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:
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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

  • Optimal Buoyancy Users Manual_v31.pdf
    9.2 MB · Views: 5,171
  • QuickStart.pdf
    457.8 KB · Views: 2,285
  • OptimalBuoyancy_v71.xlsx
    152.9 KB · Views: 4,041
I can't believe after two years I discovered this thread. I look forward to reading the attached documents and experimenting.
Where the HECK have you been?!?!? I thought every one knew about this thread!

No, seriously, I thought everyone knew.
 
Where the HECK have you been?!?!? I thought every one knew about this thread!

No, seriously, I thought everyone knew.

first I have known about this thread was today lol
 
Where the HECK have you been?!?!? I thought every one knew about this thread!

No, seriously, I thought everyone knew.
I'm going to share it with folks who are not on ScubaBoard, maybe post a link on relevant groups on FB.
 
first I have known about this thread was today lol
Honestly, I only knew about it because a buddy of mine told me about it shortly after the thread was started. Otherwise, not sure I would have known either.
 
Honestly, I only knew about it because a buddy of mine told me about it shortly after the thread was started. Otherwise, not sure I would have known either.
It is hard to read a thread about optimal weighting/buoyancy without finding it referred to.
 
Really does work. You can either figure out your buoyancy by trial and error or dial it in with this calculator… really gives you confidence knowing you’re not either underweighted or overweighted when in the water.
 
It is hard to read a thread about optimal weighting/buoyancy without finding it referred to.
I try to make sure it's mentioned if I see a thread where it's relevant... I'm that impressed with it that I really think it should be given to OW students as part of class.

You can either figure out your buoyancy by trial and error or dial it in with this calculator…
I sort of attacked it from both ends... I dialed in my weighting at the springs by trial and error as a 20 minute process one day, then I put known info into the calculator and massaged the personal buoyancy block till the calculator spit out the lead requirements that had found by trial and error. Ever since, I can adjust gear and salt/fresh water in the calculator and end up with a perfect answer for weight needs.

Respectfully,

James
 
I try to make sure it's mentioned if I see a thread where it's relevant...

This is one of the reasons the ScubaBoard Knowledge Base was created — so members can share the link instead of trying to explain their answer in a short post. Thanks.
 
How would you incorporate a 3 mm stainless steel backplate into the calculator?
 
https://www.shearwater.com/products/teric/

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