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Openwater: Sidemount vs Backmount

Words and Photography by Drew McArthur

Take two bottles into the open ocean, or do you just want to jump in and go? Photo: Drew McArthur

Over the last ten years or so, diving sidemount has become all the rage. After decades of lurking in the depths of cave systems around the globe, it’s almost like one day it crept out of its hole and became seduced by fame and fortune. Shortly after its appearance onto the mainstream scuba platform, divers seem to have jumped on to the sidemounted bandwagon in droves. While it is undeniable that it does offer some advantages in some situations, I wonder if recreational open water sidemount is the holy grail that some make it out to be, or is just a case of the emperor’s new clothes?

Cards on the table

Before I get into the perceived pros and cons of diving sidemount, first I want to get a few things out in the open. I am a scuba instructor who teaches recreational diving as well as technical diving, and within both those arenas, I also teach sidemount. That may put me in the position to write yet another article that portrays sidemount as the cat’s pyjamas, fixing everything from being an air hog to having terrible buoyancy skills, but that’s not where I’m going with this. 

Neither am I criticising sidemount as a diving style. I appreciate this makes me sound like I’m perched annoyingly on the fence of the whole subject, but that isn’t strictly true either. The reason I have been motivated to put pen to paper on this matter is the number of divers I see struggling to harness the sidemounted beast, and in many cases failing to do so. What starts out for some as a curious glimpse into the unknown, ends up being an expensive way to ruin a whole bunch of dives. When I see this happening, I often find myself asking why are they putting themselves through such torture? Is it the fault of the diver, their instructor, the agency through which they got certified, anyone else remotely connected to the subject? 

My belief is that although sidemount is absolutely the right tool for certain jobs, it is not the one-size-fits-all solution it is sometimes sold as. In a lot of cases, it’s a mis-sold product that causes considerably more hassle than it’s worth.

When deciding if sidemount diving is for you, consider the type of diving you’ll be doing, the locations, your budget, and, most importantly, which one looks cooler…? Photo: Drew McArthur

What’s the problem?

There are a variety of different ‘right ways’ of diving sidemount and a whole heap of imaginative ways to end up doing it wrong. I was shortly after I started working in Grand Cayman eight years ago that I witnessed my first sidemount catastrophe. A guy turned up on the boat and had requested sidemount tanks (2x80cf aluminums) for his recreational boat trip. While the rest of the group had a single 80cf for each dive strapped to their back via a regular BCD, he took both tanks on both dives.

In theory his approach offers some potential benefits; in practice however, he was way off mark. His tanks were clipped in a sloppy fashion that allowed them to flop around on his side, nowhere near in trim. Instead of breathing down his tanks equally, he emptied one on the first dive but took it back into the second dive, during which he breathed down the other. In addition to carrying a useless tank, because it was empty it was positively buoyant, resulting in him being lopsided for the majority of the dive. 

He also struggled to get in and out of the water anywhere near the same time and comfort level as the rest of the group. So what was he trying to achieve? 

Now it’s true that this episode was not the fault of the style but instead the product of bad (or possibly no) training…to a degree. Had the diver in this case received better training it is likely he would have ended up being far more efficient, comfortable, and safer. There are many accomplished sidemount divers who can manage their equipment configuration in style and make it look slick and appealing in a variety of environmental situations. However, there are some divers who have been sold the idea of sidemount who simply aren’t ready for it and honestly may never will be. Having read back that last line, it sounds incredibly snooty of me, but just to clarify, I don’t mean they suck as divers and don’t have the natural ability to develop their skills, they just may not want to increase complexity levels in order to do so. 

Consider the style of sidemount as a discipline. It requires an understanding of an end goal and an ongoing commitment to reach that goal. Many divers would prefer not to have to put in so much work to achieve something that they were already doing perfectly well with a tank on their back.

This Grand Cayman turtle approves of your trim and buoyancy skills. And your pristine hair. Photo: Drew McArthur

So why bother?

When compared to single-tank backmount, dual sidemount diving requires a far greater attention to detail, more thought to manage environmental changes, constant self-analysis, correction, improvement, a heightened focus on self-critique, and a desire for perfection. The intricacies of preparing and donning sidemount equipment are more involved than regular backmount and less forgiving in their appearance if the diver gets something wrong.

Backmount (recreational) on the other hand, mostly requires strapping a tank to a BCD, slinging it on your back and jumping in.

Are either of these processes or results bad? No, I really don’t think they are. Both have their place but one or other is usually suited to certain people. It is my belief that since sidmeount’s rise to fame, a good number of divers have blindly adopted it (or tried to) without understanding what they have to put in and what that then enables them to take out. 

I like to ask my potential students why they want to enroll in sidemount training. I find it interesting that many responses, when boiled down, amount to the fact that they think it looks cool.

Sidemount absolutely provides some benefits in some environments and locations for some people. Most of these advantages, however, are of very little benefit to the general recreational diving population. Many agencies, manufacturers and instructors involved in promoting sidemount boast of its benefits – but, naturally, they don’t offer any counter opinions. And when they tout the advantages of sidemount, it is often unclear against what exactly it is being compared. It is difficult to look at all perceived advantages across the board without variables like body types, cold vs. warm water, steel vs aluminum tanks, etc.

The following is a handful of advantages sidemount is said to offer, with a bit of devil’s advocate thrown in. To be clear, in this case I am comparing two-tank sidemount to what I believe to be the most common configuration for recreational divers, which is single tank backmount.

  • Redundancy: Yes, sidemount offers a completely redundant gas source. Carrying a 30cf pony bottle, however, would do the job just as well but is less weight, less management, easier to transport, and easier to don/doff.
  • Access to valves: True, this helps with problem solving underwater. A diver in backmount would have nowhere near the same access or sight. However, in the event of an issue, provided the diver was following the rules of his training then he would be close enough to a buddy to get assistance. If diving solo, then a pony bottle should suffice in getting the diver out of dodge when needed.
  • More comfortable for people with back issues: The two main arguments I hear for this are that it is easier to prepare to don in the water, and the position of the spine, neck and head while diving. In many cases the first point is weakened by the availability of crew who offer assistance. In certain environments, such as when the diver doesn’t have easy access to the entrance/exit point and no support (like a shore dive, private boat or clamber to a cave entrance), then it could be easier to cart individual tanks and regs into the water than adding the BCD and weights into the mix. Regarding spinal positioning, modern BCDs are very adjustable and should allow the diver to assume whatever position aggravates their back the least. There may be some divers out there that have conditions that honestly are aggravated less when diving side as opposed to back, but these are not the majority of divers who have back issues.
  • Efficiency: I agree it is more efficient (takes less energy, if done correctly) to carry two tanks on the side than it is to carry a set of doubles. Compared to a single tank, however, if it is (due to streamlining) more efficient to kick against two tanks and the additional weight required to sink both of them when empty, then the difference isn’t noticeable without scientific equipment.
  • Trim, balance & stability: It is too general to say that sidemount configurations enable better trim than backmount. For example, if a diver is using a backplate and wing with correct weight distribution he or she should be able to achieve perfect trim. A jacket style BCD may not be so forgiving but in most cases is still possible. Regarding balance and stability (whether you list to the port or starboard side or have tendencies to wobble around while diving), yes, a tank either side is superior to one on the back. But these problems are not of note to most divers, especially those who use aluminium tanks.
  • Easier to remove underwater: This is a genuine benefit of sidemount: being able to take the tank(s) off to squeeze them through a little hole that the diver is then able to crawl through afterwards. This would be considerably less practical to do with a backmounted rig. But how many recreational open water divers have found themselves needing to do this? 
  • Sidemount is often called a form of tech diving, which isn’t quite correct. It is possible to conduct tech dives using sidemount or backmount, and guess what… there are pros and cons of each.
Being able to unclip your tanks for restricted spaces is an advantage of sidemount, also for sandwiching your buddy’s head when a photo-op arises. Photo: Drew McArthur

Tech diving

Sidemount is linked to technical diving because many of the accepted practices associated with it were developed by the cave diving community. The benefits of sidemount really do come into their own right in unforgiving overhead environments. However, just as it isn’t black and white in the recreational world, the same can be said for tech. Not all tech dives are cave dives. Many aren’t in any form of overhead environment and therefore are considered to be open water tech dives where there is very little value in the diver strapping three, four (or even more) tanks to their side inwards towards their stomach. There is a huge amount of space available on the back that is begging to be filled with a set of doubles. Even in overhead environments it is entirely possible to explore multitudes of wrecks and caves using doubles. 

Sidemount is not a requirement for cave diving but due to the relationship between the two, it is the divers who spend time in such environments that typically manage to hone their skills and make it look easy. Those lucky enough to have access to the myriad of cave networks in Florida, Mexico, and other hotspots around the world, who use sidemount functionally with regularity, are the ones who most noticeably develop the appropriate mastery of it. That isn’t to say that sidemount is solely limited to such players, but having the need to apply the technique and the opportunity to practice it regularly helps shape a more positive end result.

Closing time

I am not critical of sidemount as a technique. I fully appreciate its value in the right circumstances and see some benefits that can spill over into recreational open water diving. However, I feel there is a lot of misleading hype originating from training agencies who see potential profit in a new product line. Fair enough; they are, after all, businesses. 

My two cents is that sidemount is a niche activity that isn’t necessarily suited to the wider community to which it is currently being marketed. I’m not suggesting we banish sidemount back to the shadowy caves from whence it originated, but diving in an overhead environment remains the most compelling reason that I know of to use it. 

If you are considering trying it out, my intention isn’t to put you off. I hope to help set expectations and maybe save those for whom it is not the right solution a good deal of time and money. If you still want to switch to the dark side then go for it, just do your homework when selecting an instructor.

Using one kind of equipment doesn’t make you a better diver unless a situation or environment demands it. So what does make one diver better than another? Diving is not the kind of sport in which ability is clearly defined by speed, distance, or duration, so it’s hard to measure. My belief is that the mark of a good diver, beyond being able to safely conduct yourself underwater, is whether or not you are enjoying it. For some that means sidemount. But for the majority, it is still backmount. And if that ain’t broke, then my advice is to not try fixing it. 

1 Comment Leave A Reply

One Response to “Openwater: Sidemount vs Backmount”

  1. Billy Om

    It seems the writer has no clue what is the sidemount diving setup all about


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