Should I go for dual tanks?

[halocline]

I know a lot of people have asked this question before, but I would just like some advice on the subject of dual tanks. I am a Master Scuba diver, with over 100 dives on my belt. And I have lately been looking into getting a dual set up. Some of the reasons that I am concerned is just the weight factor, and the actual expense. I am 5'8 and 130lbs. I dive a dry suit with 24lbs and a steel 100. Most of my dives are 40-60 min and a range of 1300-1600psi left over. I was wondering if it would be beneficial at all to purchase a dual set, or to stick with my singe.

As many of the responses have indicated, it depends on what you mean by "beneficial." I recently got into doubles solely for the reason of preparing for cavern/cave training, kind of what DA aquamaster and TS&M were mentioning. There is no doubt that doubles act differently in the water, and if you eventually see yourself diving in situations that require them, you might as well start getting used to them. OTOH, it's pretty clear from what you said that you don't need more gas for what you're currently doing. Why are you coming up with almost half a tank now? If it's your buddy, NDL, or being cold, obviously doubles won't address those issues.

As far as the expense goes, I have a feeling I went about as cheap as you can possibly go and I still spent about $550 for two used LP72s, hydro etc, bands, manifold, and a doubles wing. I already had the extra reg and a backplate. About the only way to get into doubles for any less than that is to find a complete set used at a very low price locally. Where you live that might be realistic, here in San Antonio it is not.

 

[b1gcountry]

BTW, I consider diving stages to be something that is even more complicated than diving doubles. Having two gas supplies that have to be managed separately, and which make donating a little harder calls for some serious mentoring, IMO.

A lot of folks can't manage one gas supply, let alone two.

Tom

 

[rstofer]

So, you are carrying more than enough air but, apparently, you are running out of time. Photographers tend to do that.

Have you considered switching to Nitrox? The NDL for air at 60' is 55 minutes. For EAN36 (36% oxygen), the NDL is 115 minutes! The NDL for EAN32 is 90 minutes. Not only are the NDLs MUCH longer, the SITs are much shorter. Actually, in terms of the change in pressure groups, the SITs are identical. It's just that the Adjusted NDL is longer so you have the choice of not SITting as long before starting the next dive.

There are limits to the benefit of Nitrox and it is most applicable to the 60-80 feet range. But with EAN32 the 100' NDL is 30 minutes versus 20 minutes for air.

There is no way my tired old back can handle doubles. The HP 100 is about the limit.

Richard

 

[NorthWoodsDiver]

The expense wont make it worth the few extra minutes all by its self. They are a PITA to haul around but in the water they are much more comfortable and the redundancy is nice.

If you think you might be transitioning into cave diving or other forms of overhead diving then I would say its a good idea but if you intend to stick with basic shallow open water air dives its not worth it.

A good option may be to make a set of double 45's or 50's, then you get the redundancy and still spend a bunch of money on gear ;-)

If you get big doubles like 130's you might need a forklift to move them around but you'll get 2 or 3 dives on a set per fill or 2 long dives if you fill with 30-40% Eanx.

Anyway, I would say stick with what you have unless "technical" stuff is in your future.

 

[tabhbo50]

I want to know why you think you need more AIR..not a mixed gas.. AIR. why not a 100 cube..for your Height and weight why isn't that enough??? You have a 100 dives.. gee that isn't many lets do the math..4 open water check out dives, advanced open water is, deep dive, search and recovery night dive. Rescue is about 4 to 5 Dive master is about 8 to 10 I really hope you have a rescue certification.. all divers should unless you dive 2 times a year Where have you done most of your diving. how deep do you go.. and where is the closest chamber.. remember the more air you have the more likly you stay longer and risk getting the bends

 

[WD8CDH]

"Air capacity" and "singles vs. doubles" are two entirely separate issues if you consider small doubles. I dive double 40s most of the time for redundancy, lack of bulk and trim.

 

[Citycat]

"Dive master is about 8 to 10 I really hope you have a rescue certification.. all divers should unless you dive 2 times a year Where have you done most of your diving. how deep do you go.. and where is the closest chamber.."

I'm not a dive master, I'm not even old enough to get that certification. I just turned 16, and have been certified just over a year ago. I have now over 200 dives in with at least 180 of them in the cold Puget Sound. I tend to dive to a max of 90 feet on most of my dives because most of the creatures I tend to photograph are in shallower water. Though I didn't mention this before, I've been planning to become either a biological oceanographer, or a human body search and recovery diver with the police department. Which is another reason why I've looked doubles. The reason why i said AIR is because I did not have my nitrox certification at that time, and I am not allowed to take the heliox/trimix course until i'm 18. There are at least 3 chambers close by from what I know, one at the naval base which is not usually open to emergencies if they have navy divers out practicing. St. Joe's in Tacoma where I live/dive. And Virgina Mason in Seattle

 

[WD8CDH]

<snip>
A good option may be to make a set of double 45's or 50's, then you get the redundancy and still spend a bunch of money on gear ;-)
<snip>.

And they look sooooo cooool.:cool2:

Seriously, though, small doubles do handle better than a large single. When I did search and rescue, I felt the lower profile was safer. For longer dives, I would add a third tank that was not manifolded. Having the third tank independent made following the rule of thirds very easy. Even with three skinny tanks, the rig was less bulky than normal doubles.

 

[Thunder Bay Minnow]

Just picked up a set of double 3AL 14's this weekend.

Bought them for more of a novelty I guess.

But why would someone want a set of double 14's with custom made bands? Nice work though.

Jeff

 

[DivePartner1]

I'm with TS. For diving off the Delaware coast I find that steel HP100s give me that extra margin of comfort/safty over AL80s. They're also easier to deal with on a boat than doubles -- especially where there is a possibility of rough exits in rising seas. They balance very well in the water and allow you to shed some lead; but they are slightly smaller and lighter than AL80s out of water.

To mimic someone else's comment, you'll tend to outlast those diving with 80s. My only qualm is emergency redundancy but that issue is addressed by a responsable buddy.