al80's and redundant buoyancy

[JDMerk]

Looking for opinions here...
I understand redundant buoyancy is advised for doubles and its necessary for most if not all of the tech training agencies. I get that and its obvious why redundant buoyancy is needed for sets of big steels.
However is it really necessary for a set of al80's? Would diving wet with a set of al80's and a single blader be as marginal as I am led to believe?
Does anybody here dive doubled up al80's wet and with no redundant buoyancy?
Are you dead yet?

[H2Andy]

you can always slip an extra wing behind your plate

as for double AL80's ... you're gonna need A TON of weight to avoid doing the missile breach out of the water at the end of the dive

seriously, i don't know ... i don't know anyone who dives double AL80s

[scubafanatic]

actually, twin AL 80's are pretty common 'tech' tanks at lots of dive destinations.....I did a week of cave diving a few yrs ago in Akumal, Mexico and all they had was a TON of AL 80 twinsets and everyone seemed perfectly fine with them.....Mexican caves tend to be shallow so twin AL 80's provided enough bottom time. Also, a fair number of 'tech' liveaboards offer twin Al 80's as the largest capacity gas option. AL 80's are cheap, they don't have the high maintainance/rust issues of steel tanks....and they're weight out of the water is 'reasonable' at something like 80 lbs with tanks/bands/manifold...the 'average' diver these days is in his/her mid-40's, especially the ones with enough income to tech dive AND travel expenses...so the twin AL 80's are a sufficient compromise between cost/weight/capacity.
Personally I like steel tanks (own 9 singles/ plus 2 'small' steel twinsets) but I can't take them on a plane with me, so I can only dive them locally in the lake/quarry...or road trip them down to the coast /TX Flower Gardens.
...with respect to 'redundency' , I'm a big fan of dual-bladder wings, just like I'd rather fly in a plane with 2 engines versus 1 engine....doubles my chances for coming home! The DIR crowd isn't crazy about dual wings, however, they are more 'acceptable' if you leave the back-up (right post) inflator hose disconnected/tucked away and only connect it IF you have a wing failure and need to use it.

[H2Andy]

that's cool

how's the bouyancy at the end of the dive?

specifically, how much weight did you carry?

[davetheshoeman]

As said earlier twin ali 80's are pretty common especially in tropical environments and often its wetsuit rather than drysuit. Your DSMB is a great backup bouyancy devise. Sounds crazy, not really. Its limited in that its an open water (not caves and not inside wrecks) tool. Most DSMB's have a purge valve at the top so you can adjust the amount of gas in it. We are talking a 'last option available' but it can and has been used.

[JDMerk]

Thanks for the replies guys...but what I was getting at was if the redundant buoyancy was really necessary or is it more for good diving practices when moving toward bigger steel doubles.
Based on my calculations i'm anticipating carrying 20lbs of lead. If I lose my wing at depth and have to swim up a set of lets say half full al80's I should have no problem doing it after ditching 20lbs. I might even be so buoyant by dropping all of it that the ascent may become an issue in and of itself. Is there something im not anticipating here? Are my assumptions baseless?

al80 x 2
ss bp
5mm
20lb

[scubafanatic]

...well, if ya gotta do a deco stop/stops after a wing failure, a dual wing sure would make life easier/less effort.

[TSandM]

I dive double Al80's in Mexico with a 5 mil suit and 2 mil hooded vest, with a 6 lb V-weight. Of course, I'm in a cave, so if I had a total wing failure (hard to do, really) I could crawl out

[H2Andy]

I dive double Al80's in Mexico with a 5 mil suit and 2 mil hooded vest, with a 6 lb V-weight.

that's not bad at all

[JeffG]

that's not bad at all

Double 80's with a SS plate/Manifold/Regs are close to neutral when empty. So you only need to carry enough lead to sink your suit.