Question Faber LP85s "perfect trim" even though positive when empty?

[rjack321]

Personally, I'm not removing tanks at all in normal diving and have no need to do so. I'm not squeezing into restrictions doing wreck penetration or caving, but part of the training I did (combo AN/DP and solo with TDI) the instructor had me unclip tanks and hold them in various orientations, presumably to demonstrate the dexterity of unclipping/reclipping and buoyancy control while performing this task. No problem with LP72s. Impossible with LP108s.

Unless you put a high helium mix in the 108s that's just how it works. There is zero need to actually do that though (locally) so I wouldnt based your tank selection on your ability to wing them out in front.

 

[rjack321]

I suspect it’s this. I rarely end a dive with cave-filled LP85s below 2000psi and almost never below 1500psi. I find that AL80s in sidemount get quite floaty quite quickly, while LP85s (at least at my end pressures) do not.

The tails of Faber lp85s very much float with mix in them - even full. The long since out of production Worthington lp85s are much heavier and better with mix.

 

[Tracy]

1) Other opinions on filling vintage LP72s to 3000ish PSI regularly?

You will not kill a steel 72 by routine filling to 3000 psi. You are still solidly in the elastic range of that tank.
Filling them to 3600 will kill them. I have destroyed a lot of them by playing with them and most are borderline or deformed beyond about 3400. I also haven't found one that is deformed at 3000. 3000 is a good limit to stick to.

2) Are new Faber LP85s with positive buoyancy when empty really "perfectly trimmed" at all times without moving them?

No

2a) If not, is the option of cave filling them why they are so highly regarded compared to AL80s or HP100s?

Yes

3) The Worthington LP95 has very similar buoyancy characteristics to the LP108 and appears to have been widely used in caving with significant overfills. Does anyone still use them and how do you feel about unclipping them and maneuvering them?

Personally? I think most steel tanks are too damned heavy in sidemount. But many people do use and like them.