Twin-set manifold vs Sidemount vs Independent Twins

[JohnnyC]

BM doubles unless you need SM for the overhead profile. CCR is way down the road for you. Independent doubles never. Manifold failures are so rare I would posit they are statistically insignificant. I'm not aware of anybody who has actually ever died because of a manifold failure. (Not opening the manifold is not a failure btw.....)

 

[ChuckP]

My big issue with side mount is it is a return to the compromise of independent twins. Which, after I put my buddy (and myself) at risk, I swore I would never do again. I don't see a way around that problem.
How do those regularly diving side mount mitigate the issue.
.

I've never trained or dove side mount but that thought has crossed my mind - if I was sure to drown because of an empty tank but yet carrying a partial tank with a bad first or second stage on it - I'd attempt changing first stage regulators out while holding my breath (blowing bubbles) - better yet, with a buddy, share air while switching.

Why not try it?

 

[divad]

Totally incorrect. Today's manifolded doubles have two completely independent first stages, each can access either or both tanks.

Thanks again. I was almost apoplectic......again.

 

[Caveeagle]

... If you want to have longer bottom times, learn to use less air. If your concern is safety, then OK, double everything, including your buddy (2 buddies are safer than one!).

Diving to 1/3s and depth demands more gas. Even if you have a great sac rate.

And “2 buddies are safer than one!” ....can you back that up? It has been my experience that team interreliance and communication tends to break down with teams of more than two. It’s hard to keep track of two divers in the water, so it’s real easy for a 3rd wheel to fall out of the group.

recreational openwater sidemount is often chosen because of back pain. Only few advanced divers go into so narrow caves that they need sidemount for technical reasons.

More than you might think. I consider myself to be an intermediate level cave diver, and have frequented a few “sidemount only” caves. However, I agree with your point. I see plenty of SM divers that don’t go anywhere near some of the small and tight caves that really require this configuration.

 

[tarponchik]

And “2 buddies are safer than one!” ....can you back that up? It has been my experience that team interreliance and communication tends to break down with teams of more than two.

Take it easy, I was kidding.

 

[Caveeagle]

Take it easy, I was kidding.

We’re you kidding on both comments? ....my sarcasm meter has been broken for quite some time,,,

 

[tarponchik]

We’re you kidding on both comments? ....my sarcasm meter has been broken for quite some time,,,

Only on this one. With a single tank, 3K PSI at 60+ ft, I go into deco long before I run out of air. To run out of air instead, this has to be very shallow diving, like shore diving in SE Florida, Dania Beach or LBTS. But about 2 hr dive there is enough for me anyway.

So, the PO should be aware that increasing bottom times by taking more air will likely result in deco dives.

 

[Caveeagle]

Only on this one. With a single tank, 3K PSI at 60+ ft, I go into deco long before I run out of air. To run out of air instead, this has to be very shallow diving, like shore diving in SE Florida, Dania Beach or LBTS. But about 2 hr dive there is enough for me anyway.

So, the PO should be aware that increasing bottom times by taking more air will likely result in deco dives.

When someone is talking about moving into doubles for eventual move into wreck & cave diving, some exposure to decompression is absolutely posible. Having said that, there are some caves where the depths are quite moderate, and penetration approaching 2k linear ft is possible using EAN32, with little to no deco. Peacock/peanut tunnel is one example. Would I do that dive without big double tanks.... umm. No.

 

[RainPilot]

How do those regularly diving side mount mitigate the issue.

I keep exit gas in both tanks so a single failure won't scupper my plan. If my exit is super critical, then my Z-system allows me to use both tanks in the event of a second stage complete failure. All my second stages are also strippable underwater so a diaphragm issue should be somewhat easily solved.

 

[sigxbill]

to the op: twinset manifolded vs twinset Indies was debated and overwhelmingly decided 30 years ago, and if you research that, it may help you with your sidemount question .... cheers