Blackcrusader
Contributor
What is the standard equipment for deep dive specialty course?
AL80 with 200 - 210 bar
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What is the standard equipment for deep dive specialty course?
So you bounced to 40m, were riding NDL, stayed for 57minutes underwater and surfaced with almost a half full AL80. Sure.
You mean, "Stay within N.D.L."?You mean, "not exceed NDL"?
That is amusing!No.
Rock Bottom gets re-calculated when you safely ascend to a shallower depth. New depth, new rock bottom.
1 Minimum Gas gets calculated for a max depth if you are doing a MD ascent. That's it.
Lamont had an excellent essay on calculating the early RB on SB many years ago. He then removed it and replaced it with the next version of rock bottom, which was more conservative. That essay is probably still on here. I had a copy of both on a very old hard drive and backup (2004 or 2005?). It would be a PITA to search for them.
However, this is a very old mac-tacked table (both sides) I made from the original RB way back when, with some moisture damage:
View attachment 618930
View attachment 618931
I never made a table of the next version of Rock Bottom as it was pretty much a non-starter for a single tank, and that is when the advice came out to limit a dive depth to the cf of a tank, for example, an 80 cf tank to a max depth of 80 feet.
Not sure how it evolved after that when other DIR groups ran with it.
Hi @Scuba LawyerSo I guess you guys don't want to hear about my 220' dive on a single steel 72 in Palau in 1981?
Let's do the math here. Sorry, I will speak in metric. With a 15l/min SAC (which is pretty average for an experienced diver), a 12 liter steel cylinder at 200 bars gives you:Hello. I was thinking back over the years. I worked for a Dive shop years ago as a Divemaster.
We did our deep dives on the Chester Poling off Gloucester, Mass. for the P.A.D.I. Advanced Open Water Course.
At high tide the the wreck sits in 108fsw. It always amazed me that people would do this dive "Normally." on single aluminum 80's without any type of redundancy.
I always thought it was insane???? Divers would come back on board with extremely low pressure readings on their gauges. Too me, it left no room for error, or any type of contingency whatsoever. At that time, I was diving with an Aluminum 100 cubic 3300 P.S.I. (Air.) with a 30 cubic pony bottle.(Air.)
20 years ago the shop did not have "Nitrox." (This is not an enriched air scenario.)
Staying within N.D.L.......I don't care how long you've been diving, or if, your'e the best breather on the planet your max bottom time is approximately 18 to 20 minutes, at 100fsw, not including the 3 min Safety stop.
So, I was curious? The question is: Would you personally make this dive, staying within N.D.L. on air........No redundancy?
Cheers.
Let's do the math here. Sorry, I will speak in metric. With a 15l/min SAC (which is pretty average for an experienced diver), a 12 liter steel cylinder at 200 bars gives you:.
I am at 11l/min but I figured that 15 would speak to more peopleA lot of experienced divers SAC rate is 10l/min or less but calculations at a higher rate are better.