Doubles setup recommendation

[CptTightPants21]

Min gas volume requirements for GUE doubles is 140 or 150 cuft so the tiny doubles are out. I actually think it might be 144cuft to accommodate the lp72s, but I i don't have access to the standards right now.

Your best bet is al80s, hp100s, lp85s. The al80s are the lightest on the surface in terms of weight, but they usually require a little extra lead to counteract the buoyancy which puts them a little closer to steel hp100 weight territory.

Hp100s are a popular choice. I have really come to enjoy the al80s though. They trim out great and feel like a light backpack after lugging around lp108s all the time. The popularity of the al80s with a lot of GUE divers was always something I questioned...let's just say I am a believer now.

 

[eelnoraa]

I am 5'6" in CA water as well. I will recommend faber LP85 type of tank. If you get can get a hold of older worthington LP80, they are also good. These tanks are a bit longer than HP100, make it easier to balanced in water, yet not too long like HP120. HP100 is very popular here,and I can see why. But they are not as easily as LP85 to dive.

I have to advice against HP80 kind of tank. They are very short tanks. Double setup tent to be top heavy. Most people even put tail weight on doubles, so the longer the tank, the longer piece of tail weight you can put on. More importantly, make center of gravity lower.

I also don't recommend LP95 kind of tank. They are short and wide, with long neck. If you have manifold hitting your head issue, long neck tank will make it worse.

 

[eelnoraa]

Min gas volume requirements for GUE doubles is 140 or 150 cuft so the tiny doubles are out. I actually think it might be 144cuft to accommodate the lp72s, but I i don't have access to the standards right now.

This is an incorrect statement. Min gas is a function of depth, site and dive profile, not the tank size. In open water rec profile dive, where you can ascent anytime, 100ft min gas is like 35-40CF. If depth is shallower, min gas reduce significantly.

Double LP72 is definitely a choice for GUE fundie type of class. It is just maybe not be the best choice for further class.

Double AL80 is a poor choice for CA diving too. It is butt light, which makes top heavy problem worse. And you need to carry additional 8lb just to make the tank neutral at the end of the dive. I haven't seen many double AL80 being used in CA coastal water.

 

[MichaelMc]

My mention of the tiny doubles was not so much for the class itself, or for full GUE diving after. But rather as a similar functioning setup for informal workup dives prior with the OPs buddies. If a set is enough for one of the dives they do.

The step from tiny doubles to whatever might be needed in the class is smaller than from sidemount. Happy to hear min gas is by the dive done.

And the not destroying your back either way comment is key!

 

[Marie13]

My bad - I put LP95 when I meant LP85.

 

[Tantram]

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.

 

[Compressor]

Hey all.

I'm looking for a little advice here.

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). However, my friends are jumping into the GUE pool and I'd really like to join them .. so it looks like I'm going to give this whole doubles thing a go and see if I can make it work. The main reason being I am interested in learning to be a better dive team member and expand my skills. Even if it means ditching double after learning in favor of sidemount again, I think it would be valuable.

What doubles setup strikes a good balance between not too long and not too heavy? What size would you recommend? Are there any setup tricks for reducing weight? I feel like every little bit matters for me. My friends all stack double water heaters onto their backs and it hurts just watching.

What are some tricks to dealing with a bad right shoulder and valve access? I'm concerned that especially in a drysuit the reach will be painful.

Hi:
You have not mentioned about your dive depth when considering doubles. For this reason I want to say that you can basically take any tank, take the valves off and make them into doubles. You don't have to do tech diving to do doubles. Many people dive doubles with a variety of tank sizes.

Some even take tanks like LP50s, double them up and if they need extra gas, then sling a AL80 on the side.

So it really depends. Be careful lifting really heavy tanks; IMO, it's not worth hurting your back at all.

 

[CptTightPants21]

This is an incorrect statement. Min gas is a function of depth, site and dive profile, not the tank size. In open water rec profile dive, where you can ascent anytime, 100ft min gas is like 35-40CF. If depth is shallower, min gas reduce significantly.

Double LP72 is definitely a choice for GUE fundie type of class. It is just maybe not be the best choice for further class.

Double AL80 is a poor choice for CA diving too. It is butt light, which makes top heavy problem worse. And you need to carry additional 8lb just to make the tank neutral at the end of the dive. I haven't seen many double AL80 being used in CA coastal water.

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. This is separate from Min Gas calculations which are used to calculate turn pressures.

If fundies doesn't have the min gas volume standards, the instructor may. There is a good amount of in water time during fundies and a mini doubles set could be limiting to the class if everyone else is diving larger tanks. Especially during the later days when the team is doing OOA gas ascents-do you want to be two divers breathing off of al40s from 60ft?

I'm not saying you need to go find the largest set of tanks you can find or even that you should be diving the same tanks as your buddies, but 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.

 

[Scubatude]

Hi there!

I am late to the thread, sorry. I won't recap what others have already said, however I will say that we rent doubles for many of our tech customers and students. We are in North LA County, and rent double 72s, AL80s, LP85s, and HP100s. We also rent BP/W with doubles wings and doubles reg sets. You may want to try before you buy.

 

[eelnoraa]

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. This is separate from Min Gas calculations which are used to calculate turn pressures.

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. Back gas only need to get the divers to the next gas supply, which is usually 70ft where the 50% bottle is useable.

If fundies doesn't have the min gas volume standards, the instructor may. There is a good amount of in water time during fundies and a mini doubles set could be limiting to the class if everyone else is diving larger tanks. Especially during the later days when the team is doing OOA gas ascents-do you want to be two divers breathing off of al40s from 60ft?

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'm not saying you need to go find the largest set of tanks you can find or even that you should be diving the same tanks as your buddies, but 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.

I don't disagree.