average bottom time?

[matva]

what is generally considered good bottom time for a 3200 psi ~65ft dive? i am talking about good breathing...

 

[Matteo]

don't count on my math for accuracy, but not accounting for descent and ascent and assuming you surface with 500 psi, you would get about 22 minutes with a SAC rate of 1cfm and double that to 44 with a SAC rate of .5cfm...somebody smarter wanna double check that for me?????

 

[Scubakevdm]

Average good? I get about an hour twenty. My buddy can probably do ten more minutes, maybe even fifteen. Most divers on our boat get about forty-five. New ones get about thirty.

 

[Diver0001]

why are you asking this question?

R..

 

[dive_lover88]

i normally dive with tank pressure between 200-300 bars,depends on which op i go to. Bottom time is about 45-55 mins ending pressure is 60-70 bars for 200bars starting about 110-110 bars for 300bars starting.

 

[Packhorse]

This will depend on the size of the tank and the divers SAC.
So your question should really be what is a good SAC.
Then this will depend on the dive conditions eg current, temp and work load.

 

[The Kraken]

A couple of things missing here, tank size, nominal working pressure . . .

But let's assume that the tank is an Al80 with a nominal working pressure of 3000 psi.

An Al80 at nominal w/p contains 77.4 cubic feet of air.

Extrapolated out, the tank @ 3200 psi contains 82.6 cubic feet of air.

The "average" rec diver, if such animal exists, has a SAC rate somewhere around 0.6 cf/min.

Leaving 500 psi residual at the end of a dive @ 65' this diver will have an approximate gas time of 36 minutes.

This calculation does not include the average depths of descent and ascent. It's based strictly on gas consumed at that exact depth.

the K

 

[BrianV]

A lot depends on activity as well. I recently did a shark dive at 50' and with an AL80 (starting at 3100 PSI), I lasted 61 minutes and surfaced with 1100 PSI. Half of this dive was kneeing down on the sand, the other half was very light movement within a 300' radius of the starting point.

The other person that was diving with me was at 300 PSI after the same dive. On more active dives at around 50-55' I'd last around 55 minutes with ~700 PSI left, but those were particularly active dives where I was chasing rays and other things.

I would say if you could get an hour out of an 80 tank at 65' then you're doing very good. 50 min + would be good. 40ish would be average, any less and I'd say you're consuming a lot.

 

[HowardE]

what is generally considered good bottom time for a 3200 psi ~65ft dive? i am talking about good breathing...

good breathing on what sized tank? 80, 100, 120?

 

[del_mo]

Are you moving around? Any current? First time ever at the dive site or one you are familiar with it? Good viz or poor? Etc.