al80's and redundant buoyancy

[DA Aquamaster]

Pretyt much the same thing here - I add an 8 lb v weight if "forced" to dive double AL 80's. I'd rather carry the extra 8 lbs in larger capcity tank weight with tanks that are not as bouyant rather than carry lead - but that leads you full circle to the redundant buyancy requirement.

In my opinion, AL 80's make sense in a lightweight wet suit or other thermal protection that does not have much inherent bouyancy. In that case, all you really have is a pound or tow of weight for the suit and the 10 pounds of swing weight for the gas. if you can swim up 12 pounds, redundant bouyancy is not needed.

 

[rjack321]

I dive al80s in MX (caves-freshwater), 7mm wetsuit, AL plate (for the plane mostly) and 4-5lbs of lead. I'm not getting so deep that the buoyancy of the wetsuit changes all that much (max 80-90ft).

5mm suit, SS plate and 20lbs sounds like a hell of alot to me, even for saltwater.

 

[Bismark]

double al 80's, ss plate, 3mm suit, no weight. It's a sweet set of gear.

 

[Meng_Tze]

double al 80's, ss plate, 3mm suit, no weight. It's a sweet set of gear.

Indeed that is! Dove same rig for a long time too. It was always funny to see the frowns of the DM's : 'this guy is going diving with no weights....'

 

[ianr33]

double al 80's, ss plate, 3mm suit, no weight. It's a sweet set of gear.

Yep,done lots of local dives like that. In saltwater I need to add around 4 lbs weight. When I first got my doubles I went to about 60 feet in the local lake and dumped all my air.Found I could swim them up without a huge amount of effort.

 

[Colliam7]

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?

I have, from time to time, used double AL80s, a SS BP, a 3mm wetsuit, and no redundant buoyancy and gone deep that way (130ft SW) a couple of times. I am not dead yet, at least I don't believe I am (friends and acquaintances are free to differ, of course). The ONLY reason I did it was that I was using a single bladder wing (an Oxycheq Signature 50 is really quite nice with AL80s) and failed to bring a lift bag. I usually try to have a lift bag and/or SMB with me these days because, even though the probability of buoyancy failure is small, why take a chance?

double al 80's, ss plate, 3mm suit, no weight. It's a sweet set of gear.

YES!!!

 

[JDMerk]

I dive al80s in MX (caves-freshwater), 7mm wetsuit, AL plate (for the plane mostly) and 4-5lbs of lead. I'm not getting so deep that the buoyancy of the wetsuit changes all that much (max 80-90ft).

5mm suit, SS plate and 20lbs sounds like a hell of alot to me, even for saltwater.

Your right...i did my math wrong. I thought that sounded a little much myself so my new estimate is 13lbs. That's not counting the manifold and bands, also my initial numbers may be 1-2lb overweight so that number could possibly drop by 4lbs or so once I get the gear assembled and do a final buoyancy check.

 

[ivobj]

Basically with single AL80 in warm water (wetsuit) I have no problem diving without redundant buoyancy, with my setup (SS BP, weighted STA, trim weight in STA rigs pockets) I can ditch the weight in the pockets (usually 3 kilos, little more than 6 lbls) and swim up with the rest without any problem (specially because with a single AL80 I will be in shallow waters).

I used double AL80s only once in Japan, Okinawa, with SS BP and 3 kilos V-weight, but at that time although water was warm I used redundant buoyancy (TLS 350 trilaminate drysuit), but changed the undergarnment for shorts and a long sleeve T-shirt because of water temperature

 

[deepstops]

double al 80's, ss plate, 3mm suit, no weight. It's a sweet set of gear.

Ditto, the perfect rig for 120-170' IMO.

 

[Web Monkey]

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?

Your wetsuit becomes less buoyant as you go deeper, and you'll be overweighted by at least the weight of your gas at the beginning of the dive, so the question is really "Can you swim back to the surface, do any required stops on the way up, and stay there when you're 25 pounds negative?" (12.9 lbs for the gas and maybe 12lbs for the wetsuit).

Terry