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Planning a rec dive and diving the plan

Discussion in 'Basic Scuba Discussions' started by Storker, Sep 2, 2019.

  1. Storker

    Storker Divemaster

    # of Dives: 100 - 199
    Location: close to a Hell which occasionally freezes over
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    Its been said ad nauseam that you should "plan the dive and dive the plan". And the extent of planning necessary for a rec (no-stop) dive has been discussed ad nauseam both here and other places.

    I'm used to providing a rudimentary dive plan for every dive. In my type of diving, there's no DM holding your hand, every diver is in the water by themself, preferably as a part of a buddy pair or team. We have a dive leader topside, and as a minimum every team has to provide a max depth and a max run time before splashing. While max depth can't be checked, if you exceed max time you might well expect to meet a few rather PO'd members of the emergency services when you surface. So, conscience dictates that you don't exceed max depth, and consequence analysis dictates that you don't exceed max run time.

    Back when, I got a little stressed when my more experienced buddy more or less refused to surface before we had about one minute left of called run time. It helped when I was told that that dude always used his called run time to the max.

    The other day, I was out diving. After a slightly too long dry spell. Some new gear, so I was a little apprehensive. After a short chat with my (new) buddy, we told the DL "30m max, 50 minutes max". That, of course, meant a multilevel dive, since 50 minutes at 30m would've meant quite a bit of deco and none of us were trained nor equipped for a deco dive.

    It was a pretty standard dive. Boat entry, but diving along the shore which was rather steep. Parts of the dive was a wall dive. A little bit of downcurrent, but quite manageable. My buddy was diving a rec twinset, so my gas was limiting the dive. At half tank (well within min gas, BTW), I signalled to turn the dive and ascend a bit. During the return, I monitored my gas a little more often than on the way out and adjusted my depth accordingly. At 50-something bar I signalled that we should ascend to the safety stop.

    To make a long story a little shorter, we surfaced after 48 minutes' run time, with me having about 40 bar left in my tank. Our max depth was within one meter from the called max depth. And we got there without any calculations, just a bit of gut feeling. Which had been developed through a bunch of dives regularly monitoring my gas and considering how my gas reserves would impact my remaining dive time.

    Yes, I'm probably bragging. But I'm more than a little fascinated at how it's possible to develop an almost instinctive feeling for how to conduct a dive to meet a plan which certainly wouldn't have been feasible if it were a square dive. And at how it's possible to dive a plan without any conscious calculations.
     
  2. lowviz

    lowviz Solo Diver ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Northern Delaware or the New Jersey Turnpike
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    For me, diving alone (at night) provides the undeniable immediacy and the in-real-life focus that ends up giving me my instinctive internal 'calculations' over time.

    When it is just you, there is no faking it. Baby steps. Just don't encourage those who are starting out on your path to hop up to where you are. They need to take the long road, encourage that.
     
    Marie13 likes this.
  3. Oldbear

    Oldbear Teaching Neutral Diving

    # of Dives: 1,000 - 2,499
    Location: Marshall Islands and Westminster, Co
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    I don’t think you are bragging, I think you are developing a keen instinct for diving. The human brain is an amazing thing. There are numerous examples out there that demonstrate its potential.

    When you first learned to drive a car, like most kids, you probably watched the gauges very tentatively for fear of either running out os gas or going to fast. I bet now after you fill the gas tank, you just drive for days until you instinctively feel you are getting low. Then you start reasoning and calculating in your head when to refill the car based upon factors like where the next gas station is, what your schedule is, do I what to refill today or can I make it another day, etc.

    Have you ever heard the expression, “When taking a test your first choice (of an answer) is usually the correct one. So don’t go back second guessing yourself and changing answers.”

    When I instruct or guide divers I do a gas check about half way thru the dive. Then I compare my gas usage rate to theirs. Now I have an idea what their gas usage rates are and I adjust the profile to match up better to the divers. They still get to dive their planned Max Depth and Max Time dive Parameters. But if there was a diver who had a higher gas consumption rate the overall dive becomes shallower than say a group of divers with a lower consumption rate.

    My point is over time, I have learned to make these simple adjustments in my head and on the fly. For divers who dive and think in the metric system it is even easier.

    One of the things I love about Tech Diving is the level of planning and the strict adherence to those plans, but with Recreational Diving, I use my gauges to monitor my dive, then make adjustments it needed. This is not to say I would ever dive without them, because they each are important tool...but so is the brain.

    And they must agree with each other. Water pressure from depth, directional perception and other factors can confuse the brain from time to time. So you should trust you compass and gauges as long as you are assured they are functioning correctly.

    Your second question, “How to plan a dive without any conscious calculation?” I don’t think it is possible to PLAN a dive without calculations. I think it is possible to go diving and come back safe. That is what our forefathers did in diving’s infancy. But not all of these dives were conducted safely. That is why SPGs, depth gauges, dive tables and the dive computer were invented...out of necessity.

    Let’s see what others have to say.
     
    chillyinCanada and Griffo like this.
  4. TMHeimer

    TMHeimer Divemaster

    # of Dives: 500 - 999
    Location: Dartmouth,NS,Canada(Eastern Passage-Atlantic)
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    I look at my gauges more than I need to. And my dives are usually very shallow, like usually 30' or less. But, I also check my car gas and speed way more than necessary. Some OCD I suppose. The rare times I buddy dive I probably spend at least 1/3 to 1/2 of the dive time looking at the buddy.
     
  5. Steve_C

    Steve_C Divemaster

    # of Dives: 500 - 999
    Location: Raleigh, NC USA
    4,135
    2,759
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    You check with buddy, if new one you see if they are comfortable with swim throughs or if there is anything they especially want to see or do. You find out the pressure they want to start up the anchor line at. You splash and go down to the wreck. Usually explore around the bottom first, then work more shallow. When you get within a few 100 psi of going up you get yourself back to the vicinity of the anchor line. At the agreed on pressure you go up. End of dive plan.
     
  6. Foothills

    Foothills Angel Fish

    # of Dives: 500 - 999
    Location: Alberta
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    The more familiar I am with the dive team and the dive site, the more casual the planning. To the point where we can say something like "The usual 70 minute circuit?" and we all know what the profile, bearings, and way points will be.

    With "new" dive buddies I will be more explicit, and we really focus on gas consumption since our routes tend to be circular, so "cutting a dive short" can lead to some low vis nav to avoid a surface swim. Gas management is one aspect of tech that has seeped into all my dive planning, even a 30' dive off a boat following a guide. I will calculate anticipated dive time and recalculate during the dive. For myself & my dive buddies.

    On a new site with experienced team members as guides, I will scribble notes & maps on my wrist slate as they plan the dive.

    When scouting a new site, planning can get detailed, or go completely out the window. Depends if we are looking for a known or suspected feature (we will have a detailed set of bearings to create a search grid), or are just seeing what's there. Then it is a case of making random turns and marking them on a slate as we wander, until it is time to head back, at which case a return bearing is plotted.
     
  7. CT-Rich

    CT-Rich Solo Diver

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    I normally lead the dive, I enjoy navigating and am fairly good at it. Because most of my diving is from shore and usually above 40’, they usually are fairly long traverses with the goal of very few pop-ups and exiting at a designated spot. Reading the currents, topography and gauges become pretty important. Planning a circuit dive I always try to consider the consequence of ending the dive early long surface swims suck and ones in open water suck double.

    If it is someplace new, I try to work it incrementally, start conservative and add to the next dive.
     
  8. TMHeimer

    TMHeimer Divemaster

    # of Dives: 500 - 999
    Location: Dartmouth,NS,Canada(Eastern Passage-Atlantic)
    12,321
    2,710
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    That's about what I do the rare time I boat dive. I mention that I want to spend the first part on the bottom shell hunting and then whatever the buddy wants to do. For an 80' dive on air (first dive) that's 30 mins. max. 10 out, 10 back, 5 at the anchor area and up at 25 mins. I do check my watch and DC often, but probably could do it with a lot less checking.
     
    Steve_C likes this.
  9. Diving Dubai

    Diving Dubai Instructor, Scuba

    # of Dives: 500 - 999
    Location: Dubai UAE
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    By experience.

    We do similar (no DM dives) I know that my normal cylinder size has more than sufficient gas for my diving - and has a healthy reserve (90-100 bar) if all is well on a 30m no stop bimble. My gas checks are just cursory to confirm all is well. I know from instinct/experience how much gas I'll need for an ascent thus know when I really must leave, to be on the surface with 50 bar.

    Equally if conditions go the other way and consumption is high I can alter the plan on the fly to compensate.

    If I want to hang around and do a little bit of deco, again I'm not doing conscious calcs, one look at my gas contents tells me all I need to know

    If I'm diving a Al 80 which I do infrequently, then I'm more cautious with my gas checks, but the same applies, just by looking at the contents I can adapt the dive to suit (either ensure a 60min dive or to be on the surface with 50/60 bar)

    So I don't think you're bragging, it's just a state you achieve when you've done a sufficient amount of diving and are in tune with your gear and consumption.
     

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