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So what should have happened?

Discussion in 'Basic Scuba Discussions' started by markrodg, Sep 13, 2009.

  1. TSandM

    TSandM Missed and loved by many. Rest in Peace

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    Deploying an SMB would not have kept the OP from drifting away from the boat (in fact, depending on current, it might have made him drift faster). But deploying while he was still near the boat might have allowed them to know a buddy pair was drifting, and where they were.

    GrannyScuba, it's not that the item is different (although some divers tow floats, rather than buoys). It's just the application. Some people tow floats or markers during their dive; a deployable SMB is one which CAN be inflated at depth at the end of the dive. But it could also be inflated at the beginning and towed, if the diver chose to do that.
     
  2. TerryC

    TerryC Master Instructor

    # of Dives: 2,500 - 4,999
    Location: St Kitts, West Indies
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    100 ft dive, then a 25 minutes surface interval. Sorry, I want my money back for dive 2, cos it is not worth putting my kit on for.
    markrodg you learned a lot from this experience, good for you. Keep on learning and diving.

    T
     
  3. Web Monkey

    Web Monkey Omniheurist ScubaBoard Supporter

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    I don't think your computer wanted an optional "safety stop" if the first dive was on air, your computer was probably requiring a manditory decompression stop.

    The way to avoid this in the future is to follow your training, which includes diving with a qualified buddy, planning your dive and diving your plan.

    "Follow the DM" isn't a plan, and jumping into random chum-filled water hoping to see "big fish" is never a bright idea unless you're in a shark cage.

    Terry
     
  4. Lucy's Diver

    Lucy's Diver Barracuda

    # of Dives: I'm a Fish!
    Location: New York City
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    Look, this is not all that bad. If by a 25 min SI he means they started gearing up after 25 minutes, well with aboat full of divers you're probably not in the water until 45 minutes after the first movement to gear up. Second, some computers give longer saftety stops, as well as actual deco stops (which are different things on some computers) for things unrelated to SI, incuding saw toothing the profile and any rapid ascent. I had Suunto give me a 5 minute deco stop (i.e. actual ceiling) after multiple bouce dives to 30 feet to rig a heavy lift once, the tables only start there. I did the stop because I didn't want to bend the computer, I really didn't think I'd bend myself.

    Also chumming can refer to a lot of different things. If they are throwing massive chunks of meat and gallons of blood into the water I might stay out. Some outmeal and fish oil might not bother me so much.
     
  5. Web Monkey

    Web Monkey Omniheurist ScubaBoard Supporter

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    The OP said it was a 25 minute SI. If it was longer, I would expect he would have said so.

    The algorithms model nitrogen absorption and off-gassing based on the diver's behaviour (time/depth/activity/temperature/breathing/etc.). Either you trust the computer and the algorithm it uses, in which case you should follow it, or you don't in which case you shouldn't be using it at all.

    One of my friends ended up with a completely numb arm last week, nearly drowned and got to ride the chamber because his computer was complaining and he didn't think he'd get bent either.

    I don't mean to come off as too obnoxious, but if you're going to dive a computer, it should be one that you trust and you should listen to it.

    Terry
     
  6. Ana

    Ana Solo Diver

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    I'm still curious about "longer safety stops" If it is a safety stop is just a good thing to do, making it longer sounds to me as something more than just a good idea.
    I've been using Oceanic computers for almost 2 decades, Suunto before that. Never seen "longer" safety stops. Which brands have this feature?
     
  7. Derek S

    Derek S Divemaster

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    Ana, it sounds to me like it wasn't a safety stop so much as the Suunto put the OP into deco and he was forced to do that, and he just 'assumes' it was a longer safety stop.
     
  8. Derek S

    Derek S Divemaster

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    Markrodg, I'm not going to further beat what the others have said to death ad nauseam, but to just point out that it is your right to call a dive at any time, even if it is before you get in the water. The 25 minute SI would have been more than enough for me to question the professionalism and morality of the dive operator, let alone the fact that the DM got all excited over chumming.

    Nobody should EVER give you a hard time for 'thumbing' a dive (even if it is on the surface), YOURSELF included. I know you were on a charter, and that cost you money, so you were somewhat reluctant to really question yourself, but at the end of the day, it's just a dive, it's just money. Your health and safety are paramount. Now that you know about ScubaBoard, come back here and talk to locals next time you plan a trip, they can give you the low-down on the dive operators, etc.
     
  9. Ana

    Ana Solo Diver

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    Well how about that.... thanks for the reply.

    Wow, one of the first things I'd do is to ask my dive instructor to give me my money back.
     
  10. leapfrog

    leapfrog Instructor, Scuba

    # of Dives: I just don't log dives
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    Every diver has been told to perform safety stops, yet the majority don't understand them. Many divers have been informed that performing a safety stop allows them to slowly eliminate nitrogen. This is simply not true. A safety stop assists the body in rapidly eliminating nitrogen! Bubbling does not occur in a diver under pressure, it only occurs when the pressure is reduced too much. Once bubbling occurs, gas elimination is reduced. This is because the driving force for nitrogen elimination has diminished. The bubble now has to be reabsorbed - which can be a time consuming process. However, if bubbling can be minimized or prevented, then the nitrogen stays in a gaseous solution (i.e. dissolved) in the body. If this can be maintained while surfacing, then the nitrogen pressure is maintained while the pressure surrounding the diver is reduced. When the nitrogen pressure is allowed to stay greater than the surrounding pressure, a driving force for nitrogen elimination is created and nitrogen will come swiftly out of the body. To put it even simpler, a diver that performs a 3 minute safety stop after a dive will have less nitrogen in their body immediately upon surfacing as compared to a diver that did not perform a safety stop, but has been on the surface "off-gassing" for 3 minutes. Therefore, one of the best things a diver can do for themselves is to perform a safety stop, no matter how short, after every dive.
    Years ago, a safety stop was recommended at 3 meters after every dive. This recommendation wasn't so much a depth recommendation other than a recommendation to just perform a safety stop. Later, the recommendation turned to 5 meters and is now currently 5 to 7 meters for 3 to 5 minutes. A deeper depth of 5 meters was chosen for several reasons, but a driving force behind this deeper recommendation was overwhelming information that deeper stops promote greater nitrogen elimination.

    HTH
     
    Last edited: Sep 26, 2009

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