New Doubles

[jgarysmith]

Hey Friends,

I am going to be taking advanced Nitrox and Deco procedures classes over the winter and will be buying doubles. My current tanks include 2 PST HP 120's and 1 HP 100, as well as 19CI pony. Would the 120's be way too much to handle? If so, I will probably buy 2 100's.

I dive wrecks in Va and Nc. Usually the Proteus, Morgan Etc. I am just looking for more bottom time as now I am surfacing with about 1,000 pi on dives to 125 feet on Nitrox. Seems like I am wasting a lot air. Not in a dry suit yet, but that will be next.

Most people seem to suggest LP 95's or 104's. Why, I liike the size of the smaller Hp tanks and it looks like LP tanks are faaling out of favor. Is the 100's the way to go?

Or, since I do not plan od dives over 150ft yet, would using my 120's as a single and maybe carrying a stage bottle work?

Comments or suggestions

 

[Hoosier]

I am sure there are more advanced memers though. I have used PST 119s and AL80s for the same class. You dived with your doubles, didn't you... You need to get a deco bottle, at least 40cf.

Oh~~` I see your point. The steel doubles with wet suit isn't preferred for that class.

 

[pickens_46929]

Hey there,

So there's a lot to consider here... I'll go from my perspective and experience... What's my perspective? Rec diver transitioning to doubles in the past year... not the biggest guy in the world either... cold water diving in quarries mostly... working on the Great Lakes.

So... LP vs. HP...

a) need to watch the (+) rating regardless of either... once you hydro w/o the (+) you're losing 10% of the fill... and most of the newer tanks LP or HP are shown with their initial service pressure (+)... so HP 120's (depending upon mfg)... may get your 120 cu.ft. but only at 3500 psi (3180+10%)...

See http://66.225.239.89/~scuba/tdl/nstore/pub/tanks.html?zenid=75c60c5363fce3bfbc9c0768c73cf8f9

b) size

double 120's for me? nooooo really difficult... figure dual 120's with deco bottle (40 AL) + travel gas (80 AL)... yowza...

c) sac

I can do .4 cfm... or I can do 1 cfm... once I get comfy I'm an air fairy...

d) depth

For short deco dives... dual 120's would be overkill for me... for longer deco dives or deep dives or trimix... I've got deco bottle and travel bottles... again what do large duals get me? maybe I should carry another 80AL of travel gas

e) buddy...

My buddy's sac is 0.6 cfm... 120's means plenty of gas... for him in case of emergency... if he dive's 120's what about extra air for me? ... so we planned it to have similar usage and turnaround of our duals...

....

So what did I end up with? Dual 85 LP Fabers...

 

[jgarysmith]

I have a lot of divers suggest 85's . Odviuosly a good choice. My dive buddy has about the same SAC rate as me. My tanks are Pressed Steel, the 2 120's. They do not have a plus rating. The are 3442, and my 100 is a Genessis made by ASAHI and it is rated 3500.

 

[Tamas]

The HP120's are tall tanks (28"), but skinny like an AL80. They do weigh a fair bit but not that bad.

I have LP98's and I find them too short when wiggling into them, but I guess everybody is different in that sense.

If you already have 2 120's might as well band them up and take them for a dive, then you will really know how they feel above and below water.

The HP100 are a nice size and if they will provide you with enough air for the depth you are doing then go for it.

It comes down to your size and the size of the tanks. Other thing you have to keep in mind is the type and depth of diving, those 85's might not be enough for a deep dive.

 

[JS1scuba]

Hey Friends,

I am going to be taking advanced Nitrox and Deco procedures classes over the winter and will be buying doubles. My current tanks include 2 PST HP 120's and 1 HP 100, as well as 19CI pony. Would the 120's be way too much to handle? If so, I will probably buy 2 100's.

I dive wrecks in Va and Nc. Usually the Proteus, Morgan Etc. I am just looking for more bottom time as now I am surfacing with about 1,000 pi on dives to 125 feet on Nitrox. Seems like I am wasting a lot air. Not in a dry suit yet, but that will be next.

Most people seem to suggest LP 95's or 104's. Why, I liike the size of the smaller Hp tanks and it looks like LP tanks are faaling out of favor. Is the 100's the way to go?

Or, since I do not plan od dives over 150ft yet, would using my 120's as a single and maybe carrying a stage bottle work?

Comments or suggestions

The ideal set of tanks would be

Faber or Worthington Twin LP 85s or
Faber or Worthington Twin 3442 psi 100s.

They are the perfect size for what you are doing.

Check our tank chart and then our prices.

http://www.techdivinglimited.com/pub/tanks.html

Cheers

 

[Tom Winters]

The HP120's are nice twinned, but if you're a squatty body, then you're going to get your butt whunked a lot - taller than 5'11" and you should be ok. I still like the LP85s - I got four of them for much less than a pair of twinned 120s would have run me. The Faber boots leave marks on my boat deck though, and because they're only 7" in diameter, I can't replace the tank boot. No problems with the Worthingtons though.

 

[Derek S]

I'm quite disturbed that virtually no one in this thread mentioned that diving steel doubles with a wetsuit is a very bad idea. Especially considering one poster is an instructor and another is a shop owner.

I assume you're using a 7mm wetsuit. Let's figure that you need 20lbs of ballast for buoyancy, your PST 120 is 10lbs negative. Are you prepared (or even able) to swim up that rig from depth if you have a malfunction with your BC or a catastophic gas loss?

Granted, your buddy is your redundant air source, but why put each other at such a potential disadvantage if you don't need to?

jgarysmith - I advise using your normal setup and sling a stage. That way, you can jettison the stage if need be, and you will need it eventually once you do move to doubles.

That being said, once you get into drysuit diving, I would suggest AL80s or PST 100s for doubles.

 

[JimC]

One pair of Luxfer AL80's.

These are probably the best intro doubles you could get. They are light weigth, easy to use, work with a wetsuit.

If you hate doubles; they sell off well
If you love doubles; they turn into perfect stage bottles, you can reuse the manafold on your next set and your only out a set of bands that ether fit you next tanks or sell of in a heart beat.

 

[jgarysmith]

Derrick,I agree on the Dry suit comment, but I just find it hard to dive in 80 deg water in a dry suit. Most of my diving will be off Hatteras and Morhead. And, your slinging suggestion is a great idea.

Joel, thanks for the suggestions. I am leaning towards the 3442 100's.I will probably buy from you since you have a great reputation. We are not seeing much Worthingtons in our area so I am not as familiar with them as PST's. Nobody can PST around here.

Thanks for the replies