I tried the link thing could not figure so i am sorry to everyone who had to skim down the whole florida al double thing is blown out of wack......
c_a_otoole A good way to try out various tank set ups be... 08-11-2003 12:17 PM
c_a_otoole
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Registered: Jul 2003
Guam/Colorado
Posts: 1
A good way to try out various tank set ups be...
A good way to try out various tank set ups before commiting to either AL80s PST tanks ect is to set up your BC and then rent the tanks and go with indapendent (no manafold) doubles. It can be a pain in the ass switching every 5mins/500 PSI or whatever you decide, but it does give you a chance to feel what it is like to dive the various types of tanks. This is also a option for people that are renting tanks.
That being said after about two dives of doing this you will invest in the manafold and never look back. Just my two cents, because I have been diving indapendent doubles because I am only going to be here in Guam for another few weeks and I cant justify buying more tanks.
Chris
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Chris
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08-11-2003 12:17 PM
Don Burke AL doubles. 08-11-2003 08:29 PM
Don Burke
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Chesapeake, Virginia
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AL doubles.
If you're wearing a wetsuit, standard AL doubles are the way to go. You're going to need that buoyancy on a BC failure. Steel tanks are actually lighter on the boat, but don't give enough ditchable weight. Neutral 80s are even heavier than standard 80s and give about the same ditchable weight as steel. The only use I'd have for a Neutral 80 would be singles diving and I have steel tanks that work much better for that.
My first time in the water with doubles was also my first time with harness/backplate/wing system. I just went ahead and took the plunge with the manifold and bands. It was quite a leap of faith, although I expected to at least end up with a set of tanks for digging on shallow wrecks. It turned out I like doubles better than singles and I bought a couple of sets of steel 72s for the drysuit.
I'm way the heck over here in Chesapeake, Virginia (near Norfolk) or I'd offer to loan you a set of doubles so you could try them out. Perhaps you can find someone nearby to loan you a set for a "fly before buy".
Watch your weight distribution (ditchable vs non-ditchable) and don't start thinking you have infinite backgas and you'll be fine.
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08-11-2003 08:29 PM
scubatexastony That's strange..... 08-13-2003 10:15 PM
scubatexastony
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N.E.TX aka, the piney woods(home) work in Houston
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That's strange.....
quote:
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ElectricZombie once bubbled...
With doubles you will need two 1st stages, two 2nd stages, one pressure gague and one inflator hose.
--------------------------------------------------------------------------------
Mine seem to work fine with one 1st.....go figure!
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08-13-2003 10:15 PM
FIXXERVI6 how?Do you not have an isolator valve?... 08-13-2003 11:19 PM
FIXXERVI6
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Dallas, TX
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how?Do you not have an isolator valve?...
how?
Do you not have an isolator valve?
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08-13-2003 11:19 PM
scubatexastony Correct... 08-13-2003 11:25 PM
scubatexastony
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N.E.TX aka, the piney woods(home) work in Houston
Posts: 676
Correct...
old scubapro manifold....2250/72s
tony
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08-13-2003 11:25 PM
FIXXERVI6 isn't it kind of bad not to have an iso ?... 08-13-2003 11:49 PM
FIXXERVI6
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Dallas, TX
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isn't it kind of bad not to have an iso ?...
isn't it kind of bad not to have an iso ?
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08-13-2003 11:49 PM
Don Burke isolator 08-14-2003 01:04 AM
Don Burke
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Registered: May 2003
Chesapeake, Virginia
Posts: 438
isolator
If you are treating the doubles as a big single, the isolator isn't an issue.
If you are not in a situation that calls for full redundancy in regulators, the use of just one first stage is not a problem.
Much of my diving with double 72s is so I can stay with the guys diving 131 singles. They manage to make do with one first stage.
Once I'm in an overhead environment (real or virtual), all the pieces and parts become necessary. It's easier for me to have all of my doubles set up to support overhead environments. Three sets is all I really want to maintain.
Small doubles with isolation manifolds also keep me out of the Y-valve and H-valve business, so I think it's cheaper in the long run.
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08-14-2003 01:04 AM
ew1usnr Double aluminum 100's 08-14-2003 10:11 AM
ew1usnr
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Double aluminum 100's
I've been cave diving for about the last 15-years with twin aluminum 100's. The GUE DIR people will say that this is wrong because the aluminum tanks get bouyant, but I've never had a problem. I dive in fresh water with a wet suit and sink like a rock when the tanks are full. The bouyancy doesn't become an issue untill the psi drops to below 500. But by the rule of thirds, I always exit with about 1000 psi. I like the aluminum tanks because, from my experience, they are much more maintenance free then steel tanks. The dive shops seemed to want me to tumble my steel tanks (when I had steel tanks) every time they needed a VIP. I've never been asked to tumble an aluminum tank.
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08-14-2003 10:11 AM
Don Burke Aluminum tanks with a wetsuit 08-14-2003 10:40 AM
Don Burke
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Chesapeake, Virginia
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Aluminum tanks with a wetsuit
Actually, the GUE people I have talked to are of the opinion that aluminum is the best way to go with doubles and a wetsuit.
My personal experience is that a safe application of steel doubles with a wetsuit would be the exception rather than the rule.
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08-14-2003 10:40 AM
ew1usnr Aluminum 100's 08-15-2003 09:51 AM
ew1usnr
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Aluminum 100's
Don! I stand corrected. I based my remark on something I read on a GUE site that said that (paraphrased) "a diver should have enough weight to still stay under even with his tanks empty". To me, that does not necessarily make sense on several fronts. For a long time steel tanks (104's) were regarded as the standard for cave divers because they held a larger air volume and were not as bouyant when empty. My brother and I were the exception with our aluminum 100's. Maybe as time has passed some people (though not all) have realized that the bouyancy issue was not so much a problem, and that a little less negativity might be a bit of an asset. Some of those steel tanks were so heavy that if a diver tore his BC he would literally have to walk out of a cave. That was when they started using backup BC's. Even if the BC doesn't blow, it has to be kept partially inflated to offset the weight of the steel tanks, thus creating extra frontal area and drag. The aluminum tanks are roughly neutral for much of the dive so the BC is not such a critical safety issue. Maybe my brother and I were "ahead of the curve" on this one.
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08-15-2003 09:51 AM
FIXXERVI6 ok, so double neutrals are a bad idea then be... 08-15-2003 11:19 AM
FIXXERVI6
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ok, so double neutrals are a bad idea then be...
ok, so double neutrals are a bad idea then because of the bouancy issue? I mean, if I have no wet suit on, I 'd have 0 ditchable weight.
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08-15-2003 11:19 AM
ew1usnr Neutral Bouyancy Is Good! 08-15-2003 11:32 AM
ew1usnr
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Neutral Bouyancy Is Good!
That's what you want! If your equipment selection lets you reach it by adding minimal air to your BC or minimal weight to your belt, you are doing great.
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08-15-2003 11:32 AM
Don Burke ditchable weight 08-15-2003 11:59 AM
Don Burke
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ditchable weight
You need enough ditchable weight to solve the following problems:
1. You roll off the boat and snag your inflator hose on something, ripping it to shreds. How much weight do you need to ditch to stay on the surface?
2. You get problem one straightened out and try the dive again. Upon reaching the bottom, you snag your inflator hose on something, ripping it to shreds. How much weight do you need to ditch to get to the surface?
If the number is zero, you don't need any ditchable weight. That can be the case with a single tank and no neoprene.
With the gas in my 80s and wetsuit compression, I need about 9 pounds for problem 1 and about 20 pounds for problem 2, so 20 pounds it is. I prefer not to rely on being able to swim any weight up.
With my wetsuit, standard 80s and a steel backplate, I need about 24 pounds of weight to be neutral, so I have enough.
If I went to neutral 80s, I would have to take 8 pounds off the belt, leaving 16. That means I would be four pounds short. I can swim it up, or switch to an aluminum backplate to put five pounds onto the belt. I don't need an aluminum plate for anything else.
Since I don't need neutral 80s for anything else, I stay with the standard 80s. If I decide to give up wetsuit diving, the standard 80s make better stage/deco bottles.
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08-15-2003 11:59 AM
Don Burke ditchable weight 08-15-2003 12:06 PM
Don Burke
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Registered: May 2003
Chesapeake, Virginia
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ditchable weight
Those 80s hold about 12 pounds of air, about 10 of that is extra weight at the begiinning of the dive.
If you can deal with a wing failure with no ditchable weight, you don't need any ditchable weight.
anyways this is last of this...
i am going to do what feel safe for ME with all the input from everyone else to use to tweak and find the best suited for me. thanks again everyone
Hey, dude... I'm coming into this conversation a bit late... I just noticed it.
