Aluminum vs Steel Dive Tanks

[rebel heart]

Originally Posted by s/v Beth

This must be a first for cf because I think we all agree. I think I would like to dive with a few of you, because you have the same paranoid (safe) mindset . BTW offline and SS, how do the dolphins work on cruising sailboat?

It seems like scuba diving has a lot less "arm chair admirals" going on. If you're a bad diver you're probably going to get hurt/injured early on so it thins the herd. The usual divers I go out with have great buoyancy and safe skills.

[Matt sachs]

Originally Posted by skipmac

Completle agreement on all points. Mentioning the accident in the keys was only meant to point out that the inabiliby to get positive, whether due to panic, poor training, or poor weighting, can be deadly.

Since I don't dive a BC have not looked at the weight integrated models. I assume the integrated weight is in an easily droppable form?

Yes the weight pockets are in the BC and easy to get to if needed. And the BC's are 1000% more comfortable. I love those things. There is nothing on your hips. One of the tricks we do is to make the students use both weight integrated and non integrated. They all elect to buy the integrated.
I hope I didnt offend with my comments, if I did I didn't mean to.

Of course once you cross over to tech diving, some of these guidlines go out the window.

[skipmac]

Originally Posted by s/v Beth

This must be a first for cf because I think we all agree. I think I would like to dive with a few of you, because you have the same paranoid (safe) mindset . BTW offline and SS, how do the dolphins work on cruising sailboat?

We all agree? A momentous occasion. Let me see if I can do something about that and bring rebreathers into the discussion.

Have not done this myself since I'm spending all my discretionary income on boats at the moment but the group I was diving with used the Halcyon SCCR rebreather. Designed in Germany, now built in the US. All mechanical, so no electronics to get wet and fail, no O2 sensors, etc. About as simple and fool proof as you can make a breather so would be my choice for taking on a boat. The makers have used it in some pretty extreme dives, like 7-8 hours at 300' so proven technology.

[skipmac]

Originally Posted by Matt sachs

Yes the weight pockets are in the BC and easy to get to if needed. And the BC's are 1000% more comfortable. I love those things. There is nothing on your hips. One of the tricks we do is to make the students use both weight integrated and non integrated. They all elect to buy the integrated.
I hope I didnt offend with my comments, if I did I didn't mean to.

Of course once you cross over to tech diving, some of these guidlines go out the window.

Hey, not offended at all. Just seemed like I was a little unclear in my post so wanted to make sure there was no misunderstanding.

So is the weight pocket quick and easy to ditch, some kind of quick release or do you have to get into the pocket and pull the weights? If you have a paniced diver it needs to be as easy to do as possible and easy access for dive buddy or instructor to do.

[Matt sachs]

Originally Posted by rebel heart

It's not so much for me about being positive vs. neutral vs. negative at the end as much as it is your buoyancy changing positions. If I slowly started moving weights from your back to your front, you'd notice it. Your butt will go up easier, you'll have to kick down more, etc.

I've seen a lot of folks with aluminum not realize what was happening to them and dump a lot of air because they take the changing balance for true positive buoyancy.

I see this also and agree with you. The cool thing about the weight integrated BC is that it has trim pockets just for this issue. Good disscussion

[Marksman]

In most intigrated systems, the weights are tucked into a pocket and the release handles are in easy reach. You simply grab the handle, pull and the pouch slides free of the pocket. Much nicer for reboarding the dive boat as well. Oh, and switched to steel tanks a few years ago after diving with al since '79. I much prefere the steel.


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[GeoPowers]

I like my HP 100 so I can keep up with my wife and her AL80... I'm an air hog and she sips the stuff!

[Matt sachs]

Rebreathers.....I have never used one, but my boss just got back from Cayman yesterday. He did a max depth of 225 feet, 90 minute run time and he used 13...count them...13 cubic feet of gas.

[rebel heart]

Originally Posted by Matt sachs

Rebreathers.....I have never used one, but my boss just got back from Cayman yesterday. He did a max depth of 225 feet, 90 minute run time and he used 13...count them...13 cubic feet of gas.

Ask him how much the bill was for using it vs an open circuit regulator.

[offline]

My very honest opinion of rebreathers is that you need to have a very.... VERY good reason to need to dive using them because they introduce about 20 different ways that you can die....

Rebreather diving should have a very specific reason.... IE.. you need to dive for extended bottom times and you have limited space for gas... or you need to be able to get up close to critters for photo, video or scientific reasons then a rebreather might be for you in either a closed circuit or semi-closed variety, or some other reason.

Of all the rebreathers that I am certified on and certified to teach the Dolphin is the least likely to kill you. Again rebreathers are WONDERFUL tools but in my opinion they are not for recreational divers.....

If you do decide to dive on a Dolphin then make sure you are fastidious about your maintenance regimens to your gas management and O2 monitoring.

[Matt sachs]

I'm afraid to. I know how much I paid for each fill of mix while I was there. He's getting his instructor certification so he can teach the rest of us. I'm sure the cost will trickle down to us peons...

[skipmac]

Originally Posted by offline

My very honest opinion of rebreathers is that you need to have a very.... VERY good reason to need to dive using them because they introduce about 20 different ways that you can die....

100% correct. I think there are way too many people diving breathers just because it is macho and the latest, cool toy.

Originally Posted by offline

Rebreather diving should have a very specific reason.... IE.. you need to dive for extended bottom times and you have limited space for gas... or you need to be able to get up close to critters for photo, video or scientific reasons then a rebreather might be for you in either a closed circuit or semi-closed variety, or some other reason.

In my case I'm thinking about a breather for diving in remote locations where it is difficult to get fills of any kind, much less mix or nitrox. You can put a compressor on a relatively small boat but not tanks of He and O2

Originally Posted by offline

If you do decide to dive on a Dolphin then make sure you are fastidious about your maintenance regimens to your gas management and O2 monitoring.

Same for any breather. You got to pay attention.

[2012iffy]

Originally Posted by skipmac

A couple of comments. A Luxfer Al 80 is just a couple of pounds negative full, about a pound positive when empty so situations where I want neutral buoyancy and minimal weight swing during the dive I use the Al 80. Also, Al you don't have to worry about corrosion diving in salt water.

I think the preference for steel tanks is mainly because you can get more gas in the tank and being more negative you can take some wt off the belt. This is good within certain limitations.

My take.

Al tanks

- Warm water diving without wet suit. I don't need a weight belt at all, in fact I've even dove with just a harness and no BC and maintain buoyancy with breath control.
- To carry extra gas in tech diving. I use to do cave dives using double steel back tanks and carry up to 4 Al 80s for the extra gas. Steel tanks would be much too heavy and negative for this.
- Al 40s to carry deco gas in deep wreck dives. Small, easy to carry and have sufficient gas for the deco.
- Al 80s in most ocean dives to keep my steel tanks out of salt water.

Steel tanks

- You can get much larger steel tanks. Up to 120 cu ft, Also most people overfill the steel tanks so can (safely) get about 15-20% more gas than their rated capacity.
- the old steel 72 is low pressure rated so for O2 fills from a cylinder cascade you can get more oxygen than a 3000 psi Al 80.
- If you have them the old steel 72s are light wt, slightly negative and will last forever. But you have to make sure you keep the inside dry, especially if you dive in salt water. Problem is I don't think you can get new steel 72s
- Diving dry suit you need a LOT of weight so I use steel tanks to keep the weight belt smaller.
- Have used a steel 90 cu ft ocean diving with a wet suit, again to keep less wt off the belt. Just make sure that with the tank you are still slightly positive with the tank full. You should need at least some lead on the wt belt to be negative so you can ditch and be positive in an emergency.

Thanks skipmac!

Ok, hope this thread is not too old. I am new here as well as a couple of other forums dealing with scuba and spearfishing. have been trying to find someone who is diving mostly warm water and not too many deep dives and found this.

Am moving to purchase a liveaboard soon and I dive too (Only 40-45 logged dives.). I purchased 4-AL 80 tanks before looking at all this controversy over which is better but when I realized it appeared all the divers were using wetsuits (Only dove with them on my C dives, never again!) this very thing came to my mind as I know that the wetsuit becomes very buoyant as you surface. what has come to my knowledge bank is that steel tanks have a far greater differential from full to empty than aluminum and since I dive with a pair of trunks and a mesh shirt under my BCD to protect my delicate skin it seems to me that the AL tanks would be much better for warm water dives of 60-75 feet or less. I still require about 2-3 lbs to keep neutral with my BCD dumped and only need to add some air when I surface just to make it easier there. Preferring dives to 45 feet and once living aboard, not pressured to do the 3 dives and out for days, I am wondering if there is some bias here because of the depth/water temp factor and seemingly the same tactics used for weekend as well as tourist divers to do 3 dives a day? And I do understand why steel would be used for the wetsuit and all for I would not want to be so positively buoyant that I would rocket to the surface!

Thanks for the objectivity and to all, fair winds and lots o' bubbles!

[billwa]

Browsing this , I havent seen it mentioned that:

For any given mass of contained air, modern steel tanks (eg faber 12l 232 bar) are lighter and smaller than aluminium tanks which will hold an equivalent mass of air. I have yet to see any tank specification which is heavier in steel than in aluminium for same amount of air held.

So for the same length of dive duration, the steel tanks will be lighter on the surface.

I have a set of steel in the house, as I hate carrying too much weight to the car, to the boat ets.

As a side note:
On the boat, a have a set of ali - they dont rust.

[skipmac]

Originally Posted by 2012iffy

Thanks skipmac!

Ok, hope this thread is not too old. I am new here as well as a couple of other forums dealing with scuba and spearfishing. have been trying to find someone who is diving mostly warm water and not too many deep dives and found this.

Am moving to purchase a liveaboard soon and I dive too (Only 40-45 logged dives.). I purchased 4-AL 80 tanks before looking at all this controversy over which is better but when I realized it appeared all the divers were using wetsuits (Only dove with them on my C dives, never again!) this very thing came to my mind as I know that the wetsuit becomes very buoyant as you surface. what has come to my knowledge bank is that steel tanks have a far greater differential from full to empty than aluminum and since I dive with a pair of trunks and a mesh shirt under my BCD to protect my delicate skin it seems to me that the AL tanks would be much better for warm water dives of 60-75 feet or less. I still require about 2-3 lbs to keep neutral with my BCD dumped and only need to add some air when I surface just to make it easier there. Preferring dives to 45 feet and once living aboard, not pressured to do the 3 dives and out for days, I am wondering if there is some bias here because of the depth/water temp factor and seemingly the same tactics used for weekend as well as tourist divers to do 3 dives a day? And I do understand why steel would be used for the wetsuit and all for I would not want to be so positively buoyant that I would rocket to the surface!

Thanks for the objectivity and to all, fair winds and lots o' bubbles!

Have done dives with and without wetsuits using Al 80s. Without the wetsuit I can dive without weights and without a BC. Just a harness to hold the tank and control my buoyancy by inhaling or exhaling a little more. Would not recommend this off shore or in deep water as the BC is a safety device, but the point is, the Al80 is close to neutral so you can more easily adjust your weight for the dive.

And, as pointed out, Al doesn't rust on a boat.