Who should I listen to?

[AfterDark]

Yes, in the past we have shared this concern.



The Navy Tables (like the DCIEM military tables) have always been specifically designed for Navy Divers; young men with an extreme level of physical fitness and able to pass a Navy Diving Medical. When I was at DCIEM, we wrote a separate set of Tables for Sport Diving which were more liberal.

The 2.2% figure pertains to qualified Navy Divers using the 60 FPM protocol at the limit of the tables, but marginally within them. My point was that it`s relatively easy to get bent by following the older tables that do not employ a slower ascent rate. In any regard, I think that it`s clear that you have a greater chance of DCS at 60 FPM than 30 FPM and above 30FSW your risk is decreased if you ascend at 10FPM.



Absolutely, when fitness is low or medical conditions are present, the individual must weigh the risk factors and accept them before the dive begins. That said, some people decide to accept dive plans that are not optimal. I`m aware that my risk increases if I`m diving in a cave, wreck, or on deep Heliox. Each of us must be directed by our physical and mental condition-attitude, level of confidence, training and experience. Afterall each of us are the ones that must accept or reject the risk and pay the piper if required.

IMO if the diver is at the extreme end of a bottom time then 60fpm ascent rate probably would increase the chances of DCS. I believe that was why it was stressed to us to never push the limits of the tables, always go to the next depth, time or group if you are close to the limit. Advice I followed for many years doing both air NDLs and deco dives using 60fpm on more than half of my 2032 dives without a hit. Moderation in diving profiles is no accident.

 

[ARDory]

Great, now I have to worry about zombies under water? Guess I will get me a big knife. Lol.

 

[RJP]

Note to the OP: whatever ascent rate you use to go from the bottom to 15ft... remember that the dive is not over when you complete your safety stop! You should ascend even slower from your safety stop to the surface. I see too many people clear their computer and then zip right to the surface from 15ft.

At a minimum, you should follow the same 30ft/min rate that got you safely from the bottom to 15ft. This would mean it should take you AT LEAST 30 seconds to surface after completing your safety stop. Conditions permitting, I try to take a full minute or longer to surface.

If you're not diving in an environment that requires hanging on a fixed line for dear life it also gives a chance to play with buoyancy control and check your weighting. Perform your safety stop horizontal and neutrally buoyant. Then see if you can take 15sec to ascend, still horizontal, from 15ft to 10ft... and then neutrally hold that 10ft depth for 10-15 seconds. Then take another 15 seconds to horizontally ascend from 10ft to 5ft. Hold that 5ft depth for 10-15seconds. Then see if you can take a full 15 seconds to ascend from 5ft to the surface. Go even slower if you can. It's actually kind of fun. I'll spend 5min ascending after completing my stop on occasion just for something to do. It's very relaxing to sort of "zen out" after a dive but before climbing back up on a boat, getting out of gear, etc.

In many shore diving locations (Bonaire, for instance) there's often plenty to see from 15 ft all the way to dry land. You can spend 10-15min or longer swimming in from/during your safety stop.

Experienced divers in this thread... tell the truth, do you spend 30sec or more surfacing after completing your safety stop? Whether you do or not... do you see many other people take 30 seconds or longer to surface?

 

[maniago]

Experienced divers in this thread... tell the truth, do you spend 30sec or more surfacing after completing your safety stop? Whether you do or not... do you see many other people take 30 seconds or longer to surface?

I do always. In fact, my usual stop routine often winds up being hitting the up line at 800-1200 depending on depth, SSs at 60's as required and once done with my 15' SS, I'll hang there just looking around and burn down to ~300psi before making the final climb up to the boat. Why? Because I paid for the gas and I paid to be under the water where its peaceful. Why would I want to get out of the water any sooner (unless I have dead fish on the stringer and I'm being hunted).

No I don't see anyone else do this.

 

[RJP]

I do always. In fact, my usual stop routine often winds up being hitting the up line at 800-1200 depending on depth, SSs at 60's as required and once done with my 15' SS, I'll hang there just looking around and burn down to ~300psi before making the final climb up to the boat. Why? Because I paid for the gas and I paid to be under the water where its peaceful. Why would I want to get out of the water any sooner?

The question was more along the lines of "what is your ascent rate from 15ft to the surface?" and less about "do you extend your safety stop before surfacing?"

Extending your safety stop is nice... unless you then ascend from 15ft to the surface in three seconds!

PS - what does "SSs at 60's as required" mean?

 

[Jim Lapenta]

Great, now I have to worry about zombies under water? Guess I will get me a big knife. Lol.

There is actually a Zombie Diver specialty if you have more money than sense. No lie. PT Barnum school of dive training.

As for ascents on recreational dives if not near the NDL's I have taken as long as twenty minutes to come up from 15 feet while watching something really cool or having a bass hang over my shoulder waiting for me to flip a rock and uncover a crayfish.

 

[RJP]

If not near the NDL's I have taken as long as...

Jim, are you saying you'd be concerned that time spent at safety stop depth will cause you to exceed NDL?

 

[maniago]

The question was "what is your ascent rate from 15ft to the surface?"

All that you wrote above is great... unless you ascend from depth to 15ft in ten seconds and then go from 15ft to the surface in three seconds!

PS - what does "SSs at 60's as required" mean?

Sorry , that should have been Deep Stop in the 60' range if the computer requires me to or I was bottoming and staying ~100' or better most of the dive.

Once I decide to go up from 15', I neither shoot up nor dawdle - whatever it takes me to swim up to and gain the ladder in a safe and relaxed manner. Afterall, I've just been taking a nap on the 15' line for maybe 15mins or so - I'm nice and relaxed. Might be hungry tho...

---------- Post added January 4th, 2014 at 01:27 PM ----------

As for ascents on recreational dives if not near the NDL's I have taken as long as twenty minutes to come up from 15 feet while watching something really cool or having a bass hang over my shoulder waiting for me to flip a rock and uncover a crayfish.

This is my wife's favorite thing to do after a long dive at Dutch. Just hang out flipping the rocks crayfish hunting. That's how I learned to control my buoyancy the best, and its just a lot of fun.

 

[RJP]

Once I decide to go up from 15', I neither shoot up nor dawdle - whatever it takes me to swim up to and gain the ladder in a safe and relaxed manner.

Do yourself a favor... right now. Take a look at nearby clock with a second hand and watch 30 seconds go by. That's a "30ft/min" rate, and it's a relatively l-o-n-g time. Certainly longer than it would take to "swim up to the ladder" from 15ft.

I'm guessing you're going too fast, and don't even realize it.

(We can save the can-of-worms discussion about doing a 60ft "deep stop" on a 100' recreational dive within NDLs for another time.

 

[Jim Lapenta]

Jim, are you saying you'd be concerned that time spent at safety stop depth will cause you to exceed NDL?

No, time spent at safety stop depth is not going to cause me to exceed the NDL's.