Alum80 vs Steel80, how much weight can I drop?

[Paco II]

Looking for a little knowledge transfer. I've only ever dived Alum80s. About to do a boat trip that only provides Steel 80s. I normally dive with 26lbs of weight. How can I determine how much weight I can/should use when using these steel 80s?

 

[letsgodiving]

It depends on the make, but I would guess about 6-7lbs.

 

[Paco II]

Ok, so I should plan to use around 20lbs. Thanks!

It depends of the make, but I would guess about 6-7lbs.

 

[Charlie99]

You need to find out which steel 80 the boat has.

Look at this scuba cylinder specification chart and the the "buoyancy, empty" spec for the two cylinders. The difference is the amount of lead you can drop.

The most common AL80 are the luxfer and catalina cylinders with 4.4 or 4.0 pound positive buoyancy when empty. As you can see from the chart, there are a variety of "steel 80" cylinders, with varying empty buoyancies, from -1.7 to -7.2 pounds. Depending on which steel tank you will be using, you can drop anywhere from 6 pounds to 11 pounds of lead.

I'll bet the boat has answered this question hundreds of times and have the answer on the tip of their tongue.

 

[Marek K]

I concur generally. Diving in Europe and the Red Sea, I use mostly 12-liter tanks -- a close equivalent to 80's. When going between steel and aluminum, I use a difference of four kg ~= 10 lb.

I may actually need a bit less, but weights aren't available in less than one kg... and I like to be balanced left-to-right.

--Marek

 

[Paco II]

Thanks very much for the chart and tips. Called them and found out that their tanks are about -7 full and about -1 empty. I'll probably start by dropping 6lbs, using 20lbs to start. They also said that they have no problem with me doing a bouyancy check. Sounds like a good boat.

You need to find out which steel 80 the boat has...