Question Sidemount or backmount doubles?

[PfcAJ]

God forbid someone practice to get good at something.

 

[Cheizz]

One more question...

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.

 

[Celt]

Strongly disagree.

Reaching back to do a valve drill is very hard for most people and needs a lot of practice to get the knack of doing a valve drill. It also requires constant refreshing practice. Good example is you've jumped in and not turned your gas on (stupid thing, but happens in the real world). Sod doing it for real when you're in a panic because you can't breathe and you can't reach the valve to give it a good turn. Sidemount or bailout is really simple: it's in front of you and you can grab that knob to really turn it.

Sidemount's a great system and should be the primary system for people who want to use it as an alternative to the sub-optimal backmount system. It's more reliable than backmount which still has that manifold as a single point of failure.

But there’s more than one way to skin a cat. I never used an isolator on my twins. Main reg on a valve between the tanks and my backup on the right post. In the event of a problem I’d drop the waist band and pull the tanks out over my head. I can see immediately where it is. Of course it takes practice but so does everything else. A bit of air in the wing helps. Back mount or side mount the OP will have to practice how he plans to use them.

 

[scubadada]

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…

Hi @Cheizz

I'm still not sure where you were going with this thread. You say you are an AOW diver who wants more bottom time, I'm assuming no deco. Are you talking about your current diving or are you planning for the future when you have significantly more training and are in the technical realm? I also don't know what kind of diving you currently have available to you and what the deficiencies in your current set up are.

If your current no stop dives are simply gas limited, dive with a larger cylinder. If this is all in preparation for technical diving, the discussion regarding back and side mounted doubles is appropriate.

I have about 15 years' experience diving off rec boats in SE FL. This is certainly not a sample of tech trips. However, tech-oriented divers frequent these boats and use their configurations of choice. They often do 2 rec dives or, if on a double dip on a wreck, have their choice of a single dive. In over 1200 dives, I have been on a boat with a diver with double side-mounted tanks just once. Divers with back-mounted doubles are not uncommon, small doubles are fairly frequent. It is not uncommon to dive with folks using rebreathers. It may be peculiar to ocean, boat diving in SE FL, but side-mounted doubles do not seem very common. I wouldn't be at all surprised if it were completely different up in cave county and the diving done there.

Best of luck

 

[wetb4igetinthewater]

Note that I am not going to take many deco bottles any time soon... Max two, if even that.

IMHO, more than two deco bottles is rebreather territory.

I disagree with the comment about doubles being better for doubles. While uncommon, in my area there is a shore dive that I'd like to do (Octopus Hole) where no way would I consider backmount doubles. I wouldn't consider my rebreather either. I'd take down two cylinders separately, kit up, then walk down.

Even for long walks to/from the entry/exit, I prefer sidemount for cold water OC diving.

I remember in a similar discussion when I brought up the advantage for travel. Someone here called me lazy. I just laughed as trying to arrange in advance is a PITA and often impossible. I'd rather show up the next day after arriving, take two cylinders, and jump in the water.

 

[Celt]

One more question...

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.

There’s a lot of deco gas in one tank. Off hand I can’t think of anything you couldn’t do in side mount.

 

[Wibble]

One more question...

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.

Crash into the roof of a cave? Can't get though tight spaces? Can't swim on your side through a tight corridor with ease for extended distances? Can't tell your size simply by your outstretched arms and head? Can't take your cylinders off and push them through a restriction.

Am being a bit pro sidemount here, but someone has to stand up for the backmount "must do it write" people

Anyway, go underground and sidemount rules with awkward passages and restrictions. In my experience on a boat with sidemounters, you simply don't notice them kitting up as everyone gets ready for a jump. In reality sidemounters tend to kit up standing up, so take up less bench space.

 

[broncobowsher]

In sidemount, you can't access all of your gas if you lose a regulator. It would take multiple simultaneous failures for that to even matter. Forget a full face mask with sidemount, without a lot of extra plumbing (cough, Z-manifold). Getting a fill of a mixed gas (Nitrox) is more touchy with sidemount. If the mixer is a little off you could have a little different blend when you do a reg switch. Sometimes you might be in less than great water that you don't want to do a reg swap. Sidemount also adds clutter in the chest area. There gets to be a lot of stuff under your chin. The plumbing that would normally be behind your head is now mixed in front of you.

None of that stuff is huge. Just more of details.

 

[Celt]

Crash into the roof of a cave? Can't get though tight spaces? Can't swim on your side through a tight corridor with ease for extended distances? Can't tell your size simply by your outstretched arms and head? Can't take your cylinders off and push them through a restriction.

Am being a bit pro sidemount here, but someone has to stand up for the backmount "must do it write" people

Anyway, go underground and sidemount rules with awkward passages and restrictions. In my experience on a boat with sidemounters, you simply don't notice them kitting up as everyone gets ready for a jump. In reality sidemounters tend to kit up standing up, so take up less bench space.

No doubt side mount is very versatile and you can make a lot of personal adjustments to suit yourself.

 

[Wibble]

But there’s more than one way to skin a cat. I never used an isolator on my twins. Main reg on a valve between the tanks and my backup on the right post. In the event of a problem I’d drop the waist band and pull the tanks out over my head. I can see immediately where it is. Of course it takes practice but so does everything else. A bit of air in the wing helps. Back mount or side mount the OP will have to practice how he plans to use them.

Agree in reality the chances of a manifold needing to be used is limited.

Main reason is the BOOM! a cloud of bubbles envelop you and you need to protect your remaining gas by isolating, then resolving which side's wrong. This generally brings up another common approach which is shut down the RH valve and see if that works, then open up the RH and shut down the LH valve.

I've been taught both ways: manifold first and RH first.

No doubt side mount is very versatile and you can make a lot of personal adjustments to suit yourself.

And that's the crux of the matter. Sidemount's a bit of a faff to set up, but once done it's easy street. A small adjustment here and there and someone observing you.

It's the same with a twinset as you need to be shown and practice the shutdown drills which takes/took me ages to get slick at.