Double X7-80's or Single Faber 149?

[Borlock]

I've never seen a 149 in person but spec says it weighs 47lbs.
2 x X7-80's however come in at 56lbs (lightests 80s I know of).

In the water, the 149 has an 11lbs boyancy differential full vs. empty.
2x80s has a 12lbs differential.

So to me it seems logical to get the single 149, as it's actually lighter. HOWEVER, every review comment I've ever seen says: "Don't get a tank > 120. They're too heavy. Get doubles instead."

But (banded) doubles are always going to be heavier. So what gives?

 

[micklock]

I've never seen a 149 in person but spec says it weighs 47lbs.
2 x X7-80's however come in at 56lbs (lightests 80s I know of).

In the water, the 149 has an 11lbs boyancy differential full vs. empty.
2x80s has a 12lbs differential.

So to me it seems logical to get the single 149, as it's actually lighter. HOWEVER, every review comment I've ever seen says: "Don't get a tank > 120. They're too heavy. Get doubles instead."

But (banded) doubles are always going to be heavier. So what gives?

I have never dove a tank bigger than a hp100, but I dive independent double hp80s. I think they would be a lot more comfortable and stable than a 149 plus I like the redundancy. I can take my 3 hp80s on a boat and swap the more empty tank for a full one on the second dive, you just need a second reg and spg and switch breathing between the two regs to manage you gas.

 

[Borlock]

I can see your point with the two independents.

I was more curious about a config with a manifold & semi-permanent bands. (Don't really want to have 5 regulators with me )

 

[ucfdiver]

Hard to recommend the tank for you without knowing the dives you're doing, and why you want such monster tanks. I can't think of many cases where 149cu ft would be usable within the NDL. If you're deco diving, you'll have to make the decision on how safe you feel with a single tank vs doubles.

 

[Borlock]

I started off with explaining why, then I deleted cause the post got too long .

Ok, here goes. I'm just on the cusp of NDL for dive 1 with a 100 on air. Generally can do 35mins @ 80 feet. It's a bit short, so I want to switch over to EAN40 on my next excursion.

However, I feel EAN40 in a 100 would be a waste on me. Hence the big tank(s).

 

[dumpsterDiver]

The 149 is essentially the same tank as the LP 125 with regard to size and weight. I have 2 125's and one new 149, somehow one is rated at 2400 and the other at 3500 (or whatever it is). They look and feel the same to me.

I love the big tanks because I can often get 2 or sometimes 3 no-deco dives from them (especially the 149). I also use them for deco dives to around 200 ft along with a pony and a deco bottle sometimes. I see no reason for me to buy doubles.

I also have a couple LP 108/112's and the new HP 117 (is it?). I do not change my lead when switching between any of these tanks and I can not tell the difference between them when in the water.

I dive only single tanks and it would be very expensive and a pain to switch from doubles to single tanks.

When I switch to 80 aluminums, I add 6 lbs to my belt but to be honest, I normally use the big steels and I have better trim with a big steel than an aluminum, I think. The big steels are only a hinderance on the boat, in the water they are not a problem. I even dive them sometimes with very little wetsuit and zero lead.


Incidentally, my buddy dives with double 149's (and 2 80 cu-ft stage bottles) but he is crazy.

 

[stoiclown]

As an owner of two HP 100 and one HP 130, I would purchasing the two 80.

For your everyday diving, the 150 is heavy. As shore and boat diver it is difficult (but not impossible) to shore dive with in cold water or haul yourself up the boat ladder (30lbs of weight, plus tank and dry-suit put you close to 80-90lbs). Depending on your size this may not be a problem (I'm 6-4" and weigh 248lbs, so no big deal), but for some this may be close to half their body weight, and in rough seas getting out could be very precarious in everyday situations.

Where as the HP 80 similar in size to an AL 50 and weigh close to the same, but have much better handling characteristics due to their negative buoyancy (i.e. less weight on the belt).

If your intent is to technical dive, neither tank setup has enough juice for serious deco-diving (i.e. long deco dives), and would consider up-sizing to at least twin HP 100's.

Hope this helps, and wish you many more pleasant dives.

 

[Wayward Son]

X7 80's are really short. Doubled they put the center of gravity high, might be a problem to be able to trim without being pushed head down. I find the X7 100's a bit short when diving them single, I'm 6' tall. I can trim OK with them, but I think the 80's could be a problem in that regard.

 

[fdog]

HP80's have a good history of severe trim problems as doubles. Universally, I've seen reports of them forcing your face into the bottom.

IIRC, only one persson has reported success using HP80's - a very, very petite lady.

To get to your question, though, why doubles when a single (apparently) weighs less?

I dove a water heater once, just to see what it was like. Too long, too clumsy; to trim it out I had to have it pretty high behind my head. Doubles may seem heavier at first blush, but I have less lead on the belt with doubles than with the water heater, and they feel much nicer underwater. I'd say the real weight difference (total system weight, tanks and weight belt) is only about 8 lbs.

And if you're taking that much gas, you can easily exceed the NDL, where you'll need the redundancy of manifolded doubles, anyway.

All the best, James

 

[dumpsterDiver]

I generally dive warm water, with an aluminum backplate and need little or no lead. Double negative steels would NOT be beneficial to me. The single tank is damn heavy, any additional weight would be a killer.