Question Sidemount or backmount doubles?

[Cheizz]

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?

I have scoured these forums and the internet for objective pros and cons for sidemount and backmount setups. (‘Objective’ being the operative word here. Most comments seem to be very much in favour of either sidemount or backmount diving.)

Even though I will not be cave diving or doing penetrations into particularly tight spaces - for which sidemount was originally developed - there are some benefits to sidemount that look very appealing to me. Here’s what I found, or at least the major differences between the two setups.

Backmount:

• One stable unit, preferred on boats (?)
• Quite heavy to log around on dry land (I don’t have the strongest back in the world)
• Not as streamlined as sidemount (?), but adding stage bottles doesn’t hurt streamlining further

Sidemount:

• Two units, may not be as stable on boats if tanks are donned above water
• Tanks can be hauled separately
• Sleeker in the water (?), but adding stage bottles negates this advantage somewhat
• Valves are easier to reach, and visible

A few questions regarding these two lists:

• Anything I missed on either list? There are some question marks in there, any comment on those?
• Is a set of backmount doubles harder or easier to find than sidemount tanks at dive centers/liveaboards (provided I bring my own BC and regulator set)? If itineraries and schedules allow for double tank dives, is one of these configurations easier to get when traveling and renting tanks?

Obviously, there is proper training and setting-up the configuration involved in both. Investment in special gear, too (another, bigger, wing for doubles or a sidemount BC, regulator sets) and maybe in tanks. I already have two steel 12L tanks, though. I just need to put new valves on them and sidemount rigging if I would get into sidemount, or try to build a double set out of them…

 

[Searcaigh]

There are pros and cons to both systems.

Climbing a boat ladder with steel doubles depends on the length of the boat ladder, some are too short (just like me ha ha).

Sidemount tanks can be tied off to the boat and you can splash without wearing the tanks then just clip them on in the water. clip them back onto the boat lines after the dive and climb the ladder without them, nice and easy. I'm looking to go that way at some point when my knees can't take the weight anymore.

Downside to sidemount (IMHO) is shore diving, not very secure to walk around with them? I've never tried!

Setting up a twinset takes a few dives to get the trim sorted, sidemount from what I've seen takes a lot longer for the less experienced diver.

Tech diving with sidemount looks a lot more clumsy (again IMHO) compared to back mount twins.

If I was looking to do caves and a lot of wreck penetration then sidemount has lots of advantages.

 

[Marie13]

SM has the big advantage of not putting a ton of weight on your back/knees/ankles. Depending on dive site, roll your tanks down to the water. Clip tanks on in the water. SM is fabulous for folks whose bodies can’t take the weight of 100 lbs plus of doubles on their backs.

Valve drills are significantly easier. You can see what’s going on. No fumbling about behind your head.

SM is very stable in the water.

SM can take some time to get dialed in. Mostly lots of little adjustments to get things just right, like correct hose lengths and such.

 

[rongoodman]

If you're looking at any significant increase in bottom time the issue becomes sidemount with deco bottles vs. back mount with deco bottles, and the associated training to use them and the required gas mixes properly. Not saying it's a bad idea, it's just that it's more complicated than you're making it out to be. (I'm of the opinion that backmounted doubles make more sense unless you have some compelling reason to go sidemount.)

 

[scubaozy]

Just get a bigger single tank and work on your gas consumption. You can also get 300b rated tank of same capacity you are using currently. Are you sure you need doubles? I personally start preferring doubles when I have a increased need of redundancy.

 

[rddvet]

As a long time sidemounter, start with bm first. There are pros and cons to both. But especially if you’re boat diving, bm doubles. Side mount has become a bigger and bigger fad that’s made it’s way into ow diving. There’s really zero reason to dive sm in open water (other than people like it or think it’s cool). Sm is finnicky and can be a pain when you’re first learning. Bm doubles learning curve is smaller.
Sm was invented to be a necessary tool. I dive it because it allows me access to certain caves or cave areas. I wish it stayed a purpose-driven tool. Unless you’re diving tight sea caves, you don’t need a smaller profile from sm. I will admit sm dives like a dream when it’s dialed in. But so do doubles if you learn them correctly.

 

[AJ]

Sidemount is a lot of hassle on land and on a boat compared to OC backmounted. In water it's my prefered OC setup by far. SM dives way easier and more stable than backmount and no more pesky valve drills

When you're planning the next step aka tech diving, think about rebreathers. No need to haul all those tanks, just enough gas to get back up in case of trouble. Unit weighs roughly 30 to 35 kg's and if everything goes right, you can do 4 to 5 dives with the same amount of gas needed for one OC dive (logistical advantage).

The question is: which dives do you do now and which dives do you want to do in the foreseeable future? What fits those dives best?

 

[Marie13]

Side mount has become a bigger and bigger fad that’s made it’s way into ow diving. There’s really zero reason to dive sm in open water (other than people like it or think it’s cool).

You are quite wrong there. Lots of us who dive SM do so because of physical issues. My knees couldn’t take the weight of doubles.

OP, unless you have physical issues that would be aggravated by the weight of doubles/doing valve drills, go for doubles. They’re definitely easier on boats. If no boat diving, that opens up your options.

 

[grantctobin]

OP, unless you have physical issues that would be aggravated by the weight of doubles/doing valve drills, go for doubles. They’re definitely easier on boats. If no boat diving, that opens up your options.

The vast majority of "I can't do a valve drill" is a fit issue. Yes, there can be physical impairments, such as those that result in your inability to get onto a boat with a single tank, but SM still shouldn't be the primary system for most people.

 

[Cheizz]

Thanks for all the opinions so far. In terms of availability abroad (when not wanting to fly in my own tanks), any big differences there?