Question Sidemount or backmount doubles?

[tbone1004]

@Wibble the pic below is me *and apparently at the end of my inhale since I don't have a gut that big! but that's not how most people look. The picture I sent is in fact the promotional picture for PADI sidemount, and that is how you will encounter most sidemount divers in the wild.

 

[RobPNW]

As someone with a variety of lifelong knee, ankle, shoulder, back etc injuries from active duty and college sports, some of the comments have provided great insight for me to consider doing some SM training in the future. I still have PLENTY to learn within the framework of recreational single tank diving for now. I typically have more gas remaining than about 80% of a boat full of people when surfacing so that's not an issue for me. With that said, and having no plans on doing solo diving any time soon, my bottom time limitations will likely be related to a buddy's gas supply more often than not. Down the road, I may have to do some research of rebreather vs SM if my situation changes and I drift towards more advanced dives or dive with people who aren't single tank divers. As I get older, I just assume the added weight and associated stress of doubles will only get more challenging, not less. Thanks for sharing insights.

 

[ginti]

The thing with a DIR-style backmount twinset...

Since when was the DIR standard....

... comes in all sorts of non-DIR guises ...

Wibble, seriously, what's your problem with ***DIR***? Why do you name it when it isn't necessary at all?

I mean, please continue, it's funny

ok let's start it

 

[divezonescuba]

I was going to stay out of this thread. But since my picture is in post #78, I will add my 0.02 in.

Independent backmount backmount doubles comes in at least three different configurations.

The least controversial is the use of independent tanks with left and right modular valves. This is the same as diving with a manifolded set minus the manifold with respect to the valves. It can be thought of as diving sidemount, but with the tanks on your back instead of the sides. Valves manipulation is the same as with manifolded tanks. This configuration can be very useful for people who do not want to carry two tanks on their back to the entry point. The tanks can be taken to the water dismounted in the same manner as sidemount tanks and already assembled tanks can be mounted on the backplate easily using tank bands. I dive this way regularly when I have access to my own modular left and right tanks.

The more controversial way is to use standard right hand valve tanks. To do valve manipulation in the same way as with manifolded tanks, you have to reverse one of the tanks. If one of the tanks is reversed, the regulator also has to be reversed. This is where I believe the controversy arises.

Divers who plan to go into confined spaces maintain that the configuration is not as streamlined and more likely to get caught on an obstruction and this is true.

I am not encouraging, nor instruct this practice at all, particularly for divers who are not both backmount and sidemount certified. The purpose is to show that yes, it can be done and can be done safely under some circumstances. This allows you to dive backmount doubles where are none, are too expensive to acquire, or are too logistically inconvenient to use.

Prior to diving independent backmount tanks, I would rent a set of manifolded tanks. What I found out was that I had to find a fill station three or four times a day and wait for the tanks to be filled. When I used independent modular left and right valves, the same situation existed. However, when using regular right hand valve tanks, I can just switch them out anywhere, any time.

One configuration which even I will not dive with is two standard right hand valve tanks backmounted with both tanks facing forward. Here, the left tank valve would be directly behind your head. I believe that that configuration is too different and difficult to use than the valve configuration with manifolded tanks, at least for me. Of course, I would not begrudge someone out there that could make this work for them.

I get a lot of hate and accusations when I discuss the use of backmount independent doubles. One person even wanted to know how it was possible that I had not yet injured myself or had already died. Thats ok, I am used to it. Its gotten to the point where I don't even bother disabusing these commenters.

I am currently working on maybe my fourth or fifth video on the use of independent backmount doubles. I think I will title it "OMG I dove independent backmount doubles with right hand valves for a week in Bonaire and I am still alive."

The funny thing is that this also generates a lot of agency bashing on the part of PADI. PADI does not even authorize the use of independent backmount doubles. On the other hand a lot of these people who make these comments are TDI certified tech divers and guess what, TDI specificially authorizes the use of independent backmount doubles and they dont say what kind of valve you have to use.

 

[barth]

A b'stard of a hill to climb to go diving. Sidemount's so easy in comparison!
View attachment 704566

You still have to climb the hill with your tanks. Sidemount tanks connected to a sidemount rig is not easy. Tanks will move, (even underwater my aluminum tanks positions will not be the same when my tanks are full and when they are empty). The same will be happening when climbing a hill. I prefer to climb a hill with my tanks at my back, very close to my body without moving. A backplate, harness and steel bands are the perfect solution for me.

Honestly, I did climb hills like that with sidemount, backmount doubles and gue jj. I prefer backmount doubles.

Climb a hill like that in the summer with sidemount. I have to climb a hill like that at least 3 times. First with sidemount tank 1, another time with sidemount tank 2. And then put my drysuit on and climb it again.

Climbing a hill like that with sidemount gear is still a lot of hassle. (I have seen Audrey Cudel climbing a small hill like that it wasn’t easy for her with sidemount gear.)

No it won't. They'll basically have within 30bar / 30x14 psi difference. Breathe the RH one down to 30 bar less than the left; switch and breathe that to 30bar less than the RHS (i.e. 60bar), and repeat.

Last year I did cave diving. The conditions were bad, we did sidemount dives. At the end of the week one buddy told me he first breath down the first tank until turn pressure. After that he did start breathing his second tank.

I thought all sidemount divers did keep their tanks within 30 bar difference. But I was wrong.

 

[rddvet]

I am currently working on maybe my fourth or fifth video on the use of independent backmount doubles. I think I will title it "OMG I dove independent backmount doubles with right hand valves for a week in Bonaire and I am still alive."

please dont. Do you not realize the only thing your videos accomplish is creating fodder to make jokes at your expense? And if you are adamant about it can you get somebody else to read the commentary?

 

[scubadada]

As a total outsider, single back mount with or without a pony, it's always fun to watch the factions in these types of threads. Thanks for the entertainment.

 

[wetb4igetinthewater]

As a total outsider, single back mount with or without a pony, it's always fun to watch the factions in these types of threads. Thanks for the entertainment.

Wait a few months for a new thread on the same topic with the same cast of characters saying basically the same thing to occur.

This is one of the topics that occurs more frequently than I've watched Ronin.

 

[Wibble]

You still have to climb the hill with your tanks. Sidemount tanks connected to a sidemount rig is not easy. Tanks will move, (even underwater my aluminum tanks positions will not be the same when my tanks are full and when they are empty). The same will be happening when climbing a hill. I prefer to climb a hill with my tanks at my back, very close to my body without moving. A backplate, harness and steel bands are the perfect solution for me.

Honestly, I did climb hills like that with sidemount, backmount doubles and gue jj. I prefer backmount doubles.

Climb a hill like that in the summer with sidemount. I have to climb a hill like that at least 3 times. First with sidemount tank 1, another time with sidemount tank 2. And then put my drysuit on and climb it again.

Climbing a hill like that with sidemount gear is still a lot of hassle. (I have seen Audrey Cudel climbing a small hill like that it wasn’t easy for her with sidemount gear.)




Last year I did cave diving. The conditions were bad, we did sidemount dives. At the end of the week one buddy told me he first breath down the first tank until turn pressure. After that he did start breathing his second tank.

I thought all sidemount divers did keep their tanks within 30 bar difference. But I was wrong.

Just to say that climbing up that steep hill is a killer regardless of the config. It's about 40m/130ft elevation and about 1km/1000yds to walk. You must do it twice as you'd carry your twinset + 1 bag for the first trip then carry your other gear + drysuit in the second trip. With sidemount you can balance this a bit by carrying once cylinder + other gear in one trip and the drysuit + other gear in the second trip.

Those tackle bags really are great. I use them on boats as you can carry all your "other crap" including fins and lunch in the big bag.

For sidemounting I always have the nose clips installed on the cylinders and simply put the SM harness on and clip the cylinders to the chest D-rings.

 

[boriss]

I am an AOW diver that wants more bottom time and thus more breathing gas. For single-tank dives, I really like my backplate & wing setup. No issues with that for those kinds of dives. But I would really love to get some more bottom time and expand my reach/range. I will definitely seek proper training to go beyond my current certification in terms of maximum depth and no-deco limits. But with which setup?

If you're staying within NDL I don't know why you'd want to go past singles. The complexity and expense goes up exponentially once you start getting into doubles of any kind. Just invest in a tank that can hold more gas. Most people should easily blow past NDL with an HP100 steel tank.

Some boats ban sidemount, you say. On the other hand, getting back-mounted doubles anywhere abroad seems more difficult than two separate tanks for shore dives for example. If liveaboards ban double tank diving altogether, I'll just bring my single tank set-up.

So which of these apply to you? Are you diving off of boats or are you traveling? Maybe you need multiple setups?

Underwater, what CAN'T you do with sidemount that you CAN with backmount? Note that I am not going to take many deco bottles any time soon... Max two, if even that.

So are you staying within NDL or are you going to go into technical diving? If it's the latter, then what is your purpose? Where are you going? What will you be doing? Who are you doing it with? What do other people use for that style of diving?

When it comes to technical diving things get way more.... well, technical. Having the right tool for the job is more important than being right on this forum. You'll also be planning this dive, it's not like recreational dives where as long as your tank is full of gas you plop in and go.

Before you even worry about BM or SM you need to plot a trajectory of interest. For example, my interest is deep wreck penetrations, which means live drops off a boat in all kinds of mixed conditions. It doesn't matter what pros/cons are listed in this thread, the right tool for the job is BM doubles.

Figure out what you want to do first. That will drive your gear selection, not the other way around.