Just in case anyone wants to dive backmount independent doubles

[SlugLife]

This guy’s a trimix instructor.

Remember this next time someone says AgEnCy DoEsN’t MaTtEr.

To be fair, "trimix" might not refer to a mixture of nitrogen, oxygen, and helium .... but rather a mixture of 3 different equipment configurations.

 

[KenGordon]

The setup here is terrible and you should be ashamed. The backward regulator is completely unnecessary and unacceptable. It is an entanglement hazard and exposed to damage for absolutely no benefit.

This can be done in an ok way using any of these BCDs Commando BCDs & AP Tekwings | AP Diving and these twinning blocks Twinset Cambands

The cylinders sit the normal way round and the hazard to the valves is the same as a typical manifolded twinset.

The benefit is that you have the option of taking twice the gas now and again using a setup that is a incremental change from a regular single setup. In the U.K. you might use such a setup for a week going to Scapa while all the rest of your diving was single cylinder or single and pony. The total cost of that would be £50 for the twinning bands and a second first stage.

These AP setups are quite common and I was on a late boat last year where almost everyone was doing that. They were doing shallow (less than 30m) dives but severely constrained by gas logistics. They needed to do some dives on essentially half empty setups. Getting a fill was not possible and there were practical issues in carrying many cylinders to the island.

 

[kensuf]

A former student contacted me a week ago about learning how to sidemount. He travels to conduct research in the Bahamas and was concerned that he wouldn't be able to find doubles on the remote location. I suggested they bring a manifold and bands with them, it only takes ~30 minutes to set up a proper set of doubles.

If you're traveling to a place and you want a set of doubles, talk to them in advance to see if it'd be possible to bring what you need to assemble a set of doubles correctly. I think most operators would be willing to work with you if you discuss it in advance.

 

[Heat Miser]

Even his trim weight pockets are facing upwards i.e. not ditchable - unless he does a handstand

Bad:


Good:

 

[MrVegas]

This can be done in an ok way using any of these BCDs Commando BCDs & AP Tekwings | AP Diving and these twinning blocks Twinset Cambands.

Those BCDs are pretty cool. I like my manifolded doubles, but getting them from the basement to the car is a pain sometimes, so I can see the attraction to being able to move single cylinders around until you are ready to dive. (For those that want to keep the tanks on their back.) I know there have been some other posts on this, but are there any double tank adapters for a standard backplate? (I've seen the Dive Rite version, but $230 seems expensive for what it is, and it doesn't really seem to be widely available.)

 

[SlugLife]

After putting some more thought into this, I think the reason this is getting (deserved) hate is because (1) he presents this as if he's teaching from expertise and (2) he presents this as budget-doubles.

It would be much better if he presented this from the perspective of "this is experimental & do at your own risk." I am absolutely all for (safe) experimentation, and don't think people should be **** on just for trying something new or different. Most of the things we take for granted today are because someone experimented, refined, and eventually we have the nicely packaged version we know today.

A former student contacted me a week ago about learning how to sidemount. He travels to conduct research in the Bahamas and was concerned that he wouldn't be able to find doubles on the remote location. I suggested they bring a manifold and bands with them, it only takes ~30 minutes to set up a proper set of doubles.

If you're traveling to a place and you want a set of doubles, talk to them in advance to see if it'd be possible to bring what you need to assemble a set of doubles correctly. I think most operators would be willing to work with you if you discuss it in advance.

As great as sidemount is, I'd say that was the right call. He can of course still pursue side-mount training and equipment, but this is a much quicker, less complicated, and less expensive way to solve his use-case.

Even his trim weight pockets are facing upwards i.e. not ditchable - unless he does a handstand

Bad:
View attachment 669836

Good:
View attachment 669837

This is definitely a good lesson for newer divers.

Hopefully he is appropriately weighted doesn't need ditchable weights at his experience level.

 

[jadairiii]

...I am having a hard time understanding specifically why this guy is being attacked.

Here is why, this configuration became obsolete about the mid 1990's with the advent of commercially produced din isolator valves. And by the 2000's just about every manufacturer were making din isolator valves at a reasonable price.

I used independent doubles back in 1995 (and Sherwood had a decent isolator valve then), as did a lot of tech divers, and even we didn't reverse the one tank. But "we" quickly learned how stupid that configuration was.

Fast forward to 2021, you have a PADI Master/TecRec/ TDI Trimix Instructor hocking a 20 year old obsolete configuration, but worse, adding his won special convolutions to it.

To steal a quote from a "famous" tech diver, a video like this is "Farm Animal stupid".....

 

[Heat Miser]

This is definitely a good lesson for newer divers.

Hopefully he is appropriately weighted doesn't need ditchable weights at his experience level.

Your right, to all beginners out there its OK to grab a piece of normal everyday fencing wire from a hardware shop and affix "appropriate weights" to your balanced rig permanently, no need for trim pockets. Who needs to ditch if you have two low pressure inflator hoses and bladders to your BCD. A good place to wire up such weights on this configuration is to the short spg hose with wireless transmitter he has dangling off the right tank like a Christmas decoration.

This is far better solution because on this rig the $250 wireless transmitter can double as a $20 tank banger. No need to screw the transmitter directly into the first stage out of the way from damage.

 

[SlugLife]

Your right, to all beginners out there its OK to grab a piece of normal everyday fencing wire from a hardware shop and affix "appropriate weights" to your balanced rig permanently, no need for trim pockets. Who needs to ditch if you have two low pressure inflator hoses and bladders to your BCD. A good place to wire up such weights on this configuration is to the short spg hose with wireless transmitter he has dangling off the right tank like a Christmas decoration.

This is far better solution because on this rig the $250 wireless transmitter can double as a $20 tank banger. No need to screw the transmitter directly into the first stage out of the way from damage.

There appears to be a miscommunication.

"This" refers to the contents of the post I quoted directly above that statement, which shows the correct orientation of pockets, for dumpable weights.

 

[Heat Miser]

There appears to be a miscommunication.

"This" refers to the contents of the post I quoted directly above that statement, which shows the correct orientation of pockets, for dumpable weights.

No probs .... I'm entertained .... by it.

We should start up a new thread, stupidist dive rig setups you have experimented with.

I have to say I have done some stupid things, whether I'd be brave enough to post them ... I'll think about it.