Maximum number of dives a day - DCS

[WhiteSands]

I'm travelling to a location which offers unlimited diving.
I'm just wondering how many dives a day can one do safely.
I've often done 4 dives in a day, and 5 once without incident.

However I'd like to know what is a safe way to do this.
I've read many cases of divers getting bends while still staying within the limits of their computers.

I've seen the CNS charts which seems to suggest that 4 dives a day will max out your CNS clock.

Suggestions anyone?

 

[scubadiver888]

How much diving you can do a day cannot be measured by the number of dives alone. How deep do you go makes a difference. How long you are down makes a difference. How long are your surface intervals makes a difference.

If I'm diving to 30 feet for 55 minutes I'm not even coming close to my NDL. If I add a 30 minute surface interval and I've off gassed a lot. On the other hand, if I've diving to 60 feet for 55 minutes I've hit my NDL. I'd have to have a 1:10 surface interval to off gas as much.

You mention CNS clock. Are you diving Nitrox as well? That will make a difference. You'd have to worry about your CNS clock as well as NDL.

 

[diver 85]

It all depends---on a lot of factors...................btw, how well do you trust your computer?????

 

[WhiteSands]

How much diving you can do a day cannot be measured by the number of dives alone. How deep do you go makes a difference. How long you are down makes a difference. How long are your surface intervals makes a difference.

If I'm diving to 30 feet for 55 minutes I'm not even coming close to my NDL. If I add a 30 minute surface interval and I've off gassed a lot. On the other hand, if I've diving to 60 feet for 55 minutes I've hit my NDL. I'd have to have a 1:10 surface interval to off gas as much.

You mention CNS clock. Are you diving Nitrox as well? That will make a difference. You'd have to worry about your CNS clock as well as NDL.

Yes I'll be diving Nitrox. Nitrox is "free" as well. It helps with my N2 loading but now I have to worry about CNS.

---------- Post added July 26th, 2014 at 01:33 PM ----------

It all depends---on a lot of factors...................btw, how well do you trust your computer?????

It's pretty close to the NDL times etc. I get from my training tables. I would say I trust it generally.

 

[sharkbaitDAN]

I have found my limit to be about 4 hours of diving in one day. I'm generally too tired to do more than that. Four one hour dives is easy to do with Nitrox 32, and you are unlikely to come anywhere near your CNS limits.

I was looking at my log, and the only dives where CNS limits were a concern with 32 within NDLs, are dives with an average depth deeper than ~70ft. I have very few of those, and they are all dives with a max depth between 100 and 130ft and for 30-40 mins. I generally have the energy for one dive like that per day.

My mean average depth is somewhere around 35ft, with the majority having an average depth between 29 and 45 feet. That would give an average PPo2 somewhere around 0.7, which should allow for 7.5 hours of diving over one day. An average depth of 70ft (ppo2=1.0) should still allow for 4 hours of diving. Both of those assuming 80% of the NOAA daily limit.

All of that bing said, if you're using a computer, and following the computer's rules, and understand what it is telling you, you can safely do 4-5 dives in a day using nitrox.

 

[kwinter]

From a general health as well as DCS standpoint, you will be best served by taking a day off in the middle of a week that includes multiple dives per day unless they are very shallow. Ear problems can be just as hazardous as DCS and the constant pressure changes can really take its toll.

 

[AfterDark]

If you want to stay in the 25ft range you can use surface supplied air and stay all day.

 

[fire_diver]

I'm travelling to a location which offers unlimited diving.
I'm just wondering how many dives a day can one do safely.


I've seen the CNS charts which seems to suggest that 4 dives a day will max out your CNS clock.

Suggestions anyone?

I would suggest you review the the section on dive planning and NDLs in your OW book.

 

[grantwiscour]

It sounds like you can use a "refresher" session on your dive tables. A computer is great but the understanding the tables and repetitive dive planning would help you greatly.

Check out the table tutor here: Aquaholics Dive Table Questions Online

Free table tutor that gives you countless dive scenarios. After you master the tables/tutor, you'll be able to plan dives and know your limitations. I hope this helps. After lots of work on the tutor I can run the table calculations all day with zero errors.

 

[lv2dive]

I am not condoning this, but I've been on several liveaboards that offered 4 dives per day plus a night dive, and I often took advantage of every dive offered.

The first liveaboard I did, however, I usually skipped a day dive if I was doing a night dive.

I would say that are two parts to this: what do the numbers say (ndl limits, cns, etc.), and what is your body telling you. Each is equally important.