Buoyancy properties of an AL100 vs AL80?

[scubamickey]

Generally speaking, how much more buoyant is an AL100 than an AL80? I'm wondering how much more weight, if any, I may need if all else is equal.

I take 14 lbs with an AL80 wearing a 3mm wetsuit in salt water. The 4lbs is for the wetsuit. I will do a check but I'm just trying to ballpark it so I don't blow the minimum deco on my first dive with a 100.

 

[dannobee]

The 100's are LESS bouyant. If the tank's a Catalina, it's 4 lbs less bouyant than an AL80. The Luxfer's are 1 lb less bouyant, IIRC.

Why not buy a steel tank instead?

 

[scubamickey]

The 100's are LESS bouyant. If the tank's a Catalina, it's 4 lbs less bouyant than an AL80. The Luxfer's are 1 lb less bouyant, IIRC.

Why not buy a steel tank instead?

I'm not buying. It's going to be a rental for a dive vacation.

 

[barrmust]

when i go from an 80 cf to a 100 cf tank i remove 2# of weight. so for me if i was wearing 14# i would go to 12# of weight with the 100. i am using luxfer tanks.

 

[scubamickey]

when i go from an 80 cf to a 100 cf tank i remove 2# of weight. so for me if i was wearing 14# i would go to 12# of weight with the 100. i am using luxfer tanks.

Isn't the tank more buoyant when empty though? I would expect that 20cf more air would make it a little more buoyant when you have 500 psi left.

 

[spectrum]

The 20 CF of air weighs 1.6 pounds.

Buoyancy specs however are for an empty cylinder because it is in the near empty end of dive condition when weight becomes critical.

Pete

 

[GlazierB]

Generally speaking, how much more buoyant is an AL100 than an AL80? I'm wondering how much more weight, if any, I may need if all else is equal.

I take 14 lbs with an AL80 wearing a 3mm wetsuit in salt water. The 4lbs is for the wetsuit. I will do a check but I'm just trying to ballpark it so I don't blow the minimum deco on my first dive with a 100.

When I switch between my from my 80 to my 100 I have to add 3lbs to offset the tank weight when it drops below 1000 ... Makes sitting at 20 much much much easier

 

[bradshsi]

Luxfer 80 +4.4 lbs empty -1.4 lbs full

Luxfer 100 +3.1 lbs empty -4.3 lbs full

All figures are buoyancy values in fresh water.

So figure on dropping about 2 lbs going from the 80 to the 100 in salt water with Luxfer.

OTH

Catalina S80 +4.0 lbs empty -1.8 lbs full

Catalina C80 -0.2 lbs empty -5.9 lbs full

Catalina C100 -0.4 lbs empty -7.8 lbs full

So with Catalina tanks you need to check the type. You either don't need to change your weight, or you need to drop 4 lbs depending on the combination.