steel or aluminun?

[highlandfarmwv]

I think I asked this before, but I can't find it...
In the interest of being lighter weight climbing up ladders in the open Atlantic when diving at Hatteras (up to 130ft), would it be better to get a steel 100 as opposed to the Al 100 I rent from the dive shop?

I read where steel oxidizes quickly and badly rendering them unusable, Is this true? What is your experience with them?

Thanks.

 

[H2Andy]

well, steel *can* rust... but minimal care will prevent this (basically rinse the tank, always keep some pressure in it, and otherwise follow manufacturer's recomendations)

AL 100 tanks will weigh anywhere from 40 to 46 lbs depending on manufacturer, and steel 100's will weigh from 34 to 38 lbs (quick look), so you could shave a few pounds off

but then, are you going to need to add weight so you're not too light at the end of the dive?

may be a zero-sum game

 

[highlandfarmwv]

The LDS sid I could shave even more weight off because the steels were negatively buoyant even when empty, where the als were positively buoyant. If that is the case...

 

[PerroneFord]

I'd take steel any day over Aluminum, on the condition it is hot-dip galvenized. As for the oxidizing issue, you need to stop listening to whoever told you that. I have persoanlly used steel tanks in 2006 from our shop that had 1971 and 1974 original hydros. One of them was used for years for science diving in the ocean. Meaning they were in the gulf 20+ hours per week for years.

 

[Charlie99]

Usually a steel 100 would have the lighter total weight, if you are counting your actual dive weight including both the tank and any lead you need to carry.

The easiest, most direct comparison between tanks is to look at two numbers --- empty weight and buoyancy when empty. Algebraically add those two numbers together to get the effective weight of the tank. This means that for a positively buoyant tank like the AL100, the effective weight is the 4 pounds or so positive at the end of the dive + the xx pounds of empty weight.

For the various steel tanks with negative buoyancy when empty, you subtract that number from the empty weight to get the "effective weight".

=====================
Why combine empty buoyancy + empty weight to get effective weight?:

The empty buoyancy affects how much lead you need to be able to hold a safety stop with a near empty tank. If the buoyancy of the tank is positive (such as with an AL100) then you need to add that amount of lead to compensate for the tank buoyancy. If the empty buoyancy is negative (as it is for most steel tanks), that is lead that you can remove from your belt.

 

[H2Andy]

The LDS sid I could shave even more weight off because the steels were negatively buoyant even when empty, where the als were positively buoyant. If that is the case...

i'm sorry, you're right ... you're talking about going from AL to steel

you'll probably be fine as the steel tanks won't get as bouyant as the AL's by the end of the dive

here's a chart where you can look up the numbers Charlie is talking about:

http://www.wetnotes.us/Cylinder.htm

 

[teamgs]

What about neutrally bouyant aluminum tanks? A Catalina C100 is -0.4 lbs empty. I have seen them priced between the standard aluminum and the steel.

Regards,

Gary

 

[Ben_ca]

Also to add to your confusion... Steel tanks hold their value better... one of these days you might decide it's time to hang up the fins...

 

[uspap]

Hang up the fins? NEVER!
I personally use steel 120's. I droped weight off the belt and like them better at the end of a dive compared to alum.

 

[highlandfarmwv]

Thank you all for the quick input. I feel better about getting steel ones. I had read someplace that one would oxidize in HOURS! I realize you must take proper care of them, but I didn't want to have them go obsolete fast!