What size doubles?

[xiSkiGuy]

"Then, there's also the issue of steels in the ocean without a drysuit. But, I won't go there.."

Please expand. I am using single steel 120's with a wet suit now.

This gets brought up once every two weeks. Here's a recent thread: http://www.scubaboard.com/forums/ba...diving-steel-tank-wetsuit-dangerous-idea.html

The readers digest version: single steels and a wetsuit are fine. Double steel tanks are probably negative enough you will need the redundant lift of a drysuit in case of a wing failure.

Heres the deal. I want to get full cave certified, but I don't want to go down there and take my certification using doubles for the first time.

Yeah, that wouldn't work real well.

I am real surprised to learn that there is not a magic set, or something that works for the majority. Like, I am x ft tall and wear a wet suit and want to do this...so get that,

You know what they say about opinions. . .

 

[cool_hardware52]

"Then, there's also the issue of steels in the ocean without a drysuit. But, I won't go there.."

Please expand. I am using single steel 120's with a wet suit now.

Heres the deal. I want to get full cave certified, but I don't want to go down there and take my certification using doubles for the first time. I also want to get advanced nitrox and advanced wreck training. I would like to have a dry suit, but I would also rather go on a few dive trips this year too, so a wet suit 5/7 is all I can muster for exposure suits for the forseeable near future. I wish I could buy all the gear AND go an all the trips, but I have to do half and half for a while.

Thanks for all the great info...lots of good points....lots of things to think about....and yes, my dive instructor recommended the multiple route as well.....so there goes another dive trip I could have taken.

I am real surprised to learn that there is not a magic set, or something that works for the majority. Like, I am x ft tall and wear a wet suit and want to do this...so get that,

or I am x feet tall and wear a dry suit and want to do this, so get that...it just seems odd that I have to try out everyone in the store to get what I need. Then theres the Wing it's self. Would'nt different twins perform differently using different wings? IMO, yes they would. So, now I have to try out 4-5 sets of doubles with 4-5 sets of wings...oh yeah, and don't forget your exposure suit, wet and dry.......Ughh....

Well, maybe this time next year I will have it figured out.

The admonition against steel doubles in a wetsuit in the ocean is based on the impacts of a buoyancy failure. Steel doubles, in particular steels that are quite negative, PST 104 for example, will leave the diver with no ditchable weight. With a drysuit for redundant buoyancy you have another means to returning the surface in a controlled manner.

Al80's are about +4 each vs ~4 each for 104's and as such will typically require the dive add ballast. If this ballast is ditchable then a diver in a wetsuit that suffers a wing failure can drop weight.

Doubles, and all the associated equipment is expensive, no way around that.

What I suggest to the diver considering doubles is first determine what you will be using for an exposure suit and tanks.

Once this is a "known" you can determine how much lift you will need. That alone will reduce the number of possible wings to just a few.

Now take a look at whether or not you will need a substantial weight belt, and also take a look at the length of the tanks. This provides a clue about what wing shape will be helpful. Short tanks, 95's 119's etc. and no weight belt usually means head heavy.

Longer tanks and a weight belt, for example al80's often works pretty well, long tanks, smaller person and weight belt can be butt heavy.

There's still a bit of guess work, but it's not as unpredictable as it seems to you right now.

Good luck,

Tobin

 

[fweber]

"Then, there's also the issue of steels in the ocean without a drysuit. But, I won't go there.."

Please expand. I am using single steel 120's with a wet suit now.

I am real surprised to learn that there is not a magic set, or something that works for the majority. Like, I am x ft tall and wear a wet suit and want to do this...so get that,

or I am x feet tall and wear a dry suit and want to do this, so get that...it just seems odd that I have to try out everyone in the store to get what I need. Then theres the Wing it's self. Would'nt different twins perform differently using different wings? IMO, yes they would. So, now I have to try out 4-5 sets of doubles with 4-5 sets of wings...oh yeah, and don't forget your exposure suit, wet and dry.......Ughh....

Well, maybe this time next year I will have it figured out.

Diving double steels wet= Some steel tank combinations can result in being extremely negative. A drysuit can help offset this negativity. A wetsuit that compresses at depth can magnify the issue. If going into deco(a soft overhead) some form of redundant bouyancy is generally required. A drysuit is consider to fulfill this requirement. A wetsuit needs to be dived with either a dual bladder wing, 2 wings, or a combination of a wing and some other lift device like a large smb or small lift bag. There are many threads on these optioin both here and on thedecostop. Use the search function and enjoy the reading.

There is no magic setup because people are all so different and so can be their goals or requirements. Some people are bouyant, others sink like a stone. Some people are comfortable diving to 130' on a cylinder of air, others need doubles with some helium to feel safe below 100'. Your set up is going to possibly be unique to your needs. Even within a regiment approach like DIR, there are going to be areas that you have to sort through. Like the lift distribution of different wings and finding the one that works for you, as you pointed out.

If you have it "all sorted" by this time next year, you are doing extremely well and ahead of many folks who take that long or longer to reach the point they feel "sorted" with all aspects of their tech rig. Try to find an excellent mentor, they should be able to help shorten the learning curve.

Patience, and a lot of reading, will both be very useful to you. Start with the archives here and at thedecostop, use the search functions. You'll learn tons.

Good Luck,

 

[Mr. Bubble]

Would'nt the dual bladder wing eliminate that problem?

 

[fweber]

A whole 'nother discussion for a different thread in a different forum. But, a discussiobn that's been had many times before. So, please, use the search feature. You can read the several archived threads that go over the various sides, again, and again, and again, ..............

again................

and again...................

did I say again?..............

or again?..........

 

[Rainer]

Even a modicum amount of searching yourself would help answer a lot of your questions. Seriously.

 

[nereas]

Would'nt the dual bladder wing eliminate that problem?

Yet another can of worms opened ... .

 

[Mr. Bubble]

Thanks for the great advice........I did'nt realise this was a MOC (mighty old conversation) issue!


Mr. B

 

[Eris Lucan7*]

L for Large.Not bigger....

E.L.7*

 

[b1gcountry]

How tall are you? As TS&M alluded to, some people find that certain size tanks work well for them and some don't. I'm 6'2 and I find LP95s and X7-100s to be too short to trim out well. X8-130s work pretty well for me. AL80s and LP85s are the easiest I've tried. I haven't tried X7-80s or LP120s but I imagine they would be too short and too tall respectively. If possible, try some different tanks before you buy.

SkiGuy-
I thought the X8-130s were the same height as the X7-100s? with just about the same buoyancy empty?

Tom

PS, I'm 6'6" and dive the X7-100. Diving dry, I trim fine. Diving wet, it depends what depth I'm at.