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3 or 5 minute Safety Stop?

Discussion in 'Basic Scuba' started by tracydr, Jul 5, 2013.

  1. chrpai

    chrpai Contributor

    # of Dives: I just don't log dives
    Location: Cedar Park, TX
    3,693
    964
    Nothing like insulting and threatening to back up your argument.
     
  2. lowviz

    lowviz Solo Diver ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Northern Delaware or the New Jersey Turnpike
    7,401
    4,370
    Start with 80% for the high limit and 30% for the low limit.

    All the reasons and thinking are in Mark Powell's book. In addition, get a copy of the Six Skills by Steve Lewis. Finally, for another great "mindset" read, get a copy of Sheck Exley's "Basic Cave Diving -a blueprint for survival."

    All of which draws the cloak off of the DIR types. (don't push back unless you are willing to post all the specifics of ratio deco). They start out in their education with an all encompassing ascent plan, argueably not optimal, but far better than the "NOW WHAT???" that most of the other agencies use if NDL is violated. It is interesting to resolve their plan against Buhlman, RGBM, deco on the fly, etc, etc, etc.

    There is more than one way to the top.:wink:
     
  3. Bopper

    Bopper Contributor

    # of Dives: 100 - 199
    Location: San Diego, CA
    320
    114
    Again I'll refer to the passage in the Deco for Divers book, pages 50-52, which - if I'm reading correctly - used Doppler bubble detection to measure silent bubbles on divers who did 5 minute, 2 minute, and Zero minute safety stops. It was clear from the results that there was a significant reduction in detectable silent bubbles for divers who did the 5 minutes safety stops vs those who did 2 minute ones and those who did none. The author introduces the studies as "a series of experiments researchers did in the US" and credits the graph (figure 21) from data from "AAS"...whoever that is. If this data and these studies are valid I don't see why we can't classify the improvements that longer safety stops offer as something we "know".
     
  4. Doomnova

    Doomnova Contributor

    # of Dives: 100 - 199
    Location: Playing go fish with the fishies :D
    197
    47
    Richard I wouldn't always assume low sac= woman.
    Myself and a few other buddies(all of us are guys') at all about 5'10-6'0 and are all in pretty good shape (not Olympic athletes or anything, hell I might hit the pool once a week but I usually cycle for 10min to university every day). and we all pretty much have SAC's here in cold waters with around 0.43-0.40(I consider a high SAC for me 0.50+). I can easily last on a 90FSW max 60 FSW avg dive for 47min and still end up on the surface with 500 PSI in my tank(this was one of my higher sac dives as we were working a bit of a current 0.47 for this one). I have noticed those with high SAC's have a few of these going on. This is all in waters that 2 piece 7mm wesuits at the bare min needed and drysuits are highly recommended. Which means all of us are dragging ball park 30lbs of lead with us to get down and stay down for the duration of the dive. This is also with AL80's. I'd have people yelling at me about my dives in terms of time with HP100+'s.

    1) Swimming a marathon....I really don't know what is with people who are racing around to look at stuff you'll see 2 things less area and less of whats not completely apparent.
    2) Finning technique. I see so many people doing bicycle kicks, the shimmy of the fins, and god know what else. Wasting tons of energy and thus air for doing very little.
    3) Buoyancy control. I think this one is pretty much been beaten into ground on Scubaboard, but i see it quite a bit.
    4) Over weighted/poor weight distribution. Ok there is a point to having a bit too much weight to get down and then there is a point to trying to sink a boat...I overweight a bit so if someone needs extra weight we don't have to swim back to shore to get it and honestly with my SAC a few extra pounds doesn't bother me.
    5) Always finning. I see this a lot too with people who are suffering from the above 3 all to varying degrees and thus energy=air and higher use of energy= shorter dive.
    6) Cardio fitness. Lets be honest here your rate of air consumption is directly tried to how efficiently your body uses the air in your lungs. Everyone has a maximum point where your can do something forever and never become exhausted and kick your body over to aerobic respiration. The moment that happens say bye bye to your low SAC for the time being. By being in shape the amount of effort to trigger aerobic respiration increases due to both increase in efficiency and usually having a lower resting rate of activity in terms of resting activity.
    7) Body Mass. This one is pretty simple. But is also proportional to lifestyle. You'll have a certain build but most of it is determined on how you live your life. Is it active and healthy? Not so much? This also has depending on the type of mass (fat vs muscle) an effect on how much weight you have to use to get down and thus how much effort in the dive to move that mass. Which then effects your metabolic rate and thus effects your sac. Enter vicious cycle.

    My point if you look at most of these point and generally made in order of easiness to fix. The first 4 can pretty much be done if you set your mind to working on buoyancy control and mastering fine control with 20-30 dive tops if you work at it. I spend a lot of my first 50 dives working on my skills because I was not happy with where I was. Now if I feel like it I can stand on my head look into a GPO den see if anyone is home take a bit bigger breath in and get off the bottom enough to flip back into the horizontal position i like to be in and not waste much or any air doing so. I don't swim at mach speeds because honestly you'll scare most things away that are of interest and those that don't move you won't see.

    When we all dive on a new site where we have never dove before. We pick a bearing heading somewhat into current if there is one. Swim 1000 PSI out, go 90 degrees to the left or right of that swim 250 PSI that way, Then parallel to the path we took out turn 90 degree towards the boat/shore and swim a 1000 PSI that way we should be pretty much back to where we were and back with 750 PSI and play in the shallows if there are any or a bit while doing our stop/after. Also with where I live you can easily follow some of the shore walls down to 120+ feet if you so choose hence why we use PSI as our guide. If its a really deep dive(I put in the 90+ category) I'll do 5min stops always. But with the way the dives work out a 3 min stop if all thats usually needed by the time we get back to shore.
     
  5. chrpai

    chrpai Contributor

    # of Dives: I just don't log dives
    Location: Cedar Park, TX
    3,693
    964
    Read the entire alert diver discussion. The answer to that question is in there.
     
  6. tracydr

    tracydr Divemaster

    # of Dives: 500 - 999
    Location: North Carolina, 3 miles from South Carolina
    2,730
    743
    Except that you need Advanced Nitrox training and an O2 tank with an extra regulator to do the extra couple of minutes on O2. Just about $1,000 if you add the class and tank/regulator.
    something I've been looking at doing, because I want the class for other reasons myself.
     
  7. lowviz

    lowviz Solo Diver ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Northern Delaware or the New Jersey Turnpike
    7,401
    4,370
    Take the course, get an old steel 72 and and keep it filled with O2 for the surface. When in doubt...
     
  8. uncfnp

    uncfnp Solo Diver ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: North Carolina
    6,712
    5,546
    Doesn't 100% O2 also need an appropriate regulator? Obviously I don't do deco...
     
  9. tracydr

    tracydr Divemaster

    # of Dives: 500 - 999
    Location: North Carolina, 3 miles from South Carolina
    2,730
    743
    That seems odd, given the number of tech divers that I've heard of with osteonecrosis, which is most likely caused by untreated type 1 hits.
    I'm also beginning to learn that those unlucky enough to have osteonecrosis may not have just DCS but different types of coagulation defects, such as anticardiolipin, ( lupus antibodies) or Leyden factor, basically similar to the same types of defects in the clotting system that puts a person at risk for deep venous thrombosis.
    I've been doing research into this after finding out that I have multi-joint osteonecrosis myself, which seemed to have started after diving in Catalina this March. The orthopedic doctor doesn't believe its diving related and thinks it was caused by steroids given in 2007 but the fact is I began having pain right after we went diving. I had some tests done by another doctor doing research on dysbaric osteonecrosis and was positive for anticardiolipin antibodies as well as another genetic factor called PAI-1 (4g5g heterozygous). He's talking about trying 12 weeks of lovenox if I have a second high test for anticardiolipin antibodies next week.
    Anyway, this is also part of why I've become more interested in decompression theory. The other reason is that I was planning to start taking some technical classes. When ( I don't plan to quit diving but it will have to be different and most likely sidemount ) I get back to diving, I will need to change my ascents and be as conservative as possible. I've dived for nearly 20 years and seemed to be fine until this winter. I have to figure out what was different this time. I do know my ascent rate was faster, mainly because I got vertigo while I was below 100 feet and had difficulty controlling my ascent. I had a hood that didn't fit and cold water was getting on my ears, making my ears frigidly cold.
    Anyway, for now I'm just diving in my pool and doing a lot of swimming.
     
  10. The Chairman

    The Chairman Chairman of the Board Staff Member

    # of Dives: I just don't log dives
    Location: Cave Country!
    62,363
    30,959
    You think so? Some tech divers are more like commercial divers than they are recreational divers.

    After all, this thread is about No Decompression Diving and safety, not mandatory stops.
     

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