steel 120's for side mount?

swoop603 · Jul 28, 2014

Just got offered a couple steel hp120's for a good deal and was wondering how they would do for side mount?

rhwestfall · Jul 28, 2014

start here (not even a month old thread....):

http://www.scubaboard.com/forums/sidemount-diving/486656-sidemount-hp120s.html

tbone1004 · Jul 28, 2014

how tall are you? I like them, but they're awfully long if you aren't well over 6' tall. Tanks are 28" tall without valves, so measure 31-32 inches from your armpit and that is where the boots will land. I'm 6'4" and they come just shy of my knee. Any longer and they get in the way, shorter doesn't matter

swoop603 · Jul 28, 2014

I'm am 5' 10" l was worried about the weight of them didn't even consider height

Texasguy · Jul 28, 2014

Boy, I wonder how much lift you should have having double 120's. Probably need at least SMS100 with its 65#.

I remember diving a single 130 and it was quite a sinker.

Narked Scuba · Aug 19, 2014

Are they 7" or 8" tanks? What brand?

decompression · Aug 19, 2014

There is a thread on this topic, I dive 2 hp 120's with a drysuit and either a 37# or 50# wing. They are challenging tot manage but if your willing and you need that much gas, they are good to have.

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Colliam7 · Aug 19, 2014

swoop603:
Just got offered a couple steel hp120's for a good deal and was wondering how they would do for side mount?

As several have said, it is possible. Although 120s - at least the 7.25" PSTs - are a bit long, and usually recommended for divers at least 6' tall, I dive them sidemount without difficulty, and I am 5' 10". I dive them with a 5mm wetsuit or, preferably, with a drysuit, using my original Nomad, which has >50lbs of lift. I like them better as sidemounted cylinders than I did as manifolded backmount cylinders.

djcheburashka · Aug 21, 2014

It's possible, but I think its a really bad idea. You're about the same height I am. I could manage those tanks but it would be an unpleasant diving experience. Remember that sm has more drag than bm, so you'd really have to work to move around in those things.

I think it's very unlikely you'd be able to no-mount with them to get through smaller passages, and if you can I think you'd find it quite physically taxing.

I'm also not sure how you'd keep tanks that size in trim if you're ever anything off perfectly horizontal yourself. Remember, the longer a tank is, the bigger effect a small change of angle has on the position of the back. With tanks that long and that heavy, if you rotate, or twist, or angle yourself, I think they're gonna go all funny.

---------- Post added August 21st, 2014 at 06:00 PM ----------

Let us know what you do--with pics

tbone1004 · Aug 25, 2014

how the hell does SM have more drag than backmount if you're doing it right? HP120's are perfectly fine and many people use them regularly. They're 2 inches longer and 0.25 inches wider than the LP85 which is by leaps and bounds the most popular sidemount tank in cave country, and just 2 inches longer than AL80's, I would hardly call that a "really bad idea". No mounting them isn't a problem unless you have to bend into some really contorting passages where they physically couldn't make the radius. It's not a great idea for someone that short, but that doesn't make them really bad ideas to dive. The longer tanks trim out better because there is more in the back to counter the moment that the valve has on the pivot point which means less strain on the bungees equating to the valves riding higher which lowers your drag profile

steel 120's for side mount?

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