2nd AL80 or Al40 - That is the question...

Newly certified BOW diver and I have one AL80 tank. Looking to maximize my diving time (dives) per trip, so would I be better off purchasing another Al80 or get a AL40 for the future when I get into more tech diving?

I might add that I am very interested in wrecks, am very into DIR style of diving and rigs. I am alos interested in Nitrox in the future, Wreck and Advanced OW courses - or maybe even a DIRF course.


What woukd you suggest?

Most of my diving friends are NOT DIR and will not be carrying twins, etc.

Not sure what would make the best sense for my money..

From my experience I think you will want tanks with a higher capacity than 80 cubic . I recently got back from my first 100+ fsw wreck dive trip to North Carolina so my experience is limited, but there was not a single diver on the boat diving with less than 100 cubic feet, either 100 or larger singles or doubles.

I think the key to determining tank size is to calculate which you will run out of first gastime or no decompression time, so as to safely maximize the amount of bottom time. If you’re thinking about Nitrox don’t forget to use that in the equation.

For example:

No Deco Time

Depending on the table, diving EAN 32 at 100 fsw allows about 30 minutes of no decompression time.

Gas Time

30 minutes of a SAC rate of 0.7 at 100 fsw requires 84 cf of gas. And this does not include the gas required to ascend, for the safety stop, or any margin. This is well beyond the capability of an aluminum 80, so you would end up surfacing well before you reached the no decompression limit.

Solution

More air capacity, either a larger single or doubles.

On the trip to NC I borrowed Pressed Steel High Pressure 120s, fell in love, and have since bought two. In addition to the additional gas capacity the improvement in trim is remarkable. As compared to an aluminum 80 it allowed me to take 8 pounds out of my integrated weight pouches and now not only is that weight better aligned with the lift of the air bladder but I can adjust the location of that weight by shifting the tank up or down.

Mike

Being from NY, you'll eventually find yourself in a drysuit and wanting double LP steels. A lot of people like AL40's for deco bottles, but I carry an AL80 of 50% and it lasts two dives. If you plan on diving wet, you'll want double 80's. When you find yourself going dry, you can get double 104's and break apart the 80's to use as deco or stage bottles.

Also, forget the other classes and get into DIRF as soon as possible. Stingray Divers in Brooklyn should be able to help you out with a DIRF class. After you master the DIRF skills, go onto Tech 1 and you'll be ready for the tech stuff. It only takes two classes, and you'll be where you want to be...if you can cut it.

Good luck,

Mike

Thanks Lost Yooper,
There is a DIR/GUE shop / Instructor about 118 miles from me. I am in Oneida, NY - he is in Binghamton, NY. Bob Sherwood - GUE endorsed Instructor. I need to log 25 dives in to get to DIRF.

Like many others, I'm sure I'm going to suck when I get there for that..but thats OK. In doing so, I can learn....

I want to go on to do much shipwreck diving up here, then in Fla in 3-4 yrs when we relocate. Right now, I dive wet, and just can't afford to go twins, Explorer wings and such after just outfitting myself on Pioneer's, SS BP, single Al80, etc.

I want to USE what I have first and master these basic skills, get osme OW experience down pat, before I launch myself into the 'plastic' C-card game...

Right now, I need EXPERIENCE.

Thanks,

You're lucky in that you have Bob so close to you. Take advantage of him as soon as you can.

Mike

I will!

WreckWriter spoke and the people listened...
I think a diver should have 100 dives (others may feel this number is too high) before going to doubles and/or decompression diving.

Click to expand...

After my own experience of just crossing both of these threshholds, I think you're right on.

There's so much going on with managing doubles and staged decompression diving that the diver really does need to have all of the basic stuff down so it's "instinctual". And the only way to get there is to dive.

Now I just gotta get out there and keep practicing!

For many the number 100 may be too low. Whatever the number is you should have a bunch of experience and a real good handle on the basics. It is hard to manage 3 gases, shoot a bag, hold you depth ( manage staged ascent), watch your buddy and handle the little difficulties that come up if you have to work to manage your buoyancy or equipment. Before you get to serious about tech diving all the skills that most never master you should be able to handle in your sleep. Don't rush. Don't let anyone rush you. There is lots of great diving above 130 ft. BTW, did I mention that I agree with WreckWriter. I aagree with Yooper too. However, there are other classes that can provide valuable experience and fun (don't forget fun) with the right instructor of course.

Tom....

My apologies, but I unintentionally screwed up your post above. The words that are there under your name are mine. It seems I accidently hit the "EDIT" button with out looking instead of the "QUOTE" button and then added in my comment replying to your comment. And I didn't realize my error until just now.

So if you want to change it back, you're welcome to.

Again...my sincere apologies.


--Mike

(This Texas heat is making me feel like I'm narked on dry land)

Newly certified BOW diver and I have one AL80 tank. Looking to maximize my diving time (dives) per trip, so would I be better off purchasing another Al80 or get a AL40 for the future when I get into more tech diving?

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IMHO, stick to the AL80s for most of your diving since you will want to double those up later for ocean diving and they can be used as stages. On trips where you really want to stay a little longer, we usually rent 100s, 120s, whatever...since I don't use those tanks that often, I usually rent them from the shop/boat. Once you have a couple dives under your belt you won't really need much more for recreational diving depths. My buddy and I got comparable bottom times to all the big tankers last weekend on AL80s off VA beach....once you get your underwater comfort, trim, and buoyancy squared away, you won't be using as much gas as those other yahoos anyway.

I don't own anything other than AL80s and I don't really plan to anytime soon (until I need a 70' bottle and I may use an 80 for that too).