outdoor1
Registered
Hello , I am looking for some advice . Looking to purchase a set of doubles . Will be used for boat , cave , ice diving .What should I buy? Is there one universal set that I can buy to participate in those activities ? Thanks .
al double 80's , pst 104's ?
- Thread starter outdoor1
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
sheck33
Contributor
Dont buy double AL's, their boyancy change would be unacceptable. Double low pressure 104's is a good choice provided you are strong enough to carry them. It also depends on what dives you are planning, you have to make sure that the amount of air you have is appropriate. I dive a doubleset of low pressure 72's, but these dives are not overhead or deeper than 100'. For the deeper and overhead stuff i will be buying a set of 104's. I would advise against high pressure tanks.
Hope this helps.
Hope this helps.
Please describe what you mean by "buoyancy change."
outdoor1, welcome to the file. What size doubles is the rest of your caving team using?
Roak
sheck33
Contributor
Change in buoyancy going from a full to a near empty tank.
I prefer steel tanks, that change using a steel tank is less dramatic.
The swing is the same regardless of style of tank. With alum the swing goes positive, with steel toward neutral.
Dbl alum 80s have their place if diving wet IMO.
MD
Scubaroo
Contributor
I'm sorry, but the change in buoyancy between AL80s and steel 80s will be identical. Most aluminum tanks are more buoyant than steel, but the change in buoyancy will be identical - 80cf of air weighs about 5.9 pounds, regardless of what pressure it is stored at, or what material it is held within.
If aluminum tanks feel too buoyant at the end of a dive, you need to add more lead to compensate.
If your diving wet in the ocean dont get steels. Most likely you would not be able to swim them to the surface if you lose bouancy. I dive Neutral bouyant Double 80's AL and they are not as heavy as steel and I doubt I could swim them up from depth if I was wet (I dive dry). Also you can almost get 2 sets of AL 80s for the price of one set of 104's.
Seriously, dont dive double steals wet. I know a lot of people that do but its really not very smart. Throw your double 104's on your back and see how long you can tread water with no air in your BC and a wetsuit. If your he-man and can do it without a problem, which i doubt, then go for it.
Seriously, dont dive double steals wet. I know a lot of people that do but its really not very smart. Throw your double 104's on your back and see how long you can tread water with no air in your BC and a wetsuit. If your he-man and can do it without a problem, which i doubt, then go for it.
sheck33
Contributor
I stand corrected, of course the CHANGE between an AL80 and a steel 80 is the same. What i meant to get at is the fact that i prefer a tank that swings to neutral near the end of the dive instead of positively buoyant. :bonk:
There's enough misinformation running around about cylinders that we need not contribute to it, which is why I jumped on you about how you phrased it.
What you meant to say is that you like the buoyancy characteristics of steel cylinders more than ALs (more negative when empty).
Bouyancy swings 1 pound for about every 13 cubic feet of air you stuff into a cylinder, no matter what the they're made of OR their size.
Roak
What you meant to say is that you like the buoyancy characteristics of steel cylinders more than ALs (more negative when empty).
Bouyancy swings 1 pound for about every 13 cubic feet of air you stuff into a cylinder, no matter what the they're made of OR their size.
Roak
Similar threads
