What sidemount tanks should I get next?

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jtsfour

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I am looking to get a new set of sidemount tanks so I can practice more often.

I am currently running LP85s with a SMS75. I wear a Black Ice drysuit. I am still working out a few kinks with trim but the LP85s do get quite floaty in the tails.

My LDS has been giving cave fills (however I suspect they don't know they are... so I shouldn't count on it) So buoyancy with the LP85s isn't that big of a problem so far. There are 3 tank sizes I am looking at

HP120s (I already own one of these so it is the cheapest option for me.)
LP95s
LP108s

Looking at the specs of the 95s vs the 108s the 95s are less buoyant. Will the 108s get as floaty in the tails as the 85s?

The HP120s are significantly heavier... I don't plan on doing many cold water dives this winter but if I do that could help.

What are your opinions or experiences with these sizes?
 

Marie13

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Just because you have one 120 already don’t count on another 120 being a good match for it. Could be slightly different, enough to throw you off, from what I’ve read.
 

grantctobin

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What is driving the desire for more cylinders? Frequency of fills? Running into penetration limits on your current gas in overhead? Sentiment that there's something better of a similar capacity?

If I needed a second set of cylinders for fill frequency and in your shoes, I'd get another set of 85s. In penetration distance, you likely won't get any further on 95s than on 85s and the buoyancy characteristics when low are equal or worse. The 8" vs 7" diameter is very noticeable, so if you're leaning 95s you might as well upgrade to 108s. I'd only get 108s if I needed more volume than the 85s, but at that point an AL80 stage or two is easier and more useful. The 108s are equally or more tail light and 0.5lb lighter than 85s.
 

pconsidine

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try HP100's-have been using for sidemount for years and like it far better than 120's. I still use my 120's for deeper wreck dives but all around diving I GO WITH HP100'S.
 

lermontov

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get the tanks that best fill your needs /objectives
 

rjack321

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85s, 95s, and 108s all get floaty tails - at least the Fabers. older PST 95s are crazy heavy and won't

Is tank trim the issue here or capacity?
 

jtsfour

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85s, 95s, and 108s all get floaty tails - at least the Fabers. older PST 95s are crazy heavy and won't

Is tank trim the issue here or capacity?

What is driving the desire for more cylinders? Frequency of fills? Running into penetration limits on your current gas in overhead? Sentiment that there's something better of a similar capacity?

If I needed a second set of cylinders for fill frequency and in your shoes, I'd get another set of 85s. In penetration distance, you likely won't get any further on 95s than on 85s and the buoyancy characteristics when low are equal or worse. The 8" vs 7" diameter is very noticeable, so if you're leaning 95s you might as well upgrade to 108s. I'd only get 108s if I needed more volume than the 85s, but at that point an AL80 stage or two is easier and more useful. The 108s are equally or more tail light and 0.5lb lighter than 85s.

I haven't yet reached the limits of the 85s. I am looking for new cylinders for a couple of reasons.

Immediate reason is so I can practice more often without having to drive 2 hours for 3 hours of practice.

However I would like to diversify my cylinder collection for the future. My thinking is that it would be a good idea to get something that in the future would allow me to do something my current gear doesn't allow. I already have 2 AL80s. However I want to stick with steels for sidemount for now. I'll figure out AL80s when I perfect diving with the steels.

I am planning on making some significant steps towards full cave this winter/spring and want something that would be good to use when I get there.


I was also curious how different sizes change weight distribution. I am still learning how to best trim the 85s. When cave filled they trim perfectly, but as the dive progresses the center of mass moves and slowly starts to cause front heavy condition. That is another discussion entirely as I am confident ill overcome that as I learn more.
 

AJ

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Just because you have one 120 already don’t count on another 120 being a good match for it. Could be slightly different, enough to throw you off, from what I’ve read.
Yep, it's true. But it's not a big issue. At least not for me, you learn to dive (compensate) with it. Diving single tank sm (vacation gear) I notice a slight tendancy to roll, but it's not as bad as some people make to beleive.
 

rjack321

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I was also curious how different sizes change weight distribution. I am still learning how to best trim the 85s. When cave filled they trim perfectly, but as the dive progresses the center of mass moves and slowly starts to cause front heavy condition. That is another discussion entirely as I am confident ill overcome that as I learn more.

All the Fabers will tip valve down as the gas is used up below ~2000psi (nitrox or air).
All of the Fabers will be valve down and butt up with trimix in them (even full).

You will need to look at older Worthington or PSTs which "may" avoid this tendency. Your BC will dictate how the tank trim shift plays out in reality.
 

decompression

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Easy, simple, future planning and cost effective is another HP120…..check the specs and see how close they are……120’s will give you days of gas and set up for longer/deeper dives only needing to add Al’s to complete…….
 
https://www.shearwater.com/products/swift/
http://cavediveflorida.com/Rum_House.htm

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