Tank sizing???

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Marie13

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I’ve got a couple of places I can get my 85s filled to 3000. Good enough.
 

Divin'Papaw

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Just get HP100s and be done with it. They hit the sweet spot for the majority of divers who want a back-mounted cylinder and aren't super short or super tall. You're clearly neither. They allow you to carry 6# less in ballast than AL80s and provide 22.5 cf more gas when filled to their 3442 service pressure. I have owned lots of different types of tanks (HP100, AL80, LP85, LP104, HP130) and the HP100s are my favorite. I own 4 of them that I've had for years. AL80s are fine for warm water, shallow to moderately deep diving (down to maybe 80-90' or so depending upon your SAC rate). I own 2 AL80s as well.

HP117/119s are an option if you want a little more gas.

But my recommendation would definitely be either Worthington HP100s (if you can find some used as they aren't manufactured any longer) or Faber HP100s.

Also go for Hot Dipped Galvanized if you go with steel tanks, not painted.
 

rx7diver

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I am ~6'2" with longish legs (~35" inseam). A HP 120 (28" tall) is too tall for me to dive comfortably single back-mounted. A HP 100 (~24" tall) dives very comfortable for me (such a sweet cylinder, in fact!), but is uncomfortably short when I am sitting on a bench, geared up, awaiting my turn to splash; it always makes me wish it were two inches (or so) taller--you know, the height of an Al 80.

Both the HP 120 and HP 100 have a 7.25" outer diameter--the same as an Al 80.

I absolutely hate diving an 8" O.D. cylinder for single-tank recreational diving.

A LP 85 (~7" O.D.) approaches the ("perfect"?) O.D. of the old-school PST 72 (~6.9"), and has the height of an Al 80, and, additionally, given its buoyancy characteristics, should be an excellent cylinder for me for single-tank recreational diving in a wetsuit.

I hope this helps.

ETA: The HP 120/100 I am referring to here are the Sherwood Genesis 3,500 psig cylinders that were manufactured by PST.

rx7diver
 

RyanT

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I can't imagine a tank that's 0.75" longer being that much more unwieldy.

You might be surprised. Keep in mind that a 117 or 133 is also 8" diameter instead of 7.25" (which is what AL80 and HP100s are). In addition to the weight, that extra diameter pushes the center of gravity farther from you. Granted, it's not a huge deal, but is one you're likely to notice when you dive those tanks.

Just get HP100s and be done with it. They hit the sweet spot for the majority of divers who want a back-mounted cylinder and aren't super short or super tall. You're clearly neither. They allow you to carry 6# less in ballast than AL80s and provide 22.5 cf more gas when filled to their 3442 service pressure. I have owned lots of different types of tanks (HP100, AL80, LP85, LP104, HP130) and the HP100s are my favorite. I own 4 of them that I've had for years. AL80s are fine for warm water, shallow to moderately deep diving (down to maybe 80-90' or so depending upon your SAC rate). I own 2 AL80s as well.

HP117/119s are an option if you want a little more gas.

But my recommendation would definitely be either Worthington HP100s (if you can find some used as they aren't manufactured any longer) or Faber HP100s.

Also go for Hot Dipped Galvanized if you go with steel tanks, not painted.

Do yourself a favor and take @JimBlay's advice!
 

Divin'Papaw

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You might be surprised. Keep in mind that a 117 or 133 is also 8" diameter instead of 7.25" (which is what AL80 and HP100s are). In addition to the weight, that extra diameter pushes the center of gravity farther from you. Granted, it's not a huge deal, but is one you're likely to notice when you dive those tanks.

@RyanT makes a great point here. @rx7diver made a similar point above. I too hated diving 8" OD tanks. You wouldn't think it would make a difference, but for most it does. The people I know who don't mind the 8" tanks are folks larger around the middle. Not necessarily fat, but just larger.
 

elan

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I would not by HP100 they are almost 1 inch shorter than AL80 They are in between old worthingtons hp100 which are 24 inch and the AL80 which is 26. I am the same height and I would only go for 26 AL80 and up. I used both LP85 or LP108 and they feel better as they are longer Its more apparent with doubles but singles also feel better when they match the torso size. forget about hp80 :) Unless you will mount two of them coaxially :)
 

broncobowsher

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HP100 is sweet (as mentioned multiple times. Size wise it is about the same as the AL80 you have used before. So much so if you get a short fill (only 3000) you are diving the same as the AL80 you have before. But there is that extra 20% when truly full.

They are not so big and awkward to work with. They are manageable on land and water. The little extra weight helps you trim out in the water better. But isn't so heavy that the dive shop gets out the hand truck to haul it into the back room.

You mention dives upwards of 120'. The 100 adds a nice buffer over the AL80s you have been using.
 
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