Well, if you want to use one set of doubles for two dives off a boat and have thirds for the second dive, the 100's or even 80's do make sense for no-deco dives in the 120-130 ft range.
Most Common Doubles
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FreeFloat
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Hm, I view this thread with some interest. I too am a dedicated wetsuit diver doing non-deco dives. However I'm quite small therefore not only have a reasonable SAC rate but am short in stature.
Firstly: why does nobody use double 72's anymore? There has to be some obvious reason that I'm simply missing.
Secondly: would double AL80s be the best weight/gas/buoyancy combination for someone like me?
Thirdly: if I were to go with steel tanks instead, what size would likely be best? Or would you recommend against steel in wetsuits altogether?
Firstly: why does nobody use double 72's anymore? There has to be some obvious reason that I'm simply missing.
Secondly: would double AL80s be the best weight/gas/buoyancy combination for someone like me?
Thirdly: if I were to go with steel tanks instead, what size would likely be best? Or would you recommend against steel in wetsuits altogether?
Well, first of all, 72's arent very easy to come by anymore. They arent being produced in the LP format anymore. The only way you get them is on ebay, or some guy down the street, etc, etc. Either way, you never really know if you are getting a good cylinder. I tried to get a set of 72's for doubles. Never could get two that were galvanized, and looked good enough inside, and would pass visual and hydro. So, I gave up on my search. Yes, I know, many people still find them around every now and then.
Now, the wetsuit and steel doubles issue. You might be too heavy when (or if) your BC fails, and then you wont be able to swim them up. So, if you are diving AL80's, and your BC fails, you can swim those up, by ditching lead if need be. If you dive a drysuit, you have a redundant lift source, therefore steel doubles are OK.
Now, the wetsuit and steel doubles issue. You might be too heavy when (or if) your BC fails, and then you wont be able to swim them up. So, if you are diving AL80's, and your BC fails, you can swim those up, by ditching lead if need be. If you dive a drysuit, you have a redundant lift source, therefore steel doubles are OK.
FreeFloat, the 72's stopped being an option for me because they are old, and are begining to outlast easy access to a supply chain. Lots of parts, like bands and manifolds, just are plain hard to find built for 72's.
In answer to your second question, I guess it all depends on your own mindset. I dive wet; safety is big to me; I weight for surface/empty/neutral (reasons for this found elsewhere on SB, or TDS); I dive dual bladders. With all this, diving steel has been a better solution for me, not the least being less weight on the belt.
With the same configuration, substituting Al 80's for steel, I worry that the extra lead to keep the Al 80's from floating (at the end of the dive) will be a liability at depth, as the wetsuit compresses.
If I didn't choose dual bladders, I would be diving Al 80's to give me a chance of swimming up, because of "floaty" cylinders and loss of lead when I ditched a heavy belt. This results in bouyancy problems near the surface after an emergency, which is again something that worries me.
Of course, the most elegant solution is a shell dry suit. Here your bouyancy variance is nominally reduced to the loss of your backgas, and minding ascent/descent on your wings. The suit becomes a "backup" to your BC bladder.
However, I dive rec, deco, and freedive. I like having the same suit throughout. For me, a wetsuit is a good fit for all three; the issues with a wetsuit for recreational diving are relatively trivial; and I'm willing to place better care into weight planning for diving deco. For me this has meant dual bladders, and more foresight into possible emergencies.
In my diving, there is a clear mindset "switch", if you will. Recreational=NDL=single tank; Deco obligated=redundancy=doubles. When I dive rec, I would rather carry around a single tank and have ease of swimming, gear-up, and moving around the boat. It's easier for me to schlep two singles than a single pair of doubles. So I reserve use of doubles for deco diving; for me, that's part of the "price" of diving overhead-restricted. Although I suppose you wouldn't have to switch tanks between dives, this task certainly hasn't been onerous for me.
Everything is a tradeoff; think through the consequences, and I'm sure you will arrive at the right answer...for you.
All the best, James
In answer to your second question, I guess it all depends on your own mindset. I dive wet; safety is big to me; I weight for surface/empty/neutral (reasons for this found elsewhere on SB, or TDS); I dive dual bladders. With all this, diving steel has been a better solution for me, not the least being less weight on the belt.
With the same configuration, substituting Al 80's for steel, I worry that the extra lead to keep the Al 80's from floating (at the end of the dive) will be a liability at depth, as the wetsuit compresses.
If I didn't choose dual bladders, I would be diving Al 80's to give me a chance of swimming up, because of "floaty" cylinders and loss of lead when I ditched a heavy belt. This results in bouyancy problems near the surface after an emergency, which is again something that worries me.
Of course, the most elegant solution is a shell dry suit. Here your bouyancy variance is nominally reduced to the loss of your backgas, and minding ascent/descent on your wings. The suit becomes a "backup" to your BC bladder.
However, I dive rec, deco, and freedive. I like having the same suit throughout. For me, a wetsuit is a good fit for all three; the issues with a wetsuit for recreational diving are relatively trivial; and I'm willing to place better care into weight planning for diving deco. For me this has meant dual bladders, and more foresight into possible emergencies.
In my diving, there is a clear mindset "switch", if you will. Recreational=NDL=single tank; Deco obligated=redundancy=doubles. When I dive rec, I would rather carry around a single tank and have ease of swimming, gear-up, and moving around the boat. It's easier for me to schlep two singles than a single pair of doubles. So I reserve use of doubles for deco diving; for me, that's part of the "price" of diving overhead-restricted. Although I suppose you wouldn't have to switch tanks between dives, this task certainly hasn't been onerous for me.
Everything is a tradeoff; think through the consequences, and I'm sure you will arrive at the right answer...for you.
All the best, James
scubafanatic
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FreeFloat:
Hi FreeFloat,
.....don't give up on double steel 72's......they are readily available for sale as brand new/ galvanized tanks from PST.....they currently sell an "MP-72" steel tank rated at 72 cu. ft @ 3300 psi.....admittedly not quite identical to the 'classic' 72 cu. ft. tank that was rated somewhere in the 2200--2400 psi range, but not a bad approximation for the good-'ol-days.
Presently I've got 2 twinsets ( OMS/Faber steel LP 85's and ScubaPro/Faber steel 76's) both of which are pretty close to the 'classic' steel 72's.....and I enjoy both twinsets. They're big enough to be useful, but not too heavy/bulky out of the water.
They're a little smaller than most cavers in the US seem to use, however, they actually have more capacity than the twin AL80's that are standard issue in Akumal, Mexico, which is considered to be the cave diving capital of the world, so I think they'd be fine for all but the most 'extreme' diving.
The only thing I 'miss' is that Faber's aren't hot-dip galvanized like PST tanks.......so I'm thinking that my next doubles purchase will be PST......either their 72's, or maybe their HP 100's.......big enough to be useful, yet with 6.90 or 7.25 " diameters they make a nice, compact, slim profile twinset.
In reference to your steel tanks and wetsuits question, just dive with a dual-bladder wing...that's how I dive.
Karl
rescuediver009
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scubafanatic:
I have to know how tall the hp 76's are. they must be the size of the oms/faber 66's
scubafanatic
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Hi rescuediver009,
...in answer to your question about my '76's'......they are Scubapro/Faber LP steels, they are "+" rated, meaning the max official fill pressure is 2640 psi. They're the same height as my LP 85's, namely 26" tall...the Faber 66's are only 21" tall. Both my twinsets use Highland bands, and both sets are nice and 'compact' , very enjoyable to dive, and not a pain in the butt to handle on land.
Karl
...in answer to your question about my '76's'......they are Scubapro/Faber LP steels, they are "+" rated, meaning the max official fill pressure is 2640 psi. They're the same height as my LP 85's, namely 26" tall...the Faber 66's are only 21" tall. Both my twinsets use Highland bands, and both sets are nice and 'compact' , very enjoyable to dive, and not a pain in the butt to handle on land.
Karl
rescuediver009
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scubafanatic:
i see tall and skinny rather than short and stubby
scubafanatic
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Hi rescuediver009,
...you 'see' correctly......they are 'tall and skinny'...the same length as an AL80, and a slightly smaller diameter, as an AL80 is 7.25" wide......my tanks are about 7" wide......long enough to distribute their weight along more of the torso, so easily balanced, and the right height for me such that's it's very easy to sit down with them and gear up, without them being too tall or too short. I will probably buy another such twinset later this summer, so I'll then have 3 twinsets dive-ready.
Karl
...you 'see' correctly......they are 'tall and skinny'...the same length as an AL80, and a slightly smaller diameter, as an AL80 is 7.25" wide......my tanks are about 7" wide......long enough to distribute their weight along more of the torso, so easily balanced, and the right height for me such that's it's very easy to sit down with them and gear up, without them being too tall or too short. I will probably buy another such twinset later this summer, so I'll then have 3 twinsets dive-ready.
Karl
rescuediver009
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scubafanatic:
hmm. sounds good. I guess I would get a little more bottom time than you. I am looking to get a set of oms/faber 112's. I have also experimented with genesis HP100's. I like the 112's better for buoyancy. Also I figure I can dive them for a while, while i can still carry them. I know some people who have taken them apart because they are too heavy. I logged over 2 hours of bottom time avg depth 70ft. with them once.
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