Tips on starting diving doubles

[old frogman]

Yeah, I understand more than you think.
You know, I will probably end up diving those double 72's with no BC in a 7 mm wetsuit. And I will be using a single second stage and an SPG only.
You probably wouldn't dive them without a wing and a drysuit. In fact you probably wouldn't dive them at all because they have a single center post manifold with a J valve and not two posts with an isolator. And plus its yoke not DIN.

How is it that I dive a single 120 now with no BC, but somehow I'm going to straight to hell if I put on 140 cf air split between two tanks that end up lighter together than the 120?
I'm diving your definition of a "balanced rig" now with a big single. Although "balanced rig" to me means something entirely different from what you think it means. To me I'm just properly weighted for the type of diving I do.
So, how is the twinset different? 10 more cf of air?
Or maybe not if I get a short fill.

I would like a genuine answer, not "you need to do more reading" and "you have a lack of understanding". I've been doing this a while and probably understand more about weighting and minimum weighting than most people these days.

Did you figure it out on your own or did someone feed this to you?

Hi Eric,

I have dived twin tanks with a USD Aquamaster twin hose regulator down to 200 feet on air with no BC, just a wetsuit, on numerous occasions in my younger days. I am still alive and still diving (hence the old frogman). Young men today don't spend enough time in the fresh air, spend too much time with computers and tend to overthink problems. No common sense.

Good luck with your adventure.

 

[John C. Ratliff]

@halocline Good feedback. I do already have the Lp 72's, but I'm not married to the idea of using them for this. Could always use some of my AL 80's (admittedly kinda sucks since I already have Lp 72 bands, but the $70 I spent for two sets of those isn't gonna kill me if I don't use them).

Hadn't thought through the wing profile issue. I do fossil diving, in a river, so generally I dive pretty negative, and sometimes am bring up an additional ten or so pounds of whatever I found down there (which obviously, in an emergency, is ditchable. Sharks teeth and glass bottles aren't worth dying over), so I thought I'd want the extra lift. However, you have a point, the current might make diving the big 60 wing a pain in the tuchas. I'll probably give it a try and if it sucks, see if anybody on here wants to do a 1-1 swap or something.

SM is out due to entanglement risks/me not wanting to faff around with a tank on each side of me. I'll definitely consider the manifold issue. Do you mind sharing why independent doubles would less safe? I understand issues can occur during the switch/you could lose track of which tank had what gas (pressure, both tanks will hold the same gas mix), but presuming I drill the switch a lot (which I intend to) it feels like the safety issue falls out, unless I'm missing something. I'm not super opposed to a manifold; independent doubles just seemed simpler when I was making this plan, but I could definitely pencil a manifold into the scheme.

If I were you, I’d go with the twin 72s. I’ve dived them over the years, and they really perform well in the water. Dry the independent doubles, and know that you can get a manifold if you want to change after trying the other route.

SeaRath

 

[happy-diver]

How do you know it's effing stupid if you never used it?

There are people out there that are quite capable of making a qualified assessment without having used it

Young men today don't spend enough time in the fresh air, spend too much time with computers and tend to overthink problems. No common sense.

Many people of yesterday and today of any age whether they spent time in the fresh air or prefering to read books could also be subject to overthinking issues

Thing about common sense is the people generally lacking don't necessarily need it to the degree others do

 

[happy-diver]

Thing about the cultists and their sooths of doom and their aluminium tanks and drysuits, is that I stay
away from their forum unless it rolls by in What's monthly so if they could just reciprocate the courtesy

I think they're generally okay just a little lonely