Steel HP100 or HP120 and reserve air in tank?

[boriss]

I hope this isn't a silly question, but are you able to rent an HP100/HP120 locally? That's the route I'd take before investing in anything.

I dive both and the determining factor for me is logistics and how much air my buddy has. Are you lugging the tank around from your car through the beach and then kicking out a few hundred yards before doing your dive? Or do you take it from your car onto a boat and plop into the water? In either case, both of these options are better than aluminum 80's

EDIT: I'm about 6'1" athletic and when diving an overfilled LP95 (essentially an HP120)... it's not too large and the extra gas is always welcome.

 

[divezonescuba]

Here’s a video if anyone wants to see the rule of thirds difference between turn, ascent, and rock bottom pressure.

 

[Flashgun66]

I hope this isn't a silly question, but are you able to rent an HP100/HP120 locally? That's the route I'd take before investing in anything.

I dive both and the determining factor for me is logistics and how much air my buddy has. Are you lugging the tank around from your car through the beach and then kicking out a few hundred yards before doing your dive? Or do you take it from your car onto a boat and plop into the water? In either case, both of these options are better than aluminum 80's

EDIT: I'm about 6'1" athletic and when diving an overfilled LP95 (essentially an HP120)... it's not too large and the extra gas is always welcome.

Thanks for the idea - I'll have to see if I can rent these HP steel tanks locally before purchase. Cheers

 

[Flashgun66]

You should try and borrow a 120 and dive it some first. I have a 100 and a 120, i hate the 120, way to long and heavy. I love my 100 is crazy how different they are.

Thanks InWay2Deep I'm really curious about the tanks and yes I should give them both a try. Great to hear your preference in tank size. I've got to stop thinking about it and go diving!

 

[73diver]

Hi,

I’ve completed a solo course and enjoy the freedom of taking pics at my own pace, but would like to increase tank size. I shore dive with a slung 40, and a single aluminum 80. Leaving a reserve in my main tank has been leaving me a bit limited. So .. lately I’ve been diving using my older back mounted al30 as the reserve (attached to the 80 with a bracket), and using my main al80 as normal ending dive with 500psi., while still slinging the 40 - so three tanks. Really would like to upgrade to a single larger steel tank and leave the 30 at home. I also would like to stick to one tank on my back and the slung 40 configuration. My concern is reserve volume in the main tank.

I’ve never dove steel, but the 100 looks shorter, and the 120 longer/heavier.

I’m 6’1”, 215 lbs. , SAC rate .45 ft3/min.

Do you think 20 ft3 of air reserve is enough in the steel 100 (using around 80 ft3 for a dive)?

What about following the rules of thirds?

If I dive with the 120 + slung pony, I could use 100 ft3 for dive with 20 ft3 as reserve, or 90 ft3 for dive and 30 ft3 as reserve?

Looking forward to your thoughts.

I’ve been doing solo for about 5 years and sidemount technical before that. Sidemount is my preferred setup for solo. When solo, I limit myself to no-decompression limits and seem to consume about 80cf per dive regardless of depth (deeper depth greater consumption and shorter stay). With my sidemount 85’s, I’ll consume 2/3rds of right tank and 1/3rd of left. For a “two-dive” boat trip I switch the left tank. If I’m diving 72’s I’ll need to change both tanks between dives. If I dive solo backmount, I use a 100cf and sling a 40cf pony. I used to carry a 120 but found that I didn’t need it. The idea of “thirds” I learned as part of technical diving where planning deco with a buddy (who’s equipment may fail) is important. As a public safety diver which is mostly solo diving, I carried a 100cf with backmount 40cf, with a switching valve on my waist, full face mask, etc. For recreational backmount solo, I prefer slinging the 40 with the valve on, riding under my left arm. I use my solo setup even when diving with a buddy. If my buddy prefers, I move the pony regulator (yellow faceplate and hose) to a yellow retainer on my shoulder.

 

[LCoolio]

I'm 6'3, with long legs, and used a Worthington HP120 as my single tank for a while. I liked it because it sat at a nice height on a table, and moved weight lower on my back to stabilize my light feet. I use them doubled now, and still like them for the same reason. But I agree, if you can try an assortment, do it.