How long can stay down?

[Rookie_J]

I am new to diving and I'm trying to figure what is a respectable bottom time and final PSI (with air)?


I realize air management is key and with experience the ability to breath more efficiently will improve therefore allowing longer dives.

just curious what some of your times / PSI's are.

 

[detroit diver]

Uhhh, what depth and tanks are you comparing?

 

[SueMermaid]

Respectable bottom time depends completely on how deep your dive is.

 

[H2Andy]

as has been said, your bottom time will depend on how deep you go.

the deeper you go, the faster you will use air and the faster you will reach your
no-decompression limit.

all other things being equal, experience in the water, efficiently moving underwater,
and your shape overall will determine how much air you use. also, it helps if
you are smaller and/or female: lots less air gets used that way.

for now, just concentrate on having fun. i wouldn't worry about how much air
you are using. have fun, be safe, keep on diving.

 

[herman]

It really depend on lots of things, depth, temp, dive type to name a few. If you are just interested in my best, it was 1hr 35 minutes on a single AL-80 with around 500psi remaining. This was on a dive on Bonaire.....hummm Bonaire means good air, with a max depth of about 30 feet and a lot of the time spent in 15 ft. I was diving with a good (and well known) buddy and at a well know site which has some impact on my air use and the level I am willing to drain a tank before ending a dive.

 

[pasley]

As Uncle Pug will tell you diving is not a competitive sport, and so comparing air consumption rates is not relevant.

Surface Air Consumption Rate (SAC) is perhaps a better unit of measure for this discussion than bottom time. As has already been pointed out, bottom time is a function of depth, size and pressure of air tank, workload, currents, temperature and NDL. SAC converts your air consumption to a theoretical amount you would have breathed at the surface. This allows for a more reasonable discussion as now you can talk apples to apples (of course there are still variables, like work load, currents and temperature). SAC allows you to plan a dive. If you know your sac is 0.50 and the dive is to 66 feet then you know you should be able to plan on using 1.0 cubic feet of air per minute.

Example a dive to 33 feet and a dive to 99 feet, assuming all factors like work load, temperature, currents and your comfort level are the same, will have the same SAC rate.

In general terms, once you have your weights right and your buoyancy under control, and are not moving around like a race horse underwater and are physically fit, your SAC rate should be in the 0.45 cubic feet per minute range plus or minus a bit.

Example: For a dive to 45 feet (average depth 31 FSW) on an AL80 (77.4 Cubic Feet of Air at 3000 PSI) you should have a bottom time in the 83 minutes or so range. That is a SAC rate of 0.41 SCFM (Surface Cubic Feet Per Minute) with approximately 300 PSI left in the tank.

In most cases for shallow dives under 60 feet a dive of 50-70 minutes is about right. Deeper dives will be less.

In general terms, you should be back on the boat with about 500 PSI, or on shore with 300 PSI in the tank.

Bottom time 33 Feet – 80-90 minutes on AL 80; Deeper than that the NDL is normally the driving factor on the dive rather than air. Dives to 100 feet, I usually end in a tie between bottom time and air on an AL80.

A couple of surveys have been run on average SAC rates on this board.

 

[kevink]

You can stay down forever if you want - - - oh, forgot, you wanted to come back with air in the tank.

Most new OW divers are 25 - 35 minutes in recreational range (<60') with a sqaure or multi-level profile. On at standard 80cu. ft., with some experience and confidence I think you should be able to shoot for a goal of 60 minutes and still have 500psi left in the tank. Sheer body mass will determine if this is acheivable, but if you are an average build and decent shape, it is not unreasonable.

 

[RP Diver]

I'm a big man, and I do tend to suck a bit of air. Most of my "normal" dives are in the 30-45 minute range (AL-80, air), depending on max depth and how long I stay there. My longest logged dive was at Los Islotes out of La Paz, Baja, playing with juvenile sea lions. max depth was 20', time was 1 hour and 40 minutes. It was also one of the 2 or 3 best dives I ever had. My shortest logged dive was just 16 minutes, but my max depth on that one was 150 ft at Maracaibo Deep in Cozumel.

 

[ChrisA]

I am new to diving and I'm trying to figure what is a respectable bottom time and final PSI (with air)?
just curious what some of your times / PSI's are.

One common profile for me is to dive from the beach and swimm straight out to 75 or 80
feet and stay there untill we reach the "turn around" presure and then make a slower return trip spending time at 35 feet or so. Air lasts a long time at 35ft but goes quickly at 80. I'll come up with maybe 700 psi after about 40 minutes. A shallow dive is typically anout an hour or just under

I looked back in my log book recently and last May when I started diving my first few dives were to 35 or 40 feet and logged at under 30 minutes. Now after 10 months and 90+ dives I've not quite doubled the time.

 

[Moogyboy]

My best time was around 1 hr 15 min or so at about 15-20 steady feet around Bimini, and if memory is correct I still had between 500 and 1000 psi left.

I think water temp is a factor, with warm water allowing you to use less air. I could be wrong...correct me, anyone?

cheers

Billy S.