?'s on Tanks/ use

[smithrjd]

I have picked up several used tanks recentley, all at very good prices. Now wondering just what will be usefull. 2 Steel 72's old and really old but in hydro and current VIS. Was thinking perhaps a double but one tank is 3/4" (84 date) other is 1/2" tapered (55 date) The 1955 tank has what looks like a new Sherwood 5000PSI K valve installed. Didn't know they made such a valve.. Along with the 55 steel 72 got a Catalina Aluminum 63 that needed VIS. Both for $20. Wondering is there such a thing as a Al 63double? Weight and bouyancy would seem to be about as good as double steel 72's, been reading alot in the archives, but have never seen this setup discussed. Perhaps a trim issue? Would one of the other steel 72's be worth a trade to someone to get matching valve necks? Also picked up a Catalina S80 for $20 but needs hydro and VIS. Getting my son setup for more advanced diving, he is already AOW and will be diving alot at college. Asking for more BT than a single AL 80. Daddy has some money but do not want to break the bank.

Ron

 

[halocline]

I have a set of LP72 doubles and I couldn't be happier with the way they trim and are manageable in general. Double AL63s is probably not a great idea, they're pretty short, wide tanks for doubles, and the buoyancy would not be anything like LP72s. AL63s are over 2lbs positive empty, so that's 4-5 lbs you need wear to sink a set of doubles. (minus manifold, bands, and regs) The LP72s are narrower, longer, and neutral empty.

I'd look for another LP72 with a 3/4" valve. I would avoid any LP72 that's not galvanized as well as any that has a coating inside the tank. You could almost certainly find someone in the vintage dive community that would be interested in the older tank as long as it's in good shape.

If it turns out for some reason that the 72 doubles aren't going to work, like if your current LP72 is not galvanized and you rightly don't want to mess with it, you could probably find someone to trade an AL80 catalina for your 63; the bigger tanks are more common and those 63s are great for shallow dives and/or small people. Then you double up the AL80s and that's a pretty popular way to go. You need to wear 8lbs to compensate for the empty buoyancy, but if you're wetsuit diving, especially in warm water, it's not a bad alternative to having really negative steel doubles. This is the nice thing about the LP72s; they're not so negative. LP85s (7" diameter, neutral empty) are also a classic small doubles set up, but now you're talking some money.

 

[smithrjd]

Would like the double steel 72's, might look for a trade etc. Looked in the NAUI Master Diver book at the tank charts, AL 63 .8 positive empty, -3.4 full. Steel 72 3.50 positive empty -2 full. Both of the steel 72's are galvanized. Son is wearing 31#'s with single AL 80, 7mm wetsuit with 7mm jacket for 14mm core. Has a Custom Divers Sport Wing TBK BC, setup for a double rig but works with a single. BC basically empty at rec levelsand single Al 80. I have read alot about no steel doubles with a wetsuit but weighting seems to work for him. BC has 60# lift, diving in cold Northern CA water. Dry suit maybe next, but will need to budget that. Not sure what I will do with the Catalina 63, but for 10 bucks in hydro could not pass it up.

 

[halocline]

I can tell you that my LP 72s are nowhere near 3 lbs positive when empty. Here's a chart for tank buoyancy: (LP 72s are not on it)
Scuba Cylinder Specifications from Tech Diving Limited - 928-855-9400