Right tanks for first doubles?

[CuriousRambler]

I'm well aware the question's been asked hundreds, if not thousands of times...I'm pretty sure I've even edged at asking myself in this same forum in the past. As much as I hate to be "that guy" - the only web access I have for the next seven months is far too frustratingly slow to fumble with the search engine. So sorry for posting the same question, yet again. Now here's my dilemma:

Just got dropped off in Iraq again, about the only place the US Government feels inclined to pay any decent amount. Between earning more, and having nowhere to spend it - I'm feeling like setting up a nice set of doubles might be a good investment.

I'm diving mainly in Southern California for the next couple years, then who knows...Likely far from anywhere I'm going to find a shop willing to cave fill LP tanks. That may or may not be an issue for me, depending.

I've considered the benefits of pairing up som AL80's, and thought it's tempting, I'd like to take advantage of my current financial benefits to tackle a hurdle that I can see being an issue for me at least for a few years after I get out of the military and I'm in school. I figure it will be much easier to find a cheap used Al80, or even rent one and throw stage rigging on it, than it will be to get my hands on steel doubles.

I'd like tanks large enough to get me through Tech1, possibly Cave1, depending if I find myself anywhere near caves. I would assume anything large enough to get me through tech or cave 1 would get me almost, if not all the way through full certification in either discipline? I'm obviously a far cry from even intro to tech, but again - the finances work out a little too well to refuse, so getting some practice with doubles in between now and whenever I decide it's time doesn't discourage me any at all

I'm 6'1, about 180-190, and hope to be diving dry before long after returning home. I'm hoping to avoid picking up tanks that are going to be impossible for me to trim out properly, something that's going to have enough capacity to meet tech-1 level dives, and hopefully that will also offer enough capacity to make two shallow, rec-profile dives as well.

I've got money available, but that doesn't mean that it's not an issue for me - steel tanks aren't cheap, and I am...So money is most definitely a huge deciding factor, but I also understand I'm not going to be setting up a set of steel twins for "cheap".

Where would those of you more experienced than I am suggest I start and how far to explore between tank sizes and pressures? I was considering HP80's or LP108's, but since I'm new to doubles I'm really not sure how either of those would compare in useful volume to a pair of al80's - which I seem to remember someone here helped me decide were *just* barely enough to satisfy what I was after.

If any more information would help guide me, by all means please ask, and thank you for any help!

 

[DA Aquamaster]

Douible AL 80's get bashed a lot (mostly by divers who have never dove them) but they are not bad starter doubles. With thirds and a decent SAC rate they will get you 25 minutes at 150 feet and are enough for decent but not great penetration in the average florida cave.

The nice part is the learnign curve with them is shallow as they are not overly negative when full. The downside is you end up carrying weight to keep them under when they are empty.

More good news is that if you go on to larger steel doubles the band s work with any 7.15" diameter tank and the 80's them selves make great stage/deco bottles.

Other LP 95's are always popular, especially in north Florida cave country.

 

[Scared Silly]

Just got dropped off in Iraq again, about the only place the US Government feels inclined to pay any decent amount.

Well given the new admin from the sounds of it you have a job for at least a year before you get dropped somewhere else. Good luck.

I'm feeling like setting up a nice set of doubles might be a good investment.

Good investment - HAHAHAHAHA. That is funny.

Well as usual DA has some good advise. The other thing to consider with AL80 doubles is that if you want to change to another set of double these can be broken down and used as stage/deco bottles. The other is that the 7.25" the bands used on Al 80s are the same size as many of the HP cylinders so they can be reused.

I am using a set of LP85 which are great. Although they may get used as singles as I just found an old set of steel 72s. Which are very similar in size and buoyancy.

 

[CuriousRambler]

Thanks for the advice, but like I said, I've already considered doubling up Al80's and am aware that they can be broken down to be used as stage bottles. However, the big concern for me is that once I'm out of the military and in school, I think it will be MUCH easier to afford an aluminum stage bottle (or even two) than it will be to piece together a high quality set of doubles. Like I said, I may have a little bit of money, but it's still an issue for me - so saving the money by skipping the al doubles and going straight to the steelies is enticing to me. Not to mention I've already got a few Al80's, and sacrificing one or two of them won't bother me at all for stage bottles when I make it that far..

 

[ae3753]

Unless you're in a rush, I'd recommend meeting up with local divers when you get back. You might be able to try a few sets before you make a commitment.

Buying a set of doubles is not really a good investment. Resale isn't spectacular. And if you buy based on internet only advice, there is a fair chance that you'll get something that's not right for you.

Another benefit of meeting with local divers is that tank selection is often localized by conditions, types of dives, available filling options. In MoCal, HP100s and LP85s are popular for Tech1 dives. They are nice short diving tanks and good on a boat as well.

Since you mentioned HP80s, I'd avoid these given your height. We have two sets of double HP80s, and we're pretty much the only people we know who can trim them out. We happen to be the shortest divers in the group we know too.

 

[CuriousRambler]

I'm hoping to meet up with some local divers and try out their rigs, but haven't had much luck in the past, so I'm trying to find a decent starting ground now. Thanks for the heads up on the HP80's, that's one of the reasons I'm here first.

I'm not worried at all about the resale of the tanks, I don't plan on selling them any time soon. I realize there's always a chance of the unknown forcing me to get rid of them, but I'm not too worried about the slight possibility.

There's no huge rush, but I figure if I can get it narrowed down to a few tanks of the same diameter maybe I can start looking for a deal on bands or a manifold to fit that profile while I'm still here, then chisel out the finer points of exactly which cylinders to buy after I try them out or get some first hand advice.

 

[Scared Silly]

If you are going to buy cylinders for doubles note that though the cylinders are "the same" they are not always the same height by as as much as a 1/4". This can be an annoyance for some as they will lean. So if you buy cylinders be sure to check for this and to have it noted with any order. I would not worry about bands until you have cylinders. Or in many case you might find a good deal on a rig already put together.

 

[Captain12Pk]

I think you'll find that 80's ... either steel or aluminum, will be the smallest tanks you'd ever want to consider for technical diving. I have nothing against aluminum 80's, but I think that once you start applying "Rock Bottom" rules, you'll find them to be too small for the deep (beyond 120 fsw) stuff. I'm not sure that you'll find that one set that's perfect for all occasions. I have four sets of doubles in my garage. Kinda like having the right tool for a particular job.

 

[halocline]

For what it's worth I'm putting together a set of "starter" doubles and decided to go with steel 72s, and a manifold and bands from piranha. The bands/manifold (their bands, blue steel 200 bar manifold) was about $225 shipped, and the LP72s were about $50 each shipped. Add to that hydro/vis ($35 each), and the total cost is about $400. That's the main reason I chose LP72s, but the other is that they're pretty close to neutral when empty and not too bad to carry around.

Even though the LP72s are more limiting than most other tanks, this way I can learn to dive with doubles pretty easily and I won't have much more in them than I could get for them used. When/if the time comes to upgrade to bigger tanks, I'll already have the manifold and bands, but more importantly, some experience to help me in picking the right size tank for me.

On piranha's recommendation, I bought 7.25" bands. They swear that the difference in tank spacing is negligible when assembled, maybe about 1/4" further apart at the most than using 7" bands. I'd like to hear some other opinions about that. They did agree to exchange the bands if I wasn't happy with them once I put it together. One thing I know is that the plates on the bands will be closer together, meaning the bolt is likely to stick out further towards the backplate. I'm expecting to have to get shorter bolts. Any thoughts on that?

Sorry for the hi-jack!

 

[Scared Silly]

Matt, what they told is correct. You will need shorter bolts. Personally, I would not put 7.25" bands on 6.9" cylinders. 7.0" maybe. When I recently put together a set of LP66 doubles for my wife though I had a set 6.9" bands I bought some 7.0" bands. The 1/10th of an inch was just enough difference that I would need longer bolts. Given that I have a set of LP85s that are also 7.0" it was nice to have similar hardware for both. Of course now that I have another set that are 72s I can use the bands on them.