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spectrum:
Perhaps. Let's cut to the chase...
If you toss a set of nearly empty Al80 doubles in the water, regs on but no plate, do they sink or do they float? Let's use fresh water and standard 80s for this example.
Do you prefer to dive Steel or Aluminium tanks?
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Perhaps. Let's cut to the chase...
If you toss a set of nearly empty Al80 doubles in the water, regs on but no plate, do they sink or do they float? Let's use fresh water and standard 80s for this example.
Ok, assuage my curiousity, because I've never played with twinned 80s first hand. Because, in my mind, wouldn't they be EIGHT pounds positive when empty, total? ( + 4 each)Stephen Ash:
Maybe I'm missing something, but that math doesn't make sense, in light of your assertion, unless the manifold, bands etc. weigh more than 8 pounds.
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"Surprisingly" they will sink... and you are right... they sink because the total weight of the hardware... bands,manifold, and regs... is more than the positive buoyancy of the two cylinders. In fact they sink pretty good... if I were to guess, I would think the total "package" is about 2 or 3 pounds negatve in fresh water.
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And here's something else to consider...
... say someone switches back and forth between singles and doubles. One might think that he is going to need 3 to 4 pounds more when he goes with the twins... to counter the positive buoyancy of the additional cylinder when empty. (That's what I used to think!) So, he puts more weight on his belt. What he didn't realize was that the hardware on the doubles is actually significantly negative and that his weight requirement with the doubles is actually less than with the single cylinder. Instead of putting weight on he could have taken a little off.
... say someone switches back and forth between singles and doubles. One might think that he is going to need 3 to 4 pounds more when he goes with the twins... to counter the positive buoyancy of the additional cylinder when empty. (That's what I used to think!) So, he puts more weight on his belt. What he didn't realize was that the hardware on the doubles is actually significantly negative and that his weight requirement with the doubles is actually less than with the single cylinder. Instead of putting weight on he could have taken a little off.
BadLatitude
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6 hp120 4 hp80 1 lp 104 or somthing like that 1 AL80 for a line bottle at 30 ft and one al63 for pure 02 line bottle.
Stephen Ash,
If you make this a doubles rig matter then it does change. Way back in post 17 I stated that they can be favorable for doubles rigs.
Pete
If you make this a doubles rig matter then it does change. Way back in post 17 I stated that they can be favorable for doubles rigs.
Pete
Overfills is another thread subject. Having said that, I use a LP 85 filled to around 3200 psi. This is 103 cu. ft. of gas. It is a treat to use. I hardly know it is there. I know my heavier steel LP 95 is back there when I use it. This is 117 cu. ft. of air at 3200 psi. Both require the same amount of lead in the ocean. I may consume more air hauling around the heavier tank. The bottom time is probably not 13% longer.
Going into the flow at Blue Springs, I use an AL 80. I don't need as much air, and the flow and buoyancy differences "cancel out". Using my old AL 80 means using the same lead as the steels in the ocean. It is all really easy.
Going into the flow at Blue Springs, I use an AL 80. I don't need as much air, and the flow and buoyancy differences "cancel out". Using my old AL 80 means using the same lead as the steels in the ocean. It is all really easy.
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I know you did, Pete.
I just wanted to point out something that I believe a lot of folks don't realize.
Sometimes you can learn a lot by tossing your gear in the pool and sometimes you can learn at least little from someone else who has done it.
Open minds and all that...
Don Burke:
Ditto that. I love my E8-119. I wish it were easier to travel with...
Steel, both for single and doubles.
I like that I can drop my 8lb weightbelt when I move from my single steel 80 to dive my double 116´s (15lx2)...this is diving dry...
All things being equal, I´d rather have the weight in the tank than on my weightbelt...having said that, at 80lbs (empty) my doubles are on the heavy side...
I like that I can drop my 8lb weightbelt when I move from my single steel 80 to dive my double 116´s (15lx2)...this is diving dry...
All things being equal, I´d rather have the weight in the tank than on my weightbelt...having said that, at 80lbs (empty) my doubles are on the heavy side...
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