Hello and welcome to our community! Is this your first visit?
Register
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 34
  1. #21
    New TDF Member
    Join Date
    Sep 2017
    Location
    Wilmington
    Posts
    7
    Likes (Given)
    0
    Likes (Received)
    2
    Quote Originally Posted by gobfish1 View Post
    on 33m for 30mins its all just a saving of feek all , 90 mins SI or 60 , o2 or nitrox back gas CCR your talking 3 and 4 mins


    try two dives first dive 60m +12mins o2 deco
    drop 2nd dive time to 45mins you get the same deco more dive time and day is not as long .

    other than that, it is what it is ,
    I think you're right on the money. Thanks again for the advice

  2. #22
    Established TDF Member
    Join Date
    Aug 2015
    Location
    3rd rock from the sun
    Posts
    535
    Likes (Given)
    30
    Likes (Received)
    127
    Quote Originally Posted by Xodiac View Post
    Honestly the more bottom time the better, I don't mind the artificial ceiling at all and would much rather run a few sets of twins with an accelerated deco, but I'm limited by what my dive buddy's can do or are willing to do :-/
    Didn't I post the dive plan earlier? You could get close to an hour on the bottom with some deco on 80%. It's roughly one minute of deco for every minute over 30 mins. Obviously depends on your backgas volumes, your SAC, your team, your stage contents and your attitude to deco.
    Last edited by Wibs; 22-09-2017 at 11:13 PM.

  3. #23
    Last of the Mohicans gobfish1's Avatar
    Join Date
    Jan 2013
    Location
    the grassy knoll
    Posts
    2,724
    Likes (Given)
    3255
    Likes (Received)
    1806
    Quote Originally Posted by MikeF View Post
    or in line with standard TDF advice get a rebreather. do your 90 minutes on the bottom at 33m in one go, 40 mins of deco and head on home. your day won't get much shorter than that.
    i need to get a new dial a bend as the one im using must be bending the shite out of me , its telling me to do half that number,

  4. #24
    Grumpy Git, Not Old Yet...
    Join Date
    Jan 2013
    Location
    South-West-ish, Various.
    Posts
    3,321
    Likes (Given)
    3365
    Likes (Received)
    1594
    Twinset, Al80 bottom stage (both of EAN32), 7L stage of O2 for deco.

    BT of 90 mins, total dive time 150mins.

    It's overkill tbh and I'd be tempted to do it as 2x 45 min BT dives, about 13 mins O2 deco each (67 mins total RT). No need for a bottom stage. That's a good, solid twinset dive with accelerated deco.

    O2 vs 80%? well, there's not a massive amount in it for the speed for the deco, but O2 is a good thing to have around and you don't have to mix it. I've never seen the point of the 80, but I can see that this argument cuts both ways...
    DISCLAIMER: If you don't understand this shit, ask a grown up, preferably someone with deep pockets, who your widow/kids can sue. Don't trust people on the internet with your life, your credit card details or your naked selfies! This advice may contain, or indeed be written by someone who is (clinically), nuts.

  5. #25
    TDF Member Alex Denny's Avatar
    Join Date
    Mar 2016
    Location
    Tonbridge
    Posts
    274
    Likes (Given)
    55
    Likes (Received)
    71
    It's a fair bit cheaper...

  6. #26
    Established TDF Member
    Join Date
    Aug 2015
    Location
    3rd rock from the sun
    Posts
    535
    Likes (Given)
    30
    Likes (Received)
    127
    Quote Originally Posted by Ian_6301 View Post
    Twinset, Al80 bottom stage (both of EAN32), 7L stage of O2 for deco.

    BT of 90 mins, total dive time 150mins.

    It's overkill tbh and I'd be tempted to do it as 2x 45 min BT dives, about 13 mins O2 deco each (67 mins total RT). No need for a bottom stage. That's a good, solid twinset dive with accelerated deco.

    O2 vs 80%? well, there's not a massive amount in it for the speed for the deco, but O2 is a good thing to have around and you don't have to mix it. I've never seen the point of the 80, but I can see that this argument cuts both ways...
    80% v 100% - more pressure? No air breaks? Less sensitive to depth? About the same deco?

    But 90 mins BT means (unless you've an exceptionality low SAC) you'll empty your backgas

  7. #27
    GUE Instructor Badger's Avatar
    Join Date
    Jan 2013
    Location
    East Midlands
    Posts
    699
    Likes (Given)
    101
    Likes (Received)
    236
    Blog Entries
    1
    Quote Originally Posted by Wibs View Post
    80% v 100% - more pressure? No air breaks? Less sensitive to depth? About the same deco?

    But 90 mins BT means (unless you've an exceptionality low SAC) you'll empty your backgas
    No air breaks? What are you doing, driving a truck around NDAC?
    GUE Instructor

  8. #28
    Established TDF Member
    Join Date
    Feb 2013
    Posts
    617
    Likes (Given)
    92
    Likes (Received)
    185
    Quote Originally Posted by badger View Post
    no air breaks? What are you doing, driving a truck around ndac?
    <slap>

  9. #29
    Old but keen Mark Chase's Avatar
    Join Date
    Dec 2012
    Location
    Kent UK
    Posts
    3,034
    Likes (Given)
    646
    Likes (Received)
    2012
    Quote Originally Posted by Xodiac View Post
    Hello guys and gals! First of all id like to say thank you for add. As a DM with tons of non tech dives I will try to be as helpful as I can to anyone within my experience.

    A little back-story on the types of dives I typically do these days. My typical dive profile tends to exceed the recreational type of diving. Me and a few of my diver buddies spend a lot of our time off the coast of NC diving for megalodon teeth. Our dives are about 110 feet deep so we use an EANx of 32 mostly. As the typical NDL are about 15 minutes, we will spend around 30 minutes on the bottom and do our decompression without a deco gas and spend a bit of time hanging before we do our surface interval. We spend about 1.5 hours between each dive and usually do 3 dives.

    My question might seem armature and I’m okay with that. I’m trying to gauge which direction I should go with my certs.

    I’m trying to bring our hang time down, and I’m sure the easiest way would be to grab an advanced nitrox cert and hang a near pure oxygen bottle at the surface with 2 regulators hanging to 10-12 feet for faster decompression.

    However my question here is: Could I use a trimix of around 32/20 (this would be a more cost efficient mix than a standard 21/35) or similar to keep my PPo2 where it is, but remove enough nitrogen to extend my NDL thus giving a safety net to come straight to the surface in case of emergency with out having to worry about a lengthy decompression altogether. (As I have not stepped into the direction of tech or trimix yet I’m not sure if there are other factors I should be thinking of, or if helium itself needs to off-gas.)

    I’d like to apologize in advanced if this question makes anyone cringe at the thought, but I will take whatever advice or constructive criticism you may have.

    Thank you again everyone!

    You could double that bottom time just by purchasing a proper decompression dive computer

    32% 30min at 33m = 8mins deco. Bearly more than a safety stop

    MultiDeco 4.04 by Ross Hemingway,
    ZHL code by Erik C. Baker.

    Decompression model: ZHL16-B + GF

    DIVE PLAN
    Surface interval = 5 day 0 hr 0 min.
    Elevation = 0m
    Conservatism = GF 80/80

    Dec to 33m (1) Nitrox 32 18m/min descent.
    Level 33m 28:10 (30) Nitrox 32 1.37 ppO2, 27m ead
    Asc to 6m (33) Nitrox 32 -9m/min ascent.
    Stop at 6m 1:00 (34) Nitrox 32 0.51 ppO2, 4m ead
    Stop at 3m 7:00 (41) Nitrox 32 0.42 ppO2, 1m ead
    Surface (41) Nitrox 32 -9m/min ascent.

    OTU's this dive: 49
    CNS Total: 19.2%

    2847.3 ltr Nitrox 32
    2847.3 ltr TOTAL


    Or as you say get a 3ltr of pure 02 and breath that from 6m and treble your bottom time to 45mins with 9mins deco

    MultiDeco 4.04 by Ross Hemingway,
    ZHL code by Erik C. Baker.

    Decompression model: ZHL16-B + GF

    DIVE PLAN
    Surface interval = 5 day 0 hr 0 min.
    Elevation = 0m
    Conservatism = GF 80/80

    Dec to 33m (1) Nitrox 32 18m/min descent.
    Level 33m 43:10 (45) Nitrox 32 1.37 ppO2, 27m ead
    Asc to 6m (48) Nitrox 32 -9m/min ascent.
    Stop at 6m 3:00 (51) Oxygen 1.60 ppO2, 0m ead
    Stop at 3m 8:00 (59) Oxygen 1.30 ppO2, 0m ead
    Surface (59) Oxygen -9m/min ascent.

    OTU's this dive: 91
    CNS Total: 38.4%

    3923.4 ltr Nitrox 32
    278.6 ltr Oxygen
    4202 ltr TOTAL

    The problem isn't the gas its your crap recreational dive computer

    You can get a Sheerwater persuit SH for about 250-300 these days

    Spend flash money on a Preditor if you like its easier to read but frankly does the same job as the Persuit


    ATB

    Mark
    Last edited by Mark Chase; 18-10-2017 at 07:42 AM.

  10. #30
    Established TDF Member
    Join Date
    Oct 2015
    Location
    West Lothian
    Posts
    808
    Likes (Given)
    205
    Likes (Received)
    200
    Quote Originally Posted by Mark Chase View Post
    You could double that bottom time just by purchasing a proper decompression dive computer

    32% 30min at 33m = 8mins deco. Bearly more than a safety stop

    MultiDeco 4.04 by Ross Hemingway,
    ZHL code by Erik C. Baker.

    Decompression model: ZHL16-B + GF

    DIVE PLAN
    Surface interval = 5 day 0 hr 0 min.
    Elevation = 0m
    Conservatism = GF 80/80

    Dec to 33m (1) Nitrox 32 18m/min descent.
    Level 33m 28:10 (30) Nitrox 32 1.37 ppO2, 27m ead
    Asc to 6m (33) Nitrox 32 -9m/min ascent.
    Stop at 6m 1:00 (34) Nitrox 32 0.51 ppO2, 4m ead
    Stop at 3m 7:00 (41) Nitrox 32 0.42 ppO2, 1m ead
    Surface (41) Nitrox 32 -9m/min ascent.

    OTU's this dive: 49
    CNS Total: 19.2%

    2847.3 ltr Nitrox 32
    2847.3 ltr TOTAL


    Or as you say get a 3ltr of pure 02 and breath that from 6m and treble your bottom time to 45mins with 9mins deco

    MultiDeco 4.04 by Ross Hemingway,
    ZHL code by Erik C. Baker.

    Decompression model: ZHL16-B + GF

    DIVE PLAN
    Surface interval = 5 day 0 hr 0 min.
    Elevation = 0m
    Conservatism = GF 80/80

    Dec to 33m (1) Nitrox 32 18m/min descent.
    Level 33m 43:10 (45) Nitrox 32 1.37 ppO2, 27m ead
    Asc to 6m (48) Nitrox 32 -9m/min ascent.
    Stop at 6m 3:00 (51) Oxygen 1.60 ppO2, 0m ead
    Stop at 3m 8:00 (59) Oxygen 1.30 ppO2, 0m ead
    Surface (59) Oxygen -9m/min ascent.

    OTU's this dive: 91
    CNS Total: 38.4%

    3923.4 ltr Nitrox 32
    278.6 ltr Oxygen
    4202 ltr TOTAL

    The problem isn't the gas its your crap recreational dive computer

    You can get a Sheerwater persuit SH for about 250-300 these days

    Spend flash money on a Preditor if you like its easier to read but frankly does the same job as the Persuit


    ATB

    Mark
    I would probably suggest that ADP would be a good idea as well as AFAIK gas switching is one of the biggest causes of fatalities in technical divers (this does become technical as soon as gas switching is involved in my way of thinking anyway)


 
Page 3 of 4 FirstFirst 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •