Dissimilar Tank Matching

[twaldo]

Ok I had a LARGE issue with this during Cave1, I just couldn't wrap my head around the issue.... I'm not a math whiz to begin with and it took sit down time with my instructor to get it all clear... In my free time I started working on an app in javascript to make it MUCH simpler. Was hung up for months on data collection based on a selected number of divers and finally Chris said "DUH, just do it for 2 divers" in a couple of hours I had it all roughed in. It still doesn't round like I want it to but check it out and let me know what you think. I plan on putting a pull down in for tank selection so you don't have to enter the basic info on tanks and the Team Factors is just stating the smallest amounts for the team.

Feel free to use it, share it, copy the code... After it gets all the tweaks I plan on porting over to Android and Apple platforms and putting all the tek calculations in one application.

It's at the bottom of the page.

http://www.springswildernessscuba.com/calculations

[twaldo]

Had a problem pasting the code into the page... its fixed now.

[Aotus]

awesome! well done!

I had to spend some time getting all that straight in my head too. I still like to spend a little extra time to do it slowly so I'm confident I don't F it up. This is a nice little code, but I suspect I'll still be doing it by hand and thick head in the water before the dive.

[twaldo]

awesome! well done!

I had to spend some time getting all that straight in my head too. I still like to spend a little extra time to do it slowly so I'm confident I don't F it up. This is a nice little code, but I suspect I'll still be doing it by hand and thick head in the water before the dive.

Give me time, it will be an app for your phone/tablet and who knows maybe even your dive computer in the near future.

Tim

[tbone1004]

I had run one up in Excel a few years back for up to 3 divers, was rather easy but did it to save time and more for pre-trip planning than anything. With sidemount I don't bother gas matching now, it is every man for himself. I always keep enough reserve for me in my left bottle to get out, but if you need it, you get to figure out how to get out on the right bottle. It's rather rude I guess, but in sidemount if you can't get out on your own gas then you did something really bad....

[twaldo]

in side mount if you can't get out on your own gas then you did something really bad....

Or something REALLY bad happened... I think it's more about catastrophic failure with side mount and air sharing.

[Nitrogenius]

Or something REALLY bad happened... I think it's more about catastrophic failure with side mount and air sharing.

Well that was the point I believe.. It takes 2 catastrophic failure to get into air sharing on SM.. so essentially something which standard practice is not planning for..
Or it takes 1 catastrophic failure and a messed up gas planning..
I think that was meant with did something really bad..
During your dive plan you have to be consistent to understand what level of contingency you intend to plan with..
1 level of redundancy or 2 levels..
It is not even about how to plan your dive as solo or team dive.. Just the idea to plan it solo might get you to the point where you deliberately want to plan a higher level of redundancy overall (or on gas only) but it is important to compare apples with apples..
Diving thirds on manifolded doubles in a similar team gets you exactly factor 1 in regards to redundancy and catastrophic gas failures.
Whereas the same dive done with independent doubles / sidemount give you Factor 2 in redundancy in a team.. and the exact similar factor 1 in a solo dive..

Problems often multiply in failure situations. People do screw up royally when stressed. The##### does hit the fan. You would feel pretty helpless if those "0 odds" hit one of your friends and he was staring you in the face waiting for help. It happens. I think you have thought this in a reasonable fashion...but maybe you could take it to the next level with a mental tweek...might make you a better buddy...or not. Just thinkin out loud. t

That is true, but as I stated earlier. This is a question of what level of redundancy you want to achieve.. The standard taught initially in cave diving is 1 level of redundancy. If you don`t feel comfortable with that then you have to up that redundancy.. This would also mean that for example to achieve the same redundancy factor in gas catastrophic failures you would have to add 1 same siye stage (as buddy bottle) and 1 half size stage to achieve the same level of redundancy the Indie/SM team has on thirds with just their base tanks..


Thus planning different size tanks in sidemount (and same always applies to an indie config in BM) only becomes relevant when you in fact choose deliberately to increase your level of redundancy as in the standard you should be fully self reliant.


Also be careful not to confuse the level of redundancy with the safety factor in regards to gas planning (i.e. choosing forths instead of thirds). With the latter you never get to a higher level of redundancy.. For that you need to add tanks..

After that I decided enough was enough. I never said anything to him, but he doesn't get a text when I go diving now.

The big question is: Why did you not say anything? How is he supposed to learn or at least to know?

[Draker]

With sidemount I don't bother gas matching now, it is every man for himself. I always keep enough reserve for me in my left bottle to get out, but if you need it, you get to figure out how to get out on the right bottle. It's rather rude I guess, but in sidemount if you can't get out on your own gas then you did something really bad....

Welcome to the Jungle.

Boys and girls, please choose your dive buddies wisely.

This sort of attitude can help contribute to your death.

As evidenced a few weeks ago.

[Rich]

Welcome to the Jungle.

Boys and girls, please choose your dive buddies wisely.

This sort of attitude can help contribute to your death.

As evidenced a few weeks ago.

+1

Safe diving,

Rich

[FW]

... I'm not a math whiz to begin with and it took sit down time with my instructor to get it all clear...
http://www.springswildernessscuba.com/calculations

Not a math wiz? You could have fooled me

Of course, putting the smaller tanks on the diver with the highest SAC rate would solve the problem