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Question about learning deco procedures

Discussion in 'Advanced Scuba Discussions' started by Bent Benny, Sep 10, 2018.

  1. Bent Benny

    Bent Benny Nassau Grouper

    # of Dives: 50 - 99
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    I've searched for the answer to this but can't find it. Is there a rec diver course that teaches how to make deco dives? I have been taught to never violate NDL, but I know people do make deco dives. Is this something that is only taught in tech diving courses? I am specifically asking about deco dives that are within recreational depth limits.

    I know that nitrox is an option to extend NDL. Honestly I'm still working on improving my trim/buoyancy/SAC that I don't get near NDL anyway.
     
  2. BurhanMuntasser

    BurhanMuntasser Dive Charter

    # of Dives: I'm a Fish!
    Location: Nomad
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    You need to take tech courses for this type of diving. Required Deco diving is outside recreational diving scope.
     
    tbone1004, DogDiver and Bent Benny like this.
  3. Pkishino

    Pkishino Instructor, Scuba

    # of Dives: 200 - 499
    Location: Sweden
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    most agencies classify recreational diving as max 40m and no deco, always able to ascend immediately with no ceiling. Thus, doing deco dives is technical diving, doesn't matter if it's at 30m or 50m.. There are many different courses that cover deco diving, Raid offers Deco 40 as the intro to deco diving.
     
  4. chrisch

    chrisch Solo Diver

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    Generally most agencies will consider decompression "tec" irrespective of depth. A lot of divers just use their computer for a very short deco stop without training which is dumb but we all know it happens.

    The critical skill is to be able to hold the stop which requires buoyancy control. If you are still working on that skill then you need to do even more work on it! The knowledge you can probably get from a good book on the subject, but it cannot teach the practical skills.

    If you look around for a course you should find "decompression procedures" or a similar course from a range of agencies and dive schools near you or convenient to you. The TDI one is outlined here: TDI Decompression Procedures Diver - SDI | TDI | ERDI

    This is the correct course for just learning decompression. To increase your depth ability you can undertake further training.

    Nitrox will be a useful thing as well, but a Nitrox course will not improve your buoyancy or give you any knowledge of deco. Personally I would get a decent book and read up on the subject, then when you are ready look at the TDI course or similar - whatever is convenient to your personal circumstances.
     
  5. seeker242

    seeker242 DIR Practitioner

    # of Dives: 200 - 499
    Location: Pompano Beach, FL
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    Only one I know of is GUE Rec 3. Teaches limited decompression, max of 15 min and a single deco bottle. Max depth 130'
     
  6. Dirty-Dog

    Dirty-Dog Frequently Censored ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Pueblo West, CO, USA
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    As I understand it, the definition of a tech dive can be boiled down to 'any dive during which you cannot go straight (though slowly) to the surface' which means deco and rec diving are mutually exclusive.
     
    hxtk and Cyborg Pirate like this.
  7. Zef

    Zef Divemaster

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    Decompression obligation (decompression time) racks up rather quickly once you surpass the no-deco-limits established for recreational diving. This time based obligation requires that one plan their gas consumption and availability much more ardently than with recreational no-deco diving as going directly to the surface can have debilitating/disastrous consequences. In recreational no-deco diving the safety stop is "recommended", if you ascend to the surface without doing the safety stop the likely hood is that you will not have a problem (there is still the chance but low likelyhood) due to the conservative nature of the no-deco limits.

    When you surpass the no-deco limits your safety stop(s) are no longer recommended, they are obligations/required to prevent injury. Because the stops are required, one must have sufficient air to accommodate the increased time required before attaining the surface. This area, the area of gas management, is the critical area that needs to be acknowledged and trained on when it comes to doing decompression diving. Other concerns are depth based such as N2 narcosis and O2 toxicity.....being able to control your position in the water column becomes important as well when using different mixes of gas, such as using 100% O2 for decompression since if you surpass the maximum depth for the mix it can result in serious consequences as well.

    Recreational diving, in the mainstream mindset, has traditionally meant diving within the established no-deco time limits for a given depth. Purposely exceeding those limits is not advisable without proper training such as tech diver training, advanced nitrox, mixed gas diving, etc.

    I hope I was able to adequately address your question.

    -Z
     
  8. chrisch

    chrisch Solo Diver

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    I think this is the key change in mindset, I agree that gas planning is the new learning required. If I can add to your rather good post I would say that the critical change is that in decompression diving the return to surface is generally triggered by reaching a planned time limit, whereas in "no-stop" diving the return to surface is often triggered by reaching a planned gas limit.

    As you rightly point out deco obligations build up quickly while gas goes down and the need for gas in decompression increases. So the longer one stays past the "no-stop" limits the more gas becomes an issue, exponentially. This is why it is such a bad idea to just rely on a computer and stay "just a bit longer".

    Gas planning is not difficult, but it does need the diver to have a good idea of their consumption rates. Again it is not difficult to measure consumption but it does require a few dives in which you run these exercises. A good deco course is a great way to get all this information together and to review your understanding of gas planning.
     
    SJT1961 and Diving Dubai like this.
  9. stuartv

    stuartv Seeking the Light

    # of Dives: 200 - 499
    Location: Manassas, VA
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    @Bent Benny I think you want to have a look at PADI Tec 40.

    I am not a PADI diver. @boulderjohn could definitely answer this.

    But, I think Tec 40 would enable you to do 10 or 15 minutes of deco, with max dive depths up (down?) to 40m/132' (i.e. the standard recreational limits), using up to 50% O2 for a deco gas. I think. I also THINK you can do that course in a single tank rig (as opposed to other tech courses that would mostly require you to use doubles).
     
  10. Zef

    Zef Divemaster

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    I often dive with a club that I am a member of. Depending on the number of people who show up for a dive affects the format of the dive and what gets briefed...for instance (some possible scenarios):
    A) if it is just 2-3 people the plan would be to stay together throughout the dive as one dive team, obviously.
    B) if there are 4-6 people who are familiar with the dive site the brief may state that each pair of divers would be a team and the brief will also specify that the teams will dive as a loose group but if a pair become separated the dive will continue...or it may be briefed that each pair will do their own dive.
    C) if among the 4-6 people there is not enough divers familiar with the site for each pair to have someone in it who is familiar, then the brief would be the group will stay together...if a pair gets separated from the rest lost buddy protocol would be enacted.
    D) if the there are more than 6 people, this is way too many people to keep track of typically and it is incumbent on the buddy pairs to stay with the group, follow their own dive plan, or follow another pair that is familiar with the site.

    Regardless, we brief maximum depth to not exceed and maximum dive time. The expectation is that if you end your dive because you burned through your air in a short amount of time, you will wait at the briefed point of egress until the rest of the divers finish their dive....the rest of the divers who are more efficient on air or who are diving a larger capacity tank are expected to be at the surface at the egress point by the specified maximum dive time regardless of how much air is left in their tanks. Everyone returns to the cars together. If there is an issue, such as it is cold and the wait is short, the expectation is that the divers will grin and bear it...if the wait is long then one diver from the pair that surfaced waits at the egress point while the other runs back to the car to get warm clothes on or whatever then they come back and the other dive goes to take care of whatever business they need to tend to...but there is always someone at the egress point representing that buddy pair.

    (of course, if an emergency scenario develops that takes precedent)

    When diving outside the club type environment, then I agree, the dive time is usually limited based on air consumption or comfort....I have aborted dives with plenty of air because it was just too damned cold below the thermocline at the site and for whatever reason my tolerance was not up to grinning and bearing it on those occasions.

    -Z
     
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