Cave Fills on LP tanks

[Caveeagle]

Helium helps.

Haha, yea, I just transitioned a set of pst 95s for use as SM tri-mix tanks. They are so heavy, I rarely used the. As BM doubles. I am hoping a lb or two less negative will work out well with he.

I think you're overestimating the size difference.
A luxfer al80 is 7.25" diameter, 26.1" tall. A worthington LP108 is 8" diameter, 26.5" tall So it's 0.75" larger diameter and 0.4" taller than a standard al80. As far as the size goes, other than the fact that it doesn't fit into tank holders on some boats it's a very minor difference.

Now, the LP108 is 14.5lbs heavier than a standard al80. That's a pretty big difference. I think that the weight is also a boon, as it means I generally do not need to carry much lead (if any at all).

It is not just the size difference that hurts you. Heavier, less buoyant tanks (like hp100, or pst LP tanks) will typically require more gas in wing and adds more drag.

As an example, I was diving a set of pst 95s in backmount. I rented a second set of LP108s for a day so I would not have to run out for fills. I was surprised at how noticeably better the 108s trimmed out and swam. The faber are the same 8" diameter, but are not as negatively buoyant so I had a lot less gas in my wing just to stay neutral.

 

[Fruitographer]

Since i'm only 5'6" and 145lbs it doesn't take much to be a huge difference for me. It killed my back to dive lp95's BM. In sidemount my HP100's were so much heavier that my BC had to inflated way more than I wanted or needed than with my LP85's. So the size of the tank included with the additional volume of my wing filled up and the overall weight and inability to move freely was a huge difference. I'm a slight bit heavy just from the two tanks and no added weight using a dry suit. I can tell the difference between two pounds difference on how my bouyancy is. The heavier I am it feels like trying to walk a tight rope with to much or to little air in my wing and yes I know how to control my buoyancy through breathing extremely well. I still say to improve your SAC rate rather than using larger tanks.

 

[victorzamora]

I still say to improve your SAC rate rather than using larger tanks.

I agree...but there's still only so low your SAC can get. How low is an acceptable SAC rate? At what point is it "acceptable" to use larger tanks?

 

[Caveeagle]

. I still say to improve your SAC rate rather than using larger tanks.

Those options are not mutually exclusive.

 

[LiteHedded]

I agree...but there's still only so low your SAC can get. How low is an acceptable SAC rate? At what point is it "acceptable" to use larger tanks?

immediately

 

[jerrwhy01]

I'm just here to watch Ken's garage blow up.

 

[kensuf]

I'm just here to watch Ken's garage blow up.

It was still there this morning.

 

[Stoo]

It was still there this morning.

I loaded my truck up last night... twin LP 80s @ 3200, twin HP 130s @ 3900, a couple of 80s with 100% O2. God help anyone who rear ends me today.

 

[northernone]

I loaded my truck up last night... twin LP 80s @ 3200, twin HP 130s @ 3900, a couple of 80s with 100% O2. God help anyone who rear ends me today.

Pair of lp131, lp72s, lp85 (haven't I.d. yet), and an lp 104 all @ 3200, dozen al80s and a couple o2 northbound tomorrow.

Let's stay in our lanes.

Now about that garage @kensuf.

 

[jerrwhy01]

It was still there this morning.