Dissimilar Tank Matching

[MXGratefulDiver]

I took this on for a couple of different reasons... 1. I had frustrations first understanding the principle math 2. I have since dove with several people that base their turn on my 3rds since I've been the smallest tank (guessing they wouldn't exceed their 3rds) which as long as I'm the smallest tank(volume and pressure) and controlling the turn it shouldn't be an issue as long as they didn't exceed their 3rds, I wanted a way to quantify quickly what turn pressures should be for both of us.

You however have been doing this for YEARS vs my months, so can likely just look at tank and pressure and KNOW what the turn PSI should be... I am a bit envious of your time diving.



Tim

... and I'm envious of the fact that you can do this ... I have trouble understanding what an app is, or how to load one on my phone ... much less figuring out how to create one. We each have those things that we're good at ...



But I did get plenty of practice at doing this back in the days when I was doing tech dives almost every week-end ... my dive buddies almost always were diving HP130's, while I was on either 119's or 100's depending on the dive.

... Bob (Grateful Diver)

 

[Imbodie]

WTF JUST HAPPENED? Did AJ just make a post that wasn't argumentative and judgmental while mocking and ridiculing? Am I in an alternate reality? Did the world just explode and I'm the last one to find out? HOLY CRAP.

WheresWaldo just accomplished the impossible.

it just takes time and persistence.... LOTS AND LOTS that and us math weenies appreciate ANYTHING that alleviates us having to do it....

 

[kensuf]

Tim, I'm going to jump on the bandwagon and say thanks for doing this. I'm pretty sure I won't use it just because I find a simple laminated chart works for me, but I appreciate that you're enthusiastic and trying to give something back to the sport, and we need more of that and less of the bickering / arguing / negativity that goes on.

 

[tbone1004]

I sent him my scuba formulas excel sheet so he can see where all of the rounding ends up and the if then statements. I'm not a programmer so wouldn't know how to put it into an app or script or anything, but the formulas are all there for him with everything being rounded to safety, up or down to nearest hundred, usable pressures being rounded down to the nearest multiple of 300psi, etc etc.

 

[Imbodie]

Tim, I'm going to jump on the bandwagon and say thanks for doing this. I'm pretty sure I won't use it just because I find a simple laminated chart works for me, but I appreciate that you're enthusiastic and trying to give something back to the sport, and we need more of that and less of the bickering / arguing / negativity that goes on.

BUT the bickering is FUN

ok... so maybe not the negativity part.

Just wanted something that would take the stress out from this particular chore... it added a LOT of stress to my Cave1 class (more than the diving did). There was a time that I would have panic attacks when I would walk into Algebra class and would think I was having a heart attack!!!! Math was my friend until my first algebra instructor who was not the best...then my anxiety built with each subsequent class. So, Thank you, even if my motivations were somewhat selfish.

---------- Post added May 8th, 2015 at 02:30 PM ----------

I sent him my scuba formulas excel sheet so he can see where all of the rounding ends up and the if then statements. I'm not a programmer so wouldn't know how to put it into an app or script or anything, but the formulas are all there for him with everything being rounded to safety, up or down to nearest hundred, usable pressures being rounded down to the nearest multiple of 300psi, etc etc.

I'm going to look at them, however excel doesn't transfer well to Java or Java script.... but still nice to see how other people do things, even if not specifically used it can still influence outcome.

 

[tbone1004]

the formula sheet I sent you includes things that were tested from my scuba 1 class up through leadership and cave diving. Every formula I can think of is in that sheet for you to use. Everything except the temperature change is accurate, but that one is technically accurate assuming instantaneous pressure change and no thermal mass Haven't quite bothered to import all of that because the variables are just too much. Excel would crash...

 

[descent]

I sent him my scuba formulas excel sheet so he can see where all of the rounding ends up and the if then statements. I'm not a programmer so ...

Anyone who can accomplish this much can call himself a programmer. There are some other details to learn before creating high quality software, but using Boolean logic (if-then branching) to control execution is a fundamental requirement.

A person need not receive paychecks for their code to be considered a programmer. There are a ton of open source software projects available for free download on the Internet. Even a few related to diving. Many of these projects were created on weekends or evenings by hobbyists in non-programming fields who had a specific need.

... I wouldn't know how to put it into an app or script or anything, but the formulas are all there for him with everything being rounded to safety, up or down to nearest hundred, usable pressures being rounded down to the nearest multiple of 300psi, etc etc.

Hah! Don't be misled. The formulas are the critical bones of the application. We drape beautiful, extraneous crap — edgy fonts and fancy looking buttons — around this excellent core.

I would encourage anyone who has ideas about how to better process or display information during diving to consider writing a small test program to make their idea concrete. It could be in Excel, or Visual Basic, or one of thousands of other fun-to-use tools.

If anyone has questions about how to get started doing this, or how to get past a sticky problem, please don't hesitate to send me a PM.

 

[Imbodie]

Anyone who can accomplish this much can call himself a programmer. There are some other details to learn before creating high quality software, but using Boolean logic (if-then branching) to control execution is a fundamental requirement.

A person need not receive paychecks for their code to be considered a programmer. There are a ton of open source software projects available for free download on the Internet. Even a few related to diving. Many of these projects were created on weekends or evenings by hobbyists in non-programming fields who had a specific need.




Hah! Don't be misled. The formulas are the critical bones of the application. We drape beautiful, extraneous crap — edgy fonts and fancy looking buttons — around this excellent core.

I would encourage anyone who has ideas about how to better process or display information during diving to consider writing a small test program to make their idea concrete. It could be in Excel, or Visual Basic, or one of thousands of other fun-to-use tools.

If anyone has questions about how to get started doing this, or how to get past a sticky problem, please don't hesitate to send me a PM.

I"m with you.... if you can work out the formulas.... you have pretty much written the (a) program. My personal programming style is hacking... I get the formulas I need and use googled examples of code to get me started... its not pretty... but eventually it works. I don't really care how pretty a program is, as long as the data is functional I'm happy.

Tim

 

[MXGratefulDiver]

Math was my friend until my first algebra instructor who was not the best...then my anxiety built with each subsequent class.

... very much like diving, where the choice of the right instructor can have an amazing impact on subsequent skill levels. My first algebra teacher told me I had no aptitude for math, and advised that I should not go into any field that required it. I ended up getting my college degree in physics ... go figure ...

... Bob (Grateful Diver)

 

[Kevrumbo]

oh how different this discussion would be if we were all using metric...

Much easier:

For a buddy team with dissimilar tank sizes the point is to derive a usable turn pressure for your own tank, AFTER calculating a normalized volume of Rock Bottom and/or Thirds for the teammate with the smallest tank. The arithmetic is fairly easy and straight forward (in metric of course):

Example:
12 litre/bar tank multiplied by an initial fill of 180 bar equals 2160 litres;
15 litre/bar tank multiplied by initial fill 150 bar equals 2250 litres --

Therefore the 12 litre tank has the smaller volume at 2160 litres.

Calculate thirds of smaller volume tank's fill pressure of 180 bar, and you get 60 bar delta turn pressure. 12 litres/bar multiplied by 60 bar equals 720 litres volume (this is the normalized value with respect to the smaller tank).

Hence , the calculated turn pressure for the larger volume tank is:
720 litres divided-by 15 litre/bar equals 48 bar.

(How objectively simple was that? And no App needed....)