Doubles setup recommendation

[bubblemonkey2]

The GUE monoculture is great for GUE, and it's great for some of its customers/followers. It's like a religion--one that pays its founders well.

If your dive buddies are falling into the dogma product that you can only dive safely "the GUE way (tm)," and will stop diving with you unless you also become a GUE customer/follower, then you might also want to consider finding some additional dive buddies.

I have found and/or buddied with each of the following, which can all satisfy redundancy and self-sufficiency requirements:
single backmount plus side stage
doubles backmount with optional side stage (HP100s, LP50s, Al80s,...)
closed circuit rebreather with adequate bailout, including dedicated 5 or 7 foot buddy donation hose e.g. on bailout cylinder
sidemount two cylinders plus deco cylinders

"You have to do it our one single specific way or you will drown, alone" is one heck of a brand. GUE.

I recommend also looking into a good TDI instructor/team.

I currently enjoy my twin/manifolded LP50 rig for everyday shore diving. All the benefits of the redundancy, but much more sensible for your typical shore or boat dive. Need more gas? add a stage or two.

Doing an actual tech dive that actually needs 200 cuft (minus reserve)? Then maybe the twin HP100s start to make sense.

In Truk we dove a bunch of wrecks down to ~50 metres on twin Al80s with 50% deco stages. Even as GUE-trained divers. It turns out in the real world outside of a GUE training cave, you choose your diving equipment and style to best fit your diving objective and the resources available. Not vice versa.

 

[flymolo]

The GUE monoculture is great for GUE, and it's great for some of its customers/followers. It's like a religion--one that pays its founders well.

If your dive buddies are falling into the dogma product that you can only dive safely "the GUE way (tm)," and will stop diving with you unless you also become a GUE customer/follower, then you might also want to consider finding some additional dive buddies.

I have found and/or buddied with each of the following, which can all satisfy redundancy and self-sufficiency requirements:
single backmount plus side stage
doubles backmount with optional side stage (HP100s, LP50s, Al80s,...)
closed circuit rebreather with adequate bailout, including dedicated 5 or 7 foot buddy donation hose e.g. on bailout cylinder
sidemount two cylinders plus deco cylinders

"You have to do it our one single specific way or you will drown, alone" is one heck of a brand. GUE.

I recommend also looking into a good TDI instructor/team.

I currently enjoy my twin/manifolded LP50 rig for everyday shore diving. All the benefits of the redundancy, but much more sensible for your typical shore or boat dive. Need more gas? add a stage or two.

Doing an actual tech dive that actually needs 200 cuft (minus reserve)? Then maybe the twin HP100s start to make sense.

In Truk we dove a bunch of wrecks down to ~50 metres on twin Al80s with 50% deco stages. Even as GUE-trained divers. It turns out in the real world outside of a GUE training cave, you choose your diving equipment and style to best fit your diving objective and the resources available. Not vice versa.

Diving twin al80s with 50% for deco gas on a 50 meter dive seems pretty reasonable. Where does that violate GUE procedures?

 

[seeker242]

I'm a shorter guy (5' 7") with a bad back and bad right shoulder and have really enjoyed sidemount for those reasons (tanks hitting my head or legs, and isolation valve access if too high, carrying lots of weight, etc).

I'm 5'7" and dive double AL80s and LP85s. Neither is too long, etc. Although, I don't have any back or shoulder problems.

 

[Jack Hammer]

Diving twin al80s with 50% for deco gas on a 50 meter dive seems pretty reasonable. Where does that violate GUE procedures?

My buddies had no problems passing GUE Tech1 (52m/170') using doubled aluminum 80s. According to lotsa folks on the internet I shouldn't have even been able to start or pass any GUE classes (through CCR) with the gear I used. To those who wanna know what GUE "allows" or "requires" ya might wanna consider asking folks who've actually had the training and ignore internet experts.

 

[Deep South Divers]

Just so we're all on the same page...

AL80's are +4.4 pounds each empty... So 8.8 pounds positive. Add five (5-8, depending on brands) pounds for two bands, a manifold, and second first stage, and you're looking at a rig that needs about four pounds of lead to be neutral in salt water (less if in freshwater). The weight of this rig is 73 pounds empty (2x32+4+5) and would supply the diver with 155 cuft of breathing gas.

HP80's (Faber FX80, since that's all that's manufactured now):
Total rig weight: 57 pounds (28x2+5-4).
Gas supply: 160 cuft.

Carbondive 300 6.8l:
Total rig weight: 37 pounds (14x2+5+4).
Gas supply: 144 cuft
Note on the Carbondive 300's... They can be filled to 5,000 psi, which gives 161 cuft... But good luck getting them filled anywhere, since they have no DOT rating on them - they are CE only... Which means that you'll have to fill them yourself if you're in the US.

That is... A pair of Carbondive 300 6.8l tanks are almost 6" shorter, much smaller diameter, about half the weight, and offer more gas than a pair of AL80s. They are smaller diameter, about the same length, and much lighter than a pair of HP80s too. The caveat to the Carbondive 6.8s is cost (roughly double the price of an AL80, even at cost - and retail much higher... Plus you're very limited as to your fill options (basically you're going to need your own compressor).

In Europe, there is no hydro requirement for Carbondive cylinders... And an expected lifespan of about 200 years. Of course, that won't fly here from a certification standpoint, but if you have your own compressor, you can safely ignore that fact... Because they have a burst pressure of 851 bar (12,765 psi).

...So yeah, the Carbondives are totally the way to go... If you're willing to deal with the logistical issues.

The 10l Carbondive 300 is the same size/dimension and total rig weight as a Faber FX80 (HP80), but holds 106 cuft of gas at rated pressure... So 212 cuft for doubles. Again, they can be jacked 10% for a total capacity of 233 cuft... As compared to 160 cuft for the HP80s and 155 for double AL80s.

 

[S****N]

In Europe, there is no hydro requirement for Carbondive cylinders...

Don’t know where you get that info from but I can guarantee you that at least in Belgium and the Netherlands there are hydro requirements just like for Alu or complete steel tanks. For B after 30 months visual, 30 months later it’s hydro. Tests are done at 1,5x max working pressure so 450bar.