Are 100cu/ft AL tanks common in rental shops?

[Insta-Gator]

If you plan to go to Grand Cayman, Lighthouse Point has AL 100 tanks ... or at least they did in Dec 2013.

 

[archer1960]

Not directly answering your question, but somewhat related. I recently purchased a steel HP 133 for similar reasons you're looking at AL 100: worried about being the "weak link" on local dives, limited selection of Nitrox tanks and even more limited selection of DIN valves (I use Nitrox and have DIN regulator.) All combined, it made a lot of sense to get my own tank.

As for the size, 133 is the first size where they increase diameter and decrease length, so it's just an inch or so longer and equally fatter than an AL 80. Due to increase in diameter, it's quite a bit shorter than the HP 120. Also, if it gets filled to 3,000 psi it still holds quite a bit of air. Even a "hot fill" on boats that results in cold pressure of around 2700 psi gives you over 100 cu. ft. with HP 133.

From my rental experience, anything but AL 80 yoke as a rental is a gamble.

Not quite; an HP 117 is fatter, and either just shorter, or about the same length as an AL80.

 

[gopbroek]

AL100 are not common in the Caribbean. Many shops have 1 or 2 AL100 but they end up being closer to 90's as they are short filled to 3000psi not 3300psi.

True, but on the other hand I have witnessed inexperienced divers with high air consumption rates strap on short filled AL100's @ 3K and their air consumption rates drop substantially. Most people are considerate of their dive buddy (often a spouse) and the idea that they are going to 'spoil' their buddy's dive by going up early makes them even more nervous and causes their air consumption to increase, a negative feedback loop. Often when they think they have an extra 20% they seem to relax and their actual consumption rate drops, kind of a 'placebo' effect.

 

[tlj3071]

One of my sons-in-law (son-in-laws?) was also a "hoover" in the beginning. His solution was to dive slightly higher (and very slightly behind) his buddy in the water column (7-10') - this reduced the cu. ft.-per-breath, and thus increased his dive time. His wife and buddy (my daughter) was generally able to finish her dive more or less normally (i.e. without getting back on the boat with 2000 psi still in the tank). The relatively small difference in depth didn't affect the buddy relationship and he always had his buddy in sight since he was looking down from slightly behind. As he got more comfortable, his SAC decreased such that this technique was no longer necessary. He still uses more air than his wife, but only because she is quite small and just doesn't use much air.

 

[ColoDale]

AL100's are common in Cozumel. The fills are good. Everywhere else I have dived, AL80's were the norm however that doesn't mean they don't exist - just not with the dive ops I used at the locations I have been. You would have to ask the dive shop you use for AL100s or steel tanks to be sure.

---------- Post added December 3rd, 2015 at 11:03 AM ----------

AL100's are common in Cozumel. The fills are good. Everywhere else I have dived, AL80's were the norm however that doesn't mean they don't exist - just not with the dive ops I used at the locations I have been. You would have to ask the dive shop you use for AL100s or steel tanks to be sure.

 

[IVC]

Not quite; an HP 117 is fatter, and either just shorter, or about the same length as an AL80.

I had to look it up and you are correct, HP 117 is the first that is fatter and it is a bit shorter than an AL 80. HP 133 is the one that is marginally bigger (all dimensions) than an AL 80, but holds significantly more air even if not filled to full pressure. My main concern was length and HP 120 is quite long, so I was happy to get HP 133 which trades length for girth.

 

[halocline]

I've seen rental AL100s in the caribbean, I even used one once on a cenote dive years ago. I think it was the worst tank I've ever dove with; bulky, floaty, weighs a ton on land, just overall bad. If you are looking for a bigger tank, I strongly suggest you ask for a steel HP100 or even 120. Some of the cozumel ops have them.

Another strategy would be to visit a place like Bonaire, where there's unlimited shore diving, so it doesn't really matter how quickly you go through air. Your wife could use a AL63 in that situation. Those are much nicer to dive with than AL80s anyhow.

 

[drrich2]

I learned a great tip from a former navy diver. I sat watching TV with my mask and snorkel on. First I lasted about 20 minutes, but as I learned to relax I soon was up to watching full length movies with my mask on breathing thru my snorkel. It sounds funny, looks weird but holy cow did my SAC drop nearly in half. Where I use to get about 30 minutes out of an AL80 at 80' I nearly get an hour out of an AL63 now (I am still a big guy).

Thanks for that! Might have to try it sometime. I'm a 'reformed air hog' and would like lower consumption to come more naturally.

When U.S.-based divers say 'Caribbean,' I tend to take that to mean regional warm water diving, which depending on time of year can include Florida, North Carolina and so on. A few places I've found bigger tanks...

1.) Cozumel. I'm told 3 operators offer 120 cf steel tanks; Living Underwater (low pressure steel), Aldora (high pressure steel) & that other one (I can't recall the name of for sure).

2.) Rainbow Reef Dive Center in Key Largo has 2 100 cf aluminum tanks when I went back in 2013, first come first served, & I reserved them for the week.

3.) When I did a guided Cai dive site dive in Bonaire with Bas Tol, he suggested I ask for one of the big tanks at Buddy Dive Resort (where I was staying). I had no idea they had anything bigger than an 80, but yes, they did. I think it was a 100 cf AL, but can't promise. Got a nice, long dive out of it.

4.) I was provided a 100 cf AL tank on Sun Dancer 2 live-aboard trip out of Belize last May.

The above destinations (including Bonaire; don't mess with Cai if you're not with Bas and early in your diving) are appropriate for a fairly new diver (but request big tanks well in advance, and don't assume you'll get them in Bonaire otherwise, or in quantity. I don't recommend Bonaire for big tanks unless you get some special arrangement). I've got a couple of other options for when you're a bit more seasoned:

1.) Jupiter, Florida, with Jupiter Dive Center. They provided 120 cf steel tanks, no problem, and I dove Nitrox EAN 36. It's deep drift diving, so plenty of gas & longer bottom times on nitrox are a plus.

2.) Morehead City, North Carolina. Olympus Dive Center provided 120 cf steel tanks & I dove Nitrox EAN 30. Deep wreck diving, where volume & nitrox are a plus.

Getting past warm water considerations, checking into the California dive scene (I have not dove California as yet), I found 95 cf steel tanks for rent, but IIRC 120 rentals would be hard to come by. Cold water diving, some deep & some divers using dry suits, seemed odd to me, but that's my best understanding of it so far.

Richard.

 

[Shasta_man]

I'd also suggest that you are really looking at this the wrong way. First, seems like all women seem to make air rather than use it, so if she is smaller and a woman, there is probably always going to be a gap greater than zero between you, but you can improve towards her. As a new diver, you'd be surprised at how much air you save (or use) by controlling your breathing particularly at the beginning of the dive and most importantly by getting your weighting exactly right. At the beginning of the dive, you are shallow so every breath takes more volume of the tank and you are typically breathing faster from excitement as well as finning down to your destination. Proper weighting saves a surprising amount of air as well because you are not adding and dumping air out of your BC all the time like you tend to need to do when overweighted. You tend to dump it all then add a little at the bottom and then just a little adjustment here or there while overweighting tends to cause you to keep overshooting or undershooting how much air you need and you keep bobbing up and down. When weighting is right, it just feels so much easier. Check your weighting at the surface at the end of the dive with 500 lbs left. With a normal breath of air and an empty BC, you should be floating so the water level is right level with your eyes. You'd be surprised how much a pound or two can make positively or negatively. Fix that on dive one and you will be good for the rest of the dives. Make sure that you did spend some time at depth to get your suit compressed as right out of the suitcase it tends to have more air in the material and be more buoyant. That also applies to setting your weighting after buying a new suit.

 

[scubafanatic]

AL 100's are sometimes available, I've dove them off Carribean liveaboads and in Cozumel, but I did check ahead for availability. While, in an ideal world, I prefer HP steels, many dive ops/boats don't offer them as they are more expensive to buy and they rust out fairly quickly in an abusive, humid, salty environment, so the AL 100 (which cannot 'rust') is the next best option. I never had any trim issues diving AL 100's, once underwater I didn't notice any difference between AL 80 vs AL 100.