Info Optimal Buoyancy Computer

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The Optimal Buoyancy Computer
A tool to help nail buoyancy and improve safety, before you splash​
1) How much lead should I carry with my new wetsuit?
2) How big a wing should I buy?
3) Will my BCD support my lead, both at the surface and when my wetsuit is compressed at depth?
4) Will my BCD support my rig without the help of my wetsuit/drysuit, if I doff it at the surface in an emergency, or underwater due to an entanglement?
5) How do I balance my rig?
6) How might partial weight ditching help me deal with an emergency? Will it really result in a runaway ascent?
7) How does the neutral buoyancy check change with thick neoprene?

I’m excited to announce the release of the Optimal Buoyancy Computer.
Designed to answer a variety of buoyancy questions, it provides accuracy directly proportional to the precision of your data input. Starting with as little as your height, weight and suit thickness, you can get ballpark weight requirements quickly. With additional information, you can compare equipment configurations, and plan for self-rescue after hypothetical equipment failures.

This tool is an Excel spreadsheet, and is a revision of a tool originally released in Buoyancy, Balanced Rigs, Failures and Ditching – a comprehensive tool , which was itself a revision of a toy spreadsheet first introduced in this thread: Advice on lift capacity for BP&W in April, 2018. After months of user suggestions, this new tool uses a simpler, modified data input system, and produces both simple and complex analyses of buoyancy. It works in both metric and Imperial units, salt and fresh water, and with both U.S. and European tanks.

Included is a 50-page user’s manual to lead you through the more complex parts of the tool, and a Quick Start section to get you going with minimal familiarity with spreadsheets. Additionally, the manual discusses the theory behind the more complex buoyancy calculations, whether you need help with Excel or not. If you are not facile with Microsoft Excel, the manual will take you through it all, step by step.
Here's the Table of Contents:
2019-08-30_3_1.jpg
Download the .xlsx file for current versions of Excel. Use the .xls file for Excel 97-2003. Other spreadsheet programs may or may not recognize the internal links, but trial versions of Excel are available for free. You will see a generic Excel warning about possible viruses - don't worry, there are none! Click "Enable Editing", and save a copy. After saving, you will be able to edit the data fields for your use.

Many thanks to @stepfen , @johndiver999 , @kmarks , @Akimbo and the many others who have made suggestions and comments along the way.

NOTE: If you are using Excel 2003 and download the .xls file, extensive protective formatting is not functional. Thus, when you are diving a wetsuit (for example), you may be able to see drysuit "data" on the same page. The data for the "other" suit is NOT accurate under those conditions and should be ignored. With current versions of Excel, this information is blanked out for safety.

As each new version is uploaded, the count of downloads returns to zero. We are currently at over 2000 downloads of the tool, counting repeat customers! Thank you for your interest!

WARNING: These spreadsheets are experimental tools using formulas created by amateur divers for educational use only. Numerous assumptions regarding buoyancy have been made based upon only partially tested equipment configurations. The information herein is for your personal educational use and should not be relied upon to determine the adequacy of a given equipment configuration. Consultation with a dive professional regarding equipment, weighting and performing a neutral buoyancy check should all be strongly considered before diving a new equipment configuration. Note specifically that the practice of ditching weight at depth is a controversial one, and the theoretical data in this spreadsheet should not be considered a recommendation of that practice.

Selected for the ScubaBoard Knowledge Base.

This thread was selected for the ScubaBoard Knowledge Base on 22 November 2021. Special rules discouraging off-topic and counterproductive replies apply after this date.
 

Attachments

Click to expand...
@The Cosmicist, I also had great success working backwards. I had a 3mm wet suit & jacket BCD that I knew my exact weight requirements. Punched in the suit, rig, & tanks and tweaked the manual personal buoyancy until the quick results told me the weight I knew I needed.

I replaced my jacket BCD with a BP/W and bought a drysuit (which has much more guessing than wetsuit). The tool was within 4 lbs of what I needed. After the dive I went back in and told it my drysuit was a little thinner than my original guess until the Quick Results matched the results of my drysuit dive.

I decided to go drysuit diving with a different tank metal and changed to fresh water. Punched those into the calculator and it was dead on! I have every expectation that when I take my 5mm wet suit out with my BP/W, the calculator will get me real close to what I need. The tool is great!
 
vinsanity:
@The Cosmicist, I also had great success working backwards. I had a 3mm wet suit & jacket BCD that I knew my exact weight requirements. Punched in the suit, rig, & tanks and tweaked the manual personal buoyancy until the quick results told me the weight I knew I needed.

I replaced my jacket BCD with a BP/W and bought a drysuit (which has much more guessing than wetsuit). The tool was within 4 lbs of what I needed. After the dive I went back in and told it my drysuit was a little thinner than my original guess until the Quick Results matched the results of my drysuit dive.

I decided to go drysuit diving with a different tank metal and changed to fresh water. Punched those into the calculator and it was dead on! I have every expectation that when I take my 5mm wet suit out with my BP/W, the calculator will get me real close to what I need. The tool is great!
Click to expand...

Awesome, thanks for that! I will do what both you and @James79 advise and go from there. They should teach this kind of stuff in AOW courses, honestly. That course really wasn't all that enlightening.
 
The Cosmicist:
Awesome, thanks for that! I will do what both you and @James79 advise and go from there. They should teach this kind of stuff in AOW courses, honestly. That course really wasn't all that enlightening.
Click to expand...
True that!! In my OW and AOW they basically tossed us in a jacket BCD and helped us determine the right weighting, and said in an emergency drop your weights and head for the surface. Comments like "better to get bent than drown out of air."

It wasn't until playing with this spreadsheet that I stopped to consider that one could predict for your rig, exactly which types of failures will and will not require ditching weight, and that you could map out exactly how much weight you should ditch for the circumstance in order to recover while maintaining a controlled ascent and make your safety stop. The fact that I only learned this stuff due to @rsingler's generosity makes me 1) grateful to rsingler, and 2) even more disappointed in PADI and my instructors.
 
My thoughts exactly. I was fighting to stay down at a safety stop during my AOW due to an near-empty AL80 and positively buoyant rental BCD. I mean actively swimming 180 degrees down - fins up to the surface. I had to ask my instructor to give me more weight afterwards. She wouldn't have bothered otherwise. She never bothered to do a weight check with me or anything until I asked her to check me after asking to get more weight!

After that, I swore I would never rent a BCD again. I bought an SS backplate BP/W setup and I'll only dive aluminum tanks in fresh water. I also swore I would not take a class from that dive company again.
 
Probably a good time to reprise the discussion of wetsuit expansion in the last 15 feet on ascent, and how that interferes with your surface estimates when doing a weight check...
Post in thread Weighting for Neutral Buoyancy
 
The latest version of the spreadsheet is
v71, with the .xlsx version dated 1/26/2021 and the .xls version dated 9/11/2020.

The latest version of the manual is v31, dated 8/30/2019.
 
rsingler:
The Optimal Buoyancy Computer
A tool to help nail buoyancy and improve safety, before you splash​
1) How much lead should I carry with my new wetsuit?
2) How big a wing should I buy?
3) Will my BCD support my lead, both at the surface and when my wetsuit is compressed at depth?
4) Will my BCD support my rig without the help of my wetsuit/drysuit, if I doff it at the surface in an emergency, or underwater due to an entanglement?
5) How do I balance my rig?
6) How might partial weight ditching help me deal with an emergency? Will it really result in a runaway ascent?
7) How does the neutral buoyancy check change with thick neoprene?

I’m excited to announce the release of the Optimal Buoyancy Computer.
Designed to answer a variety of buoyancy questions, it provides accuracy directly proportional to the precision of your data input. Starting with as little as your height, weight and suit thickness, you can get ballpark weight requirements quickly. With additional information, you can compare equipment configurations, and plan for self-rescue after hypothetical equipment failures.

This tool is an Excel spreadsheet, and is a revision of a tool originally released in Buoyancy, Balanced Rigs, Failures and Ditching – a comprehensive tool , which was itself a revision of a toy spreadsheet first introduced in this thread: Advice on lift capacity for BP&W in April, 2018. After months of user suggestions, this new tool uses a simpler, modified data input system, and produces both simple and complex analyses of buoyancy. It works in both metric and Imperial units, salt and fresh water, and with both U.S. and European tanks.

Included is a 50-page user’s manual to lead you through the more complex parts of the tool, and a Quick Start section to get you going with minimal familiarity with spreadsheets. Additionally, the manual discusses the theory behind the more complex buoyancy calculations, whether you need help with Excel or not. If you are not facile with Microsoft Excel, the manual will take you through it all, step by step.
Here's the Table of Contents:
Download the .xlsx file for current versions of Excel. Use the .xls file for Excel 97-2003. Other spreadsheet programs may or may not recognize the internal links, but trial versions of Excel are available for free. You will see a generic Excel warning about possible viruses - don't worry, there are none! Click "Enable Editing", and save a copy. After saving, you will be able to edit the data fields for your use.

Many thanks to @stepfen , @johndiver999 , @kmarks , @Akimbo and the many others who have made suggestions and comments along the way.

NOTE: If you are using Excel 2003 and download the .xls file, extensive protective formatting is not functional. Thus, when you are diving a wetsuit (for example), you may be able to see drysuit "data" on the same page. The data for the "other" suit is NOT accurate under those conditions and should be ignored. With current versions of Excel, this information is blanked out for safety.

As each new version is uploaded, the count of downloads returns to zero. We are currently at over 1000 downloads of the tool, counting repeat customers! Thank you for your interest!

WARNING: These spreadsheets are experimental tools using formulas created by amateur divers for educational use only. Numerous assumptions regarding buoyancy have been made based upon only partially tested equipment configurations. The information herein is for your personal educational use and should not be relied upon to determine the adequacy of a given equipment configuration. Consultation with a dive professional regarding equipment, weighting and performing a neutral buoyancy check should all be strongly considered before diving a new equipment configuration. Note specifically that the practice of ditching weight at depth is a controversial one, and the theoretical data in this spreadsheet should not be considered a recommendation of that practice.

Selected for the ScubaBoard Knowledge Base.

This thread was selected for the ScubaBoard Knowledge Base on 22 November 2021. Special rules discouraging off-topic and counterproductive replies apply after this date.
Click to expand...
thank you for this!
 
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