Doubles setup recommendation

[Tribal]

You silly americans make this way to hard
It’s so much easier to make a dive plan as a team if you all dive the same size of tanks. Like 90% of the twin sets over here are 2x12L.

 

[Ryan Mcshane]

For you probably twin 10s. You could get a kydex or carbon backplate but that’ll only reduce it by 3-4 lbs. use aluminium tanks, but then you’d need more lead

Twin 10s are too short and are a pain to trim.

 

[Ryan Mcshane]

Speak to your instructor.

Ideally if you’re going the GUE route you want the same tanks that your team will
be diving. It simplifies gas planning and puts everyone on the same page.

 

[Lorenzoid]

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.

As I understand the OP’s position, his immediate goal is just to learn how to (recreationally?) dive the GUE system with his buddies, not to progress up the GUE tech-side. He did mention a possible longer-term goal of tech, but if he can take Fundies with rec-only in mind, I think that would set him on the path he’s looking for.

 

[EireDiver606]

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.

I don’t remember seeing min gas volumes in the fundies material....

 

[EireDiver606]

Twin 10s are too short and are a pain to trim.

I’m 5’9 and 12s are perfect for me so I hypothesised that that if you’re 5’7 they will be slightly too long. Body composition like different length arms, legs, muscle change it for different people, and harness adjustment too.

Maybe I’m wrong, are you 5’7, how does it feel for you?

 

[beester]

There is really something to be said for standardisation... which is after all the bread and butter of GUE diving. There are real benefits diving the same tanks (tankvolumes), from planning a dive (min gas, turn pressure), communication underwater to, how your bp/wing is setup (can be a bit different depending on tank size, length, buoyancy)... nothing easier being able to interchange tanks within a team.

That being said, there is nothing wrong with experimenting with tank sizes, however you need to be aware that it might make things a bit more complicated if you and your team mates are diving different tanks.

I can't contribute to the specifics, regarding tanks, because US tank sizes are a bit black magic for me, besides al80s, I have no idea what you guys are diving. However with the exception of very very small people, tank length (taking al80 as an example) is in most cases not an issue, and should not be for someone your length. Weight of course is another matter.

But be aware that in technical diving (if that is in your future), weight is a thing you need to bear ;-), equipment stress (in all forms and factors) and handling this above and below water is a integral part of technical diving.

 

[eelnoraa]

Speak to your instructor.

Ideally if you’re going the GUE route you want the same tanks that your team will
be diving. It simplifies gas planning and puts everyone on the same page.

Why? I think fundie also solver gas management for different tank size in a term.

I just don't think it is realistic to assume people show up in fundie with the same type of tanks.

 

[Marie13]

If @Tantram really can’t go the twinset route due to his back/arm issues, he could always continue on with SM, although that means GUE isn’t an option.

 

[Celt]

Carbondive 300 10ltr twins same weight as 1 10ltr steel