DCS @ < 60 feet

[paixx01]

am i wrong or is it near impossible to do into deco at less than 60feet

as one's air in say an alum80 is going to run out long before 60 min @ 60 feet?

i was reading that above 40 feet it is near impossible, just curious about how and why

aloha from north shore

 

[Kstnbike]

You can get DCS at any depth. It isn't necessarily a matter of your nitrogen load being within NDL's, but many other factors such as age, hydration, weight, physical condition, etc. Air Embolisms can happen ascending from any depth if the person isn't careful and I've even heard of instances of people getting DCS in pools. Also, for many divers it is possible to exceed 60 minutes at 60 ft. w/ an 80 cu. ft. tank, it's just a matter of control and experience. I dive the pacific northwest in a dry suit, 46 degree water, and with 35lbs of lead on me and I can do close to 60 minutes at 60 ft. However, on a single 80 cu. ft. tank it is near impossible (there's always someone lol) for a person to go into the NDL's by following the RDP. Even though it is near impossible to reach your NDL it is still possible to get a DCS hit.

-Kstnbike

 

[Prostar]

I was talking with someone from DAN a few years back. They told me that they have had reports of DCS happening in four (4) feet of water.

 

[Kray_Z]

I was talking with someone from DAN a few years back. They told me that they have had reports of DCS happening in four (4) feet of water.

man im not even sure if i could dive in 4ft of water

 

[rawls]

Well you pretty much answered your own question related to going into deco...I can't speak for others but an 80 ft3 tank...steel or aluminum by the way...won't last me 60 minutes at 60 feet. At 40 ft your NDl is around 200 minutes. Your gas isn't going to last 3+ hours. So that's why it is pretty much impossible to go into deco at 40 ft. If your tank lasts less than 60 minutes at 60 ft then you won't go into deco then either.
Your thread however was titled DCS less than 60 ft. You need to specify which you are talking about. You can get DCS via 2 ways...Overstaying your bottom time or to rapid an ascent. Henry's Law...

 

[friscuba]

I think that 4' was an air embolism. There was a thread in another forum back in about '99 or '00 where a British fighter pilot had one doing a flipped plane in water training scenario in a three and a half foot pool.

If you do a search on New Zealand shallow water decompression sickness you'll probably find a couple of studies of their decompression chambers where they found numbers of scuba instructors who got hits in something like 6-8 meters of water, that's pretty darned shallow but it was lots of ascents over the course of the day.

60 for 60 isn't all that tough to do on an 80 for some who are fairly experienced, moving slow and good on air. That said, it's the second dive of the day that could mess you up even if you don't push that limit on the first dive. Some people have it in their heads they can't get bent at 50-60 feet and just go burn a couple of tanks without paying attention to make sure they've had enough of a surface interval to off gas.

 

[skinnydogdives]

i dove in the bahamas last may and did 1hr 15min at 18-20m (thats about 60ft) on an al 80. when i'm diving in kilkee west clare i use a 300bar (4500 psi) tank and i've been knomn to use this for 2 dives without filling. so i would sat your wrong to think you can't go into deco at 60ft all depends on how heavy you are on air and what size tank you bring
as for getting DCS that can happen at any depth as has been said all depends on previous dives that day state of health hydration assent rate what you do after the dive. remember you may not know you've got a hit untill hours after the dive

 

[ianr33]

I doubt there are many divers that can do 60 feet for 60 minutes with a square profile on an 80.
Pressure at 60 feet = 60/33 +1 = 2.8ATM
With a SAC rate of 0.4 (very few divers will do better than that) diver will be using
0.4 X 2.8 =1.12 cu ft/min
After 60 minutes will have used 60 X 1.12 =67.2 cu ft
Al 80 actually contains around 77 cu ft so that will leave 77-67.2= 9.8 cu ft
9.8 cu ft corresponds to 9.8/77 X3000 = 381 psi

So,even with a very low SAC rate of 0.4 after 60 minutes at 60 feet the tank will be down to 381 psi.Not the smartest move.

IMHO a diver that does not have a freakish SAC rate and starts the (slow)ascent with a sensible amount of gas (say 900 psi) should not get bent doing a single dive with air on an AL 80.

None of the above would stop me taking my computer though!

 

[stepup]

There was a thread in the accident forum where a guy got a DCS hit when he dove to 30 ft. of water. He had o go to a recompression chamber. It messed him up pretty bad.

 

[ReefGuy]

There are other tanks and setups other than the standard al80s. For instance, I frequently use steel 120s, which hold plenty of air to go into deco at 60'. Double them up, and plenty for 40'