Deco dive plan sheet

[rjack321]

one-off gas selections may make sizable changes to my deco, I may feel differently.

I don't know what you define as "sizable" but if you stick to some basics like rock bottom <100cf, ENDs 100ft or less, deco ppO2s of 1.6 stuff like this its actually pretty hard to generate wildly different results by tweaking the gases.

Ie.
EAN80 is not that much different than O2
EANxx is not that much different than EAN50
21/35 and air are for most practical purposes interchangable...

Saving 3mins here vs there is within my fudge factor, although I suspect many of the posters here would consider 3mins at some point in the dive significantly "different".

Cut with an axe and all that jazz.

 

[Blackwood]

Say I'm planning a dive where standard gases give me 3 hours deco and best mixes give me 2.5 hours. I may opt for best mixes; half hour is a long time to get cold and hungry.

(But that's pure speculation far beyond my purview. I don't even know if it's a realistic scenario; I've never bothered running anything that deep/long)

But considering the same percentage difference, if standard gases give me 35 minutes deco while best mix gives me 30, I will opt for standard gases.

In that case - which is more in line with my personal diving - the flexibility afforded by standard gases outweighs the cost.

Shrug.

Edit: I just ran 260 for 30 minutes (yes, I realize that's an impractical OC profile, but bear with me).

10/70 (standard) with 190, 120, 70 and 20 bottles = 174 minute runtime.
15/50 ("best mix") with the same bottles = 147 minute runtime.

27 minutes is substantial.

 

[Jax]

How about you guys that mix your own tri-mix gasses? What do you mix? Standard or custom?

 

[wedivebc]

How about you guys that mix your own tri-mix gasses? What do you mix? Standard or custom?

Well both. Our own standard mixes for a given dive, just not the same ones the kool-aid drinkers use.

 

[Jax]

Well both. Our own standard mixes for a given dive, just not the same ones the kool-aid drinkers use.

:ignore:

 

[Blackwood]

How about you guys that mix your own tri-mix gasses? What do you mix? Standard or custom?

The standard gases I use are a byproduct of home brew; they can be made by topping off home-filled He with 32%.

 

[rx7diver]

I'm having a mental image of a large pile of exploded goats!

Funny! Hopefully the Medical IRB's will stipulate on-site hyperbaric chambers so that the volunteer human subjects won't suffer a similar fate.

 

[Randy43068]

All this horse-malarkey of planning decompression dives longhand makes about as much sense as me walking from Columbus to Cincinnati, Ohio. It can be done, but it's not so very practical.

Maybe they exist, and I've never seen 'em but for deco all I've seen were USN tables. v planner has an increasing large number of successful dives on it. Given that, it makes no sense to me whatsoever for an experienced diver to plan his or her deco dives long hand.

 

[rjack321]

Edit: I just ran 260 for 30 minutes (yes, I realize that's an impractical OC profile, but bear with me).

10/70 (standard) with 190, 120, 70 and 20 bottles = 174 minute runtime.
15/50 ("best mix") with the same bottles = 147 minute runtime.

27 minutes is substantial.

Many would consider 12/65 a standard mix for 250-300ish. The 5% drop in O2 is what is generating the 27min differences.

15% at 260 for 30 is going to have quite a few CNS implications later in the dive.

 

[Jax]

All this horse-malarkey of planning decompression dives longhand makes about as much sense as me walking from Columbus to Cincinnati, Ohio. It can be done, but it's not so very practical.

Maybe they exist, and I've never seen 'em but for deco all I've seen were USN tables. v planner has an increasing large number of successful dives on it. Given that, it makes no sense to me whatsoever for an experienced diver to plan his or her deco dives long hand.

Now, you keep that up, and I'll invite some of the "Do / Don't teach tables in OW" crowd in.

But seriously -- learning to do it long-hand in the classroom makes sense, doesn't it? Especially if you incorporate the results of vPlanner and dive computers?