Buoyancy, Balanced Rigs, Failures and Ditching – a comprehensive tool

[rsingler]

Hi there. I am experimenting with the calculator as I hope I will get my first BP/W soon and I think I fount a problem with the latest version (v22).

Great pickup @stepfen !!!
Your recommended formula change is exactly correct. Adding those generic tanks bumped the formula calcs incorrectly.

TO ALL:
New spreadsheets (v23) added to Post #1.
I apologize for the error. It's a big tool, so keep crowdsourcing this with me and let me know if you find anything else.

Dive Safe! (My Mom would have said "...safely, Robert. Safely!" But you get the idea)

 

[AfterDark]

@rsingler, great tool! I got to play with it today for quite awhile. While I understand the limitations, it is a far better starting point than the typical formulas and advice!

I plugged my personal data for the 4 different configurations that I dive into it, each came up good in all the cells.
I had to go and get the data for my tanks and, use the manual input. My tanks were probably diving before a lot of people reading this were born. My oldest is 1960, newest is 1981 so they didn't appear in the tool's very long list.

This tool should be made a sticky . Thanks for all the hard work.

 

[Compressor]

Agree with AfterDark. The tool is VERY useful.

 

[rsingler]

I had to go and get the data for my tanks and, use the manual input. My tanks were probably diving before a lot of people reading this were born.

Hey, great news! Can you PM me with the data on your old tanks? I have some U.S. Divers stuff from the 1960's that I've just started to do buoyancy measurements on. If you've done some of the leg work, can you share? I'll add it to the spreadsheet (and credit you, of course!). Those old LP steel tanks just won't die! Hydro keeps coming back fine.

Cheers!
Safe diving!

 

[Bent Benny]

I can't wait to get to my laptop and try this. Thank you for your contribution to the community.
I have a drysuit coming next week but I have been diving in a really.thick wetsuit. Your example helped me understand better why I am having trouble with my buoyancy check and the last 10 feet or so of my ascent.

 

[AfterDark]

Scuba tank size and buoyancy calculator @rsingler here's where I got the data for my tanks.

 

[Eric Sedletzky]

Robert, you also have to take into account the differences in wetsuit materials, spongy vs dense. Thick spongy suits are a nightmare for going deep, but dense commercial material wetsuits lose a lot less buoyancy at depth.
This is a whole different level than of-the-rack suits, it’s venturing into custon made commercial suits where the diver actually gets to choose the material the suit is made from to match the application.

 

[rsingler]

Thanks, Eric! I believe that issue is addressed to a limited extent in the dropdown box for Wetsuit Condition/Type Cell H12 of Initial Data Entry. Stiffer "Standard" neoprene has a different formula for buoyancy loss at depth than "New_Soft" neoprene. And "Old" neoprene is docked 20% for buoyancy loss from closed cell deterioration.
I'd like to do even better, but we just don't have enough data points yet.
Please let me know how the results correlate with your known weight requirement for a given suit, so we can continue to refine this.

 

[anchochile]

Very interesting tool. I'm using your calculator for wetsuit buoyancy to try to estimate my weighting for my upcoming first warm water trip, based on my known cold-water weighting.

Here's my methodology:
I am 5'8" 145lbs

I dive Worthington HP100s in cold water (-2.5lb empty) and will be diving AL80s on this trip (+4.4lb empty), so I will need 7lb more lead, all else equal.

Cold water suit:
7mm semi-dry + separate hood (entered on spreadsheet as 7mm full w/ 3mm hood new/soft = 24.6lb positive)
5/3mm shorty (entered as 4mm shorty = 9.7lb positive)
Total suit buoyancy (not including boots and 3mm gloves, which I plan to wear in warm water also): +34.3lbs

Warm water suits (I will be renting, so assuming "old"):
3mm full suit: +9.1 lb.
Change from cold water suit = -25.2
Tank factor 7lb
Total lead to remove: 18.2lbs

5mm full suit: +15.1 lb
Change from cold water suit = -19.1
Tank factor 7lb
Total lead to remove: 12.1

Does this methodology look right? I wear 12 lbs of lead with my cold water rig. So, if I wear a 3mm suit with an AL80, I would need no extra lead and would be about 6 lbs overweight. And in a 5mm suit, I would need no extra lead and be perfectly weighted.

 

[rsingler]

Does this methodology look right? I wear 12 lbs of lead with my cold water rig. So, if I wear a 3mm suit with an AL80, I would need no extra lead and would be about 6 lbs overweight. And in a 5mm suit, I would need no extra lead and be perfectly weighted.

Man! You must not have very much body fat, or are bringing a steel back plate with you on your trip. Without the spreadsheet in front me that looks pretty close. I think you're on the right track.