Tank Boots, Boats and DIR

[Soggy]

You could do two MDL dives in those ranges on single 80s.

EDIT: I misunderstood and thought you were trying to suggest you could do two MDL dives on ONE single 80.

You guys can use whatever steel tanks you want. However, the SAC rates bounced around here shed some light on the desire for huge tanks.

What would you consider an "acceptable" SAC rate for someone diving in 38 degree water with no scooter?

 

[RTodd]

EDIT: I misunderstood and thought you were trying to suggest you could do two MDL dives on ONE single 80.



What would you consider an "acceptable" SAC rate for someone diving in 38 degree water with no scooter?

I think you are trying to attack my sac rate as being ridiculously low to justify doubles in this context. It is fairly low but it is basically the same regardless of whether or not I have a scooter since getting your sac too low tends to cause CO2 retention issues, including headaches which are a warning sign. Where this line is depends on the individual.

As for the water temp having an effect on dive time, it might. But, not necessarily in the way you are thinking it does. You should have the right insulation for water temp not to affect your breathing rate too much. Plus, in very cold water, if you are affected by the cold enough to affect breathing, your time before hitting MDLs would need to be decreased anyway. A lot of this stuff does actually boil down to what they taught you in PADI OW. But, you have to know which parts to ignore.

 

[Soggy]

I'm not criticising your SAC rate. Hey, if you can breathe a .2 and not die, all the more power to you. You still didn't answer my question. What is an acceptable SAC rate, in your obviously not very humble opinion? I want a number. Be concrete.

As for cold water, regardless of undergarment, it substantially effects your SAC rate. I have always breathed around a .4-.45 on my very few warm water trips and around a .55-.65 in cold water. If you can suggest a better undergarment than a 400g thinsulate with wicking layers combined with dry gloves and an ice cap and 7mm hood, I'm open to suggestions, but when the water is cold, it is cold and there is only so much you can do about it. Diving in Massachusetts or Canada in February is cold.

Most of the people who quoted SAC rates are cold water divers (cold being below 40 degrees at times, not warm 72 degree water springs for a long duration). While I often agree with your posts and you obviously have a lot of cave diving experience, unless you have substantial cold water diving experience, you really should **** about criticising SAC rates.

I think you are trying to attack my sac rate as being ridiculously low to justify doubles in this context. It is fairly low but it is basically the same regardless of whether or not I have a scooter since getting your sac too low tends to cause CO2 retention issues, including headaches which are a warning sign. Where this line is depends on the individual.

As for the water temp having an effect on dive time, it might. But, not necessarily in the way you are thinking it does. You should have the right insulation for water temp not to affect your breathing rate too much. Plus, in very cold water, if you are affected by the cold enough to affect breathing, your time before hitting MDLs would need to be decreased anyway. A lot of this stuff does actually boil down to what they taught you in PADI OW. But, you have to know which parts to ignore.

 

[MXGratefulDiver]

A lot of this stuff does actually boil down to what they taught you in PADI OW. But, you have to know which parts to ignore.

You need what you need ... diving ain't a contest.

I didn't take a PADI OW class ... but my YMCA instructor taught me that cold water, current, and a host of other things can factor into increasing your gas consumption rate. My limited experience (1,400+ dives) in various conditions tend to bear out that he was correct.

It is true that in the tropics I can get 70 minutes + out of an AL80 ... but for local diving, my consumption rate is higher ... and I prefer larger cylinders. To my concern, it's just an added safety factor ...

... Bob (Grateful Diver)

 

[Derek S]

Isn't that the idea behind rock bottom?

Also, ease in gas planning is a poor choice to dive similar tanks, gas matching is something every doubles diver should be able to do on the fly.

Hi Ben! That is what I surmised was the reasoning behind RB as well. Of course added levels of conservatism can be built in by dive teams if the desire is there.

I agree with you that gas planning (on it's face) is a poor reason to dive similar tanks. I believe that teams should dive similar tanks for redundancy and familiarity reasons. Ease of gas planning would just be an added side effect.

Again people, do what you want. I'm not policing anyone, and I'm surely in no position to tell anyone what they should be doing. A question was asked, and I answered it the best I know how. This is what I understand has been handed down from the "GUE brass" as the current train of thought, not solely a NEUE vs SCRET (or anyone else for that matter) issue.

So like I said, get an electronic membership to GUE, subscribe to the Quest list and search the archives, or e-mail JJ and ask him yourselves. If I don't see someone post anything definitive between now and next Saturday, I'll ask JJ when I see him at CaymanQuest.

Enough. In the words of Jaques Cartman: "S*rew you guys, I'm goin' divin'!"

 

[Jason B]

I believe that teams should dive similar tanks for redundancy and familiarity reasons.

huh?



Still waiting an answer on this one...

I didn't see anything that said only the only acceptable doubles for OW diving were AL80s, except for the caveat about diving doubles in wetsuit. :06:

Now before someone can say "balanced rig", that concept is touched on though its not thoroughly explained. But (and this was pointed out to me elsewhere) what is the reasoning behind doubled AL80s if you are just going to dive them with a 5 lb steel plate or an 8 lb v-weight (or both)?

What am I missing?

 

[RTodd]

I'm not criticising your SAC rate. Hey, if you can breathe a .2 and not die, all the more power to you. You still didn't answer my question. What is an acceptable SAC rate, in your obviously not very humble opinion? I want a number. Be concrete.

As for cold water, regardless of undergarment, it substantially effects your SAC rate. I have always breathed around a .4-.45 on my very few warm water trips and around a .55-.65 in cold water. If you can suggest a better undergarment than a 400g thinsulate with wicking layers combined with dry gloves and an ice cap and 7mm hood, I'm open to suggestions, but when the water is cold, it is cold and there is only so much you can do about it. Diving in Massachusetts or Canada in February is cold.

Most of the people who quoted SAC rates are cold water divers (cold being below 40 degrees at times, not warm 72 degree water springs for a long duration). While I often agree with your posts and you obviously have a lot of cave diving experience, unless you have substantial cold water diving experience, you really should **** about criticising SAC rates.

An acceptable sac rate is what you can acheive exercising strenuously for a minimum of one hour per day and diving regularly. That is the goal, not a number.

My diving career started out in cold water. It sucks. I like warmer water. Far less changes than you guys like to think. Cold water does affect SAC some, but the goal is to keep it from affecting you too much and to dial back the dives if it is. Feel free to pull the standard NE mantra of "our conditions are different so we can justify stupid things." I tired of arguing against that long ago.

 

[onfloat]

I agree with you that gas planning (on it's face) is a poor reason to dive similar tanks. I believe that teams should dive similar tanks for redundancy and familiarity reasons. Ease of gas planning would just be an added side effect.

My point about gas planning. I agree that you should be able to make adjustments for different tanks on the fly. Now the turn pressures and rock bottoms would be different for each player. If you all have the same tanks then you have one turn pressure, rock bottom for the team. Less confusion, now it's 1500 for turn and 500 for rock bottom or what ever numbers the dive plan dictates. If that's a poor reason, then so be it!!

 

[Soggy]

Cold water does affect SAC some, but the goal is to keep it from affecting you too much and to dial back the dives if it is. Feel free to pull the standard NE mantra of "our conditions are different so we can justify stupid things." I tired of arguing against that long ago.

We do dial back the dives. Ya still get cold. If you have any suggestions on how to prevent getting cold, I'm all ears. Even if you aren't feeling cold, simply being immersed in cold water has an effect on your physiology that is pretty well documented. You say it doesn't affect people as much as we think? Yer just plain wrong. I know how my own personal SAC rate is affected when I go from warm to cold water. Everyone else I know has the same experience. We must all be stoopid NE divers.

What are the stupid things we are doing exactly? Diving with adequate gas reserves? Steel doubles, OMG!!!!!!!! Wow, that's wicked dumb. Do I really need to visit baue.org and show all the pictures of Rhea, Sherwood, Jablonski, and countless others diving 104s in California on reasonably shallow dives?

 

[WaterDawg]

http://forum.5thd-x.com/viewtopic.php?t=1231&start=15

I think AG said it best here.



I dive AL80's and love them, they trim out fine. BUT I use 0 to 5lbs (depending on WETsuit and type of water). If I had to add 14lbs of non ditchable weight...dyh, Id rather that = more air.