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One Long Deco Dive vs Two Shorter Deco Dives with a longer total bottom time?

Discussion in 'Technical Diving Specialties' started by lukeb, Aug 6, 2020.

  1. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    I have done mixed boat dives many times doing rec level dives. I think I always get more bottom time than my tech colleagues on RBs, something like 2 hrs vs 1 1/2 hrs. Of course, that is not the the only reason you dive tech.
    lukeb likes this.
  2. bubblemonkey2

    bubblemonkey2 Marine Scientist

    # of Dives: 200 - 499
    Location: Earth
    That depends on how it's planned out though, for example a CCR dive could span the whole three hours, skipping the surface interval entirely as well as running for the entire length of the two rec dives
    NothingClever likes this.
  3. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    why is that? The CCR divers should either be doing what @bubblemonkey2 said and just staying down the whole time, or at least matching what you're doing. If they're coming up early, that's their choice, but not a limitation of the CCR
    Lew Nance and NothingClever like this.
  4. kensuf

    kensuf Cave Instructor

    The ocean is very dynamic and conditions can change quickly. In a place like the gulf stream, I try to keep my run-times less than 2 hours, currents can make you cover long distances, boat traffic can keep things sporty, waterspouts, moon jellies, etc. We had a sporty dive last month where we covered 5 miles on a 30 minute hang.
  5. flymolo

    flymolo DIR Practitioner

    I like one long dive for anything with deco. Anecdotally, I seem to feel better afterwards than if I do two dives with deco. But in the northeast we can't really do a longer surface interval than 1.5 hours so that plays a role.
    lukeb likes this.
  6. RyanT

    RyanT ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Maryland
    Another consideration is what the operator is doing. If they're planning to hit two wrecks, then two dives it is. If the boat is doing a double dip with recreational divers, I almost always opt for one long dive. I don't enjoy climbing a boat ladder with doubles, so if I can do it once, it's just nicer. Also, by doing one long dive, I can usually time my dive to avoid most of the other divers on the boat. I don't enjoy doing my deco hanging in traffic.
  7. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
    Not sure where I got that idea carry on then!
  8. lukeb

    lukeb Divemaster

    # of Dives: 200 - 499
    Location: Central Florida
    Looking at the one long dive plan then, it seems that gas volume is almost always going to be the primary limiting factor. In South Florida, where double ALU 80s are the norm, it seems to be difficult to plan a dive where I am not considering trying to do 2 dives, to get the most of of my time on the boat (Otherwise I will end up sitting on the boat for over an hour thinking about how I could be in the water!). This is also what is leading me to want to invest in the biggest steel doubles I can safely manage, so as to extend my single dive time.
  9. RyanT

    RyanT ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Maryland
    I don't know if you have any doubles currently. If not, you might consider starting with a set of AL 80s. Dive those for a bit and see where the deco diving takes you. AL 80s are substantially cheaper than a set of steels and if you decide you want more gas, you can sell them or use them as a spare set. Here's why I say this... When I started down the tech road, I thought I was going to move towards doing 300' dives. Along the way I learned that I really don't enjoy doing the kind of deco (and gas needs) those dives require. My favorite dives these days are in the 120-160' range. These dives give me a nice ratio of bottom to deco time. I'd rather have something like 40 min bottom time with 20 min of deco, rather than the other way around. I don't mind doing deeper dives, but it needs to be a wreck I really want to see. Perhaps multi-hour, 300' dives are in your future, but even so, you need to take your time and develop your skills. Don't forget that there are lots of fun dives on the way to more advanced dives and you don't need a huge set of doubles to enjoy that part of your journey.
    WinfieldNC and lukeb like this.
  10. Degenerate

    Degenerate DIR Practitioner

    When you say one long dive, how much bottom time are we talking, and what depth/gas are you running it at in multideco?

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