Doubles Recommedation - New Tanks

[The Kraken]

Thanx, Doc !!!
I'm familiar with the limits of nitrox and the MOD's.
One thing that I do want to incorporate in the doubles set up is the ability to use a single tank to accompany my wife on recreational dives and take advantage of the extended NDL's that nitrox offers to the 132 mark.
The combinations and permutations are astounding !!!! I'm lost in a sea of aluminum and steel devils !!!! HELP ME, HELP ME ! ! ! !

 

[Don Burke]

My first set of doubles were AL80s and it worked out so well I just replaced the cylinders with brand new ones.

There is always something I can use an AL80 for, so there is little chance a change in my diving will make them paperweights.

I now have two sets of steel 72s, and a couple of 112s that I can double on short notice, but the double 80s will always have a home. They are just too handy to be without.

At this point I am glad I did not spring for 104s. I still might get to where I need them.

 

[The Kraken]

Don,
I'm a tad concerned about the positive buoyancy characteristics of the Al 80's as I'm still diving wet. Hitting the 18' mark in a 6.5 doubled up with hollow Al 80's generates a wee bit of apprehension.

I've been eyeballing the PST HP 80's and 119's. Do you feel that these are viable options?

 

[simbrooks]

One thing that I do want to incorporate in the doubles set up is the ability to use a single tank to accompany my wife on recreational dives and take advantage of the extended NDL's that nitrox offers to the 132 mark.

One thing you might want to consider is keeping the doubles banded and manifolded together, they are a pain (easy enough, but its a chore to do it all the time) to keep pulling apart and putting back together. So just keep your doubles doubled and keep using AL80's for singles for now, even if you cant get all the advantages of nitrox at all depths.

I'm a tad concerned about the positive buoyancy characteristics of the Al 80's as I'm still diving wet. Hitting the 18' mark in a 6.5 doubled up with hollow Al 80's generates a wee bit of apprehension.

Wear some weight ditchable and some nonditchable, that way you can drop if you need to, but not drop it all and shoot to the surface - if that is your concern. I currently wear all my weight in singles as "non-ditchable", but i can pull it out in a few moments.

I've been eyeballing the PST HP 80's and 119's. Do you feel that these are viable options?

The 80's are really short, even compared to the 119's - i would think the 119's would be a reasonable option given your size etc, but i would recommend the drysuit, or back up buoyancy if you are doing it in the salt. Almost all the PST tanks are neutral at 0psi, so being excessively negative isnt as much of a problem as it used to be with many HP tanks, many LP tanks are postive when empty, so even more considerations there.

 

[OneBrightGator]

I'm going to side with the good Doc on this one.

Go with some AL 80s to start off with, diving wet and I assume new to diving in doubles they will last you a long time for not a lot of money and when you go through with your mix class you can break them down into stages, they certainly won't go to waste.

 

[Doc Intrepid]

One thing that I do want to incorporate in the doubles set up is the ability to use a single tank to accompany my wife on recreational dives...

You should set up your own doubles, preferably with the help of an experienced buddy or the shop where you bought the bands and manifold, etc. Inspect your tanks yourself. You'll soon see that its a pain in the butt to get them set up exactly right. Once done, you don't want to be pulling them apart all the time. Get them right then leave them alone. If you want to dive with your wife who is wearing a single cylinder, have at it - but do so in your doubles. Getting used to them, the valve drills, the trim, the whole thing, requires lots of practice. If you're transitioning, plan to dive in them all the time. (Which is another reason not to get a set of heavy-as-hell steel pigs that you have to hump all over.)

I'm a tad concerned about the positive buoyancy characteristics of the Al 80's as I'm still diving wet.

Then get neutrally bouyant aluminum 80s. Luxfer makes some nice ones. Thicker walls, so heavier, pumped to 3300 psi. I have a set of these, and they are excellent tanks. Remember also that you weight yourself to trim out with your doubles empty. There are many options. I use a 10lb Halcyon V-weight with my aluminum doubles (and a 6lb backplate), with my sets of 130s I simply leave off the V-weight. You can use trim weights, channel weights, plates that bolt to your backplate (Tobin has some nice ones), etc. - but you'll weight yourself to trim out empty. No worries on that end. Its just that in a wetsuit you'll be heavy on the front end of the dive (when it compresses at depth), thus need more gas in your wing, thus more drag, thus more energy, etc. etc. You want to think about the front end, not the back end.

I've been eyeballing the PST HP 80's and 119's.

Try'em before you buy'em. 119s are not bad tanks, but could get interesting in the ocean in a wetsuit. I owned a set of these. They stood me on my head. I went to 130s. Much better. Depends on many factors. Best is to borrow different sets and try them out in an open water setting. Generally speaking, get a drysuit BEFORE you buy steel tanks. Why? Because the drysuit you buy and the undergarment you select plays a huge role in how the tanks trim out on you in the water. Its a system. The parts all have to work together.

FWIW

 

[matt_unique]

I would like to request, from those of you experienced with doubles, what you would recommend based on the following parameters:

1: New Tanks
2: Mixed gas
3: Use: Recreational, wreck penetration, max depth 187 FSW
4: Physical size - 5'7" 160# avg SAC .39

I've come to the point wherein I've enlisted training to advance into a higher level of diving and would like some knowledgeable input. It's seems to be a bit difficult to get objective input from the LDS's. I'm sure $$$ has something to do with it.

If you choose to respond, please use the parameters set forth to make your recommendation.

Thanx . . .

Safe dives . . .
. . . safer ascents!!!

The AL 80's get my vote as well. Plenty of gas considering your SAC rate and you can use them as stage bottles in the future if you ever want to upgrade to steels. Way less costly to get into them as well. I use double alum 80's on my back and an alum 80 as a stage bottle. I use the alum 80 stage bottle as my back bottle when diving from shore in the winter. Doubles for the rest of the year off the boat.

--Matt

 

[DA Aquamaster]

AL 80's are a good choice for the diving you are describing. Assuming you are advanced nitrox certified and doing accellerated deco with one or 2 slung 30's or 40's, a set of double 80's will provide enough air to do 20-25 minutes at 170 ft with a 1/3 reserve (and enough in reserve to do a longer deco on air if required.)

Personally I think 187 ft is way too deep on air, with 150 ft being about the maximum practical limit and 170 ft being something I would only even consider in optimum conditions.

Steel 72's are also a good way to go, as they are neutral when empty and also 3-4 lbs lighter each than AL 80's so you end up carrying a lot less weight. You'd need a 20% overfill (2700 psi) to get the same capacity as an 80, but with a 10% overfill, you are not giving up that much (6 cu ft per tank).

 

[matt_unique]

....Personally I think 187 ft is way too deep on air, with 150 ft being about the maximum practical limit and 170 ft being something I would only even consider in optimum conditions....
QUOTE]

I most notice the narcotic affect when I descend below 140'. I decided 160' would be my absolute max depth on air/leaned nitrox. It is interesting to descend straight down past 140' and notice the change. I make a point to cycle through (grabbing) all my valves and checking air and time more frequently at these depths. I would not personally even consider anything past 160' on air. My "deep" dives have been in NE so I don't know how I may feel in a warm water/good vis environment.

--Matt

 

[The Kraken]

OK, bubble buddies,
I've pretty much settled on neutral Al-80's, but I'm going to throw one more thing at ya and then leave ya alone.

I've the following options, each of which is immediately available. Keep in mind each is a turn key set up, bolts, bands and manifold:

Neutral Aluminum 80's - $660
PST HP E-80's - $660
PST HP E-119's - $760
PST HP E-130's - $800

Any changes in your recommendations?