Rental-Steel 120 vs? ??-Educate Me Please

[bdklein]

I have done about 20 dives over the last 10 years-almost exclusively Hawaii or Caribbean, with a dive operator supplying the tanks. They have always been silver, but it I never took note of what size they were. I was only concerned that they looked ok, were functional (valve opened and closed), and BC, regulator and pressure gauge (with decent PSI) were able to get air from the tank.

I just recently booked a dive with an operator in Cozumel. They say they are giving me 120 steel tanks. Can you kind people explain what that means? What type of tanks have I probably been given in the past? Will I get significant more air, and more dive time. I am kind of an air hog.

Thanks in advance for helping the ignorant.

 

[Wayward Son]

most likely aluminum 80's, which actually hold about 77 cf.

Yes, you'll have 43 cf more gas. Pay attention to your BT, you can get bent with bigger tanks if all you watch it the pressure gauge.

You will also need less lead.

 

[diveandclimb]

Wayward son is right. You have almost definitely been given AL80s in the past. You can drop a few pounds of weight and not worry about gas supply as much but you need to watch the computer or timer more. That said, if everybody on the dive is getting ST120s the dive master may address some of these issues in the briefing before the dive.

 

[divenutny]

My guess is you used Aluminum 80's. With a steel 120, you will need a lot less lead. Full steel 120 weighs more than aluminum 80, it may be tougher to move around out of the water. I would do a check out dive with the steel tank before jumping off a boat. I'm surprised they are offering a steel 120.

Watch your deco, with more air, you may exceed your NDL's.

Enjoy. Cozumel is a great place to visit.

 

[bdklein]

. I'm surprised they are offering a steel 120.

Now you have me scared. Is the weight of the tank too much? Too much air? Please elaborate. Thanks.

 

[Clammy]

I have done about 20 dives over the last 10 years-almost exclusively Hawaii or Caribbean, with a dive operator supplying the tanks. They have always been silver, but it I never took note of what size they were. I was only concerned that they looked ok, were functional (valve opened and closed), and BC, regulator and pressure gauge (with decent PSI) were able to get air from the tank.

I just recently booked a dive with an operator in Cozumel. They say they are giving me 120 steel tanks. Can you kind people explain what that means? What type of tanks have I probably been given in the past? Will I get significant more air, and more dive time. I am kind of an air hog.

Thanks in advance for helping the ignorant.

OOOOooo what boat is giving you 120s in cozumel!?

aluminum 80s have 80 (okay 77) cubic feet of air usually at 3000 psi. They tend to be 2-4lbs negatively buoyant when full and 2-4lbs positively buoyant when empty. This means you add an extra 2-4lbs of weight to compensate for the positive pull towards the end of the dive.
Steel tanks can vary on their buoyancy characteristics a lot depending on who makes it and what kind and all that BUT they are pretty much all negative when empty. This means you get to drop that extra few pounds of weight. A 120cf tank also means more gas! wheeeee!!!

Plus don't go exclusively by psi number when you check your tank. Low pressure steel tanks will usually be at around 2400psi when full and High pressure tanks will all be over 3000 psi to be full (3180+10%-3442 and sometimes higher). Find out what the tank is suppose to be pressured at to be full (it's stamped on the tank).

 

[bdklein]

OOOOooo what boat is giving you 120s in cozumel!?

Aldora

 

[Clammy]

Now you have me scared. Is the weight of the tank too much? Too much air? Please elaborate. Thanks.

Don't worry too much about being too heavy. Since you're SUPPOSE to be neutral anyways, the extra few pounds you throw onto your belt or that you get when strap on a steel can be compensated by your BC easily (Consider that a lot of these regular BCs have like 40lbs of lift in them when technically you're suppose to be neutral and only need a little bit of air to become positive). Now if your BC fails... well then.. that's why you wear ditchable weight!

 

[marchand]

You will be fine as long as you plan your dive before hand with tables and follow that plan, or you keep an eye on your computer and make sure you do don't get into obligated decompression.

 

[Wayward Son]

I like bigger tanks