Two Divers from same boat die in a week

Whatever. Still over my head I guess.
Have fun with the innuendos. I'll go find a thread where I can speak to some level of experience.

He is talking about a submersible with scrubbers I'd wager.

breathing at 1 ata from a rebreather

Doesn't that depend on the amount of air you have access to and the deco stops you're willing to make?

Bring out the Snark!

Number one, your first post about what depth you get narced and where o2 pp problems begin to occur was the right idea but wrong in fact. The record depth for diving on compressed air is...509'!

Number two, "how long do you expect your bottom time to be" is just completely irrelevant: on air your bottom time is about 5 minutes (give or take, it's been a long time since I actually consulted the tables) but that doesn't seem to stop some people from WANTING to go to 150' and NOT CARING that they ONLY get to spend 5 minutes there. The fact that they got to 150' seems to be the motivation.

Some people are motivated simply by pushing the envelope.

Diving to 240' or 290' in cold, murky water prone to strong current is a completely different animal.

At 48 meters of sea water it's 7 minutes. But this is no-deco diving. If your planning stops at 30, 15 and 5 meter you'll get a totally different outcome.

*edit*

Geez, Prop, lighten up before you throw a blade.

NYCAP twigged on it, Tirekicker and Bill pretty much nailed it. The 80 was filled with pure O2 at 200ats and was used to replace metabolic consumption and CO2 was scrubbed in a 1 atmosphere submersible, just like being inside a big rebreather.

I guess those guys have a deeper level of experience ...


And by the way, Webster defines innuendo as: "an oblique allusion : hint, insinuation; especially : a veiled or equivocal reflection on character or reputation."

Makes me wonder what the humidity inside was like. Dehumidifiers?

Dripping wet with condensation, 80 to 100 percent humidity. Once you get below 500 meters or so the temperature is pretty much constant at 1 or 2C no matter where in the world you are.

There is something like 40g of water per cubic meter of exhaled breath so with 2 people breathing normally there is about 50g of water produced per hour or about a half a liter during a 10/12 hour dive.

It could get very uncomfortable but at least you didn't have to sit in a chamber for a month and when the hatch opened it always felt like a Spring day no matter what the weather was like outside.

They pump the air trough a scrubber to 'scrub' the CO2, why wouldn't they pump the air trough a dehumidifying 'scrubber' as well? I guess improving the working environment to bearable standards would reduce the risk of errors.

Over the last years many accidents have happened especially with the full electronic rebreathers. (the Evolution is nicknamed the 'little box of death') Makes me wonder how the air quality is controlled in a sub.

Because condensation moves the moisture to the bilge, it doesn't collect in or on the warmer electronics. A moisture "scrubber" using the most likely dessicant (silica gel) would require a large container with about 5 pounds of the stuff and the power to operate a fan which is noisy because it has to have enough power to force air through the media. Trust me, listening to that is more hazardous than leaning against a wet hull.

Air quality? It is what it is, flatulence fades with familiarity, bleed O2 to replace what you burn and scrub CO2 when you need to.

I kinda missed this one point. From my understanding, gravitation moves the condensed moisture to the bilge, so in near-100% air humidity electronics could still "take in" some water condensed nearby? Or equipment is just proofed properly?

Well, moisture in the air has to condense before gravity moves it to the bilge so I didn't think that needed more explanation ... I thought everyone knew that is why clouds float and rain falls.

Operating electronics are generally warm enough that internal condensation is not a problem. We rarely had issues with most electronics due to condensation. Video recording equipment was a sometimes problem as tape heads are very much moisture sensitive. Most of what we used otherwise was marine or aviation grade stuff. We had frequent electrical grounds on feeder circuits but they went away when the boat was on the surface and and conditioned air was supplied to dry the interior.

Are there maybe some pics of this sub you could post?

Sure, had to scan a couple from old slides so pardon the quality.

The odd pic shows the use of that large manipulator, it was used to recover torpedoes that didn't quite make the grade.