Tank/weighting conundrum
- Thread starter gtto
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As new a diver as you are, I'd stick with the Al tanks for a while and make sure you can be easily positive on the surface. There are solutions to diving a little heavy, and ways to ensure buoyancy at the surface, but they're best employed by people with enough experience to know that they can remain calm in exigent circumstances.
If you are considering switching to the 100 cu ft tank, why not switch to an Al100? And if you are switching because your gas consumption is high, you're better served to work on that directly.
If you are considering switching to the 100 cu ft tank, why not switch to an Al100? And if you are switching because your gas consumption is high, you're better served to work on that directly.
OP
In response to some of the above, I don't have a problem with air consumption but wanted more volume for Eax dives. I dive a lot, at the moment. 2-4 times a week. And many of those are beach dives. The AL 100 is very heavy when having to walk in the 95 degree heat. Granted, none of the tanks are what I would call light but if my info is correct , an AL 100 weighs between 7 and 13 lbs more than a PST or Faber/Blue Steel 100, depending on the tank.
rstofer
Contributor
An HP100 (Worthington X7-100) weights 41# when full. An Al 100 (Luxfer 100) weighs 49# but you have to add 1# for the valve - call it 50#. HOWEVER, you aren't wearing 20# of lead in a harness and a 6# plate so somehow I can't get excited about the weight difference between the tanks. Heck, the difference between an aluminum and SS backplate is 4# which is about half the difference in the tanks.
The Luxfer Al 100 is only about 2# positive at the end of the dive so you carry about 4# more lead than with an HP 100. You're still lighter than a cold water diver. And carrying a few pounds of ditchable lead is a lot safer. In my view...
It's all about the darn valves. For aluminum tanks, the specs usually are 'less valve' and for steel they are 'including valve'.
Richard
OP
Maybe my system of thinking is wrong here but isn't the main idea to 1) be weighted so that you are neutral at 15 ft with 500 psi in the tank and 2) be weighted so you can swim to the surface without any lift from a wing. I know there are other considerations but aren't these the most important? If not , I have to start rethinking this thing.
black1
Contributor
My steel 120 weighs -2 @500psi...2 Regs -2...Backplate -6.
My 3/2mm full body w/ 3mm vest w/hood and 3mm booties weigh + 4lbs
-2 + -2 + -6 = -10lbs
wetsuit = +4 difference of -6lbs which is overweighted but diveable.
Kydex plate (-1lb) 2 regs (-2lb) tank empty (-2lb) 4lbs on weight belt (-4lb) = -9lbs total
3mm fullsuit w/vest and hood and booties is + 4 lbs
so here im -5 lbs overweighted, not much of a difference
My reason to not mind being a little overweighted besides what i already stated is this, I dive alot were there are currents usually on the surface, I would rather be slightly heavier when doing my stops which are almost always by drift and my lungs when inhaling keep me neutral with very slight kicks. I would rather be like this then being completely neutral and slightly fighting staying in my depth (especially on deco) due to surface current and tension from surface marker and current, this is just good for me. I have experimented with many different setups and weight and find this to be the best (for me).
My lung capacity with deep breaths for clearing out CO2 really moves me about pretty good, some people it doesnt but this is just me.
My 3/2mm full body w/ 3mm vest w/hood and 3mm booties weigh + 4lbs
-2 + -2 + -6 = -10lbs
wetsuit = +4 difference of -6lbs which is overweighted but diveable.
Kydex plate (-1lb) 2 regs (-2lb) tank empty (-2lb) 4lbs on weight belt (-4lb) = -9lbs total
3mm fullsuit w/vest and hood and booties is + 4 lbs
so here im -5 lbs overweighted, not much of a difference
My reason to not mind being a little overweighted besides what i already stated is this, I dive alot were there are currents usually on the surface, I would rather be slightly heavier when doing my stops which are almost always by drift and my lungs when inhaling keep me neutral with very slight kicks. I would rather be like this then being completely neutral and slightly fighting staying in my depth (especially on deco) due to surface current and tension from surface marker and current, this is just good for me. I have experimented with many different setups and weight and find this to be the best (for me).
My lung capacity with deep breaths for clearing out CO2 really moves me about pretty good, some people it doesnt but this is just me.
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You are correct - what counts is to be neutral at 500 psi with no gas in the wing or BC - any more weight and you are over weigthed and any less means you can't hold a 10-15' stop.
I hear you on the 100 cu ft tank and nitrox - no fun using 32% or 36% if you can't enjoy the extra bottom time.
As a technical diver, I dive either double X7-100s or double LP 95s with a SS plate and no ditchable weight. But I have a dry suit for redundant floatation in the event of a wing failure.
The major use for ditchable weight, even in recreational diving, is to drop it at the surface to establish immediate positive buoyancy in the event of a wing failure or an OOA situation where the wing cannot be rapidly inflated. Dumping weight at depth is problematic as if you are light on gas or drop a lot of weight, you have a one way ticket all the way to the surface. In an overhead diving situation that is not really an option so most techncial divers don't think twice about not having ditchable weight. And not having it also means it can't be lost accidentally.
With a hog harness and no ditchable weight, the drill would most likely be for a teamate to cut the tanks/regs/etc off my unconscious self on the surface in an emergency if the wing could not be inflated.
---
Luxfer AL100s are about 3 pounds positive when empty (with valve) while Catalina AL 100s are about .5 pounds negative when empty (with valve), but they weigh 41 and 46 pounds each when empty respectively.
Faber made a 3180 psi service pressure tank (3498 psi with 10% overfill) that held 100 cu ft at 3498 psi but it was 7 lbs negative when empty and heavy at 39 pounds. Faber's special permit 3442 psi 100 cu ft tank has the same external dimensions but weighs 6.8 pounds less making it about a half pound negative when empty - only about a pound less negative than a Worthington X7-100.
I hear you on the 100 cu ft tank and nitrox - no fun using 32% or 36% if you can't enjoy the extra bottom time.
As a technical diver, I dive either double X7-100s or double LP 95s with a SS plate and no ditchable weight. But I have a dry suit for redundant floatation in the event of a wing failure.
The major use for ditchable weight, even in recreational diving, is to drop it at the surface to establish immediate positive buoyancy in the event of a wing failure or an OOA situation where the wing cannot be rapidly inflated. Dumping weight at depth is problematic as if you are light on gas or drop a lot of weight, you have a one way ticket all the way to the surface. In an overhead diving situation that is not really an option so most techncial divers don't think twice about not having ditchable weight. And not having it also means it can't be lost accidentally.
With a hog harness and no ditchable weight, the drill would most likely be for a teamate to cut the tanks/regs/etc off my unconscious self on the surface in an emergency if the wing could not be inflated.
---
Luxfer AL100s are about 3 pounds positive when empty (with valve) while Catalina AL 100s are about .5 pounds negative when empty (with valve), but they weigh 41 and 46 pounds each when empty respectively.
Faber made a 3180 psi service pressure tank (3498 psi with 10% overfill) that held 100 cu ft at 3498 psi but it was 7 lbs negative when empty and heavy at 39 pounds. Faber's special permit 3442 psi 100 cu ft tank has the same external dimensions but weighs 6.8 pounds less making it about a half pound negative when empty - only about a pound less negative than a Worthington X7-100.
OP
So I guess the only real solution is the lighter bp............
All you need to know can be found at Scuba Cylinder Specifications from Tech Diving Limited - 928-855-9400
Also, I've never had a Faber tank that didn't rust within the first three years.
Also, I've never had a Faber tank that didn't rust within the first three years.
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