LP95 or even LP108 for Sidemount Diving?

[Caissy]

Hi everyone!

I've been diving LP85 in sidemount for a while now and I love them! However, I'm starting to do deeper technical dives (no cave) and I wouldn't mind having more gas...

So anyone having experience diving LP95 or even bigger tanks, say even LP108? How to they trim compared to the LP85? What are their buoyancy characteristics from full to near empty?

A few notes about my diving:
- I have my own compressor, so cave fills are easy for me...
- I dive in cold water in Canada with a drysuit and a thick undergarment that I use most of the year, so I need quite a few pounds of lead to compensate for my undergarment, so the extra weight of the cylinder simply means less lead for me, as oppose to warm water divers being over weighted with heavier cylinders...
- I dive with the xDeep Stealth 2.0 Tec harness with 42 lbs (19 kg) of lift
- I very often dive with a deco cylinder (40 cf of 100% O2) and often a stage, so I'm used to dive with 3-4 tanks. I'm hoping to go deeper/stay longer with this set up...

Let me know what you guys think!

 

[tbone1004]

@Caissy how deep and how long?
Assuming cave fills.
85's hold ~220cf
85's+stage=~300cf
95's=~260cf, so it's pretty negligible and certainly not worth switching for
108's=~300cf so they allow you to get basically one extra "free" stage and have similar buoyancy characteristics and length so you don't have to change your rigging at all

Why not keep the 85's and use an extra 80?

 

[northernone]

They behave pretty much the same, doubt you'll notice much difference. They hang negative like ballast just like a lp85.

I enjoyed my lp131 cave filled tanks SM. (Before the dive boat we chartered this summer sank and lost one.)

Less drag compared to adding a stage. Makes a difference in river diving. One less reg to snag on things as well.

 

[Caissy]

Thanks tbone1004 for your answer,

I'll be taking a trimix course this coming Spring, so although I'm currently diving between 120' and 150' on nitrox, I'm planning on going up to 200' once I can use helium. I have been told that I will quickly want to dedicate a set of tanks to trimix, so I figured that I would keep my LP85 for nitrox and buy a second set of tanks for deeper dives on trimix. So while buying new tanks, I thought I would consider slightly bigger ones.

Adding a stage (AL80) is what I currently do if I need more bottom time, but it's always nice having one less tank to worry about, especially that I often dive from a boat, with many other guys in twins and therefore quicker in the water... :/

So should I buy another set of LP85 or go a little bigger while I'm there?

 

[Caissy]

@northernone,

Your LP131 would give you around 175 cf each with a cave fill, so 350 cf for both!!! That's a lot of gas... But that seems like a pretty big step up from the LP85... Maybe too big?

I like the idea of LP108, and like @tbone1004 mentioned, don't need to change anything to get a "free" stage. My stage could become 50% nitrox and help speed up my deco...

 

[tbone1004]

@Caissy if you are going to trimix you'll want another set of tanks, and in that case you'll want to go as big as possible. How tall are you?

Of note, my 3 sets of sidemount bottles are 50's, 85's, and 121's

 

[Caissy]

@tbone1004 I'm 5'10" with a long torso and kind of short legs.

Maybe LP121s then? That would give me about 160-165 cf per tank, 320-330 for the set?

 

[northernone]

@northernone,

Your LP131 would give you around 175 cf each with a cave fill, so 350 cf for both!!! That's a lot of gas... But that seems like a pretty big step up from the LP85... Maybe too big?

-edited for bad science. Thanks-

Ya it's a lot of gas. Too much for my dives, I'd get cold/hungry. Just extra gas reserves because I'm in a remote area.

 

[tbone1004]

@tbone1004 I'm 5'10" with a long torso and kind of short legs.

Maybe LP121s then? That would give me about 160-165 cf per tank, 320-330 for the set?

way too long for you. 108's will have to be it.

@northernone how high are you pumping those?

 

[rjack321]

You might also consider:
hp120s, 7.25" tanks and long, also fairly heavy
hp130s, 8" tank, not as long, not as negative as lp121s trim out surprisingly good with 18/45+ in them.

Since you are diving in cold water using hp tanks that are more negative when empty than lp tanks makes sense to me. But I would not just get giant tanks because you want to "go deeper on mix". With 2 deco gases you can easily do 200ft wreck dives on 18/45 in the cave filled lp85s with decent reserves. Beyond 200ft is the switch point for bigger tanks IMO. I would look hard at what you can find used - since they are going to sit around in your garage quite a bit you don't need fancy new tanks. Lp95s are usually available on a budget and would be fine as a "trimix set" down to 220ft-ish and 30mins BTs. That would cover 95% of your wreck diving for at least the next few years and not be a total pita either.