stop" when your depth is greater than 60 fsw.

 

[fnfalman]

Thank you all for your prompt replies. I think BoulderJohn explained it perfectly.

So as long as I follow my dive computer I should be safe right?

and to willembad: Yes the computer recommended a 5 minute deco stop. I did 10 to be safe.

Thank you all again for your reassurance.

Others have already addressed the dive computer versus table issue.

Let's talk about something else. YOU DID NOT do a "Deco" stop. Yuo did a "Safety" stop. Big difference.

 

[The Chairman]

Let's talk about something else. YOU DID NOT do a "Deco" stop. Yuo did a "Safety" stop. Big difference.

If it was suggesting five minutes, then it probably WAS a obligatory deco stop. As for a safety stop NOT being a deco stop, there are a number of us who would disagree with you. All stops involve decompression of some sort. Some are optional and some are not, but they are still deco stops.

 

[ozorowsky]

Others have already addressed the dive computer versus table issue.

Let's talk about something else. YOU DID NOT do a "Deco" stop. Yuo did a "Safety" stop. Big difference.

Point taken thank you for clarifying.

and to ianr33: during my "safety stop" I still had 1800psi. Also there were 2 dive buddies with me, and 3 classes going on with about 5 students each.

That was part of the reason I picked this dive spot "controlled environment" without an instructor to get my feet wet and get more and more comfortable with diving.

Thank you all for sharing your experience, and not slamming me for potentially making a mistake.

One thing I am trying to gain a better grasp on is the safety stop. I know per the dive computer when to make one and per the table approximately when to make one, but what if you mess up? Will you go to the surface feeling sick? Go into convulsions, die instantly, is there any physical forewarning?

Thank you.

 

[The Chairman]

One thing I am trying to gain a better grasp on is the safety stop. I know per the dive computer when to make one and per the table approximately when to make one, but what if you mess up? Will you go to the surface feeling sick? Go into convulsions, die instantly, is there any physical forewarning?

Thank you.

Probably none of those things.

There are two types of stops: obligated and optional (Safety).

Violating either of those will not necessarily give you DCS. However, doing them does not completely keep you safe from them either. There are many factors that affect DCS including ascent rate, breathing rate, temperature, hydration, sickness, elevation and so on. Its up to you to dive in a reasonable manner and mitigate those risk factors by decreasing your dive time (conservancy) or not diving until things are normal.

If you miss an optional stop, there is nothing to be done. You can continue to dive normally.

If you miss an obligatory stop, then you should stay out of the water for 24-48 hours and monitor yourself for symptoms of DCS. Call DAN and get to a hospital/hyperbaric chamber if you are suspicious.

Signs and Symptoms of DCS

 

[rhwestfall]

I applaud you for asking why, but am disturbed as to the apparent lack of education by a person with a c-card. What is in dive training/certification these days?

 

[boulderjohn]

I applaud you for asking why, but am disturbed as to the apparent lack of education by a person with a c-card. What is in dive training/certification these days?

I would say that in most cases the problem is where it always was: teaching tables with square profiles only to the OW student. Multi-level and computer diving is not usually part of OW training. This is changing.

 

[DevonDiver]

YOU DID NOT do a "Deco" stop. Yuo did a "Safety" stop. Big difference.

5 minutes on a PADI table is an emergency deco stop. It is mandatory, in the event of exceeding an NDL. Full rules for emergency deco is written in the special rules on the table.

Likewise, a 5 minute STOP on a computer is also highly likely to be deco. I don't know of any computer that gives more than 3 minutes as a safety stop. If it was deco on the computer, then it would also indicate a ceiling, that you could not ascend beyond for the given stop time.

 

[fnfalman]

Safety Stops are optional. Deco Stops are not.

You may or may not get a DCS hit by skipping a Safety Stop. I'd like to see somebody does a 45-minutes dive at 150-ft and skip a Deco Stop while not getting the bend.

The OP's second dive profile was nowhere close to having to do a deco. Maybe the computer was generous in the 5-minutes safety stop.

I suppose we need to clarify a bit about deco stops. If a rec diver were to push the No Decompression Limit for a little bit, then the computer will recommend a "deco" stop that either longer than the typical safety stop, or maybe a "deco" stop somewhere deeper and then a longer safety stop. This is a lot different than technical/commercial divers doing some serious deep bottom time and have to use the hyperbaric chamber or have to hang for an extended period of time while sucking on high-O2 mix while doing a true obligatory deco stop. Skip this stop and you'll be in a world of hurt for sure and not just maybe.

Decompression diving (even if it were just a little bit over the NDL) should not be executed until the diver knows what he or she doing. Trust the computer to do a "deco" stop for you is a recipe looking for trouble.