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Safely diving with heavy tanks

Discussion in 'Basic Scuba' started by Nathan Doty, Jul 16, 2019.

  1. Caveeagle

    Caveeagle Rebreather Pilot

    # of Dives: 500 - 999
    Location: High Springs, FL
    1,701
    1,236
    ^^ Not true for everyone. Depending on individual BMI. Many people will sink just fine wit only a rash guard.

    At the end of the day, you wand as little add on weight as possible. To be as close to neutral as possible at end of your dive ~500psi etc. and have tanks you can get proper fills on for where you are diving.

    In Hawaii I have found only AL80 for rentals. Other places I either bring my own steel, or rent LP85/HP100. 85 are great tanks, as long as you can get good fills. Hp100 are ok too, but might be a tad neg if you are already a “sinker”. For many folks who are natural “floaters”, a HP100 is a near perfect tank.

    Dual, or redundant floatation bladders should not be necessary if you are not overweight and can swim up your rig.
     
  2. helodriver87

    helodriver87 DIR Practitioner

    # of Dives: 500 - 999
    Location: New Mexico
    479
    846
    So, the reality is that you need redundant buoyancy for big steels. No way around that. My LP120s are somewhere in the neighborhood of 25 pounds negative when cave filled. Swimming them up isn't an option, so I use a drysuit when I dive them. Or I don't dive them. Some people use dual bladder wings, but I'm not a huge fan of those. More clutter, complication, and potential to screw things up in an emergency. Lift bags work ok when you're over a hard bottom that won't exceed your MOD. Kind of an ass pain to deploy as redundant buoyancy in a hurry though.

    If you can find a confined water site, you can experiment with various solutions. Try different exposure suits and tanks (if you can get your hands on some to borrow). Try swimming things up, deploying lift bags, etc. Get an idea for what's manageable. Cut weight where you can as well. Backplates come in a few flavors. Steels are super negative, AL is about -2, and you can even find Carbon Fiber plates that are essentially neutral. Ultimately, you're going to be limited by tank size and exposure protection, so it's all a bit of a balancing act.
     
  3. melanie.

    melanie. Contributor

    # of Dives: 200 - 499
    Location: Ontario, Canada
    298
    227
    Hp100 are awesome for short people. By far best tank that I have ever dove in my life, will never buy a different size now.

    As mentioned above, if you don't have ditcheable weight generally think of having a secondary source of lift for an emergency. I have wing, drysuit, and an smb.

    Honestly everyone should have an smb anyways so there you go, problem solved. Learn how to use it
     
  4. wnissen

    wnissen ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 50 - 99
    Location: Livermore, Calif.
    623
    384
    I'm not aware of any way in which steel tanks are better (for the diver) except the reduction in weight and the possibility of cave fills. Why would you pay twice as much and worry about corrosion otherwise? Most operators don't even rent them, and the ones that do are in cold climates where you'd have a significant wetsuit and need more weight anyway.

    Being overweight is not typically a primary cause, but it certainly contributes in the couple DAN annual reports I read. People start dealing with an issue and start descending because they're not really neutral, and it snowballs.
     
  5. helodriver87

    helodriver87 DIR Practitioner

    # of Dives: 500 - 999
    Location: New Mexico
    479
    846
    Steels offer better capacity than aluminums, even without cave filling. They'll also last forever if you take care of them. They tend to have better bouyancy characteristics as well since they stay more negative than aluminium tanks. They're not right for every dive though, so it's important to match what you're using to what you're doing.
     
    Diving Dubai and RyanT like this.
  6. NAUI Wowie

    NAUI Wowie Contributor

    # of Dives: 50 - 99
    Location: Silicon Valley northern CA
    760
    345
    Sorry not going to buy that theory. Redundant boyancy with a large steel? I have an HP120 I dive with and I fully deflate bcd when heading to the surface. Even when tank is full and I have 16 pounds of weights I can kick up to the surface easily. 7 mil wetsuit.
     
    Bob DBF likes this.
  7. helodriver87

    helodriver87 DIR Practitioner

    # of Dives: 500 - 999
    Location: New Mexico
    479
    846
    7 mil is pretty floaty, so if you're not deep, you're getting some serious help. Also, from the phrasing, it sounds like you're taking about the end of the dive. You need to consider the beginning, as that's your worst case. There's also a difference between "I can do it" and "I want to deal with this in an emergency". Single tank isn't terrible, but on deeper dives or dives without a safe hard bottom, you need to consider alternate buoyancy in a way that you never have to with aluminums.
     
    RyanT likes this.
  8. helodriver87

    helodriver87 DIR Practitioner

    # of Dives: 500 - 999
    Location: New Mexico
    479
    846
    The whole point of redundant buoyancy is to compensate for a BC failure. So sure, it's fine when everything is working. I could dive my LP120s with a rashguard and 60lb wing and be fine. Until the wing pops. Then I'm screwed. At 100', a 7mm is only providing a few pounds of lift. If your BC fails catastrophically, you're negative. Maybe just a few pounds, sure, but negative is negative. Even if it's a sand bottom shallower than my MOD, I'd rather not kick my way to the surface and doggy paddle to keep my head out of the water. Just carry an SMB (which you should anyways) and use that. It's not difficult or an inconvenience, but it's your risk calculation at the end of the day.
     
  9. Billy Northrup

    Billy Northrup ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Key Largo / Norcal
    305
    136
    You DO carry redundant buoyancy in case of wing failure.

    Removable weights mitigate the problem in the rec world , redundancy when you don’t have any weight to remove.

    In the rec world you can remove just one weight and evaluate. If one need 10 put two and threes and dole them out until you can kick up.
     
  10. Darnold9999

    Darnold9999 Solo Diver

    # of Dives: 500 - 999
    Location: Victoria BC Canada
    2,561
    788
    Did a liveaboard with steel 100 and a 2/3 shorty. No weights. No possible way I was going to swim the full tank up if my BCD failed at the start of a dive and even if I could no way to keep it on the surface.

    Moved to a full 2/3 suit (much newer) and even then was marginal. The plan became get to the surface and then abandon everything if the BCD failed.

    Probably should have switched to an AL80 but I really like to have lots of gas. Gives me options.

    AL100 is probably best option for you. I find they are just about neutral with my rig and an old worn out shorty. I use an AL backplate and wing for tropical dives.
     

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