Doubles setup recommendation

[MichaelMc]

There are minimum total gas volume standards before starting a dive-100% in the cave curriculum, I would have to go double check the tech 1.

The OP is a bit far from cave and tech 1. And said they would not continue tech in doubles. (Correction: not limiting that to doubles)

if you are going to do it in doubles rather than single tank then do it in a proper set of doubles, LP72 or bigger

But what if some of your classmates were in singles? How would they handle an OOG sharing ascent from 60', the fundies depth limit? And tiny doubles to small doubles just for the class is not a big jump.

 

[eelnoraa]

Thank you for the very thorough breakdown of options. This gives me a lot to look into and talk with my GUE instructor about. I'm also going to see if I can find a set of mini doubles to try out just to see how my back tolerates things so I can step it up in increments, thanks for pointing those out.

Maybe I will sound too stragiht forward. Why do you need double for GUE fundie in you case? If you just need the education, you can get it done in single tank. You can even team with with people with double.

GUE fundie tech pass will only enable you to advance to T1 or C1. In those classes, you will not only need a reasonable size double, say LP85 for example, but also need to sling an AL80. So why even bother with small double like LP50? If you won't go onto T1, then why bother with double in fundie?

What I am trying to say is double is a significant investment. Why spend money on a set which you aren't going to use in the future.

 

[wetb4igetinthewater]

@Tantram

Are you doing rehab work? I’d also suggest talking to your doctor about this. I hope you are physically able to do what you want without risk of injury.

 

[CptTightPants21]

Keep in mind, OP wants to start GUE training. He isn't doing C1 or T1. If he is, he 100% won't need to ask for double recommendation. And again, min gas is not a fixed value. It depends on the dive. You don't need 140cf of min gas when you are doing a rec dive. In a lot of T1 profile, min gas on the back gas isn't even 140cf.



This is also incorrect. The concept of min gas is taught and enforced in fundie. The definition is simple. The minimum amount of gas for two divers to exist the dive while still fulfilling the safe ascent profile. For rec profile, the ascent strategy is min deco. For open water, the exist plan is ascent. For 100ft bottom, min gas is ~40cf. And for 60ft bottom, min gas is 20cf. So yes, technically, you can dive a AL40 to 60ft, and ascent when you have have 20cf left. You will still have enough gas to get 2 relatively nervous divers, ascent by min deco profile to the surface. Is it practical? No. Is it safe to do, I don't see why not.



I don't disagree.

You are not understanding. I know what Min Gas is and how to calculate it. Go look at the standards, there are minimum GAS VOLUME standards for even starting a Cave 1/Cave 2 dive. I believe these volumes/tank sizes were covered in my fundies, but I can't seem to locate the slide.

Part of fundies is learning the equipment and making the proper modifications/adjustments to achieve perfect balance, sizing, and trim. Why would a person take the class in a double set up that wouldn't be practical with the diving they are currently doing. OP dives sidemount, is OP going to start doing dives with half the gas volume than he has become accustomed to? My point is this. If OP is going to do the class is doubles, do it in a real set of doubles; OR just relax and do it in a single tank.

 

[eelnoraa]

You are not understanding. I know what Min Gas is and how to calculate it. Go look at the standards, there are minimum GAS VOLUME standards for even starting a Cave 1/Cave 2 dive. I believe these volumes/tank sizes were covered in my fundies, but I can't seem to locate the slide.

Part of fundies is learning the equipment and making the proper modifications/adjustments to achieve perfect balance, sizing, and trim. Why would a person take the class in a double set up that wouldn't be practical with the diving they are currently doing. OP dives sidemount, is OP going to start doing dives with half the gas volume than he has become accustomed to? My point is this. If OP is going to do the class is doubles, do it in a real set of doubles; OR just relax and do it in a single tank.

Oh ic, I got it. I totally agree with you on this. Sorry for the eariler posts. I have never encountered this, or even remember this because none of my doubles are that small.

 

[MichaelMc]

Are there minimum GAS VOLUME standards for Fundies?

OP, or I, might want to take fundies in doubles against any future desire to use them, but without any strong current need, or even with an existing sidemount bent. OP did not say what size tanks they were using currently. Just that buddies strapped on twin water heaters. If that is for two dives, OP may be matching that on one dive with small sidemount, possibly LP50s.

 

[eelnoraa]

I just read my fundie material from 2011, there is no mention about min gas volume. Better check with the instructor.

If I have to guess, just guess. If I showed up to fundie in double LP50, and assumed the tank choice discussion never happen, no matter how well I did, I won't get tech pass. It just doesn't seem fair. I am carrying 100cf of gas and 40lb worth of tanks on my back, buoyancy and trim will be a lot easier than my team mate who is carrying 200cf and 80lb worth of tanks.

Like i said before, fundie tech pass is prereq for T1 like class, instructor needs to evaluate your ability to handle those class. With LP50, I am not sure that can done accurately.

 

[CptTightPants21]

I just read my fundie material from 2011, there is no mention about min gas volume. Better check with the instructor.

If I have to guess, just guess. If I showed up to fundie in double LP50, and assumed the tank choice discussion never happen, no matter how well I did, I won't get tech pass. It just doesn't seem fair. I am carrying 100cf of gas and 40lb worth of tanks on my back, buoyancy and trim will be a lot easier than my team mate who is carrying 200cf and 80lb worth of tanks.

Like i said before, fundie tech pass is prereq for T1 like class, instructor needs to evaluate your ability to handle those class. With LP50, I am not sure that can done accurately.

I found the numbers under the specific class standards. Under Cave 1, need at least 100cuft of gas before start of dive. Cave 2 is the 140cuft of gas.

I wouldn't make the fairness argument and I wouldn't want to assume to know what an instructor would do. I would agree that the tanks are not suitable for future classes and it is difficult to say that a person could get a tech pass given that fact.

 

[MichaelMc]

Thanks. I'll keep learning with tiny doubles and bump up on size prior to fundies if those aren't available, or maybe for a tech pass on the first round. To me, more is too much weight for easy shore diving.

 

[eelnoraa]

Well, I wasn't assuming anything at all or don't pretend to know how students are being evaluated. I was simple making a wild guess. And as I mentioned, better to talk to instructor about equipment choice.

I just went throught T1 material from 2014. There is a mention about "reasonable capacity" to be double 80CF (11L) tank.