Technical diving is always a little more fun when it has a purpose

[kierentec]

thanks for all the feedback everyone. We had a blast with this project, and it's nice to see others are able to appreciate and enjoy it as well!


it was great to have our videographer back in the action (his wife made him sit out for the last few months till he got his life insurance straightened out...), hopefully we will be able to document more of the deep dives we are doing down here now.


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[kierentec]

Very cool.

Need any help?

(What does helium cost there? )

more the merrier, especially if you can blend your own gas

we are currently paying $240 for a t-bottle of UHP



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[Bhtmec2]

Great video. I always look forward to finding things and that was a good find.

 

[dumpsterDiver]

The video was OK, but I would have liked to see a little work being done after the measurements were recorded. Maybe a little reef clean up?


Say, hook up a few lift bags, inflate them, slide the thing over a few yards and then cut her loose over the wall. THAT would have been some cool video for the DPNR!

 

[Helipilot86]

Saw this on facebook some where!! Pretty sweet, Id give at least two arms and a leg to go on a dive like that. (as long as i had nice dpv to replace the leg)

 

[MG11]

On a 220ft training dive a few weeks ago we spotted a massive anchor laying on the bottom in 250-270ft of water. The DPNR found out about the new discovery and asked if we could go back and get an accurate survey for their archaeologist. Hmmmmm, trimix dive with a purpose... didnt have to twist our arms too much! we managed to get all of the necessary data, and are currently in the process of drawing it up in CAD. now if we could just get them to buy the helium....

I will post the drawing with dimensions when it is finished for anybody interested in that kinda thing.

here is a link to the video of the dive
https://vimeo.com/44355753


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As a new diver with future interests in deep diving, could you start a seperate thread or post on here the various gases y'all are carrying and give a play by play of what steps you follow from surface to 270ft and back? Time/gas used/depth of stops etc.

If there is a source somewhere that describes this process that you use on a dive of this sort I would be happy to read that to save you some typing.

Mike

 

[rongoodman]

Bottom mix might be something like 10/70(%O2/%He), with deco gases of 35/25, 50%, and 100% O2. The logistics are complicated by the fact that you can't breath the 10/70 on the surface, because of its low O2 content, so you would have to start the descent on one of the richer mixes and switch to the lean bottom mix on the way down(not shown in the plan below).



V-Planner 3.91 by R. Hemingway, VPM code by Erik C. Baker.


Decompression model: VPM - B

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 3

Dec to 200ft (4) Trimix 10/70 50ft/min descent. <<< Low pp
Dec to 260ft (5) Trimix 10/70 60ft/min descent.
Level 260ft 15:00 (20) Trimix 10/70 0.89 ppO2, 41ft ead, 55ft end
Asc to 200ft (22) Trimix 10/70 -30ft/min ascent.
Stop at 190ft 1:00 (23) Trimix 10/70 0.67 ppO2, 23ft ead, 34ft end
Stop at 180ft 1:00 (24) Trimix 10/70 0.64 ppO2, 21ft ead, 31ft end
Stop at 170ft 1:00 (25) Trimix 10/70 0.61 ppO2, 18ft ead, 28ft end
Stop at 160ft 2:00 (27) Trimix 10/70 0.58 ppO2, 16ft ead, 25ft end
Stop at 150ft 2:00 (29) Trimix 10/70 0.55 ppO2, 13ft ead, 22ft end
Stop at 140ft 2:00 (31) Trimix 10/70 0.52 ppO2, 11ft ead, 19ft end
Stop at 130ft 2:00 (33) Trimix 10/70 0.49 ppO2, 8ft ead, 16ft end
Stop at 120ft 3:00 (36) Triox 35/25 1.62 ppO2, 44ft ead, 82ft end <<< High pp
Stop at 100ft 1:40 (38) Triox 35/25 1.41 ppO2, 34ft ead, 67ft end
Stop at 90ft 2:00 (40) Triox 35/25 1.30 ppO2, 29ft ead, 59ft end
Stop at 80ft 3:00 (43) Triox 35/25 1.20 ppO2, 24ft ead, 52ft end
Stop at 70ft 3:00 (46) Nitrox 50 1.56 ppO2, 32ft ead
Stop at 60ft 3:00 (49) Nitrox 50 1.41 ppO2, 26ft ead
Stop at 50ft 5:00 (54) Nitrox 50 1.26 ppO2, 20ft ead
Stop at 40ft 7:00 (61) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 10:00 (71) Nitrox 50 0.95 ppO2, 7ft ead
Stop at 20ft 12:00 (83) Oxygen 1.60 ppO2, 0ft ead
Stop at 10ft 21:00 (104) Oxygen 1.30 ppO2, 0ft ead
Surface (104) Oxygen -30ft/min ascent.

Off gassing starts at 225.4ft

OTU's this dive: 122
CNS Total: 70.4%

153.2 cu ft Trimix 10/70
19.7 cu ft Triox 35/25
32.3 cu ft Nitrox 50
23.3 cu ft Oxygen
228.5 cu ft TOTAL

 

[Johng723]

Wow, I'm not a tech diver either, but deep diving interests me quite a bit as well. From my small amount of knowledge, doesn't a PPo2 of 1.6 have a high risk of oxygen toxicity? I don't know if the helium would counteract that in any way.

 

[rongoodman]

A ppO2 of 1.6 is usually considered acceptable for the non-working portion of the dive, i.e., hanging on a deco stop. A ppO2 of 1.4 is usually considered to be the max for the working portion, although several agencies recommend that it be kept lower. There is some speculation that helium mixes might actually make you more sensitive to oxygen toxicity as opposed to nitrogen, but as I've never heard that there is any real evidence to back that up. Increased CO2 levels are definitely considered to be a Bad Thing in conjunction with elevated ppO2s.

 

[MG11]

Thanks Ron!

Trimix in the doubles on your back based on the cu ft and everything else waiting in the wings?

The numbers in the () brackets are total dive time?

Mike