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Math is Scary - Drowning is (probably) Scarier

Discussion in 'Advanced Scuba' started by oya, Nov 9, 2020.

  1. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    I am a cave diver and a trimix instructor. I wrote and teach a distinctive specialty course on advanced dive planning for recreational dives. One of the things I teach in that course is that there are many ways to plan dives and carry out those plans, and you choose a plan that is appropriate for the dive you are going to do. Planning levels that are essential for some dives are unnecessary for others.

    Let's say I am planning to do a recreational drift dive on a flat reef, such as is found in south Florida. Here would be my entire dive plan:
    1. Jump into the water,
    2. drop down to the reef,
    3. swim with the current until either my gas supply reaches a certain point, my NDL reaches a certain point, or I have reached the maximum time allowed by the boat operator
    4. Ascend
  2. oya

    oya Rebreather Pilot

    # of Dives: 2,500 - 4,999
    Location: Akumal, MX

    My chief credential to this end is, "Having had to track a dozen people's gas at a time for them every single day for several years."

    But the reason I wrote this blog post in the first place is that it has not been infrequent that I have had technical divers or even instructors who have stared at me blankly when I start this critical component of the course, so I need to spend an hour of class time explaining all this to them.

    Do I think it needs to be incorporated into an OW course? Nope.
    And AOW course? SAC rate maybe.
    Deep Diver? SAC rate definitely. Maybe the rest because it's really not that hard.

    That way, even if everyone doesn't do it on every dive, at least they've been exposed to it before. And they have more of an idea of what their pressure gauge is going to say other than, "HOLY CRAP WHERE'S THE GUIDE I'M ALMOST OUT OF AIR AND I DON'T THINK WE'RE NEAR THE BOAT!"
    CharlotteJacket and rick00001967 like this.
  3. moose_grunt

    moose_grunt NAUI Instructor

    # of Dives: I'm a Fish!
    Location: Saipan
    "But there’s always that one 80lbs woman on the boat who has been diving for 50 years and comes back with more gas than she left. @#$% that jerk."

    Ahahahaha, almost spit out my coffee at this one. Thanks for the laugh.

    DiveClimbRide, NothingClever and oya like this.
  4. Scared Silly

    Scared Silly ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: on the path to perdition
    4 out 3 divers prefer not to drown.
    oya and BlueTrin like this.
  5. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    As a dive guide, you participate in a spiral of learned dependency.

    As an instructor teaching OW classes, I have on several occasions had students tell me that their friends who are experienced divers have told them that they only have to learn the dive planning stuff for the class. Once they are out in "the real world," they can forget all that planning stuff because the DMs do all of it for you.

    In the OW class, students are supposed to be taught to monitor both their own gas supplies and their buddy's gas supply continually, but "in the real world," they learn that it is not necessary because the DM will do that for you and tell you when it is time to ascend. So what do you do? If you do not monitor them carefully, some may run low on gas. If you do, you teach them that they are to depend upon the DM for that role.
  6. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    I see that you are from Akumal, and I would like to take a moment, perhaps an off-topic moment, to suggest other ways you could work to improve OW training.

    A number of years ago, PADI changed its OW class, adding a number of new requirements and putting a significant emphasis on buoyancy and trim. There was a transition period after the announcement before they had to be fully in place. During that transition period, I went to Akumal with some friends and was allowed to use a shop's resources to certify them. I fully used the new requirements, including teaching them trim. Since I knew they would be using rental BCDs, I brought bungee loops that I could use to put weights on the cam bands in order to distribute the weights for better trim. As my students were putting them on the tanks, the shop's instructors gathered around to see this strange sight. What was I doing? Why? What is the point in distributing weights like that? I explained what trim was and why it was important, and I told them they were going to have to be teaching it soon because of the new standards. "What new standards?" they asked.

    Two days later, we came back from a morning dive in Akumal Bay, and the DM, who we had not seen before, came to the 3 of us and told us he noticed that we were the only ones signed up for the next dive, and he wondered if he could take us some place more fitting our experience level. We eagerly agreed. Unfortunately, we were joined by another couple, and when we got to the more advanced site with its coral canyons and swim throughs, they were not skilled enough for it, so we swam over all of the good stuff. After the dive, the DM apologized, saying the new couple only had about 25 dives and so were not skilled enough, not having the vast experience the three of us had. I pointed to my two friends and told him that I had just certified them the day before, and he had just witnessed their first 2 dives as certified OW divers. It turns out that when you teach buoyancy and trim in the OW class, people learn those skills pretty quickly.

    A year ago in October, I was in Akumal again with family. I took my granddaughter out to snorkel over the reef in Akumal Bay (or what is left of it), and we passed over an OW class. They were in a circle, kneeling on the bottom, obviously overweighted as they did basic skills. There was no sign of trim weights.

    So, while you are working to reform OW instruction on gas planning, you may want to branch out to other areas of instruction that could stand some improvement. Before adding new skills to the class, get your colleagues to teach the ones that are there now.
  7. oya

    oya Rebreather Pilot

    # of Dives: 2,500 - 4,999
    Location: Akumal, MX
    It has been some time since I have taught an Open Water class.
    NothingClever likes this.
  8. JoeFriday

    JoeFriday Photographer

    Agreed. Rec dives are supposed to be forgiving. In theory you can ascend to the surface at any time.

    This simplifies life to needing to know a minimum of rules / theory:
    - the deeper you go the faster your air gets consumed - this is good to know, no math required
    - for return to entrance point dives, use the rule of halves, you need to be able to divide by 2
    - for drift dives start to ascend at X psi - where X is provided since you are part of a cattle dive. No math required.

    Anything else may be useful, but not required.
    boulderjohn likes this.
  9. divezonescuba

    divezonescuba ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Houston, Texas
    Just because you check in on a bunch of computer kiosks doesn’t mean they’re a cattle boat dive op.
    oya likes this.
  10. NothingClever

    NothingClever ScubaBoard Sponsor ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: Red Sea and Atlantic Ocean
    This started out as one of Roger’s normally funny blog posts but now it’s really getting funny.
    oya likes this.

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