How much additional ballast does a 30 cu ft Alum pony add to your load?
I'm diving dry with a single 120 steel.
I'm diving dry with a single 120 steel.
30 cu ft pony: Weight?
- Thread starter tridacna
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mikemill
Contributor
Using the information from Catalina Aluminum Scuba Cylinder Specifications - Imperial
Buoyancy Full: -2.4 lbs
Buoyancy 500 psi: -0.7 lbs
Weight Empty: 13.6 lbs
Buoyancy Full: -2.4 lbs
Buoyancy 500 psi: -0.7 lbs
Weight Empty: 13.6 lbs
ScubaAl
Contributor
I have a 30cf luxfer I use for O2 rigged with regulator and stage rigging, full. Put it on the scale and came in at exactly 20lbs. Out of the water of course.
Al
Al
I dive with a Luxfer al30 attached to my PST hp120 with a SS Highland pony band.
Here's a good tank specs chart from Huron Scuba:
Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan
The chart shows buoyancy figures of 1.2 full, -1.0 empty, a shift of 2.2 lbs.
EDIT: Correction- Should be "1.2 empty, -1.0 full".
I did a separate buoyancy check of the empty pony with the SS band and a Sherwood regulator attached. Together, those three items were barely negative, perhaps only -0.2 lbs. Without the SS band, the pony and regulator was just barely positive, IIRC.
I rarely dive without the pony, but when I do, I don't bother to make any weight changes, despite the slight increase in buoyancy. I always prefer a bit of overweighting, though.
Dave C
Here's a good tank specs chart from Huron Scuba:
Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan
The chart shows buoyancy figures of 1.2 full, -1.0 empty, a shift of 2.2 lbs.
EDIT: Correction- Should be "1.2 empty, -1.0 full".
I did a separate buoyancy check of the empty pony with the SS band and a Sherwood regulator attached. Together, those three items were barely negative, perhaps only -0.2 lbs. Without the SS band, the pony and regulator was just barely positive, IIRC.
I rarely dive without the pony, but when I do, I don't bother to make any weight changes, despite the slight increase in buoyancy. I always prefer a bit of overweighting, though.
Dave C
Last edited:
OP
Thanks all. So consensus seems to be to use usual weights. No add or minus.
I think you got that backwards. 1.2 empty and -1.0 full makes more sense.I dive with a Luxfer al30 attached to my PST hp120 with a SS Highland pony band.
Here's a good tank specs chart from Huron Scuba:
Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan
The chart shows buoyancy figures of 1.2 full, -1.0 empty, a shift of 2.2 lbs.
I did a separate buoyancy check of the empty pony with the SS band and a Sherwood regulator attached. Together, those three items were barely negative, perhaps only -0.2 lbs. Without the SS band, the pony and regulator was just barely positive, IIRC.
I rarely dive without the pony, but when I do, I don't bother to make any weight changes, despite the slight increase in buoyancy. I always prefer a bit of overweighting, though.
Dave C
I guess if you have your weight dialed in perfectly you would have to add 2lbs. I know I tried dropping 2lbs last fall and had to hold onto the line at my safety stop because I was too buoyant with an empty tank.
I think you got that backwards. 1.2 empty and -1.0 full makes more sense.
I guess if you have your weight dialed in perfectly you would have to add 2lbs. I know I tried dropping 2lbs last fall and had to hold onto the line at my safety stop because I was too buoyant with an empty tank.
Yep, wrote it backwards, thanks for correcting the mistake.
Dave C
When I dive my 19cf BOB, I don't notice any weight change and leave the same weight as usually.
$.02
$.02
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