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Thread: Diluent / Bail-out / Deco Line gas choice

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    Re: Diluent / Bail-out / Deco Line gas choice

    Quote Originally Posted by Mark Chase  View Original Post
    Total scrubber flood. He could breath in but couldent breath out at all and he got a taste of lime in the loop as well.

    ATB

    Mark
    Did he find out why his scrubber flooded?

  2. #12
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    Re: Diluent / Bail-out / Deco Line gas choice

    Quote Originally Posted by PCDiver  View Original Post
    Did he find out why his scrubber flooded?
    Not yet. Hes headed off to Swannage for a further two days diving so i haven't had a chance to talk to him since he stripped the unit.

    I know hes had problems with the scrubber housing being rely hard to get off but i don't know if this is part of the problem.

    Trip report is up now its on day two:

    ATB

    Mark

  3. #13
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    Re: Diluent / Bail-out / Deco Line gas choice

    Quote Originally Posted by wondersea  View Original Post
    Hi all,

    Just wondering about your choice in matter of diluent / bailout and Deco line for let see :

    1 / Dive at 40 m (130 ft)

    2/ Dive at 60 m (196 ft)

    3/ Dive at 100 m (328 ft)

    Same or different gas for diluent / Bailout / Deco line (gas/depth) ?

    Heliair / Trimix / Heliox / Triox / Nitrox ?

    I presume that we are with CCR and we don't take all decompression bailout gaz onboard but just enough (with security) to join the Deco line if need.

    Can you argument your choice :)

    I think not all of you as the same strategy and it's will be great to compare it.

    Thank's for your cooperation.
    OK, pulling this one back on track (I think there's a trip report from Mark's dives today on another thread anyhow), after a lot of thinking and trying different ideas, this is my new bailout strategy. Kind of. Subject to change :)

    I carry all my gas wherever I can. Always. I would rather rely on team bailout and have done in the past then rely on a boat seeing a bag or anything else go up. That said, it's a possible solution to the problem of having enough gas to deco out on deeper longer dives. I also carry anough gas to get me to the surface with a realistic SAC, and relying on the worst failure happening at the worst point. Which I know is extreme, but it means I can just get on with it when I'm diving, and reduces the stress of a shit hitting fan moment.

    1. 40m dive. Up to no deco limits one AL60 of 30%. That should be plenty to get me up. If there's deco planned or possible, or a return to shotline required, then I carry another AL60 of 100%. The leanest mix is always plumbed into my BOV, just as a footnote.

    2. 60m dive. AL80 18/45 and AL80 50%. That should get me out, but if I'm planning a massive bottom time (which so far I haven't, it would have to be an exceptionally long dive which isn't possible in the tidal conditions I dive in) then I'd add a small tin of O2 as well. But essentially it's two AL80s down to 80m for me.

    3. 100m dive. Then I start to look at carrying everything. :) I don't do a lot of 100m dives, one so far, and that was a case of me carrying two AL80s and relying on team bailout, which worked fine as an exception for one dive. If I was doing a lot of 100m diving (as in taking the chance of a unit failing more often) then I would mount the AL80s on my back (did this recently and it's no difference to diving the unit standard really) and the AL60s on my front. Then I can deco out on my own, but it's a whole lot of tanks, and very hard work in anything but the shortest surface travelling or on a boat rokcing around. I would expect support divers if I'm honestly planning a series of 100m dives, or a very well drilled team for team bailout.

    This is what works for me, and fits with the level of risk I am prepared to accept. Which for bailout seems to be lower than most from a quantity of gas point of view but more from the point of view of being on the actual dive. Strange.

    Digs.

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    Re: Diluent / Bail-out / Deco Line gas choice

    Much respect for Diggers post. Its a post from a diver who has seriously considered the option of actually staying alive in a FUBA situation.

    IMHO: The important points are these:

    How safe is the plan?

    A safe plan is surely gas for a total OC bailout on a 10/80GF

    So side slung 18's blown to 250bar should do the job on a 60m dive for an hour????

    Alternatively you can do OC bottom times on your CCR???? cool for people who are not mad for the wrecks /fish but for the likes of me, its only the stupid deco commitment and related boredom that makes me come up at all. Take deco away and Id do three hour bottom times every dive.

    In my mind i have two plans:

    The "I will live" plan:

    This involves making surface and a lot of pain and possible recompresion treatments but not death.

    The "gosh thats annoying plan:"

    This involves bailing out but still doing my chosen 20/80GF profile

    I always intend on the dives being capable of the latter but I never dive with the possibility of anything less than the forma
    .

    Sort out an honest SAC and do the math with your most aggressive deco plan. Its just a numbers game.

    ATB

    Mark Chase

  5. #15
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    Re: Diluent / Bail-out / Deco Line gas choice

    As another footnote, I have never been on a boat with anyone carrying more bailout than me. Ever. I have always had more gas or the same amount of gas as everyone else. But that allows me to relax. I could never relax on a 80m dive with 2 x 232 bar 7 litre tanks, I'd be forever thinking about the what ifs, and staying bloody close to the shotline and anyone else with gas attached to them :) As for alpinist, they can whistle. I'll discuss how much my gas costs when they come for it, and they will come for it one day. I consider pence per litre to be multiplied by ATMs and TTS. If I hand off a tank and it wasn't in the plan you may as well keep it as the gas inside will cost more than the tank :D

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    Re: Diluent / Bail-out / Deco Line gas choice

    there was an old saying you can survive, a bend you will not survive a drowningsafe diving
    dave

  7. #17
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    Re: Diluent / Bail-out / Deco Line gas choice

    Quote Originally Posted by wondersea  View Original Post
    2/ Dive at 60 m (196 ft)
    OK. Just back from a 5 day dive trip to Cherbourg (France) to dive the wreck of the Leopoldville (58m). We went by boat from Brighton (UK) doing a mid channel wreck on route to/from France. The boat normally does day diving, so logistics was an important factor, 10 divers doing 5 days gas diving with no access to He/O2 at destination & only compressed air from boat's compressor. Deco was done drifting under a DSMB, rather than back to lazy shot. On the Leopoldville, I did bottom times of 45 - 60 mins giving total run times of 2 - 2.5 hours. We took a J of O2 on the boat.

    Day 1: Used a 3L diluent with 150 bar of 12/51 (left over from a previous trip). Dive was to 70m in mid channel, He was higher than I'd normally use at that depth & increased deco a bit; would normally have used 12/43.

    Day 2 -5: After dive #1 cylinder had ~115 bar left, air topped this on boat to 220 bar, this analysed as 15/32. Had obvoiusly estimated mix on laptop first! I used this for next 4 dives (1 dive per day) in the 50 - 58m range. END between 33m & 37m depending on your view of O2 narcosis @ 57m on a 1.3 SP.

    The "rich mix & air top strategy" meant I got 5 dives out of a 3L cylinder & ended week with 100 bar left over!

    My personal bailout was a 7L of 18/36 & 7L of 50%, my buddy was carrying 10L (steel) tanks of similiar gases, we'd obviously support each other in case of a bailout. My bailout tanks can be connected to the loop & breathed semi-closed if necessary.

    We used a "yellow bag" system to get a drop tank set from the boat, which consisted of a 12L (232bar) of 50% on 21m of rope with another 12L of 80% at 6m.

    JT

    PS. Donning flak jacket :D
    Last edited by jptaylor9; 10th June 2007 at 12:35. Reason: added END comment

  8. #18
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    Re: Diluent / Bail-out / Deco Line gas choice

    Quote Originally Posted by jptaylor9  View Original Post
    OK. Just back from a 5 day dive trip to Cherbourg (France) to dive the wreck of the Leopoldville (58m). We went by boat from Brighton (UK) doing a mid channel wreck on route to/from France. The boat normally does day diving, so logistics was an important factor, 10 divers doing 5 days gas diving with no access to He/O2 at destination & only compressed air from boat's compressor. Deco was done drifting under a DSMB, rather than back to lazy shot. On the Leopoldville, I did bottom times of 45 - 60 mins giving total run times of 2 - 2.5 hours. We took a J of O2 on the boat.

    Day 1: Used a 3L diluent with 150 bar of 12/51 (left over from a previous trip). Dive was to 70m in mid channel, He was higher than I'd normally use at that depth & increased deco a bit; would normally have used 12/43.

    Day 2 -5: After dive #1 cylinder had ~115 bar left, air topped this on boat to 220 bar, this analysed as 15/32. Had obvoiusly estimated mix on laptop first! I used this for next 4 dives (1 dive per day) in the 50 - 58m range. END between 33m & 37m depending on your view of O2 narcosis @ 57m on a 1.3 SP.

    The "rich mix & air top strategy" meant I got 5 dives out of a 3L cylinder & ended week with 100 bar left over!

    My personal bailout was a 7L of 18/36 & 7L of 50%, my buddy was carrying 10L (steel) tanks of similiar gases, we'd obviously support each other in case of a bailout. My bailout tanks can be connected to the loop & breathed semi-closed if necessary.

    We used a "yellow bag" system to get a drop tank set from the boat, which consisted of a 12L (232bar) of 50% on 21m of rope with another 12L of 80% at 6m.

    JT

    PS. Donning flak jacket :D


    No flack jacket required m8 lets face it thats how a lot of CCR divers do 60m dive with two 7s. The question is, do you consider it adiquate to deco out on alone?

    On a 20sac you need 253 bar of 18/45 and 660 bar of 50% to do a 10/100GF ascent

    Halving your SAC on the 50% to 10 you only need 330bar :D

    So basicly you have no chance unless your buddy has spare gas or the drop tank reaches you. Best you can hope for is a not too serious bend. If your buddy only has a 7 of 50% you still dont have enough gas on a 20SAC on a 15 SAC if you and your buddy have a 7ltr you would need at least a 250bar fill in both to do a 10/100 profile

    Altering the profile to 40/100 dosent help.

    Last edited by Mark Chase; 10th June 2007 at 16:30.

  9. #19
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    Re: Diluent / Bail-out / Deco Line gas choice

    Quote Originally Posted by Mark Chase  View Original Post
    do you consider it adiquate to deco out on alone?
    No. Put then again, I don't expect to be alone, I have buddies (x2) I trust & don't expect to be seperated.

    JT

  10. #20
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    Re: Diluent / Bail-out / Deco Line gas choice

    Quote Originally Posted by jptaylor9  View Original Post
    No. Put then again, I don't expect to be alone, I have buddies (x2) I trust & don't expect to be seperated.

    JT

    Well I hope they carry 10's :D

    I am not much better I have 11ltrs of 50% at 230bar and 10 ltrs of 18/45 at 250bar

    I am still 170bar short of completing 10/100 deco.

    I can do 45mins max run time at 60m before my bailout is blown out. However with an ali80 and a 10 I can complete deco on my buddies gas even if my buddy is a lazy sod and only carries 7's ;)


    ATB

    Mark Chase

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