al double 80's , pst 104's ?

[MASS-Diver]

sheck33,

Could you lay out the anti-hp double case (while diving dry)? I'm in the market for doubles and trying to decide on cylinder type. Thanks.

 

[LUBOLD8431]

I would like to add my two cents to this: people in this post seem to be bashing HP tanks. I, myself, have two sets of Faber 112's doubles. They are very heavy, weighing in at just over 105 pounds when filled. The LP tanks are a favorite of cavers, because they overfill them and get more air jammed into them. Of course, this is illegal if your cylinder is stamped 3AA. However, a set of HP 120's is a nice set of doubles, and they hold enough air for caving or wreck diving. Alot of guys i dive with use double HP 120's, and they like them very much. They actually have very similar buoyancy characteristics to the 112's. the 120's when filled however weigh in at just over 80 pounds (if my addition is correct) when filled. Substantial difference. The 104's (doubles) are about 8 pounds heavier than the 112's. Basically, its your call man... How much can you carry???

 

[outdoor1]

WOW , thank you for all the information . I am just getting into caving this year . I didn't want to buy the wrong tanks . I was advised to get 104's by one person and al80's by another. after this post I have a better knowledge of cyls . thanks!

 

[lucid]

Hey Outdoor1,

I have an example of how dangerous big steel tanks can be in the ocean with a wet suit. I recently took an the IANTD Full Tech course and during one of our dives another student had a problem that could of killed him if our instructor didn't help him.
The student had been diving for 30 years and had over 5000 dives (He used to do it for a living in the Military I believe). Anyway he was diving double steel 80's in a 5mm wetsuit. While assembling his gear the little ball on his deflator got stuck between his tank and Backplate and was forced open. At some point in the dive he lost all of his bouancy and ended up hitting the ground and couldn't swim up because his wing wouldn't inflate. Even though he has thousands of dives he started to panic and probably would have drowned if my instructor hadn't immediately started helping him. Bottom line is that he was unable to deal with the weight of the double steels once he lost his bouancy device. Just something for you to think about.

 

[LUBOLD8431]

Ok, im sorry, but the guy that lost his buoyancy should have cut that little ball off of his BC before he used it in the first place. Secondly, if you are diving wet with doubles, you should have a backup inflator system with a second BC. Its called redundancy and it can save your life.

 

[lucid]

-
But lets be realistic. Most people dont have redundant bouancy devices( At least from what I see in South Florida). Most of the people I dive with dive wet and several dive large steels every once in a while. I know a guy that dives double LP120's wet. Sto0opid. People just don't think about worst case senarios.

 

[O-ring]

Where are you guys diving that you need so much gas? Depth, BT, deco gas carried, etc. I am assuming this is all cave stuff with these twin water heater steel doubles?

 

[lucid]

I dunno o-ring. When I go out on recreational charters I do both dives with one set of double 80's. Its nice not having to change out tanks =]

The guy that has double HP 120's. How can that be safe? I dive single HP 120's every once and a while and they are friggin heavy. You dive dry? If not try and swim up for 30-40' with no air in your BC.

 

[Rick Murchison]

Here's GI3 on tanks...
"For ocean, aluminum 80's are the tank of choice. If more gas is needed, take an aluminum stage, but don't risk your life being over weighted at the beginning of the dive. The buoyancy characteristics of aluminum, especially when using helium , are such that a weight belt and or canister light will provide the necessary ballast which can be dropped in an emergency, making the rig only reasonably negative when full, neutral when empty, but swimable by dropping the weight. In cave, steel must be used with a drysuit and they must be negative enough to allow the diver to stay down in a low on gas emergency. There is nothing worse than being too light to stay off the ceiling while low on gas and then struggling. For this reason, the rig must be balanced to a no gas situation prior to cave use, and weighted accordingly."
I agree.
Rick

 

[O-ring]

That may be the root of the matter here...using the right tool for the job. I have cave ambitions myself, and it was tempting when I started diving doubles to save a few hundred bucks and just get a set of 104s and dive those off the coast until I got into caving. Luckily, I talked it out with my buddies and they explained how it didn't make sense. For the 99% of the times I am not diving caves, I am diving wrecks off the coast. I can't imagine enjoying being on a 25' boat in 6' seas with 104s. I would much rather use double 80s and carry a 40 if I need a little extra gas. So, to go back to the original poster's question, I would submit that a set of small steels or double AL80s is a lot more universal than a set of 104s or other large steels (HP 120s, etc.).