?? 3 dives planning help

[alcina]

I've just been told that our dive plan for tomorrow has changed. I don't have any of my tables here with me tonight so thought I'd pop a question in here for some help before the morning (when I will have my tables)

We are going to do a 30m on 32% - ideally for 35-45 minutes. The dive profile is short time at 30m and more time at 25-22m.

Very short SI of about 20 minutes.

Second dive 14m for around 60 minutes. Air.

Longer SI of around 60 minutes.

Third dive 14m for around 60 minutes. Air.

Those with tables...how are we doing?

How long does that first SI need to be to work?

I can take another Nitrox tank for one of the other dives if I need to so that all will work...suggestions? Thanks...

 

[jbd]

I've just been told that our dive plan for tomorrow has changed. I don't have any of my tables here with me tonight so thought I'd pop a question in here for some help before the morning (when I will have my tables)

We are going to do a 30m on 32% - ideally for 35-45 minutes. The dive profile is short time at 30m and more time at 25-22m.

Very short SI of about 20 minutes.

Second dive 14m for around 60 minutes. Air.

Longer SI of around 60 minutes.

Third dive 14m for around 60 minutes. Air.

Those with tables...how are we doing?

How long does that first SI need to be to work?

I can take another Nitrox tank for one of the other dives if I need to so that all will work...suggestions? Thanks...

A really fast glance at NAUI tables indicates you are riding the NDL on the first dive. With a short SI NAUI tables don't give you any drop in pressure group. The resulting max dive time for the second dive on air is 43 minutes on the NAUI air table. To get close to 60 minutes on the second you would a SI of at least 37 minutes instead of the 20 minutes you mentioned.

Other tables may have slightly different results.

 

[Jason B]

Just quickly looking over the TDI nitrox table and using the PADI wheel, the second dive passes the NDL by a few minutes.
Definitely need a longer 1st SI and probably another bottle of EAN32 for the second dive.

Jason

 

[scubatoys]

You can download the Computerized Table Tutor and it will give you 9 different table formats you can view on screen, and make up custom questions.

Hope that helps!