Faber 23 HP steel vs Luxfer 19 AL pony

[toshman001]

Hello all,

New to diving, and love the term insta-buddy, which is exactly what I will have in the carribean so I want a pony as back up. Already read the spare air posts which are a riot of good fun so I want a reasonable sized pony. I won't rely on the air in any dive calcs!

Can someone assist me as to why the Faber 23 HP steel pony doesn't work. Weight is approx. the same (8.4 vs 8.2lbs), its 1/2in thinner, length is approx. same and bouyancy when full is -2.6 for Faber -1.5 for Luxfer, not much different. The way I see it, I get ~4 more cft of air in a thinner, streamlined package that is really no different otherwise. What am I missing?

Could I get your recommendations for a recreational pony from the above selections or other, and a recommended reg to keep it streamlined. Thanks, Tom

BTW ordered a DSS long plate setup from Tobin(I'm 6'7") as my first rig. Great service, lots of help, great price.

 

[SteveAD]

More important than weight is bouyancy. Steel tanks usually go fairly negative when full. An al40 is effectively neutral (just a bit negative when full, just a bit positive when empty) so you can dive with or without the al 40 without having to make any other changes to your weighting or trim.

I am not familiar with the faber 23 but if you are saying that it's dry weight is within a quarter of a pound of an al 40 and is 1/2 inch smaller diameter that would make it sufficiently negative to have a noticeable effect on bouyancy and weight distribution.

 

[keithdiver]

Get yourself and aluminum 40, and yo will not be held back from anything. That tank has a lot of all around use. From intro to tech -adv. open rec dives. that tank will get you out of a jam. Put it this way, you will be able to get off the bottom of a 120dive, without there being and issue. What type or size steel tank are you going to purchase 100, or 120, 130 ?

 

[toshman001]

That's what I keep hearing, its a bouyancy issue. But..

Faber(HP steel) Full:-2.64 Empty:-0.66
Luxfer (AL) Full:-1.4 Empty:-0.1
Diff Full:-1.2 Empty:-0.56

Does 1 pound of additional negative bouyancy on one side really matter?

 

[toshman001]

Also, I will mostly be traveling and renting tanks to start, so that means AL80 as my single on a DSS SS long pattern backplate. Thanks everyone!

 

[halocline]

Either one will be fine. I think the main reason for buying an AL pony is cost. There is one other issue; if you travel by air, you will have to take the valve off the pony for checking, this leaves the tank exposed to atmospheric air with moisture. AL tanks are probably more tolerant of this.

I assume you'll be wearing some lead, so you should be able to balance by moving some weight around. BTW, those buoyancy numbers might not be accurate (1.2lbs different full, .56 different empty) because they imply that the steel tank has almost twice the air. If it's 23 vs 19 cft, and the true difference in full buoyancy is 1.2 lbs, then the empty difference should be .99 lbs. (I think)

A good pony reg is the SP MK2/R190 which you can get used for a very reasonable price. They are very easy to rebuild, super reliable, will give you some warning before the tank is empty, and can tolerate being flooded.

 

[Scared Silly]

Not all buoyancy measurements are the same. IIRC Faber's are without a valve while Luxfer and Catalina's are with a valve. As such, you need to add a couple of more pounds to the Faber. Which at -4 lbs does make a difference if you are slinging the bottle. If you are strapping it along side your main cylinder then as was said just reduce and shift some weight around.