Extending bottom time with AL80s

[RonFrank]

It does not make a huge amount of sense to me. Most divers can push AL80's to their NDL, and at most may need a pony like CF20 to provide a bit of safety margin. If you want to sling an AL80 fine, that adds about 4~5lbs negative buoyancy on one side. Doubles would be a better option, but that requires a whole new setup.

If you are doing deco, sure take the advice of others here, and get some higher capacity steel tanks. Other than that, the world dives on AL80's for a reason.

So I have to ask, what is so special at 130 feet you need to see, because diving that deep to just dive that deep IMO is pointless.

 

[ianr33]

. But my first idea was just to use it descending down the anchor line, leave it at the bottom, do the dive and return to the anchor line and use sling bottle for travel up.

That could be embarrassing if you dont make it back to the anchor line for any reason. I would be happier taking it with me.

 

[ianr33]

If you are doing deco, sure take the advice of others here, and get some higher capacity steel tanks.

Two Al 80's work great for "light" deco dives. Much cheaper than steels, lighter to carry around and no need for redundant buoyancy. Unless I need a ton of gas I prefer 80's over my 104's any day !

 

[iztok]

So I have to ask, what is so special at 130 feet you need to see, because diving that deep to just dive that deep IMO is pointless.

Nothing special at 130ft really.

I know several people diving doubles or higher capacity that I would end up shortening their dive if I dive AL80. So short of be changing whole rig or buy extra high capacity steel I was looking for a solution that is relatively inexpensive at this point.

 

[Doc Intrepid]

"Would that make any sense or am I just barking up the wrong tree?"

The problem with convoluted approaches is not when things are going well. The problem emerges when things go to hell - current blows you off the wreck and you're on the sand attempting to swim back in the lee of the hulk; you miss the upline in bad vis and have minutes to find it or go to Plan B; someone's reg craps the bed and now you're donating to someone while aborting the dive winging around a slung 80 off your BC - and things continue to go further off-plan. That convoluted setup now - instead of being helpful to you - adds to your task loading.

If you are going to dive wrecks in 130 fsw 60-70 miles offshore, even if you're doing recreational NDL diving, spend the time and money to be safe when situations go south. You've got the tanks. Get a couple double manifolds, two sets of bands, and a used backplate and wing. We're not talking about that much expense, relative to the cost of other avocations where, similarly, if you screw the pooch you die.

Learning to dive deep wrecks offshore is a process. Like other processes, you take it incrementally, learning about offshore weather and currents; correct gasses, SOPs and response protocols; practicing skills drills in quarries; and acquiring equipment that optimizes your diving rather than creating or adding to your issues.

Can you cut corners and come up with convoluted duct-tape-engineered configurations? Sure. Will they work? So long as nothing goes seriously wrong, probably. Are they the optimal solution to dive wrecks at 130 fsw 60 or 70 miles offshore? - particularly given the things that can go wrong in a deep offshore environment?

No, they're not.

In my humble opinion, if diving deep wrecks three hours offshore is what you want to do, slinging 80s off a recreational BC is barking up the wrong tree. If thats not where you're going, then perhaps your concept is safe for local diving where you live. It depends on what diving you want to do.

JMHO... Your mileage may most certainly vary.

Dive safe,

Doc

 

[RonFrank]

Nothing special at 130ft really.

I know several people diving doubles or higher capacity that I would end up shortening their dive if I dive AL80. So short of be changing whole rig or buy extra high capacity steel I was looking for a solution that is relatively inexpensive at this point.

That makes no sense whatsoever, unless they are doing deco, and/or you are diving tables.

Sounds like a solution is to dive without idiots?

I can take an AL80 to over an hour hitting over 100', and pushing NDL's beyond what I recommend for most divers with under 200 dives. These are MULTI-LEVEL dives, but that is the norm on ALL dives. You would have to give more specific expamples of what you are trying to accomplish, but unless you are doing 110~ foot dives and pushing NDL's AL80's work fine. Of course some folks are BIG, and breath, BIG.

I seem to see a very technical trend here lately, and it bothers me. Why? Because most of the folks asking questions have a LONG way to go to come close to technical. Why are you not getting great advice from your deep diving doubles buddies?

Not sure what is higher capacity than doubles? There is no such thing, unless they are doing re-breather?

 

[Skunky]

FYI.. I dive a 5 oceans as well and yes, the plastic plate on the back is only setup for a single tank. If you know someone who does fabrication you can get a aluminum or stainless back plate made for it so it will do doubles as long as the lift from the BCD (40+lb's) is sufficient for your weight, etc.

 

[Doc Intrepid]

Or you can buy them on SB --

http://www.scubaboard.com/forums/classifieds-tanks-valves-bands/306564-sherwood-manifold-bands.html

If you look at the bands in the photo, you'll see a curved metal strap connecting the bands. It is called a "bow". (I"m not familiar with the polymer backplate in the BC you're referring to, but) in most polymer plates found on BCs there is a concave shape where the single tank fits. The "bow" on these bands fits into that concavity, and bolts into place - sometimes there are even recesses in the polymer backplate where you drill the holes to bolt the band to the plate. You buy the stainless steel bolts, washers and nuts at Lowes...

Not sure whether or not it will work with your rig, but these style of bands were how divers used doubles with their BCs before backplates and wings came along. You can still find them for sale from time to time.

 

[Skunky]

Yup.. that works too!!! pd:

 

[brutus_scuba]

I believe IANTD has introduced an openwater side mounting class, and as part of the class they talk about converting a traditional BCD into a sidemount rig. Many sidemount divers, a group of which I am not a member, wear a rig that is strictly setup for sidemount, i.e. The Nomad, but I've been told it actually works pretty decent with other BCD arrangements.

I've heard rumor that PADI, and other recreational agencies are talking about introducing O/W sidemount classes. I can only believe it's too facilitate divers looking for the same things you are.