Want to double up tanks, but which ones?

[paddler3d]

Want to double up a set of tanks. I want to have a redundant air source w/o slinging my pony.

I have two Worthington HP130's and two Faber Blue Steel HP100's.

I dive a SS back plate that is roughly 5# negative.

I dive a semi-dry wet suit.

I have a Dive Rite Rec wing, 55# lift, and a Dive Rite Classic wing, 60# lift.

Diving my HP130 in fresh water and the only weight I have is my back plate, I am absolutely neutral with 500psi at 15ft and not one bit of air in my wing.

According to the Faber website, the HP100's are 34.3# and are -8.41# full/-.59# empty and the Worthington's are 43# and are -11.7# full/-2.0# empty.

I can't recall my SAC, it isn't bad, but isn't great. I do describe myself as a heavy breather. That could sound wrong taken out of context.

I dive with a couple and on the exact same dive profile, we'll all end up with the same amount of PSI left at the end of the dive when I use my HP130, Matt uses the HP100 and his wife uses an AL80. Not kidding. I don't think she breaths.

Aside from the 17# weight difference, I'd love to hear what you guys would double up and why.

Thanks,

Chris

 

[ianr33]

You say you are neutral with a single 130 almost empty.With filled double 130's you would be around 20 pounds negative at the start of a dive. (Actually a bit more if you add on the weight of an extra reg,bands and a manifold) You have no redundant buoyancy in a wetsuit and no weight to drop. A wing failure would dump you on the bottom and I would not want to try and swim up 20+ pounds.

Double 130's are horribly heavy to carry around

Either the 130's or the 100's would give you a huge amount of gas for recreational dives.Put another way you can get seriously into deco with them,even with a lousy SAC rate.Not a problem as such but something to be aware of.

So I think doubling the 100's would be best.Seriously consider an Aluminum backplate (1 lb negative) and start thinking about a drysuit!

Also you said you wanted redundancy. Doubles are not truly redundant as an isolator failure would leave you SOL. Not likely but possible. I assume you will be getting some training/mentoring in how to use doubles?

 

[paddler3d]

The savings account for the dry suit has been developing. My goal is to save $2300 so I can have an assortment of good ones to look at.

I've got a buddy that dives doubles and I've actually dove his doubles in a pool. He's got HP117's. I found it was really easy to stay horizontal, but I found I felt like a turtle when I would roll onto my side. I then found myself on the floor of the pool LMFAO.

Last night I was looking at AL back plates and they appeared less costly than I had remembered. That is a potential 4#'s gone.

One for the HP100s!

More thoughts?

 

[The Kraken]

HP100's make for very nice doubles.

the K

 

[Colliam7]

Want to double up a set of tanks. I want to have a redundant air source w/o slinging my pony. ... I have two Worthington HP130's and two Faber Blue Steel HP100's. ... Aside from the 17# weight difference, I'd love to hear what you guys would double up and why.

Tough question , because the choice is best determined by the type of diving YOU want to be doing. EITHER 100s or 130s make a very nice set of doubles. I dive both, and find them enjoyable. A 55 lb or 60 lb wing is fine for either set. But, I would want redundant buoyancy (dual bladder, lift bag, big SMB, two wings bolted to the plate, whatever) if diving them wet or semi-dry. I also use an AL BP when diving double steels wet. I tend to use the 100s for shallower, non-decompression dives, and the 130s when I want a lot of air for deeper / longer. As Ianr33 mentioned, I am not sure I would consider manifolded doubles to represent a true redundant air supply, but that is a minor issue. If you want to dive recreationally with others who have single tanks, and you don't plan to stretch the air, to get two dives from one set of doubles, to match their use of two tanks, I would suggest doubling up the 100s. That way you still have single 130s when you want to dive single tank, and still have plenty of air in the 100s. But, if you think decompression diving is in your near future, and you plan to go deep - 200' or greater, I would suggest doubling the 130s. Yes, that is a heavy set of doubles, but manageable.

 

[paddler3d]

The type of diving I like to do the most are the dives off of NC.

We're talking about dives within recreational limits >140ft and due to the fact that most of the dives out there are 95-100ft you inadvertantly end up with 7-9minutes of time to surface after it is all said and done. So 4-6 minutes of 'decompression'.

Diving my 130's in the NC profiles I mention above, I tend to get back on the boat with 1100-1200psi, so clearly I carrying too much air.

Ideally I'd be able to 2x up my 100's and get two NC dives on them and a bit of reserve, but I think it would be cutting it close on that 2nd dive.

Also, as soon as I get my dry suit, Tobermorey, here I come!

I'd love to get to the deeper diving, but fiscally that isn't going to happen any time soon.

I guess I could still dive with the slung pony, but them I'm getting back to one more thing I have to strap on.

 

[TSandM]

It sounds to me as though there are a bunch of reasons why doubling the 100s makes sense.

First off, it leaves you the single 130's for the dives where you don't want to lug doubles, and the 130s are plenty of gas for any single tank dive you could want to do. Second, from the gas consumption information you give us, you don't NEED the gas in double 130's at this point. And they are brutally heavy -- even my beloved dive buddy, who can lie down in the grass in his double 130s and get back up, or carry MY doubles while wearing his, has realized that he's a lot more comfortable in double 72s. Even if you CAN carry them, you will eventually find that there are days when you just don't WANT to

In addition, there is the issue of double 130s and a wetsuit . . . which is real. You definitely need redundant buoyancy (drysuit, lift bag, or, although I don't like the option, a double wing).

You should have plenty of gas in double 100s to do two typical recreational dives, even with appropriate rock bottom reserves.

I like double 100s, and wish I had a set (I steal my husband's from time to time).

 

[cwkline]

Chris,
Have you checked with your shop to see if you can rent or borrow? You might want to ask about it at the shops. I started with twin 72's, and still dive them. They make a really nice set of doubles. Used to be a guy that dove Bainbridge with a trailer full of doubles. I can't recall his name, but folks there know him. You could join this club Maryland Hydronauts Scuba Club They can be a very helpful group. Just a couple of options
Safe Dives
Charlie

 

[Colliam7]

The type of diving I like to do the most are the dives off of NC.

Of course, that is the ONLY place to dive. OK, OK, just kidding all you NE, NW, Pacific Coast, etc divers. We just have some great wrecks off the coast. Most of the recreational wrecks are in the 115' or shallower range, except for a couple of really enjoyable dives at 135-140' - the Tarpon and the Naeco, for example.

Diving my 130's in the NC profiles I mention above, I tend to get back on the boat with 1100-1200psi, so clearly I carrying too much air.

No such thing as too much air! Seriously. Diving a 130 and surfacing with 1200psi is a good thing.

Ideally I'd be able to 2x up my 100's and get two NC dives on them and a bit of reserve, but I think it would be cutting it close on that 2nd dive.

You might be. I also dive some double 120s off the NC coast and, if I push them to my NDLs, I can still get two dives. But, if you are diving with folks working with an AL80, for example, you should still get two comfortable recreational dives.

I'd love to get to the deeper diving, but fiscally that isn't going to happen any time soon.

Then I wouldn't worry about doubling the 130s.

I guess I could still dive with the slung pony, but them I'm getting back to one more thing I have to strap on.

It probably seems that way. But, a slung 40 is almost not noticeable, yet it adds a nice element of reassurance.

 

[rongoodman]

Another thing you could do would be to double up the 100s and take along a 130 and a fill whip to top off the doubles between dives.