Free Anchor?

Rattlesnake Guy · 07-28-2011, 11:28 PM

Is a dive tank weighted? Or are the tank walls just that heavy> I was surprised to hear you say it sank.

DickR · 07-29-2011, 09:42 AM

Quote:

Originally Posted by Rattlesnake Guy

Is a dive tank weighted? Or are the tank walls just that heavy> I was surprised to hear you say it sank.

The weight of air compressed into a dive tank is not negligible. As noted in this reference:

http://en.wikipedia.org/wiki/Diving_cylinder

as a tank goes from full to empty, the tank goes from negative to positive buoyancy. See "Weight of Gas Consumed," a table about 2/3 the way down that piece.

Winnipesaukee Divers · 07-29-2011, 07:25 PM

Of course it sank... it's steel. Well, at least mine are, there are two types of tanks; steel and aluminum. One of the main aspects of diving is to stay on the bottom. If you float and your rubber suit & other gear floats and your tank floated too, you'd need a awful lot of lead ballast to keep you down there. The greater difference between the items that float and the ballast the harder and more fatiguing the dive will be. With a weight belt you become sway-back, as your gear pulls you up and the belt pulls you down.

As a professional diver, I need to stay focused on the task at hand. So, I can't be thinking about my gear, it simply has to work together. My tanks are steel which weigh 50 lbs. full and about 30 lbs empty, contain 120 cubic feet of air (in the water they are 9 lbs. negatively buoyant and go to about 3lbs at the end ). The rest of my gear is all negatively buoyant and my suit is a special grade of neoprene with a tritium lining (high insulation factor, low buoyancy). An aluminum tank on the other hand, becomes positively buoyant near the end of the dive and would become very distractive.

Once you put a few thousand dives under your belt, you become one with your equipment and the environment. Your equipment gives you subtle little reminders on how much air is remaining or when something is wrong. All new divers are over concerned with two things: how much air they are consuming and how much weight they require and therefore become nervous and retain air in their bodies make it even harder stay down. For me I purposely over weight myself (I need to stay put on the bottom) and I could care less how much air I consume, there's always more.

For you divers out there; I use steel 80s, 100s, 120s & 135s, 18 lbs of lead shot in a integrated BC and a BARE extreme suit. I also carry enough tools, shackles and bailing wire to get any job done. Oh and of course, I never leave home without my "PADI" dive tool (if you don't know what that is, you'll just have to take lessons to find out).

Dave R · 07-29-2011, 09:07 PM

Quote:

Originally Posted by Winnipesaukee Divers

Of course it sank... it's steel.

Aircraft carriers are made of steel, just sayin'...

jrc · 07-30-2011, 08:59 AM

Use this logical method to see if something will float:

http://http://www.youtube.com/watch?v=zrzMhU_4m-g

07-28-2011, 11:28 PM	#1
Rattlesnake Guy Senior Member Join Date: Sep 2004 Posts: 1,254 Thanks: 423 Thanked 366 Times in 175 Posts	Is a dive tank weighted? Or are the tank walls just that heavy> I was surprised to hear you say it sank.

07-29-2011, 07:25 PM	#3
Winnipesaukee Divers Senior Member Join Date: Apr 2004 Location: Exeter, NH or @ WCYC on weekends Posts: 250 Thanks: 7 Thanked 46 Times in 28 Posts	Of course it sank... it's steel. Well, at least mine are, there are two types of tanks; steel and aluminum. One of the main aspects of diving is to stay on the bottom. If you float and your rubber suit & other gear floats and your tank floated too, you'd need a awful lot of lead ballast to keep you down there. The greater difference between the items that float and the ballast the harder and more fatiguing the dive will be. With a weight belt you become sway-back, as your gear pulls you up and the belt pulls you down. As a professional diver, I need to stay focused on the task at hand. So, I can't be thinking about my gear, it simply has to work together. My tanks are steel which weigh 50 lbs. full and about 30 lbs empty, contain 120 cubic feet of air (in the water they are 9 lbs. negatively buoyant and go to about 3lbs at the end ). The rest of my gear is all negatively buoyant and my suit is a special grade of neoprene with a tritium lining (high insulation factor, low buoyancy). An aluminum tank on the other hand, becomes positively buoyant near the end of the dive and would become very distractive. Once you put a few thousand dives under your belt, you become one with your equipment and the environment. Your equipment gives you subtle little reminders on how much air is remaining or when something is wrong. All new divers are over concerned with two things: how much air they are consuming and how much weight they require and therefore become nervous and retain air in their bodies make it even harder stay down. For me I purposely over weight myself (I need to stay put on the bottom) and I could care less how much air I consume, there's always more. For you divers out there; I use steel 80s, 100s, 120s & 135s, 18 lbs of lead shot in a integrated BC and a BARE extreme suit. I also carry enough tools, shackles and bailing wire to get any job done. Oh and of course, I never leave home without my "PADI" dive tool (if you don't know what that is, you'll just have to take lessons to find out).

The Following User Says Thank You to Dave R For This Useful Post:
lfm (07-29-2011)

07-30-2011, 08:59 AM	#5
jrc Senior Member Join Date: Apr 2004 Location: NH Posts: 2,689 Thanks: 33 Thanked 439 Times in 249 Posts	Use this logical method to see if something will float: http://http://www.youtube.com/watch?v=zrzMhU_4m-g