Aluminium 100's, Steels, and Breath Control...

[scrubbo]

So... I'm a big guy, and I've been an air hog ever since I started diving. And my Fiancee just started diving herself, and already she's using way less air than me. (She's on Dive 15, I'm on dive 80ish)

She has recently purchased everything except for her tanks from the LDS and ScubaToys, and is really enjoying diving. Today (after I convinced her not to swim like a madwoman at full speed... I couldn't tow the dive flag fast enough to keep up with her) she and did a dive at 15-30ft (lake diving, ain't it grand?) for 68 minutes. We both had AL80's. She had 3100 PSI, I had 3000. At the end of the dive, I had 600 PSI and she had 1200. Obviously I'm sucking gas quite a bit faster. 2400 PSI vs. 1900 PSI used is a pretty big difference. And I was working on my breathing on this trip. :) When I'm not paying attention to my breathing, I suck air like crazy. Slow, deep breaths was what I did.

So since she hasn't gotten tanks yet, I was thinking of giving her my old tanks and trying to up the cf of air I carry to try and try and equalize our bottom times. Of course, going on trips we'll always be using the AL80's that every outfit uses, but there's enough local lake diving and she's shown enough interest (We've gone every weekend for the last 4 weeks and she did the OW class for a month before that) for me to think that tanks are worth getting for her.

So, that means either AL100's or Steel. I know steel has a much more negative boyancy. Diving in the lakes, I don't think it'll be a big deal as being well weighted at the surface makes me a couple of pounds heavy at 30 ft. Diving the deeper quarrys and great lakes, however, makes steel tanks more worriesome. I have my dry suit rating and own a drysuit and even enjoy diving in it (I like the boyancy control with the DS better than with a BCD, really.) so it's really not a problem. If my BCD goes down, I can michelin man it enough to get off the bottom.

However, the AL 100's are cheaper, and the boyancy characteristics looked closer to what I'm used to on a tank (even if they're heavier to lug around.) But it looks like to get the extra CU out of it, you need to be over the standard filling PSI. 3300 PSI instead of 3000PSI. Do most LDSs fill tanks that need a higher pressure? I'm just worried that most of the places I run into will only fill to 3000 PSI and if so, will the added cost and effort really give much more air?

Does anybody run AL100s?

[jonnythan]

No one I know who has bought Al 100s has been happy with them.

The PST E7-100 and E8-130 are great tanks.. particularly the former.

[ScubaSarus]

The steel 98's or 100 are great tanks and providing you use or will require some weights you should have no problem with buoyancy. If you are in warm water were you use no wetsuit and need no weights then the tank can be too negative to use safely.

[spectrum]

I get from your post that you're OK with the offset between her usage and yours. Odds are it's phyisiology and there's nothing you're going to do about it. The gap may close but genrally women will do better on air consumprion.

AL-100, IMO that's just plain evil. I would think that when diving in Wisconsin you will have enough exposure protection that even the residual wetsuit bouyancy on a fairly deep dive will leave you fine with something like a PST E7-100. Do watch the specs since there are some cylinders that are exceptionaly heavy.

The lower mass when you drop some of the ballast will help close the consumption gap.

Can you get good fills? "Usually" I''d say. We're diving 4 E7-80s and usually get nice fills. There are some shops that just pump them hot and that's it. We can't always wait for cooling and a top-off. Then again I see plenty of AL-80 buddies show up with 2700, 2600 PSI so it's all relative. Nearly any shop is banking air above 3000 so it's usually available. Even with a short fill an E7-100 will give you an edge. At 3000 PSI you have 87 CF if I remember right. Remember that if you give her your AL-80s she only has 77.4 CF on a perfect fill.

Do your homework and you should improve your situation.

Pete

[Firefyter]

No one I know who has bought Al 100s has been happy with them.

The PST E7-100 and E8-130 are great tanks.. particularly the former.


There are several of us around here who dive AL100's, and like them just fine. I've always been happy with them, and so have my friends. With that being said, the PST's are a better tank. The only drawbacks to the PST's are price and availability. If money isn't an object, and you don't mind waiting to get them, I'd go with the PST's strictly for the better bouyancy characteristics.

[jonnythan]

There are several of us around here who dive AL100's, and like them just fine. I've always been happy with them, and so have my friends. With that being said, the PST's are a better tank. The only drawbacks to the PST's are price and availability. If money isn't an object, and you don't mind waiting to get them, I'd go with the PST's strictly for the better bouyancy characteristics.
That's OK... I don't know you :eyebrow:

[PerroneFord]

Something to consider....

How is your bouyancy/trim, and how are you rigged? One thing that really causes issues is poor trim. If you're swimming with your feet down, you're causing a HUGE amount of work and drag for yourself and that will bring your consumption up. Also, if you are overweighted and swimming with a bunch of air in your BC, and stuff dragging all around and not streamlined, you'll increase drag and burn more air.

Not to say you'll be able to match your fiancee, but you might improve your diving if you haven't worked on these things already. And you might find your change to a 100cuft tank will bring you even or even make her the limiting factor.

As a quick aside, I'd be careful at this point of ending dives with 500-600 psi. Should something happen, you're cutting things awfully close. Just my opinion.

[alibee]

Spectrum, I think that we're both okay with the offset between our usage -- I'm not one to risk my honey's life just because I want more bottom time, so hopefully he feels no guilt. (Although we've now discussed having a little piggy in scuba gear as our wedding cake topper... air hog! :D )

Perrone, re: your concern -- our dive was, at its deepest, around 28' today; we spent the last 10 minutes of the dive where he ended w/600 psi at 5-8'. (Yay shallow fresh water lakes!) We were mostly trying to avoid a long surface swim in the windy, wavy lake. In any other conditions, I don't think we'd push it that far.

[Wreck]

What is your's and your fiance's SAC? It will get better down to a point. Cold water runs mine up a bit above normal, no matter whether I'm warm or comfortably cool. More dives will make you more relaxed.

Is your goal to really maximize your bottom time more or just to match up air consumption? It seems like the former. If that's the case, I'd recommend 100+ cf. 130's are nice if the weight isn't an issue for warm water diving (are you going to carry your tanks south, or rent 80's on location?). If you can't get a good fill, 130's become 113's at 3,000 PSI, and 97's @ 2600 PSI

Using a DS as a BCD..... I've been forced into a situation where that would have caused me to get bent. Personal preference for some, but not for me.

[Charlie99]

We both had AL80's. She had 3100 PSI, I had 3000. At the end of the dive, I had 600 PSI and she had 1200. Obviously I'm sucking gas quite a bit faster. 2400 PSI vs. 1900 PSI used is a pretty big difference. And I was working on my breathing on this trip.
2400psi vs 1900psi used isn't really all that big a difference in SAC. Since her SAC is lower, that's a good excuse to have her tow the flag.

If your local diving is shallow lakes, then the tanks you already have should be fine.

If you're just using this as an excuse to buy some more gear, then the HP100 tanks look pretty nice. Just be forewarned that once your fiance sees high much lighter it is, that she'll be out looking for an HP80 tank ;)

[dbg40]

Don't go nuts, generally speaking a woman will, almost without fail, best you on sac.
Just the way it is, less mass to shove through the water, and less muscle to do so = better fuel mileage!

[starpilottom]

I own a pair of AL 100 tanks and I'm very happy with them. I purchased them for the same reasons you are considering buying yours. I do my best to max my air consumption but it really comes down to a matter of size. Being 6' 3" and 240 lbs I have more water to move out of the way and more O2 burning tissue than many divers. Good technique will help close the gap as I've surfaced with more air than some divers half my size when using the same tank. It comes down to a percentage thing with you and your lady 100's should help close the gap. Also some liveaboards allow you to request 100's. Nekton uses steel 96's as standard. I do get annoyed when I request 100CF tanks and I get the "I don't know anbody who uses them response or why would you want them response" I feel like telling them that divers come in all sizes not just midget and medium and your just too cheap or lazy to look at what bigger people are coming aboard with. The ones that don't have to fly that is.

[jonnythan]

Whoa, I just looked up the specs on those Al100s...

They weigh more than my PST E8-130 steel tanks!!

[Wayward Son]

I also dive some AL100's and like them.

Why? Bc I can afford them. I want steel 100's & agree that they are superior in many ways. But they can be handed down from God on high & it doesn't make a flip if you can't pay for them, which is where I'm at right now.

I've been fortunate to snag 3 of them used. One simply took a new AL80 traded even (cost me $135 for the 80, and I was about to buy the 80 any way). The last 2 cost me $80 each with a new hydro & VIP.

In comparison, E7-100's are running about $350 each, when you can find them. Do the math:

3 used 100 AL tanks for a total of $295.
3 new 100 E7 tanks are $1050.

I'm a rec diver who mostly spera fishes. I have no technical needs that justify the extra cost of steel tanks. I prefer their size, weight & bouyancy characteristics over AL, but I can deal with the AL just fine.

Since I don't have the cash for all those steel tanks, it's a moot point. I can have & use the AL now, or I can have nothing until I can buy the steel tanks in what looks like 2 to 3 years from now. Put in perspective, those big AL tanks make me pretty happy.

[dbg40]

Steels are a tough nut to crack ($$$$!!!!) and can kill an entire dive budgett in one shot. (possibly even two budgetts) I was very fortunate to have a good relationship with my lds owner, who called me with two HP 100's he took in trade. $400.00 out the door with fresh hydros. If not for that, I would have had a tough time getting into any more new steels! I have logged a many a dive on AL tanks, and could go back to them without issue, if needed. Its not what you dive, its how you dive them ;-) Personally, I think that aluminum tanks get this sport way closer to the budget of real world divers. Wayward son is right,, you can dive AL now, or have nothing. And the diference between the two is a new Halcyon, or a sweet Apeks rig!

[Jim Lapenta]

Have two pst 80's and they are fantastic. I'm a little shorter (5'7") and the fact that they are not much taller than a 50 are perfect for me when going backwards off of boats or when doing a seated entry. Their buoyancy characteristics are what really justified the extra cost. in my 3/2 shorty an al80 requires about 8 lbs for me. the pst's let me cut that in half. It also helps in the drysuit by reducing the weight requirement from 28lbs to about 24. I also have 3 steel 72's that while not as fun to dive as the 80's still let me dive with less weight. Total outlay for them was 50 bucks each with new hydro's and vis. Our lds is replacing their steel 72's with the pst'80's,we still have al80's but I don't dive em. Plus the pst's are rated at 3442 so I'm normally getting good fills of about 3600-3800 once the tank warms up in our lake where the water is right now 91 at surface and 88 at 92ft. Some others have suggested working on your trim and technique which is cool. My air consumption has been dramatically reduced with proper buoyancy and breath control. last outing first dive was multi level altitude to 92 ft(116 alt adjustment) for 8mins then up to 50 for 10 mins then to 35 for 14 mins add 4 min safety stop with 2min ascent along bottom from stop to surface. Total bottom time of 34 mins. beginning pressure 2700 in steel 72 ended dive with 1700. Compare with first dive to 92 ft in aow course 63 dives ago which lasted 22 minutes including safety stop and used 1800 psi. Now when I switch to nitrox which is what I keep in my 80's I can get around 2 1/2 hours out of a tank if most of the diving is in the 35 ft avg depth range when assisting with students. Would I like to have some 100's or even 95's yeah but for now I don't need em. The time is coming though, probably within the next year and a half, when I'll be putting together a set of doubles and am leaning towards using two more of the steel 80's. That should give me enough air to do anything I need to.