Options for sail boat: Compact AL cylinder purchase

[charlier]

Does anyone have suggestions for purchasing compact scuba tanks that we can store on the deck of an open ocean sail boat. For context, we will be open ocean sailing in remote regions of the Indian Ocean for scientific sampling in tropical waters (yes we have permits etc). We want to purchase 4 AL tanks and a portable Bauer compressor. Most of my experience is with 11 or 15 liter AL tanks, I was told that one can purchase smaller (e.g., ~9 liter) AL cylinders with thicker walls that will accommodate fills that are greater than 200 bar. I have not heard of such cylinders. We want to save space and wt. on the deck of the boat.
thanks in advance, charlie

 

[halocline]

I'm not sure what tanks you're talking about, but at least in the states I have never seen a high pressure AL tank other than the huge AL100s that go to 3300 PSI. Maybe there's something new? There is more of a selection and size variance with steel tanks, so you might want to look at those.

However, I would first consider the diving you'll be doing, depth, dive time etc...and choose tanks best suited for that. There is not going to be much difference in physical size or weight. That said, the most compact tanks I know of are the old LP72 steels; 26 lbs dry weight, 6.9" diameter, and with a slight overfill, the same gas capacity as an AL80. But I have no idea how you find those in the far east.

If tank height is the issue, and your dives are shallow and short, maybe AL63s would be a good bet for you. Those are not bad to dive with at all, and they're easy to lug around.

 

[tbone1004]

how deep are you going? It may be easier and cheaper to dive with a hookah if you're staying relatively shallow. Other than that there's no really compact AL cylinders that offer a decent amount of gas. LP45's from PST are probably my first choice for that depending on how much gas you need.
Brownies third lung is good for 60ft for 4 divers or 90ft for 3. I'd start there.

 

[runsongas]

do you want them to be light and short or just light? steel 72s aren't very compact, but are pretty light. if you want a more compact tank, the 232 bar steel tanks are another option such as the faber fx71/80.

 

[tbone1004]

or skinny....

 

[JohnN]

Does anyone have suggestions for purchasing compact scuba tanks that we can store on the deck of an open ocean sail boat. For context, we will be open ocean sailing in remote regions of the Indian Ocean for scientific sampling in tropical waters (yes we have permits etc). We want to purchase 4 AL tanks and a portable Bauer compressor. Most of my experience is with 11 or 15 liter AL tanks, I was told that one can purchase smaller (e.g., ~9 liter) AL cylinders with thicker walls that will accommodate fills that are greater than 200 bar. I have not heard of such cylinders. We want to save space and wt. on the deck of the boat.
thanks in advance, charlie

How about this?
[h=1]

[/h]

[FONT=Verdana,Arial,Helvetica,sans-serif]This is a special cylinder manufactured by Luxfer. It is a composite cylinder manufactured of both aluminum and fiberglass. It starts out as a standard scuba 80 cuft cylinder. Hoop-wrapped fiberglass and resin is added to strengthen the side walls. This allows for an increased service pressure to 4350 psi and a capacity of 106 cubic feet. This cylinder falls under DOT Special Permit 12479. Requirements of SP12479 is a hydro re-test each three years and a fifteen year service life. The inlet to this cylinder is unlike most other scuba cylinders, utilizing 7/8" x 14 UNF threads (a smaller hole). The choice of valves is restricted to a 300 bar DIN valve with the correct 7/8" x 14 UNF threads.[/FONT]

 

[1bubbleoff]

I second the steel LP 72...big fan..I own 11 of them, 2 sets doubled the rest singles. Another option if ya want COMPACT....steel HP 80's.

Just a thought..

Bubs

 

[charlier]

how deep are you going? It may be easier and cheaper to dive with a hookah if you're staying relatively shallow. Other than that there's no really compact AL cylinders that offer a decent amount of gas. LP45's from PST are probably my first choice for that depending on how much gas you need. Brownies third lung is good for 60ft for 4 divers or 90ft for 3. I'd start there.

Thanks for the suggestions. The owner of the boat used to use a hookah, but decided to swap out it out for a portable compressor and tanks. We will be diving in a warm water setting, on the Chagos Archipelago. We will dive in teams of two or three, at a depth of 30 m or shallower. We are sampling water and thin microbial biofilms. My SE Asia experience is mostly with Al 11liter or 15liter cylinders or twin Al80's. Thus, I am completely squared away for my weights with such cylinders. FYI, I use 1 kg with a light wetsuit and Al BP, 2 kg with my 2mm free dive wetsuit (custom fit, so little water gets next to my skin). Unlike my past life in California, I do not use my lead.

This is getting a bit far field, but we might consider HP80. Does anyone have any comments replacing the AL80 with the HP80.

From a diving perspective, I do not need light or compact tanks, it mostly from my conversations with the owner of the boat. The owner of the boat is concerned about space on the boat deck, thus he was trying to find out if he could purchase slightly smaller cylinders or lighter weight that could be filled in excess of say 200 bar. We are also traveling from Phuket to Chagos Archipelago (avoiding the Maldives on this trip) and onwards to the Seychelles, so it nice to have standard cylinders that can be inspected and tested. I have never sailed on any long long-distance legs, so it will be an experience for my wife and I.

I have only heard anecdotal data on the Luxfer Limited 106. It seems that corrosion is still an issue, with water percolating between the fiberglass wrap and aluminum. It is perhaps more fragile than aluminum.

One more question - I assumed that the best compressor is a Bauer portable compressor for reliability and finding spare parts. thanks, charlie

 

[tbone1004]

I prefer Rix for boat diving, but parts aren't cheap. No oil and can be mounted in any orientation anywhere on the boat. This is what spec-ops uses in the military.

HP80's won't save any deck space, only deck height. The only tanks you can purchase new that will save you space are Faber LP-50's and then pump them up to 3600psi which is what we do in cave country. Saves 2" diameter per tank and holds almost as much as an 80 when filled to 3600psi.

 

[Rich Keller]

Without knowing the specifics of how you are conducting your diving operations it is hard to give you a firm answer. I am assuming that if you are only collecting samples that your dives are not going to be too long so I would go with either a steel HP50 or the old LP72. The weight difference is not much in either case but the 50 will be narrower then the 72 for storage. The other thing to consider is the life of your compressor and how much more often you will need to service it filling tanks to 3600psi vs 2400psi that the 72s need. If I had to pick between the two I would go with the 72s as they will give you more air and not be as hard on your compressor. I would recommend the Bauer primarily because the parts are more readily available.

PS: There is one other advantage to the 72s that I would not normally mention to anyone but might work for you in a remote area with your weight considerations. You could bring a doubles backpack and bands for the 72s and connect them with a suicide bar if you need to go deeper or stay longer. This is not to be done lightly as you need to get this exactly right or the bar earns its name. The same thing could also be done without the bar by putting a reg on each tank like SM divers do.