To go to doubles or not.

[fdog]

This is probably true. In fact, I am one of those divers that started diving doubles "because they look cool." I have no logical, defensable reason to dive doubles. I just wanted them. In the relatively shallow, freshwater environments where I usually dive, they really aren't necessary. But all reason and logic go completely out the window when I see my twin 72s sitting there, mated to my DA Aqua-Master and ready to dive. Does it make any real sense? No, but it's fun!

No, no, this sounds perfectly reasonable... it's all in the name of compliance with "Rule 6", eh?





All the best, James

 

[TSandM]

Having watched people do it both ways, I think there is a lot to be said for getting your skills down in a single tank setup before you switch to doubles. If you have really internalized what being horizontal looks and feels like, it's easier to get back to it when you add the confounding factors of head-heavy double tanks. The people I know who went to doubles before they had buoyancy, trim and position down in single tanks have taken much longer to get things right in the doubles.

Personally, I don't think you have to have a reason to dive doubles. I like them -- in the water -- a lot. They're very stable and are almost like cheating when it comes to buoyancy control. They give you a solid rock bottom reserve for any recreational dive. They don't have to be switched out between dives (although you have to have big enough ones to make the second dive a good one!) and the gas you didn't use on the first dive adds to the reserves you have for the second.

They are not useful if you can't manipulate your valves, and they aren't VERY useful if your buddies don't know how to use doubles or to help you if you have a leak.

They are very heavy and awkward, and many charter boats are not set up for them. You may run into problems securing them, or boats where they put the bottoms of the tanks in wells or troughs that make getting doubles OUT very difficult. (We had to go buy 2 x 4s to fill the wells on the Peace for our DYFO trip last year.) You will also pay a lot more for fills at most shops, since they will consider doubles as two tanks, even if you have only used a few hundred psi out of them. If you are also diving Nitrox, this adds up.

I still dive a single tank for a lot of my recreational diving, just because it makes life easier. I honestly think one of the dubious things about the DIR communities is that a lot of people end up thinking they SHOULD dive doubles when they don't actually need them and would, at least secretly, prefer not to. DIR works just fine in single tanks

 

[ScubaFeenD]

+1

...I see so many people who dive doubles because of the image, not because they need the gas. The divers who do this have all kinds of justifications, too, that ring hollow when you really dig at them. <shrugs> You might consider this part of your first real technical training: a realistic assessment of your equipment needs.


All the best, James

No way would I do it just to look good. I have had them on once and they are way to heavy; I just dont look nearly as suave when I am walking funny.

Having watched people do it both ways, I think there is a lot to be said for getting your skills down in a single tank setup before you switch to doubles. If you have really internalized what being horizontal looks and feels like, it's easier to get back to it when you add the confounding factors of head-heavy double tanks. The people I know who went to doubles before they had buoyancy, trim and position down in single tanks have taken much longer to get things right in the doubles.

Personally, I don't think you have to have a reason to dive doubles. I like them -- in the water -- a lot. They're very stable and are almost like cheating when it comes to buoyancy control. They give you a solid rock bottom reserve for any recreational dive. They don't have to be switched out between dives (although you have to have big enough ones to make the second dive a good one!) and the gas you didn't use on the first dive adds to the reserves you have for the second.

They are not useful if you can't manipulate your valves, and they aren't VERY useful if your buddies don't know how to use doubles or to help you if you have a leak.

They are very heavy and awkward, and many charter boats are not set up for them. You may run into problems securing them, or boats where they put the bottoms of the tanks in wells or troughs that make getting doubles OUT very difficult. (We had to go buy 2 x 4s to fill the wells on the Peace for our DYFO trip last year.) You will also pay a lot more for fills at most shops, since they will consider doubles as two tanks, even if you have only used a few hundred psi out of them. If you are also diving Nitrox, this adds up.

I still dive a single tank for a lot of my recreational diving, just because it makes life easier. I honestly think one of the dubious things about the DIR communities is that a lot of people end up thinking they SHOULD dive doubles when they don't actually need them and would, at least secretly, prefer not to. DIR works just fine in single tanks

I have noticed a heavy dominance in the DIR community. I suppose that is because a lot of people that are doing fundies and such are doing so because they immediately want to go into the tech realm or have been in the tech realm and are trying to get more training.

From all the great, honest advice everyone has given I think I will stay in singles for a while longer and enjoy the learning experience while i perfect my technique.

 

[DennisS]

I started my diving with doubles when I went through a marine tech program. This was back in the 70's so they were basically one large tank with no isolator. We were required to use them during training. When we went recreational diving we would dive singles. The doubles were just clunky and heavy. I rigged up a pair of 80's about a year and a half ago. They're still heavy and clunky, I took them apart and dive mainly with my single 130s

 

[gsk3]

I would then suggest for you to get with a reputable Technical Diving Instructor. They will teach you the right way & help you get into the proper configuration needed for the type of diving you want to do.

This is where it gets funny because I know drdr in person and don't know how much he wants put all over the net, so I'll simply say that he mentioned he had found superlative instructors for his upcoming Intro to Tech and Fundies classes, and he wasn't kidding.

 

[noreastDIVER84]

So I am a relatively new diver, and recently I have been getting involved in communities of highly skilled divers. I am taking a lot of training, and the way to go seems to be doubles tank setups. I have talked to some mentors privately and gotten some great advice, but I want to see what the community on SB thinks about going to doubles. They seem to serve my diving quite well. Since they have larger gas volume I can do two boat dives without needing to change my rig between dives, they will give me greater stability, and in my opinion are easier to quickly set up once everything is just right. They are, however, more dangerous in my mind due to events such as a manifold failure or a "roll off" which i still cant picture in my mind. So, my questions are:

How soon is too soon? I only have 30 dives under my belt, am I missing out on learning necessary skills and comfort if I go to doubles now? If you went to doubles early and could do things over again, would you stay in a single tank for awhile?

Before anyone flames me for going to double without training please realize that I would not go into this setup without comprehensive training in valve drills and practice in controlled environments becoming solid with my skills. Ive learned alot from you all on here, and I look forward to all of your insight.

Thanks!

Hey Tim, I am going ot throw this one out there to you as well. You can do sidemounted independent doubles. That way when you need that much air you can carry two tanks(or more) or if you are doing shallower shorter dives you will need only one.

I know you are taking Fundies with Bob Sherwood, and the sidemount setup does not fly with GUE, but I am throwing it out there as an option.

I am starting to want to do some of the Northeast wrecks and they are deeper than I would feel comfortable having a single tank. I am working now with a single LP112 and a sidemounted AL40. You will probably see me at Dutch sometime soon getting some time in and getting used to the new setup.

Brent

 

[Sas]

I moved to doubles for overhead diving (decompression diving and cave diving). The main purpose was redundancy not greater air source (I have a low SAC and can easily do a long dive at about 40m on a single tank). I would rather switch tanks on a boat dive than take doubles to do two dives personally. Doubles are heavy, less streamlined and they are expensive to set up (my setup cost $3000 AUD for the tanks, bands, manifold, new hoses, spg, two new regs, double BP/W) and that was very cheap).

Overall doubles are not particularly hard to use though and it took me about half an hour to get comfortable in them but I did have a few hundred dives in a single tank first (which helps a lot). You don't need formal training imho, just an experienced friend to show you the ropes.

Personally given your experience level I would recommend borrowing kit off friends and seeing what you like. Some doubles don't suit all people. That's what I did for about a year before I got my own twinset.

Manifold failures are rare, and not hard to deal with as long as you can reach your valves.

Roll off is another issue that is easily avoided by doing flow checks any time you hit your tank on anything or after you go through a restriction. Flow checks are when you check each valve to make sure they are open.

 

[dumpsterDiver]

I recently started diving doubles and the thing that got me right from the start is the weight. Those things are heavy! They're heavy on land and heavy in the water. I dive twin steel 72s and one thing I learned real quick was that I needed to shave 6 to 8 pounds off my weight belt. With a 3mm wetsuit and horsecollar BC, I usually use 14 pounds with a single 72 and 16 pounds with a single eighty. The best weight with my double is about 8 pounds, 10 if I'm diving in a river current. Another thing I quickly learned is that doubles like to turn turtle. All that weight, even underwater, wants to pull you over until you are on your back, gazing at the surface. This might not be a problem with a BP/W setup, but it is a nuisance with my kind of rig. A little while back, I was diving the Ohio River and was on the surface with my horsecollar half inflated for the swim back to the boat. A boat came by and the wake flipped me over, onto my back. Those heavy doubles tried to pull me to the bottom while the BC tried to keep me floating face up. I was like a turtle on its back. All I could do was flail helplessly. My buddy couldn't help me because he was laughing too hard. I finally deflated the BC and sank back down where I could regain control.

I really don't need doubles for the kind of diving I usually do, I just think they're cool coupled to my USD DA Aqua-Master double hose regulator! (Ala Mike Nelson!) I'll eventually master the technique and I might use them when I go for my AOW this fall.

A horse collar and double steel tanks is really a poor choice. As you found out, the bc has all the bouyancy in the front of the diver and a lot of weight is behind them, perfect recipe for turing turtle. "Real" steel tanks, modern ones are much heavier and many are MUCH more negative than the double steel 70's.

 

[Rainer]

I'll make it simple. You have 30 dives. No, you don't need doubles. At all.

Enjoy your diving.

 

[Paladin]

A horse collar and double steel tanks is really a poor choice. As you found out, the bc has all the bouyancy in the front of the diver and a lot of weight is behind them, perfect recipe for turing turtle. "Real" steel tanks, modern ones are much heavier and many are MUCH more negative than the double steel 70's.

It doesn't really matter that much to me. I rarely use the BC, even when I wear it. I got it primarily just to have a BC for the places (like quarries and dive OPs) that require their presence. That and the unlikely event that I might need emergency surface flotation sometime. I don't think I'd like the new steel tanks because they are so negative. I've used steel 72s for decades and they are my preferred tanks. I've got 5 of them and will soon have 3 more.

If I were to decide that I actually want to start using a BC, I would probably pick up a wing.