• Welcome to ScubaBoard


  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Bouyancy characteristics for hp steel tanks

Discussion in 'Tanks, Valves and Bands' started by formernuke, Nov 27, 2019.

  1. formernuke

    formernuke Manta Ray

    # of Dives: 50 - 99
    Location: New England
    603
    329
    63
    I'm looking at getting HP steel 100's for single tank diving. The options are new fabers or used PST.

    Does anyone know the bouyancy differences between these tanks?
     
  2. Kupu

    Kupu Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: NC
    661
    142
    43
    Have you seen this thread?
     
  3. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

    # of Dives: 500 - 999
    Location: Napa, California
    3,571
    4,078
    113
    Faber FX100 is 100cuft at 3442psi, if you can get it, and has an empty buoyancy of -0.6lb.
    7.25" x 25"

    PST special permit 100 is 102cuft at 3500psi, if you can get it, and has an empty buoyancy of -1.3 lb.
    7.25" x 24"
     
  4. formernuke

    formernuke Manta Ray

    # of Dives: 50 - 99
    Location: New England
    603
    329
    63
    Ok I feel like an idiot I searched instead of just reading the top post.
     
  5. Bob DBF

    Bob DBF Solo Diver

    # of Dives: I just don't log dives
    Location: NorCal
    6,720
    7,155
    113
    Or if you can find a Faber MP 100, 100cuft @ 3498# (3180 +10%) -7.25 empty, nice for cold water. 7.25 X 24", 38.7# empty.



    Bob
     
  6. Doctor Rig

    Doctor Rig Nassau Grouper

    # of Dives: I just don't log dives
    Location: Michigan
    164
    31
    28
    What ARE the “buoyancy characteristics” of dive tanks? The compiled tank table values might be a great resource for the experienced diver, but not to me.

    Can anyone provide some insight on how to use this data to select a tank that will give the diver the most manageable buoyancy through-out a dive (full to empty) and help optimize the least amount of lead required for the dive?

    I’m guessing there are some preferred tanks (either aluminum or steel) that are are better for buoyancy optimization than others. I’d love to hear what your favorite tanks are and why!
     
  7. Kupu

    Kupu Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: NC
    661
    142
    43
    I will offer an example of of how I used the spreadsheet for a recent tank purchase when looking for an alternative to AL80s. For single tank, warm water dives with wetsuit the goal was to minimize added lead without being over-weighted by the tank itself. I wanted a tank that is close to neutral at the end of the dive rather than positively buoyant.

    Looking at the spreadsheet, my Luxfer and Catalina AL80s have 77.4 CF capacity and are about 1.5 lbs negative at the beginning of the dive but over 4 lbs positive at the end. The OMS steel LP85 has 85 CF capacity and is about 6.5 lbs negative full and is neutral at the end of the dive. Using the OMS LP85 allows me to remove 4 lbs of lead from my weight belt with no loss of air capacity and about the same tank dimensions.
     
    Doctor Rig and rjack321 like this.
  8. Doctor Rig

    Doctor Rig Nassau Grouper

    # of Dives: I just don't log dives
    Location: Michigan
    164
    31
    28
    @Kupu Thanks for sharing. Did your LP85 change your trim or weight placement any?
     
  9. broncobowsher

    broncobowsher Solo Diver

    1,109
    632
    113
    The chart gives numbers but does not tell the whole story. I have found that the steel tanks rest on your back better. They are heavier, but the weight is in the right place. You don't have a floaty aluminum tank pulling up while weights are pulling down. A steel tank just feels more relaxed on my back. I just trim out better. In both wet and drysuits.
     
  10. Kupu

    Kupu Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: NC
    661
    142
    43
    Yes, as described by broncobowsher above. The horizontal trim I am looking for comes easier using steel LP85s and LP80s rather than AL80s.
     
    Doctor Rig likes this.

Share This Page