I tasted the Kool Aide and it didnt agree with me

[PfcAJ]

Have you actually calculated minimum gas from a depth of say...120ft? Thats a "reasonable" depth that many recreational divers visit.

Its not just about your SAC rate. It's about your SAC rate, plus your buddy's SAC rate, plus the increase when Sudden High Intensity Training happens, not to mention carrying out your stops in a controlled manner.

 

[Blox]

Have you actually calculated minimum gas from a depth of say...120ft? Thats a "reasonable" depth that many recreational divers visit.

Its not just about your SAC rate. It's about your SAC rate, plus your buddy's SAC rate, plus the increase when Sudden High Intensity Training happens, not to mention carrying out your stops in a controlled manner.

Which assumes that you DO have a buddy to take care of, right?

 

[Blox]

Blox,

I think you might be forgetting something else about using doubles. One hint, reach back over your head and grab the little knob thingy........

I think I did address that in my post.

 

[rainman_02]

Which assumes that you DO have a buddy to take care of, right?

And once again, if you're answering posts in this forum, you do have a buddy (or two) to dive with.

 

[almitywife]

***** mod post *****

dear all,

once again, i remind you all to refer to the original post of this thread
to get back to the topic.

many parts of this thread have been very informative to a non DIR person such as myself but i need you to remember that this IS A DIR forum so if you cant add constructively to this thread i ask that you abstain from posting and let those that do have the knowledge and the training to share here.

many thanks

***** mod post *****​

 

[Bismark]

Blox,

I re-read your post and I guess what you are referring to is where you mention the phrase "ignoring gear redundancy". Is that what you mean? Is "gear redundancy" your comment on the importance of being able to isolate portions of your gas supply in a failure? Maybe I am missing something here, but if you are comparing an isolation manifold on doubles with an independant redundant gas supply such as a pony bottle, then you are essentially advocating two independent single tanks??? Am I missing something else here?

 

[Sloth]

Being that this is the DIR forum and I just got through DIR-f class I'll test my new found skillz and calculate min gas or rock bottom on a dive to the Sea Tiger with a max depth of 100ft.

First min gas or rock bottom is the least amount of gas needed for you and your buddy to safely ascend to the surface during an OOA emergency.

Some assumptions that GUE wants you to make when calculating:

First, assume that it is an emergency and you and your buddies SAC is off the charts at 1 cft per min.

Second, give yourself 1 min at max depth to deal with the problem before calculating ascent time.

Third use GUE recreational deep stops with your first stop at half your max depth and then 1 min at each ten foot increment up to the surface.

So our time would be 1 min at 100ft, 2 mins to get to 50ft, 1 min at 50ft, 1 min at 40ft, 1 min at 30ft, 1 min at 20 and 1 min at 10ft.

Our gas consumption for one person following the times and depths listed above would be 4cft at 100, 6.4cft getting to 50ft, 2.5cft at 50ft, 2.2cft at 40ft, 1.9cft at 30ft, 1.6cft at 20ft, and 1.3cft at 10 ft for a total of 19.9cft to go from 100ft to 0ft.

Now since this is an OOA event so we have to double it and we now come up with 40cft for you and your buddy to safely ascend to the surface from 100ft.

So in this case our absolute rock bottom or min gas on an alu80 filled to 3200psi would be 1600psi.

Then if you throw in wreck penetration GUE would consider this “rules of third” territory so you would have to take your remaining gas after calculating min gas and divided it by thirds to determine a turn pressure that would allow you and your buddy to exit the wreck during an OOA.

So simple put with a fill of 3200 psi on a alu80 and min gas of 1600 psi at 100ft we would have 1600 psi as usable gas. Now divide that number by 3 to get 533 psi then subtract this number from your starting psi to come up with a new turn pressure of 2700 (conservative) psi on an alu80 at 100ft and doing a wreck penetration.

This is the logic that GUE uses to try and convince people that diving on a single alu80 at depths around 100ft my not be ideal.

Whether or not you agree with this logic is up to you. For me, after diving double 80s for the first time in the class, I would rather dive double 80s anyways. Having said that I personally wouldnt have an issue with diving to 100ft on a single 80 in the conditions that we have here in Hawaii if I couldnt dive doubles for whatever reason.

However, my days of doing wreck penetration on a single 80 are over.

 

[Blox]

Blox,

I re-read your post and I guess what you are referring to is where you mention the phrase "ignoring gear redundancy". Is that what you mean? Is "gear redundancy" your comment on the importance of being able to isolate portions of your gas supply in a failure? Maybe I am missing something here, but if you are comparing an isolation manifold on doubles with an independant redundant gas supply such as a pony bottle, then you are essentially advocating two independent single tanks??? Am I missing something else here?

Bismark,

Seeing that Almitywife has now intervened twice in this thread, reminding everybody to keep the thread on track, I believe that this discussion side-tracks the thread, and I have decided to not discuss this here any further. I would hate to be the cause (or a contributing factor) for this thread being closed, as this would be unfair to the OP.
I'm happy to exchange PMs, however, if you wish.

 

[Thalassamania]

Being that this is the DIR forum and I just got through DIR-f class I'll test my new found skillz and calculate min gas or rock bottom on a dive to the Sea Tiger with a max depth of 100ft.

First min gas or rock bottom is the least amount of gas needed for you and your buddy to safely ascend to the surface during an OOA emergency.

Some assumptions that GUE wants you to make when calculating:

First, assume that it is an emergency and you and your buddies SAC is off the charts at 1 cft per min.

Second, give yourself 1 min at max depth to deal with the problem before calculating ascent time.

Third use GUE recreational deep stops with your first stop at half your max depth and then 1 min at each ten foot increment up to the surface.

So our time would be 1 min at 100ft, 2 mins to get to 50ft, 1 min at 50ft, 1 min at 40ft, 1 min at 30ft, 1 min at 20 and 1 min at 10ft.

Our gas consumption for one person following the times and depths listed above would be 4cft at 100, 6.4cft getting to 50ft, 2.5cft at 50ft, 2.2cft at 40ft, 1.9cft at 30ft, 1.6cft at 20ft, and 1.3cft at 10 ft for a total of 19.9cft to go from 100ft to 0ft.

Now since this is an OOA event so we have to double it and we now come up with 40cft for you and your buddy to safely ascend to the surface from 100ft.

So in this case our absolute rock bottom or min gas on an alu80 filled to 3200psi would be 1600psi.

Then if you throw in wreck penetration GUE would consider this “rules of third” territory so you would have to take your remaining gas after calculating min gas and divided it by thirds to determine a turn pressure that would allow you and your buddy to exit the wreck during an OOA.

So simple put with a fill of 3200 psi on a alu80 and min gas of 1600 psi at 100ft we would have 1600 psi as usable gas. Now divide that number by 3 to get 533 psi then subtract this number from your starting psi to come up with a new turn pressure of 2700 (conservative) psi on an alu80 at 100ft and doing a wreck penetration.

This is the logic that GUE uses to try and convince people that diving on a single alu80 at depths around 100ft my not be ideal. ...

This assumes a SAC rate of 1.0, I think Catherine's is much lower. Also there are WRECK PENETRATIONS! and there are wreck penetrations ... if you know what I mean.

 

[*Floater*]

A bit of kool-aid never hurt anyone (except when laced with potassium cyanide), just remember to consume in moderation.