Doubles, singles and boats

[MXGratefulDiver]

If you need the gas for a dive on something worthy like the Hydro Atlantic or the Andrea Doria or you're doing some cave stuff, use doubles by all means. You'll probably be on trimix anyway. For run-of-the-mill stuff, why bother?

Well, for me, the answer is simple ... because I want to ...

... Bob (Grateful Diver)

 

[Mark Vlahos]

How else would you learn do dive doubles except by diving doubles?

It could be part of the Deco Class, or other class. You do not NEED and instructor, but at least a mentor would be a really good idea. Details like valve drills, someone to make sure you are ready to deal with the considerable added bulk on your back, hose routing, and what to do if there is a problem.

If you are diving in the open ocean and have the wrong gear with doubles you could have lots of trouble getting back to the surface if you don't have enough lift. An instructor can give you the tools so you can safely practice on your own, but without those tools you might have some real problems.

You probably dont NEED instruction to operate a small boat, but there are many threads on this board about idiots using dive flags as pylons and running over divers. Wouldn't it be better if the boating public was well informed about dive flags?

Mark Vlahos

 

[DA Aquamaster]

How else would you learn do dive doubles except by diving doubles?

Exactly.

I love it when doubles divers imply some sort of great mystisim to using doubles. This then means that Joe or Jane Blow, aspiring doubles/tech diver, avoids diving doubles due to the "risk" of diving doubles without proper training. He or she then enrolls in a deco procedures class, advanced nitrox class, extended range class, or (fill in other applicable course here) and then struggles as he or she has to adjust to diving with doubles for the first time and resolve all the configuration, bouyancy and trim issues at the same time he or she is trying to master and demonstrate all the other skills required in the class.

To dive either manifolded or independent doubles you do need to adjust your configuration somewhat to accommodate another regulator, etc and this is a good time to also understand the long hose philosophy. But it is not rocket science and the demands of doubles diving can be managed by the well read and/or well informed and moderately experienced diver without having to take a class on the subject.

If you can find one, a course on gear configuration can be a big help and can get you off to a good start with a minimum of wasted money and effort. Finding a more experienced diver who already uses doubles can also be be a very big help and can speed up the learning process. But when it comes to the in water process of transitioning to doubles there is no substitute for time in the water and diving with doubles is a good way to learn how to dive with doubles.

So read what you can, get advice and supervision from knowledgeable divers in your area if possible, but my advice it to not wait until you get into a class that requires doubles to use them for the first time.

 

[mossym]

Exactly.

I love it when doubles divers imply some sort of great mystisim to using doubles. This then means that Joe or Jane Blow, aspiring doubles/tech diver, avoids diving doubles due to the "risk" of diving doubles without proper training. He or she then enrolls in a deco procedures class, advanced nitrox class, extended range class, or (fill in other applicable course here) and then struggles as he or she has to adjust to diving with doubles for the first time and resolve all the configuration, bouyancy and trim issues at the same time he or she is trying to master and demonstrate all the other skills required in the class.

To dive either manifolded or independent doubles you do need to adjust your configuration somewhat to accommodate another regulator, etc and this is a good time to also understand the long hose philosophy. But it is not rocket science and the demands of doubles diving can be managed by the well read and/or well informed and moderately experienced diver without having to take a class on the subject.

If you can find one, a course on gear configuration can be a big help and can get you off to a good start with a minimum of wasted money and effort. Finding a more experienced diver who already uses doubles can also be be a very big help and can speed up the learning process. But when it comes to the in water process of transitioning to doubles there is no substitute for time in the water and diving with doubles is a good way to learn how to dive with doubles.

So read what you can, get advice and supervision from knowledgeable divers in your area if possible, but my advice it to not wait until you get into a class that requires doubles to use them for the first time.

thanks for that, that's been my thinking all along, and the direction i'm headed...get in doubles soon, get used to them, then take deco classes..

 

[Jason B]

I agree with StSomewhere and DA Aquamaster, a cave class or deco class is not the time to be working out the issues of diving doubles. If you plan on taking a class requiring doubles, go ahead and start diving them way before hand. When I was taking my cavern course this past winter there was a class of students taking cavern through full cave in 7 days, on top of that they were just learning to dive doubles in this 7 day class. I don't get this mind set...

 

[Leadking]

I don't really need (or want) doubles. Just trying to think ahead should the need arise. The only reason I may want to have doubles is for the redundency. I just recently started carrying a slung pony (bailout bottle). Aside from needing them, having doubles keeps the rig all together, ie no other tanks to carry on the boat, could be rigged the night before, won't roll around my truck....and so on.

Based upon your diving profie, I would stay away from doubles. Why would you want to dive with the extra weight and bulk. When you are going to do more advanced (deeper) diving and need the extra capacity then go doubles. I cut my teeth diving at Isle Royale 30 years ago and we (my dive club) never bothered with doubles unless it was 150' or greater and that still holds true today. And this was in the days when it was 72's or 80's.

p.s. You'll still find me at Isle Royale most weekends in the summer-it never gets old.

 

[oversea]

I don't necesarily believe the is a mysticism to diving doubles. A close friend (who dive them) basically tells me "baby steps". No reason to jump into them, just keep diving. I agree, but at some point I will be doing advanced nitrox and some of the wrecks up here in the NE go deeper than the 110' I started this thread with. I agree with having a need for the doubles and that is why at this time I will be with singles. As far as doubles, I figured I'd start asking questions and doing some research so if and when the time comes, I'll be ready.
Thanks for the info,
BTW, I would love to try a set on my next beach dive to get a feel for em though.

 

[matt_unique]

I will soon be diving with single 119's. Eventually I had thought about doubles. Maybe doubling up the 119's. Having never dove anything larger than an 80, would doubling these typically be good for (2) dives at a max depth of 110' or would that typically be running short on gas? I would assume based upon gas consumption with an 80, the doubled 119's should work. I realize my sac rate and physical condition and physical stress affects this, so it is just a ball park. Oh, and the main point for me is "do I need to have two sets of doubles" or will one set work for diving within NDL?

It boils down to your SAC rate for a given dive. There are people with a better SAC rate than I for sure but I can do 3 dives on one fill of my alum 80 doubles. I did a short deco dive to 150' max (34 minutes total time breathing from a deco bottle for deco portion), a 30 minute non deco dive to 120' max, and a 33 minute lobster dive to 80' max on one fill of my alum 80 doubles weekend before last. I surfaced with 300psi at the end of this third dive. The profile of this last dive was such that I was OK with surfacing with that amount of gas. There are dives when I would be surfacing with a lot more gas of course.

The point is you can do a lot of diving with 154 CF of gas assuming a 3000psi fill on a double 80's rig. You could very likely do 2 non deco dives to 110' with double 80's. I would explore the weight of rigged 119's compared to other tanks. My double 80's rig weighs 96 lbs full (tanks/bands/manifold/tank boots). I already owned two alum 80's when I began diving doubles so it was a no brainer for me to band em up and start there. I suspect at some point I will buy double steel 100's but the 80's will do a lot for you.

--Matt

 

[Tom Winters]

BTW, I would love to try a set on my next beach dive to get a feel for em though.

Wearing doubles on a beach dive going in is ok - but when you come out of the water and start the hike back up the beach, you're going to be having some severely unkind thoughts about the twin aircraft carriers on your back.

 

[Tom Winters]

How else would you learn do dive doubles except by diving doubles?

I'm not so sure about a learning curve diving doubles so much as a conditioning curve. There are some hose routing considerations and some equipment adjustments, but wearing your rig in the backyard for a few months would be one good way to get used to doubles. They are heavy - each of my 121's max-gassed out weighs 58 pounds, and coming out of the water on a ladder or hiking out from a cave site puts an unreal strain on your body, especially your back. The twin 130's are a good load too - I had friends who couldn't load their trucks with the filled tanks or swing them safely abouard a boat, so I got to do it for them.
I'm not sure about twin aluminum 80's at all - yeah, there's that redundancy stuff...two regulators and all that, but I can get 166 cubic feet of gas in a single 121 so my aluminum 80's are going on the block. Way easier to dive.
I realize this opens up the door to "Beaten to Death" topics of isolation manifolds, H-valves on singles, and a whole slew of topics that I can live without seeing any further rehashing.
I still don't see the whole point of HP steel tanks - the 119's twinned hold just a touch more gas than twinned LP 85's at 3,600psi.
It all boils down to personal preference though, so feel free to rig out the way you want to. Just have fun and watch the back.