Rock Bottom Calculator for Excel

[traumadiver]

Hey Gang!
I have to learn how to use Excel for work. Not the most enjoyable thing to do. I did attempt to make a Rock Bottom Calculator for Excel. I think its pretty bare bones but it does the job. The plan is to get this document into my trusty Blackberry and take it with me on dives. Blackberry does not have alot of dive related apps. Screw 'em, I made my own.

If you are unfamilliar with Rock Bottom Gas Planning is you really need to read this:

NWGratefulDiver.com

There are many articles on the subject of good gas planning for the rec diver. It will save your life.

Please take a look at my RB calculator and check my work. I am really open to suggestions.

Thanx!

 

[Peter Guy]

TD -- thank you for doing this exercise -- a few comments:

KISS! Some of us (most of us?) have simplified Rock Bottom into just a few numbers --
40 ft3 for 100'; 25 ft3 for 60'; 500 PSI for 30' -- no need for a lot of precision since there is so little precision in our assumptions.

In looking at your spreadsheet you appear to be doing the calculations for a single diver but Rock Bottom calculations are for you AND YOUR BUDDY -- so you need to double your calculations. (At least that is how I read your spreadsheet.)

Here is my "Cheat Sheet" regarding Minimum Air Reserves:

Minimum Air Reserve Cheat Sheet

 

[traumadiver]

Hey Peter Guy,
Thank you very much for your response. I totally understand the KISS attitude of Rock Bottom planning. I find nothing wrong with it. I however am a more precision type person, that is kinda what attracts me to diving, there is a science to it. The second reason for making the whole worksheet complex was because I had to incorporate those math formulas in it. That was super complex for my computer illeterate brain. What happened to 1+1=2?
You are very true about your second comment. Rock Bottom is geared towards 2 divers breathing off the same tank in an out of gas situation. In the protected version of the spreadsheet you fill out the Emergency RMV...that is the volume of gas you expect to use during an emergency for one minute. That number will double to the right, labeled "ERMV double", wallah! 2 divers.
I like the cheat sheet you posted. I hadn't seen it before. That TSandM chick ROCKS OUT!
I know the spreadsheet is a bit disorganized and hard to read. Feel free to clean it up and make it useful for you!

 

[Peter Guy]

That TSandM chick ROCKS OUT!

Huh??

 

[Diver Tim]

Huh??

I think he's referring to the fact that the URL for the guide you posted starts with "http://www.tsandm.com/"

 

[Peter Guy]

It is still a big "Huh?" for me and I'd still like to know why the reference to that "TSandM Chick"!

 

[traumadiver]

TSandM is a member of this board. She is a super awesome diver that is also a doc. She posts alot and is one of the people who taught me about Rock Bottom.

 

[Blackwood]

One suggestion: round the first stop to the nearest 10 feet (unless you actually plan to ascend to 45 feet from 90).

TSandM is a member of this board.

She's also Peter's wife, and that's their website, not just her's.

 

[traumadiver]

Ahh, I see..so the thank you must go to both TSandM and Peter Guy for the awesome cheat sheet. Maybe Peter Guy made the cheat sheet and posted it on TSandM's website? I duuno, it is still awesome info.

 

[CharlesFoster00]

Hey Gang!
I have to learn how to use Excel for work. Not the most enjoyable thing to do. I did attempt to make a Rock Bottom Calculator for Excel. I think its pretty bare bones but it does the job. The plan is to get this document into my trusty Blackberry and take it with me on dives. Blackberry does not have alot of dive related apps. Screw 'em, I made my own.

If you are unfamilliar with Rock Bottom Gas Planning is you really need to read this:

There are many articles on the subject of good gas planning for the rec diver. It will save your life.

Please take a look at my RB calculator and check my work. I am really open to suggestions.

Thanx!

Hi Traumadiver,
I have a question about your spreadsheet. I'm new to this RB stuff, so maybe I don't understand. The RB volume is calculated by adding up several totals, the first of which is the 'Emergency Mitigation Volume'. This seems to be the volume of air that you would need, just in case something goes wrong, for you and your buddy at depth, for one minute.

Assuming your ERMV is 2 (as the spreadsheet does), then at sea level (1ATM) you and your buddy suck 2cu ft of air/min or 2*1ATM.

At 33ft (2ATM) you suck 4 cu ft of air/min or 2*2ATM.

If that is true, then the EMV calculation cell has a small, but important, typo. The EMV in the cell is calculated as depth/33*ERMV*1. I think the intent is for depth/33 to give ATM, but of course it doesn't, because we need to add 1 to that total (at 33 ft we're at 2 ATM). So perhaps that cell should read (depth/33+1)*ERMV?

Does that make sense?

Thanks