Double Tank Manifolds, Bad Idea!

[DaleC]

I don't consider this thread to be a fight, although I'm sure some disagree...

This is my perspective too. I see it as an argument in the Greek sense where people debate their ideas to "test" them. In that way it can be quite constructive. I have no real criticism of peoples choices.

In this discussion I keep reading that redundancy for MD's is based on simply being able to close the isolator. Is that so? Doesn't this only place the MD user on the same plane as the ID user (lower actually because I have that without isolating). Being able to take advantage of the max usable gas potential of MD's also has to do with being able to shutdown posts and diagnose which failure is resolved by which action. I see flow chart, not Y/N.

Now, for a twist.

So far this looks like an ID vs MD battle with MD's winning for tech diving, but I really see an ID vs MD vs RB debate with RB's being the better all around choice. Deeper, longer, in a far smaller package. It seems the most advanced dives are being done on RB these days so a tech diver, beginning with the end in mind, should skip OC MD's all together and choose RB. Yet many MD divers might vehemently oppose such a suggestion. How would those self limiting arguments (excuses) be any different from the current ID vs MD discussion. In the end, an inferior system is chosen, be it for safety, familiarity or personal preference reasons.

 

[ianr33]

Also for divers like me that have had several rotator cuff ops and can't get to MD valves the IDs or just the thing. After all how good are MD's if the diver can't reach the valves during the dive? I guess I'll never be a real diver.

You obviously need a slobknob.

 

[DaleC]

If they had those for the posts I'd take two

 

[TSandM]

I think almost anyone would agree that the most likely malfunction in a set of doubles is going to be a regulator-based malfunction. They have more moving parts and are more complex. Where manifolded doubles truly shine is the ability to shut down a post -- thus completely negating any regulator-based problem -- and retain access to all of the remaining gas. If you have a failure that requires isolation, you probably would have been better off in sidemount or IDs. But such failures are extremely rare.

You won't catch me arguing that backmounted doubles are clearly superior to sidemounted double tanks. I think there are good arguments on both sides of that one, and it is definitely true that, to make USE of the advantages of doubles, you have to optimize your gear AND practice until you can easily reach and manipulate those pesky valves, and that is a challenge for many people. If you are diving a standard dry suit and gain a few pounds, that may be all it takes to lose access to those important knobs. If you CAN reach and shut down valves quickly, I think there is probably an edge for BM doubles with a manifold, at least in applications where having every last drop of gas available is important. If you CAN'T, you are probably better off in sidemounted tanks, where you can see and cope with any failure.

What I just don't see is where ID, backmounted, have anything to offer. They have all the disadvantages of sidemount AND backmount, and no advantage I can see other than that you can put them together without a manifold, so it might be useful for rental gear. Personally, if I really wanted to dive doubles somewhere where I couldn't rent them, I'd either sling an 80 with a single, backmounted tank, or I'd go to a sidemounted type of configuration.

 

[DevonDiver]

What I just don't see is where ID, backmounted, have anything to offer. They have all the disadvantages of sidemount AND backmount, and no advantage I can see other than that you can put them together without a manifold, so it might be useful for rental gear. Personally, if I really wanted to dive doubles somewhere where I couldn't rent them, I'd either sling an 80 with a single, backmounted tank, or I'd go to a sidemounted type of configuration.

I agree. Given the increasing accessibility to 'off-the-shelf' sidemount rigs and adoption of sidemount training by the mainstream agencies, there really is little justification for diving backmount ID nowadays.

My once beloved ID rig has been gathering dust for years...

 

[Slamfire]

Personally, if I really wanted to dive doubles somewhere where I couldn't rent them, I'd either sling an 80 with a single, backmounted tank, or I'd go to a sidemounted type of configuration.

This is a picture just before my very first dive in Maui on Sept 3rd, 2013. I couldn't get doubles easily.



This video has footage taken during said dive.
Maui Day 1 on Vimeo

[vimeo]74174222[/vimeo]

 

[pocky21]

So far this looks like an ID vs MD battle with MD's winning for tech diving, but I really see an ID vs MD vs RB debate with RB's being the better all around choice. Deeper, longer, in a far smaller package.

 

[Rich Keller]

If you add another "old school" idea to the mix you could easily set up doubles using two single rental tanks. All you need to bring is a set of double tank bands and a harness that connects directly to the bands without a backpack.

 

[DevonDiver]

If you add another "old school" idea to the mix you could easily set up doubles using two single rental tanks. All you need to bring is a set of double tank bands and a harness that connects directly to the bands without a backpack.

Yep, that's what I did for years (see earlier in the thread).

 

[AfterDark]

You obviously need a slobknob.

View attachment 166690

I don't need that with ID's. I also like the fact that I can carry them one at a time until I make them doubles. For me ID's are the way to go, Thanks much.