Shell Oil Mk15 1800fsw Info Desired

JonnyB

Hi GKAM, during my commercial diving course i saw a video of the dive, i believe it was 768m and it was done by Institut National De Plongee Professionnelle in Marceille.

/Jonny

GKAM

Hi Jonny, I am not too sure about a dive deeper than 701m. I could not locate such info about a deeper dive. The Comex dive is the deepest a man has been I think. This was back in 1992.

GKAM

abowie

This dive (and others) are referred to in Bennett and Elliott.

You'd have to have real balls to do the 1800ft seawater dive.

__________________
Andrew Bowie

Rebreather-friendly Buddy

AD_ward9

There have been a fair few dives from 450m to 700m I am aware of, but the ones I am aware of did not use the Mk 15. I am very interested in specific details, if someone could send me them.

Big problem with closed circuit on oil rigs: dive service companies are not allowed to handle gas of more than 23% O2, generally, without a lot of HSE issues. This means the RBs for bells are normally SCRs. In a bell, you do not want an O2 cylinder leaking, especially at 600 or 700m: another reason for SCR.

As regards O2 concentration, that is not a problem. The PPO2 is what matters and an Rebreather can maintain that whatever the depth.

There is a fair bit of activity right now in special super deep rebreathers. If anyone has a real interest, not just academic, please email me and with appropriate NDAs we may be able to introduce you to some interesting developments. These are SCRs, with negative or near zero Work of Breathing, being developed for serious concerns who want to go very deep indeed on a regular basis. NDAs and some vetting by a client would be a prerequisite.

In case someone on the forum has in mind diving very deep on an existing rebreather, I would suggest you try it out first on the surface, adjusted to have the same breathing resistance you will encounter at the depth you have chosen for your last dive. To do this is quite simple: Just put a restrictor plug in each end of the breathing hose, and a third plug in the hose from the scrubber to the inhale bag, with a hole in the plug to create the same breathing resistance. A fat cork with a hole the right size will do nicely. Then go for a jog with it on your back. See how long you last before you fall over. Not long, at 700m. If you want to try it, post me and I will send you the hole sizes for the depth you want to try out.

The problem is breathing resistance is linear with depth. So at 700m you are breathing through the equivalent of a 2m long snorkel (that is assuming the rebreather meets the WOB requirements of EN14143:2003 comfortably in the first place).

By the way, so not to do yourself an injury on the way down, you would need a compression schedule. This increases exponentially with depth. 500m is 2.5 days, 600m 5 days if you want to be safe.

Again, in case anyone is contemplating this: there is a lot of history of this sorting of diving. Tom Mount may wish to comment, as there are few others about still from the first 1000fsw dives (Peter Small, Hannes Keller, 1962) to the Comex dives. The 1000fsw target even claimed Sheck Exley, probably the best diver who has lived to date, but died at 906ft in 1994: his body when it popped up fizzed and DCS was so bad his bones were exposed. The bottom line is, if you have the kit you can do 700m safely, if you do not, it would be not balls but brainless to try it.

Bill Stone developed the Cis_Lunar just for an extreme dive he wanted to do (along with Nigel Jones, Jim Brown and others). Bill Stone went quiet for 10 years to develop the kit to allow him to do his Huautla dives. Extreme diving for things at real depth has again become a technical development activity: see the Extreme Dive Team site - it moved from www.technicaldivers.com to www.extremetechnical.org. There are some interesting dives planned, but right now team members are trying to get the kit together.

Cheers
Alex