Poor Man's Doubles ???

[Mako Mark]

There is a lot to be said about sidemount. It was first developed for caves that were too tight for backmounted doubles, but they have over the last few years become accepted as a rig that allows for a tremendous flexibility of gas management, with the added advantage of not haiving to lug doubles around.

Do a search for Curt Bowen and the Armadillo sidemount rig if you want to know more.

IMHO tho, sidemount is something you should only approach when you are thouroughly familliar with multiple aspects of technical diving, not just a simple solution for rec divers taking more air. If that is you, I suggest a bigger tank.

 

[FishDiver]

There is a lot to be said about sidemount. It was first developed for caves that were too tight for backmounted doubles, but they have over the last few years become accepted as a rig that allows for a tremendous flexibility of gas management, with the added advantage of not haiving to lug doubles around.

Do a search for Curt Bowen and the Armadillo sidemount rig if you want to know more.

IMHO tho, sidemount is something you should only approach when you are thouroughly familliar with multiple aspects of technical diving, not just a simple solution for rec divers taking more air. If that is you, I suggest a bigger tank.

Thanks for the insights, and I will do the search. BTW, the goal is a redundant gas source for occasional solo dives not just extended BT.

 

[paulwlee]

Judging from the class you took, looks like you are talking about no decompression dives in the 100ft~130ft range when you say 'deep'.

If that's the case, doubles are overkill, although nice if you already have a set.
All you need is a gas supply that will get you to the surface safely, and for that, anything more than a 19cf pony bottle would get the job done.
You can mount it on the tank, sling it stage style, or whatever else you like.

If slinging stage style, you can use the 19cf, 30cf, or 40cf bottles, and the bigger the bottle, you have more gas for additional margin for error, but it also gets heavier and larger. This mostly concerns carrying it around out of the water, as once you get underwater they don't really differ that much. Either you have a stage, or you don't.

Before I started diving with doubles I used to dive with a 19cf bottle for >100ft dives, as it's a nice point where the weight/size is significantly less than the 30cf bottle, but it's still enough gas for a couple minutes to solve the problem, nice slow ascent, safety stop and a little bit of reserve.

For people used to diving doubles, even a 40cf stage feels like nothing out of the water, but I still remember a time when I dived single tank, so my recommendation is to rig a 19cf bottle stage style and sling it, and be happy that you were smart and decided that you didn't need to haul around 20~30 extra pounds.

IMHO bringing a 80cf stage bottle on every dive to 100ft is like carrying 15 gallons of reserve gasoline in a separate container in your car trunk just to go to the supermarket.
Now if you already had it in the car for a 20 hour drive across the Sahara, then sure, leave it in the car, but if you had to buy the gas can to do it?

 

[Mr.X]

I hate to quote myself, but I am NOT looking for a permanent solution for deep dives. I do not plan on getting a twin set now or in the future. I estimate that I would use the single/stage setup for perhaps 10% of my diving.

I undestand this setup is not optimal. My question was, Is there anything wrong with this setup for the applications I outlined?

If you look under "Monkey Doubles" you'll see a link to a pic (not a terrific one) of me using a single 80 as back gas with an 80's bailout. It was the only combination I had on a remote island in California. If I had known this was the only tank available I would have shipped in a Luxfer 30, or 40. 80's works...but there are far better combinations. As a techie I was used to wearing multiple 80's which is why it worked. For those unaccustomed to big bottles it can be all a bit too much. X

 

[John_B]

I like what this guy has to say:

http://www.njscuba.net/gear/eqpt_05_tanks.html#tanks

That idea you MUST have banded fixed doubles or you are unclean smacks or religion and not logic to me.

The same guy also says this:

"The only allowed DIR setup is double steel tanks with permanent stainless-steel bands and isolation manifold. There are other details, and some variance is allowed in tank size to suit the individual diver, but otherwise, it is implicitly assumed that this setup will cover all situations. It does not."

 

[Vicente]

Forgive me, John_B, but what part of that exactly are you calling BS on? Just wanta hear some more about what you think, than a simple emoticon-flag graphic.

 

[John_B]

Forgive me, John_B, but what part of that exactly are you calling BS on? Just wanta hear some more about what you think, than a simple emoticon-flag graphic.

Saying that DIR *requires* doubles (steel or otherwise) is BS. Hence the BS flag.

John

 

[ArcticDiver]

Today I completed the last dive of my Deep Diver Speciality class. In previous dives, I used an independent twin set with one SPG and reg per tank. I learned to breathe both tanks down evenly so in the event of equipment failure I would have enough gas to ascend. This was shop gear, I have a standard rec setup.

Today the instructor decided to minimise the task loading for my last dive by having me dive using my own gear. I have a Zeagle Stilleto and Zeagle regs; two secondaries. The instructor wore a twin set and carried a 80 cf stage bottle as backup for me. He claimed the stage tank was barely noticable in the water.

I own all of my own gear including two 80 cf tanks. I don't plan on diving deep or solo often and don't want to spend the money to reconfigure my setup for these types of dives. I am considering buying an extra set of regs with SPG and using my second tank as a stage/de facto twin set when diving solo.

I plan to use the setup the way I was taught to use independent twins and breathe both tanks down evenly. Both tanks are the same size and I would not let either tank get below the volume of gas needed to make a safe ascent.

Have I overlooked anything, or is this a sensible rig for the applications I have in mind?

You have posted that you are used to diving doubles, you have most of the gear to do it and your instructor has encouraged you in that direction.

Therefore the most reasonable way to go is to get a bit more instruction until you are comfortable with your proposed rig. Then instead of carrying a Primary Tank and a Small Pony you have Two Primary Tanks. For a typical tourist dive set where the first is to 100-130 and the second is shallow you have a good backup for the first and adequate remaining gas for the second.

Plus, you don't have the hassle of taking a pony with you on the airplane.

Later when you actually figure out what kind of diving you will be doing you might want to buy some steel tanks. But that is later.

You are the guy in charge. Do What Works for you. Crosscheck with the instructor you have faith in.

Have Fun.

 

[Vicente]

Saying that DIR *requires* doubles (steel or otherwise) is BS. Hence the BS flag.

I believe the point was not that DIR requires doubles on all dives. It is that in the DIR dogma, the only valid configuration for doubles is steel bands and a manifold. If there is some other doubles DIR configuration, let me know. I have read much and dive with many DIR people, and use many of the ideas myself. But it seems to be all-or-nothing on certain things.

 

[Tek Adventure Diver]

Judging from the class you took, looks like you are talking about no decompression dives in the 100ft~130ft range when you say 'deep'.

If that's the case, doubles are overkill

How can you say doubles are overkill, if you have dove with doubles then you should know that they are never overkill. Its better then bring 2 al. 80 and a pony or 2. Then having to switch regs and BC after every dive. Doubles are usally always set up and depending on the size of the tank. ( I can easly get 3 dives out of my LP 95) Dont put down the doubles. Doubles are the best. Even when i go do a shallow reef dive, i will bring along a set of travel bands so that i can have doubles. Plus doubles have reduncey.