Pros and cons - steel tank vs aluminum?

[Marvel]

Next question: when I did the bouyancy check a month ago, 16# seemed to be right. I got in the water, let my breath out, let the air out of the BC, then sank down to eye level. It was as close as you could get it.

But I learned from that dive that it was hard staying neutral at 15' with approx. 500 lbs.

Is there an easy, quick way to guess at what a better weight should have been? It would have to be more - 1 or 2#?

Weight checks should be done with a tank at about 500 psi.... & a buddy next to you to hold some weight for you to use to make adjustments. Suggestion: Note the configuration you are using, tanks, etc. complete with type of wetsuit & water (salt or fresh) in your log book. That way, a year later you can go back & verify what you need when you realize it's time to pull out the old 7mm again.

 

[Rick Inman]

Sorry, don't know how to do that quote thing yet...

Here's some help with that, Mike.

To quote an entire post, just use the quote button. To quote one line, copy it to your clipboard, go to advanced & paste. Highlight the quote & click the quote symbol & voila! You get a plain vanilla quote. To add the quotee's name , put an = sign right after the word QUOTE & then add the name without any space in between: QUOTE=GEEKYMARVEL. Of course, this is all contained in the brackets without spaces: [ ] The easiest way to understand it in context is to actually hit edit on a post that contains a bunch of snippets & see how it is structured.

 

[NJMike]

Here's some help with that, Mike.

Did it work????

TS and M, yes, you are right on, that's exactly what happened, hence the lesson.

So my trip yesterday, they gave me a bag of 30#. I was with a group of guys I didn't know, was still a little anxious, didn't want to look to stupid, so I worked with the BC and weights in the back of my Jeep while waiting for someone to come and open up the gate.

I thought about all this...and decided to use 22# instead of 20#. Worse case scenario - I'd be a little heavy and would use a little more air in the BC? Thought that would be better than going with this guy who offered to dive with me, PLUS the instructor who decided he would tag along as a third. (I'm sure he quickly sized me up as his biggest liability for this dive ! ha ha!)

So I got in the water, floated off the platform to the other two who were patiently waiting, and....I couldn't descend!

No, this can't be happening to me!

Eventually, I just jackknifed over andused my arms to help get me down enough so I could kick, and from then on all was fine.

I had to use more air in the BC, compared to the other trip (with the 1 pc 5mm), but I expected that, so that was ok.

I had much better control on the ascent, and at different depths. We only went to 50', followed by some more shallow depths.

After the dive, I asked the guys to critique my diving, you know, did you see anything that you thought I could improve on. They both said I actually looked pretty good in the water, which just goes to prove that people are naturally nice.

I related the difficulty I had in getting down. One of them said that maybe I had some air trapped in my suit....said that he opens his neck seal to make sure all his air is out. Something new, I didn't think about that.

Also, I'm wondering if I did not get all the air out of the BC. But we had a nice dive, the water was very nice, and now I know a little bit more than I did before the dive...

 

[Wingman_]

Ok Mike you are exactly where i was a two months ago before i decided to buy my first gear with some notable differences. After reading a couple of posts it was clear to me that BP/W was the way to go (even tho i was a complete noob) and after a couple more posts, i decided to go Hogarthian. Difference is i didn't buy a tank. I can rent a tank with air for 7 bucks here or fill my own tank for 3 bucks so no real reason to buy one, what's four bucks i pay a lot more than that in gas to drive to the dive spot or even to the LDS. With all and all if i were you i'd go BP/W anyway. You may think you are a noob now but you buy your jacket BC and it won't be very long before you start eying those sexy backplates at your local dive spot because yes, they are indeed sexy.

Now about that tank. SS lasts longer than Aluminium, not the other way around. Don't buy SS to be more negative, you can achieve that with:
1) heavier SS backplate
2) tank weight pockets like the ones from XS Scuba
3) BP weight plates
4) weighted STA

All this without even using a weight belt, i'm pretty sure there's enough weight there to sink the titanic although what you really need for that is just a big floating ice cube, but that's a another story.

AL tanks are bulkier than SS because aluminum is not very tough, they need huge amounts to make the tank solid, SS on the other hand is very tough so tanks are thinner. ALs are better for your balance simply because they are closer to neutral boyancy and anything you add to your rig that's not neutral will mess up your balance, pretty obvious isn't it. Just try holding a backpack with 6 pounds some inches from your chest and you'll see what difference it makes.

So pro/cons?
- SS lasts longer than AL although both last pretty much forever, or at least a lot more than let's say girlfriends
- AL doesn't mess up your balance like SS does. Exactly by what amount depends on the driver's skills or how used to SS he is
- SS requires you to wear less weight somewhere else, however this can be a pro or a con since there are better places to wear weight balance wise than in the tank's center of gravity
- SS doesn't change from negative to positive boyancy during the dive, i'm not sure how this could be a pro since the difference in boyancy is still the same for both tanks
- SS is thinner than AL
- AL costs probably less than SS where you live
- AL weights less, easier to transport

as you can see the differences are quite insignificant so you should look at prices first. I'd say AL's better for balance and price reasons.

 

[NJMike]

countryboy, thanks for the links. Three of them worked (techdivinglimited did not) so I printed all 3 out and have some good reading material for the weekend.

 

[FishDiver]

HHhhaaarrrr!
Good point.
Now I don't necessarily "hate" AL 100s, and if someone gave me one then I'd put it to use... but I don't think I'd go very far to pick one up
and I sure wouldn't actually pay for one...
Rick

Where on earth do you buy AL 100s? I've never seen such a thing. I have two AL 88s and I get funny looks when I use them.

I just bought a pair of steel 63s for the reasons mentioned in this thread. I feel like I got a great price for them on Ebay. Only problem is, nobody bid against me, which makes me feel like either a genius or an idiot.

 

[mania]

[hijack]

See, mania? I TOLD you he liked you better.... [/hijack]

well..........
you can always change yourself to the redhead

[/hijack]

 

[jeckyll]

....
Now about that tank. SS lasts longer than Aluminium, not the other way around. Don't buy SS to be more negative, you can achieve that with:
1) heavier SS backplate
2) tank weight pockets like the ones from XS Scuba
3) BP weight plates
4) weighted STA

Yeah but they all require you to carry additional weight

.....
ALs are better for your balance simply because they are closer to neutral boyancy and anything you add to your rig that's not neutral will mess up your balance, pretty obvious isn't it. Just try holding a backpack with 6 pounds some inches from your chest and you'll see what difference it makes.

I'm not sure how they will mess up your balance. You should be able to move the weight your do end up carrying forward. To use your earlier example, if you got weight pockets for your tank straps, you will change your 'balance' more than you would with a steel tank

- SS requires you to wear less weight somewhere else, however this can be a pro or a con since there are better places to wear weight balance wise than in the tank's center of gravity

Well if you are in trim position, won't the tank's center of gravity be over your lungs? Isn't that why you like a SS BP/W?

- SS doesn't change from negative to positive boyancy during the dive, i'm not sure how this could be a pro since the difference in boyancy is still the same for both tanks

Because you get to take weight off your belt. If you're diving with a drysuit and use significant amounts of weight, less is much better.

- AL weights less, easier to transport

as you can see the differences are quite insignificant so you should look at prices first. I'd say AL's better for balance and price reasons.

AL doesn't necessarily weight less for a tank of similar size.
A Luxfer 80 weighs about 31.4 lbs
A Faber LP 85 weights about 31 lbs and a Worthingon HP 80 is down around 28 lbs.

So steel can actually weigh less than AL for the same volume.

If you were to look at AL100's they are around 40.9 lbs whereas a Faber FX 100 is 34 lbs, and even a Faber LP 108 is only 41 lbs (a whole 0.1 lb more!).
(Source for all numbers http://www.techdivinglimited.com/pub/tanks.html.)

As I said earlier in the thread, I currently own AL80's simply due to the cost factor. For pretty much every other reason I'd choose steels.



Bjorn

 

[Wingman_]

Yeah but they all require you to carry additional weight

Sure they do, but carrying an heaviear tank means carrying additional weight too! A pound is a pound whether you carry it in your tank or your BP.

I'm not sure how they will mess up your balance. You should be able to move the weight your do end up carrying forward. To use your earlier example, if you got weight pockets for your tank straps, you will change your 'balance' more than you would with a steel tank

An AL tank is better than an SS tank for balance in lateral position. In this position your lungs tend to go up and your SS tank tend to go down which means you have to put a lot of effort to stay in that position. Granted this is not the most usual position while diving but it's still a pro. Remember i wasn't defending ALs, i dive SS, i was just listing pros and cons.

Well if you are in trim position, won't the tank's center of gravity be over your lungs? Isn't that why you like a SS BP/W?

In trim position ALs are no better than SS yes, but i wasn't talking about trim position.

Because you get to take weight off your belt. If you're diving with a drysuit and use significant amounts of weight, less is much better.

You are taking weight from your belt and putting it elsewhere, in the tank. Yes it's better to take weight from the belt and put it in the tank, but it's also better to take it away from the tank by switching to AL and putting it on your BP.

AL doesn't necessarily weight less for a tank of similar size.
A Luxfer 80 weighs about 31.4 lbs
A Faber LP 85 weights about 31 lbs and a Worthingon HP 80 is down around 28 lbs.

So steel can actually weigh less than AL for the same volume.

I didn't know this, as i said i dive SS i am not that familiar with different ALs, but do these tanks all cost the same? I know there are some pretty light tanks out there with carbon grid. However the tank weight was the most insignificant factor in the comparison.

I dive SS because around here SS is less expensive than AL but it seems to me than AL is better for balance than SS, at least where i get to dive it which is tropical places.

 

[BKP]

So here we are on the great tank debate again. I dive Aluminum 100's which makes me a side show freak.

My reasons:

#1) I am lazy and a procrastinator. I do not take care of my gear as I should and rinse my tanks whenever I get a chance. I have seen the boots removed from steel tanks along with large flakes of tank failing rust.

#2) I got one of the tanks for $100.00 with a O2 clean and new Hydro, Which made me match the this one with the other one.

#3) I do not dive much wieght in the summer time as it is and like the idea of having ditchable wieght at depth.

#4) Noone will ever steal my AL 100 tank, people sell them all the time and many people down right hate them.

I have alot of wierd likes though. French press over automatic drip. Boot cream over wax. Clear Silicone mask over tactical black. 1911's over GLocks. And lastly Redheads and Brunettes over Blondes.

You're not all that weird...

I dive an AL C80... negative when empty...

I prefer boot cream (and live in boots)...

I happen to prefer Sig Sauer over Glock...

...I married a Redhead...