Tips on starting diving doubles

[nadwidny]

It's 2 yoke connections, tightened with a wrench (knot hand tight on a knob). Plenty secure if you take the few minutes to assemble correctly. Not exactly "a multitude of failure points."
Granted, not as solid as a modern isolation manifold or solid bar manifold, but has 2 advantages... The ability to mix and match tanks without emptying them, and at the low cost of borrowing (free) let's him try double 72s in the water with gear he already has.

I had one. Never used it because I saw how effing stupid of a setup it was.

 

[rjack321]

It's 2 yoke connections, tightened with a wrench (knot hand tight on a knob). Plenty secure if you take the few minutes to assemble correctly. Not exactly "a multitude of failure points."
Granted, not as solid as a modern isolation manifold or solid bar manifold, but has 2 advantages... The ability to mix and match tanks without emptying them, and at the low cost of borrowing (free) let's him try double 72s in the water with gear he already has.

There is a very good reason every manifold made in the last few decades is DIN and you have to scrap the bottom of some barrel at Ebay to find this. A-clamps aka yokes are a terrible connection form and the threaded DIN connection is vastly superior.

 

[SouthernSharktoothDiver]

To the concerns about failure points on the “straight pipe” manifold…I do have the same concerns. I mean, even if the yoke itself is ironclad, there’s still the fact there’s no redundant air supply, so if something screwy were to happen and my reg died, I’d have no backup. Versus as I understand it, the isolation manifold has two regsets and a valve between them for just such a situation. If one reg blows, shut off the manifold and switch regs if needed.

That being said, I’m not averse to giving it the old college try if I’m ever able to run down to the panhandle when @James79 is there. If nothing else, a dive buddy is also a solution, as far as redundant air goes, and it would make for a cool experience. Put it on my steel 72’s with my old conshelf reg and dive like it’s 1980 again.

 

[halocline]

To the concerns about failure points on the “straight pipe” manifold…I do have the same concerns. I mean, even if the yoke itself is ironclad, there’s still the fact there’s no redundant air supply, so if something screwy were to happen and my reg died, I’d have no backup. Versus as I understand it, the isolation manifold has two regsets and a valve between them for just such a situation. If one reg blows, shut off the manifold and switch regs if needed.

That being said, I’m not averse to giving it the old college try if I’m ever able to run down to the panhandle when @James79 is there. If nothing else, a dive buddy is also a solution, as far as redundant air goes, and it would make for a cool experience. Put it on my steel 72’s with my old conshelf reg and dive like it’s 1980 again.

You don’t shut off the manifold if a regulator fails. The whole point of the manifold is to give you access to all the gas in both tanks if a regulator fails, and for that, the isolator is open. In the event of a regulator leak or failure, you switch regs and shut down the valve on the affected tank. The manifold allows gas to flow from that tank to the other regulator.

The set up that someone described with yoke fittings and a center-mount single regulator is exactly what you don’t want for redundancy. Just forget about it.

This discussion is starting to become a good example of why people seek professional training for technical diving, which includes learning about the best equipment configurations for a given dive. I understand that you are wanting to have some fun and try diving with doubles in a recreational setting; that’s how I started diving with doubles too. There’s nothing wrong with that at all, but stick to the proven set ups that people have used successfully for decades.

One last thing that is a little strange; you’ve mentioned you’re worried about the cost of opposing valves and a manifold. First, the manifold comes with valves, so that’s a non- issue. And the whole thing will probably cost under $100 used or under $200 new. If those numbers are causing you to re-think this, then you’re in a lot of trouble in terms of moving in the direction of diving multiple tanks. I’m a dedicated cheapskate myself so I totally understand, but this is a small amount of money given the expense of diving. And were you planning on using two right hand valves? Meaning the left tank valve handle is not on the outside? Do you understand that reaching that valve is a lot more difficult, and that reaching your valves in any sort of technical diving situation is a necessity? Are these yoke valves? That’s another no-no in any sort of tech diving, and while yoke valves are fine, the DIN connection is more secure and (more importantly) less of an entanglement risk. If you’re not already using DIN, that means changing your regs to DIN, that’s another expense. Do you have the right length hoses? Another expense. It adds up quickly.

 

[VikingDives]

@SouthernSharktoothDiver If you're going to use doubles, you're eventually going to use a manifold.

BUT, you've mentioned the weight issue a couple of times IIRC. Sidemount is a whole lot easier on your back and knees.

There aren't a lot a things that have come along since the 90s in scuba that are worth the money, but if you take a look at your "average doubles diver" you're going to see gear that evolved from the make-do and bandaid solutions that people were forced to use 50 years ago.

 

[eelpout]

Do you know anybody that dives with twins? You have two options to learn how to dive twins. 1. Take a class from a place that sells and dives them. 2. Find some divers who dive them and get mentored. As a member of a group many years ago that got into diving twins we realized that all the time that it took us to learn on our own was shortened and cheaper if you find the store/operation or a group of divers who already dive them. Our group was located 1.5 hours away from a major Metropolitan area where you could find any "group of Tech divers" that could mentor us. So we all bought our equipment, played in the pool, and spent a couple of years buying stuff to experiment with. The internet helped but we finally had to find a better way. We all took the GUE Fundamentals course back when it just a workshop. We already knew the basics but that class got us squared away and also left us with skills to improve and learn. We took a key learning tool from that course, using a underwater video system to film each other while doing skills. It helped us all. We also lived in a transient community where people moved away a lot for work. That meant to sustain a continuing dive group we had to take new people to mentor. As you mentor other people your own skills get sharpened. That was 20 +years ago. I myself have moved away and don't get to dive as much as I used to. When I do dive locally, I wear my twin LP72's and Twin LP 85's just to retain my skills and familiarity with the equipment.

During the years that I was active, I was also teaching and I used my twins all the time. I used them teaching OW, AOW and so on. To use them (twin lp72's) for OW courses I have to be able to demonstrate all the skills that you have to teach. If you can do it you can use them.

Good luck!

 

[paddydiver]

2 10l steel tanks with a manifold and join a gym . Honestly, from experience, anything smaller or set up differently for back mount is just arseing around for zero reason or benefit.

 

[rx7diver]

... For tanks, I had figured on using a set of lp steel 72's... I'm planning on setting them up as independent twins ...

I like this idea, myself, for solo diving. When I first returned from MI to live in MO, I split apart my manifolded PST HP120 doubles (my erstwhile extended-range Great Lakes shipwreck cylinders) and dove them a few times as BM independent doubles for solo, no-decompression, walk-in dives in MO and AR lakes. This configuration worked perfect for me for this--except the cylinders were too large (too much capacity) for these types of dives. Too heavy, and too long/tall, for no good reason.

I purchased two Alum 80's to use, instead. Hated diving these this way! So much so, that I traded these still-new 80's almost immediately for a pair of old-school 72's. I imagined that the 72's would be the Goldilocks tanks for this. (Lower weight, smaller OD, better buoyancy characteristics.) Alas, one of the 72's turned out to be unusable, so I never tried the 72's as independent doubles. I still occasionally think about doing this, though.

rx7diver

 

[SouthernSharktoothDiver]

@rx7diver well, my plan currently is to try them out as independent tanks in some safe dive conditions, just to see what all the fuss is about. If it’s as much a pain as everyone here says, then I might switch to a manifold. Trouble @halocline is right about one thing: my current regs are yoke, and modern manifolds are all DIN. Not really looking for a total gear replacement at the moment. Was thinking about using a din to yoke insert, but idk if such a thing would work on a manifold valve. So, if independent doubles ends up being a pain, we’ll go back to the old drawing board

 

[ofg-1]

Not all modern manifolds are DIN only. Look into 200 bar manifolds, a lot are convertible to yolk.