[Andy Phillips]

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Just watched a program on wreck diving in Malta, these guys did a 70M warm up dive with single 12's, no pony or carried backup gas, but with stages as hang tanks.

OK, a 12 can hold 2400L and they would have used roughly 1600 up to the first deco stop, but still, strikes me as a tad risky, added to which they did two deco stops apparently the first one was on 100% O2.

Me thinks this can not be right, either I know even less than I thought (hard to belive that I know less than I think) or the commentry was wrong - big time.

Biggest #### underwater camera I have ever seen though.

Andrew

 

[Mark Chase]

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Damm I would have liked to have seen that.

I did hear that the instructors dived the Stubben on single 12's which is 56m I think and they dont even have accelorated deco??? Mad me thinks.

On the subject of hang tanks for deco. I can see the point. When I dived Gozo Ferry at 40m to find the wreck we swam out and looked down and said 'there it is' No kidding we could se it at 40 on the bottom. Looking up is even better so you wouldent have any problem spotting your deco station.

In the UK you could be 2m away and miss it compleetly

Mark Chase

 

[MartinS]

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I'm glad I wasn't the only one to wonder about that - especially when the commentator stated that they'd be breathing pure oxygen at their first stop, which by my reckoning was at least 6M. From my understanding, wouldn't 100% O2 give you a hit at 6M?
Great viz and well worth watching otherwise.

 

[Dr Stevil]

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That depends on what you've decided is your max ppO2, for diving this is usually given as 1.4 with 1.6 being your margin of error. Navy divers are (apparently) expected to deal with a max ppO2 of 2.0 bar.

An O2 toxicity incident isn't an absolute certainty at a particular ppO2, it depends on the individual and the diving circumstances. At least that is my understanding but I'm sure there are others here who have more info to hand on this than myself.

Chee-az
Steve

PS Historically, TV producers aren't that particular about getting their facts right on programs like this, usually they describe us as diving with oxygen tanks on our backs, sigh... Like Marvin Gaye sang "believe half of what you see, and none of what you hear"


(Edited by Steve W at 10:59 am on Feb. 12, 2003)

 

[Jay]

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6m = 1.6atm
So on 100% you are at a ppO2 of 1.6 which is the maximum recommended ppO2 with most diving agencies and therefore quite acceptable for deco. A lot of divers use 80% though in the sea to account for surges which may, at times, leave you at more then 6m.

 

[Pierre Farrugia]

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Hello,
I think that the documentary was about the southwald? Are you sure they had only 12l tanks as here, many use singles but normally are of 15l to 18l. Was is old documantary?

PS. MArk this summer at Dwejra Bluehole I could easily see the surface 100% clear from 55m...wow...never had that felling before.

Regards

Pierre

 

[Andy Phillips]

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Yeh it was the Southwald, trying to decide whether to do Malta or the Canaries as a warm up to Truk next year, after the program Malta is ahead.

As a note I somehow doubt the first stop was at 6M more likely to be 9M which is why I was a tad confused by the comentary

Andrew

 

[Gimbo]

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Saw the program last night, I believe it was a National Geographic one but the commentating was really really bad. It did look like they had 12l's, if so I just can not believe they went down to 70m, even if it was a 15l tank.

 

[Dr Stevil]

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and on air too...? not particularly wise IMHO