When to choose a lower capacity tank

[ptyx]

What am I missing that prevents people from spending the extra $50-100 when purchasing tanks and just going with 130's all the time?

One thing:

 

[meagicano]

I'm a 5'7" female and I dive with HP 120's - a lot of the men I dive with use the 130's. Yes, the 120s are heavy and a bit annoying to carry around, but we do a lot of hour+ drift dives in the St Lawrence at recreational depths (actually our max is generally around 50ft for the cool stuff) and I like coming up with enough to get me (and a buddy) back to shore if necessary. Popping up in the river is never a good idea.

When we do the shorter/easy dives I find that I can often make two dives without changing the tank - we have a wreck that's close to shore with a max depth of around 25 ft (perfect for introducing rookie divers to the current) and the 120 is serious overkill. I came up last week with about 1400 psi left after two dives and total bottom time in excess of an hour.

 

[BioLogic]

I imagine in some places it's no issue; but I know that around here most shops have fill systems that won't take you much over 3000 psi ... so HPs are not as useful as they look.

I'll dive either 80s or 63s depending on the dive plan. If we've got an overhead, I use bigger tanks to get my buddy back; but if we can ascend right to the surface (so he wouldn't need to share for long) and I know the dive's going to be limited to an hour (boat rules in some places), I'd prefer a 63. I'm not a big woman, and my buddy is a big guy. Us carrying the same gas would be a waste of effort, handling the bigger tanks increases my risk of injury, and a car full of steel 120s is both hard to pack and hard on the suspension.

Right tool for the right job is best. If you're only going to buy one tool though, yeah, I'd look for the big boy.

 

[kanonfodr]

It depends. Most of my diving is shallow tropical reefs and I can go past an hour on AL80s, LP85s, LP95s, whatever. Lately I have been using the 85s and really liking them: light, trim well, plenty of gas for even deeper air dives (<100 ft) while maintaining a comfortable reserve. I love my LP95s, but the weight difference is substantial and for any dive involving a hike, the extra gas I get may not be worth the hassle of carrying the extra weight (lazy diver).

What I would ultimately suggest is trying as many different tanks as possible and see which tanks work the best for you in regards to trim, bouyancy shift, and gas capacity. Also, see what local divers are mostly using in your area, they may be preferred for some good reasons.

Peace,
Greg

 

[noreastDIVER84]

I am using LP112's and am going to be using them as independent doubles in the near future, but I am finding that compared to an Aluminum 80, I get either one lone dive, or about 4 shorted dives off the 112's. That said my 112's are usually filled to around 2800 after they have cooled. I have had the tanks filled more on a few occasions but would not depend on a single tank and regulator setup for a deep dive.(I sling an Al40 as backup gas)

 

[spectrum]

What am I missing that prevents people from spending the extra $50-100 when purchasing tanks and just going with 130's all the time? I know in many cases it's overkill (shallow reef dives) for my purposes, but if you're going to go with one tank, why not get something good in all scenarios?

Thanks in advance!

Based on your one cylinder viewpoint you make a reasonable point of making it a significant cylinder.

When cylinder shopping there can be a considerable swing between sizes. I know when I got my 4 HP80's by PST they were commonly retailed for $205 while the 100's fetched $349. That's a real difference. Since the crowd I was (am) diving with is largely using 80 and 72 CF cylinders and I have good air usage lugging a bigger cylinder had no upside.

As used cylinders came around I rounded out the collection with 72 and 100 CF steels. The smaller cylinders are all I may need for some dives either solo or when I understand my buddy's air supply well enough. The 100's are fun for longer dives and my wife (a power breather) is usually using those.

Since my local diving is almost exclusively shore diving using a smaller cylinder is noticeably nicer getting to and from the water.

While we don't dive at a high velocity the lesser mass and often smaller diameter do reduce inertia and resistance.

While I dive mainly steel I do have a few AL80's for mild freshwater dives where the steels alone have me over weighted.

Those are some reasons for cylinder diversity.

Pete

 

[Van Isle]

As has been mentioned HP 130's are heavier to man handle around, at the dive shop and the site, than HP 100's. The extra gas may or may not be needed. When doubled up (if you ever go there) they are very heavy and offer LOTS of gas. Doubled 100's (or even alu 80's) offer enough gas for most tech 1 level dives so 130's aren't even needed there.

Some things you may think about are boat dives vs shore dives, availability of HP fills, how hard the shore hikes are, what your buddies are diving, and what else you could spend that money on.

I've gone with doubled HP 100s and they are perfect for me. Lots of gas for 2 long, cold water recreational dives. Lots of gas for tech 1 dives in the future. Relatively easy to slog around on shore and in the water. Not so heavy that I pass on dives because I don't want to do the hike, or that I want a single set up in addition to the twins. With double 130's (or single 130's even!) I could imagine this to be the case.

I have certainly done dives where I wished all I had was a slung alu40 and nothing else.

Good luck!

VI

 

[Jrock1062]

I own steel 80's 100's and 119' different dives different tanks IMHO I would start with the 100's again IMO best all around single tank and a great doubles tank

 

[elmer fudd]

I own 4 HP119's and 2 LP72's. IMO, more air is always better. I don't usually need all the air in my 119's, but it doesn't hurt to come back in with 1800 psi. My 72's on the other hand just don't last me as long as I'd like.

 

[halocline]

I like using smaller tanks for my local diving, but most of that is very shallow. The less weight I have to lug around, the better. I use 72s mostly; 26 lbs empty weight, tough to beat that.

To the OP, you should evaluate what kind of diving you primarily want to do, then buy cylinders that best serve that. As you get more experience, it's likely you'll end up owning tanks of different sizes.