Help Moving Into Doubles
- Thread starter WreckDiver1321
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NO! Not true. Complete nonsense. Double 80s are my favorite doubles for recreational doubles diving, and I have double AL80s, double HP 100s, double HP 120s, and double HP130s to compare. Great trim, good bouyancy characteristics. Having said that, I would also suggest you consider double HP 100s, for gas supply.
An 80 is 5 pounds positive when empty. Double them up and you got 10. If having a giant cork on your back gives you great trim, hey go for it. Enjoy the extra weight you have to carry to off set it towards the end of your dive. Can you say safety rock???
VooDooGasMan
Contributor
Why would you wear the extra 10#, you only dive 2/3rds of the gas supply out, and put a 12' long hose on the primary and release the tanks if you need to delete the air supply on an unplanned deco, and it would be a marker for the boat to tell your having difficulty on this dive and have them ready for emergency procedures.
Back plate: Aluminum or steel?
Exposure protection: Wet or dry?
Relevant questions for those wanting to argue Al vs steel, don't you think?
Exposure protection: Wet or dry?
Relevant questions for those wanting to argue Al vs steel, don't you think?
halocline
Contributor
Much of the added buoyancy of double AL80s is offset by the bands and manifold. I find I ended using a little less weight for double 80s than a single 80. I was very skeptical about the idea of double 80s for exactly the reasons mentioned, but was pleasantly surprised when I tried them. In some ways I liked them better than my 72s. Two caveats, I've never breathed down double 80s to 500PSI, only about 1300 or so, and I've only used them in warm water (mexican caves). But, my next double set will be 80s for sure, mostly to get more used to what I'll certainly be diving in Mexico.
Why the suggestion for luxfers? I have a single catalina, which is .4lbs less positive than luxfers, and it's my intention to find another catalina for my doubles. I understand lots of people seem to prefer luxfers for stages, but I don't see the advantage for backmount doubles.
In terms of buying your first doubles set w/out a lot of training or experience, I have to agree that a used set of AL80s makes the most economic sense. If you buy a new set of worthington X7s, new bands and manifold, you're looking at close to $1K, where you might be able to get a little more than half that back should you want to sell them. Used AL80 double sets are all over the place for a deal, then when/if you figure out you're not going to use them, you can probably move them for close to what you paid.
But, the best advice is to start some technical training, get some advice from your instructor, and go from there.
Why the suggestion for luxfers? I have a single catalina, which is .4lbs less positive than luxfers, and it's my intention to find another catalina for my doubles. I understand lots of people seem to prefer luxfers for stages, but I don't see the advantage for backmount doubles.
In terms of buying your first doubles set w/out a lot of training or experience, I have to agree that a used set of AL80s makes the most economic sense. If you buy a new set of worthington X7s, new bands and manifold, you're looking at close to $1K, where you might be able to get a little more than half that back should you want to sell them. Used AL80 double sets are all over the place for a deal, then when/if you figure out you're not going to use them, you can probably move them for close to what you paid.
But, the best advice is to start some technical training, get some advice from your instructor, and go from there.
ddmattos
Contributor
OP..... "
I want to get into wreck penetration. Caves too, eventually, but mostly wrecks. As well as mixed gas deep diving. I'd prefer LPs."
Luxfers are prefered stages, like you said. He will need them later.
I agree that a person should find a competent tech instructor (ask around) that will take you from basic through to trimix. Take a TDI-Intro to Tech or GUE/UTD fundies class. See if they will lend you doubles and wing for the course with some pool time for orientation. Hopefully you have been using a backplate for your singles diving. It will be money well spent. Get all your questions answered and test out gear. I was groomed for this route and didn't even know it at first (Thanks Wayne). Buying right the first time is the best way to get the correct gear, ultimately spend less money and spend less time getting accustomed to different gear configs since your foundation will not change. (See DIR gear config)
Unless of course you come across some great deals on the correct gear. It is very rare to buy something scuba related and not sell it for a loss.
elan
Contributor
Catalinas are better for the backgas in terms of buoyancy and trim.
But in case the OP later realize he does not like AL80 doubles he can break them down in 2 stages. And in case he realizes that he loves the AL80 he can brek them down into stges and replace with catalinas. So with luxfers its a win win situation. They will likely end up bein stages anyways.
Very good point. Exactly why general statements that any particular tank (metal, size, manufacturer) has poor buoyancy characteristics are probably not useful. The attractiveness / functionality of a tank depends on all of the above, plus the environment (salt vs fresh water) in which they are used, as well as the personal bouyancy characteristics of the user, and their personal preferences.
DevonDiver
N/A
Don't you guys travel at all? I understand the merits of discussing tank characteristics... but if you dive away from home, you use what you can get.
In many locations, that'll be AL80s, or maybe AL100s. Building the 'perfect rig' is applaudable, but a diver needs to maintain the flexibility to utilize available resources whilst still maintaining a good capability and not diminishing performance..
If X, Y or Z cylinders are believed to have "crappy" buoyancy characteristics... then any user of that mindset is going to display "crappy" buoyancy when needing to use them. That makes for a bad situation on your next holiday...
In many locations, that'll be AL80s, or maybe AL100s. Building the 'perfect rig' is applaudable, but a diver needs to maintain the flexibility to utilize available resources whilst still maintaining a good capability and not diminishing performance..
If X, Y or Z cylinders are believed to have "crappy" buoyancy characteristics... then any user of that mindset is going to display "crappy" buoyancy when needing to use them. That makes for a bad situation on your next holiday...
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