Marathon dive inplications?

[WetDane]

Hi Dr. Deco,

A friend of mine just suggested that we consider doing a "marathon" dive day with up to 6 - 7 dives in one day.

My initial plan calls for 1.5 hour surface intervals between the first 3 dives - then 2 hours to # 4 (doubles as lunch break), then 3 more with 1.5 hours interval and 2 hours before a potential 7th bonus dive...
We will dive Air.

There is no "purpose" for this dive other than curiosity...
Oh - and potentially to do a fundraiser dive in the future.

I do not have a set of table handy, but so far has considered 60 fsw as the absolute max depth, althought I think I will have to move that down to 40 fsw if my memory serves me right.

I would like to know what you think of this - are there other hazards to look for when doing multiple dives in succesion in this manner?

Thanks,
Dane

 

[sky50960]

Try to get a dive computer which simulate the dives you are expecting to do and look what the computer has to say?

Would you be diving air or NITROX?

fa

 

[scubakat]

Just make the check payable to "scubakat's drysuit & underwater lighting fund"... Better yet, a dive bag filled with small unmarked bills dropped at the base of the pier, I'll sneak out to get it during my deco stop.

-kate

 

[DocVikingo]

Hi WetDane,

Dehydration, thermal deficit & fatigue are three factors you will have to counteract.

DocVikingo

 

[jbd]

WetDane,
I was going to post the same thing that DocVikingo mentioned so I'll just say that I agree with what he mentions. Remember hypothermia can occur on a summer day with the right conditions.

 

[WetDane]

Hmm - interesting point - we aqre diving in cold water so dry suits are a given - but I will make sure to have warm stuff to drink on the breaks...

Dane

 

[Warhammer]

I know some people that were on a liveaboard recently that completed 19 dives in 3 days. That's just better than 6 a day. They didn't have any problems other than extreme fatigue by the time the weekend was over. Don't know what their profiles were though. Personnally 4 dives a day is all I'd care to do and one of those would have to be at night and then not for an extended period of time.

 

[Dr Deco]

Dear WetDane:

What you have is an interesting scenario. I have always said that tables are “road maps” and not “licenses.” That means that they tell you where you are in the time/pressure realm, but do not imply that all dives “allowed” by them are a good idea to actually perform. :yelling:

That said, what would I recommend for this situation. It would be none other than Dr Deco’s old standby that the decompression does not end when you hit the surface.:nono:

That is a main theme of this Dr Deco FORUM and that is what is in my Decompression Physiology class.

What am I recommending here?

• Perform slow ascents to the surface, because this will keep the micronuclei small {and they will not sequester the free gas phase and retard off gassing};
• Perform some relatively slow arm and leg movements while at the safety stop to promote blood flow to the arms and legs during off gassing;
• Do not use stressful climbs back onto the boat, but rather doff your tanks and weight belt and have someone assist you up the ladder;
• while on the boat during the surface interval, do not perform any heavy physical exercise (e.g., lifting tanks);
• keep you arms and legs moving during the SI but do not run, swim, climb ladders, etc.; and last
• do not sleep during the surface intervals as this reduces the blood flow to the body and hinders off gassing.

As others mentioned, avoid being warm in the water (promotes nitrogen uptake) and cold on the surface (as this hinders blood flow and off gassing). Certainly, hydration is important since it promotes blood flow and nitrogen elimination.

Best of luck - - -

Dr Deco :doctor:

For those of you who are interested, this is a reminder of the [red]Decompression Physiology class[/red] I have at the Catalina Island station. For more information, connect on:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[Poulpe]

Hello Dr Deco, I'm new on this forum but interested in this topic. Could you please inform me about some tables which could help me calculating the deco of these "multiple dives" (more than 2 dives in fact) in the same day ?

Thanks a lot

 

[Dr Deco]

Hello Poulpe:

Actually any table that has residual nitrogen and surface interval groups will work for this. If one wishes tables for multilevel dives , then the PADI Recreational Dive Planner is fine. Computers will also work in the “planning mode” and can be tried.

Now this Marathon diving is quite rigorous. I do not know if they ever really did this activity. :scuba:

Dr Deco :doctor: