Reading this thread is like listening to a bunch of 16 year old floridians debating how to drive in the snow.
First up.. a qualifying test:
Step 1: drain your tanks to empty. Take out the bladder in your wing [no cheating!]. Go out to 130 ft of water. Gear up, jump in.
Step 2, if you are still alive: swap your empty tanks out with full tanks. Take your lift bags/smbs/etc out and leave them on the deck. Jump in.
Now.... If you don't have that level of confidence that you've got your setup right, then you really have no business debating the issue. And I don't mean for anyone to answer.... Just think about that and be -perfectly- honest with yourself.
Now. Let's talk about "Don't dive steels wet". This isn't a rule of thumb, this isn't a blanket statement... this is a tagline to denote a concept. The -concept- being more crucial than the tagline now in the world of lighter steel tanks and heavier aluminum tanks.
First up. warm water aluminum vs. steel. Get your steel doubles on, put on your 3mm, proceed to Litmus Test Step #1 as described above. If you are still alive, you either are underweighted, or you've completely missed the boat on the whole fitness concept [e.g. you qualify as a HFS].
THAT is the core base of the concept... people actually being overweighted to begin with.
NOW. For those of you that picked up -that- part of the message, and have passed Litmus Test Step #1.
Next up is step #2. We're going to the other end of the extreme for this one.... cold water wetsuits; since this is the tough concept. IF you pass step #1, and you are doing step #2... what is the difference between sitting at 130 feet with steels on, vs. sitting at 130 feet with aluminum tanks on?
NOTHING! Zilch. Zero. NADA.
Oh but you disagree. 77.4 * 3000 psi blah blah blah blah blah. YES. The difference between double 104s and double 80s is about 4 lbs of gas.
If you can't swim that extra 4 lbs... FREEFLOW IT OUT!
Now... All those that are convinced you will survive Step #2 with your double aluminums, are you comfortable enough to try Step #2 with double 104s?
If you aren't... you've been talking out your ***.
NEXT UP. DITCHABLE WEIGHT! Here's the biggest rub I have with all the damn steel vs. aluminum debates. If you need 11 lbs to get down and you do that with a double 104s and a 5 lb plate, or you do that with double AL80s, a 9lb plate and an 11 lb v-weight... you made the tanks THE SAME WEIGHT. You are just as screwed with the aluminum tanks as the steel tanks.
Anyone that condones aluminum tanks in a wetsuit, blasts steel tanks in a wetsuit, and doesn't dive with ditchable weight is completely FOS... I don't care who they are. They are missing a crucial concept.... the reason one can swim aluminum tanks up and can't swim steel tanks up is either 1) you have too much gas in your steel tanks [easily solved], or 2) you failed step #1 with those steel tanks, or 3) The light nature of the aluminum tanks allowed you to carry enough ditchable weight to offset the compression of the wetsuit.
BUT. Your wetsuit will expand on your way up. So the amount of weight to ditch needs to be less than or equal to the amount of gas you used out of the tanks. If you are 12 lbs negative on the surface at the start of a dive, it's because you have 12 lbs of gas that you are prepared to not have when you return. Then while you're sitting at 130 feet watching your pressure guage while panting profusely and finally realizing my point, you know you have the weight of the gas, plus the weight that you used to offset the buoyancy of your wetsuit.
Lets say you used 1/3 of your gas. You now have 8 lbs of gas. You are 4 lbs lighter than before. If you ditch much more than that, you aren't going to be able to control your ascent when you become to light near the surface [otherwise you wouldn't have survived Step #1].
But is 4 lbs going to be enough weight to make a difference? What about you freeflow it down to 1/3 of your gas remaining. That lets you ditch around 8 lbs. Now is that enough to get you up?
Dunno. Depends how compressed your wetsuit is!
I once had a situation where I dumped a little too much gas out of my BC, and needed to add more. But my deflate button was stuck and the gas coming from the tanks just went right out the oral inflation mouthpiece. Looking back there were a dozen different solutions, but at the time I didn't have many good ideas. I treaded water at 15 ft during the safety stop. It sucked. That was only with a single aluminum.
NOW to take this one step farther, just to make sure I've pissed off -everyone-.
If you are diving a cold water wetsuit, and you know how much gas you need to bleed off in order to ditch enough weight to swim to the surface. Then by all means. Good job. I apologize for calling you a 16 year old floridian debating snow.
BUT if you do believe that you can swim your full doubles rig [aluminum -or- steel], in cold water, while being warm enough [no cheating with dead or thin wetsuits], without ditching anything, from the bottom to the surface.... you are just trying to make up crap to justify the nickel rocketry of not buying a drysuit.
-I- Believe that there is just as much chance of someone being able to do that, as someone being able to swim against a 4 knot current.
