Sidemount Diving: It’s Not Just for Caves

By Steve Lewis

Sidemount-Diving-Not-Just-for-caves… but we should remember, that is where it started!

Perhaps typical of divers who use and teach sidemount today is the phrase, “it’s not just for technical divers anymore!” And the truth is that sidemount is a truly versatile kit configuration that in the past few years has stormed into just about ALL areas of technical diving (even rebreather divers side-mount their bailout bottles!), as well as gaining favor with sport divers who have no intention of pushing ANY limits whatsoever. However, it’s worth remembering that for all the flexibility and adaptability that sidemount configuration offers to tech and sport divers, it started as some weirdness that only crazy cave divers got up to.

My personal introduction to “sidemount” was as a kid dry-caving in the UK. We were not divers, but we had access to small cylinders filled with air – probably three or four litre steel tanks about the size of the bottles you’d find on most rebreathers these days – and there were a couple of short sumps between us and the best parts of the caves we were playing around in. We strapped a tank to the side of a climbing harness, put the regulator in our mouths, and walked/crawled through the sump. And believe me, the reality was a lot less dramatic than the description. The sumps – a part of the cave completely underwater – were probably no longer than we could have covered holding our breath, and the cave we were exploring, at least the part we were exploring, was a very well-travelled passage. Nothing at all note-worthy.

The point being that if we’re looking for the spot to place a commemorative plaque celebrating the beginnings of sidemount “diving” in caves, we could easily argue for the Mendip Hills, in England’s West Country. In fact, that area has been – and remains – the focus for “real” cave diving and true exploration since the late 1930s.

But, if the birth of sidemount cave diving took place in England, the technique was raised to adulthood in the area of North Florida famous for its karst landscape, fresh-water springs, pioneering explorers, and organized clubs and associations promoting ecology, preservation, understanding, and formal dive training.

Within a generation, SM (sidemount) cave diving, as taught and promoted in Florida’s cave country, has evolved from a somewhat marginal extreme undertaken by a tiny percentage of trained cave divers, to a level where today, in some systems, close to 100 percent of the divers playing in the cave are configured in sidemount gear. In short, it has grown to the point where the question, “Who does that crazy stuff?” seems to have morphed into, “Who isn’t doing it?”

So, if we know who – everyone or close to everyone – let’s find out why and how.

Why use SM in a cave? Well, the traditional answer would be that a sidemount configuration allows a diver access to areas that would simply not be open to them if they carried tanks on their back.

Configured correctly, SM gear is extremely streamlined: that is, when hoses are optimal lengths, nothing is left hanging off the diver to simulate being a Christmas tree decoration, and primary bottles run along the diver’s lateral line without their noses pointing to the floor and their backsides in the air. The diver’s in-water top-to-bottom profile is much smaller than when wearing doubles, a single or a rebreather. It’s true that her side–to-side profile will be wider (incidentally giving a very comfortable lateral stability), but the way sidemounted tanks are attached to the diver’s harness allows them some latitude to move out of the way when side-to-side space gets restricted.

Indeed, a skill taught to SM students, during even a very basic orientation class and certainly in a SM cave diving program, is to unclip the rear snaps and swing one or both cylinders around so that while the tanks nose remains attached, the bottoms now face forward. This gives the diver a very long, narrow profile.

In short, for smaller, tighter spaces, sidemount rocks.

By the way, this last technique is NOT no-mount diving. No-mount is an extremely advanced technique used to explore very tight passages. The diver pushes a SINGLE, unattached cylinder ahead of them through small passages. Doing this offers access in very limited space, but is hugely risky for several reasons, not the least of which is that the diver has zero back-up gas and may have to exit without being able to turn around. For the record, John Chatterton famously used this technique to explore the U-Who wreck.

A lot of sidemount’s popularity is due to the wide-spread availability of purpose-bought SM harnesses. In sidemount’s adolescent years, sidemount cave divers used stab jackets (traditional sport BCDs) as the core of their SM kit. These were highly modified with bungee, bolt-snaps, sewn loops of webbing and added DRings to the point where when modifications were completed, the end-result was barely recognisable as a shop-bought piece of sport diving kit.

This DIY approach certainly seemed to restrict the growth and popularity of sidemount diving. A change came when mainstream equipment companies started to sell integrated wing and harness rigs custom-designed for sidemount cave diving. The leader on this score was Dive Rite, a cave-oriented manufacturer based in North Florida but with distribution world-wide. Currently, Dive Rite sells several models of SM harness each designed for a slightly different purpose and are probably the best-known and most popular SM brand. But they are no longer alone, and several other companies have one or two models on the market including Hollis, Oxychek and OMS.

This sudden explosion of available, well-built, purpose-designed harnesses – and the accessories such as CAM bands and various length LP and HP hoses that make rigging for SM much less of a DIY project than it was just a handful of years ago – has helped fuel the growth of SM cave diving. But there is certainly something else at play.

Lamar Hires, president of Dive Rite, describes it as a life-style choice. “Using SM to explore tight spaces is a mission-specific decision,” he says, “But a lot of divers are uncomfortable carrying a set of double cylinders, and for them, SM offers a lot less stress because cylinders can be carried to the water one at a time!”

And a straw-poll of a lot of SM cave divers turns up that the number one reason for being configured the way they are is convenience and comfort, rather than something “mission specific.”

The ‘HOW’ of SM cave diving is what’s taught in a TDI Sidemount Diver course. Most of the techniques and procedures are the same as a “regular” cave course with kit configuration being one major difference. Another is the slightly more complex system employed to manage gas volume. With two independent cylinders as opposed to two cylinders joined by an isolation manifold, the diver has to switch regulators during her dive to distribute gas consumption “evenly” between each tank.

In all TDI overhead programs, the Rule of Thirds and related modification of it are hammered into students’ minds with constant repetition. The simple mantra of “one-third in, one-third out, one-third (plus an additional reserve) for contingencies” holds true for SM cave diving, but there is a twist on account of the need to swap regs during the dive.

There are a couple of protocols that are taught but one that is popular goes like this:

Given that gas-matching and volume requirements are worked out and agreed with the rest of her team, the diver begins her dive breathing from Tank A. When she has consumed ONE SIXTH of her available volume, she switches regs and begins to breathe from Tank B. She continues to breathe it until she has consumed ONE THIRD of her available volume, at which point she switches regs once again. She is now back to breathing from Tank A. When she has consumed ONE SIXTH of its volume (which adds up to a total of ONE THIRD of the available volume in EACH cylinder), she signals turn the dive. But she keeps breathing from Tank A until she has used an additional SIXTH. At which point she switches regs for the last time. Let’s use some simple numbers to illustrate the point (and we’ve avoided using pressures or actual volumes to make this work for both imperial and SI unit users, and the asterisk indicates the tank being breathed from).


Using this technique, the difference between the two tank volumes during the critical phases of the dive are never more than one-sixth of the starting pressure. In the event of an OOA situation at the maximum penetration, the OOA diver can be given a cylinder containing 2/3 of the starting volume… enough to get them out if proper gas management rules are followed. As the exit progresses, the gas buffer, the contingency, gets wider and wider. Using this method, there are only three regulator switches. Most other options require more.

Obviously, there’s much more to be said about SM cave diving – that’s what a course is for – but we hope this has at least reminded you where the SM “craze” started: wet rocks and holes in the ground, like so many of the innovations in diving today!

Have fun, and dive safe.

Below are a few of the TDI sidemount/cave courses offered.
TDI Sidemount Diver >
TDI Cavern Diver >
TDI Intro to Cave Diver >
TDI Full Cave Diver >

Contact SDI TDI and ERDI

If you would like more information, please contact our World Headquarters or your Regional Office.

Tel: 888.778.9073 | 207.729.4201

Email: Worldhq@tdisdi.com

Web: https://www.tdisdi.com

Facebook: www.facebook.com/TechnicalDivingInt



The Sidemount Diver: an Interview with Pete Nawrocky


Pete Nawrocky

SDI sat down with avid sidemount diver and instructor Pete Nawrocky with Dive Rite to discuss how and why divers get involved in Sidemount Diving.

SDI – How long have you been diving?
Pete – I started diving in 1971 and then in 1998 started with sidemount.

SDI – Why did you want to dive sidemount?
Pete – Caves. I got into it because I simply could not fit safely with backmount. And back then, the only way to do sidemount diving was to build your own harness.
Originally that was the whole intent, and it was more in terms of getting into areas that were not accessible with backmount. Now, it’s changed to the point where it could be called a lifestyle change where people actually make the commitment to diving sidemount. Here are a couple of factors that make that decision:

  1. The inability to carry weight because they have a back problem, lack of mobility, or shoulder problem, is usually a reason people switch to sidemount.
  2. People feel comfortable with it once they have it on in the water; they find it a lot easier to work with after they have been trained and they are using the unit for a while. They seem to stick with it, whether boat or shore diving.
  3. And another common one is ahh… ‘cause it looks good. It’s a lifestyle change. People want to do something different than they have been doing before.

SDI – Who is the ideal candidate for sidemount diving?
Pete – The minimum certification level a diver should have is advanced scuba diver, but there is no ideal candidate. It really comes down to somebody who has a desire to do this type of diving and they make a commitment to it.

SDI – Are there pre-requisite experiences for sidemount? If so, what are they?
Pete – We want to make sure divers are comfortable in the water and with their equipment before trying a different style. A lot of people think in terms of wearing 2 tanks when talking about sidemount. Well, you don’t have to wear 2 tanks; you can wear a single tank while diving sidemount, and deciphering between 1 or 2 tanks really depends on the person. By and large the people that want to be in sidmeount have already made that decision, and the way they made that decision is most times they have tried it, whether they tried at the pool or a demo day event, or they have talked with their friends or seen people with it. Once they get started, they tend to stick with it.

SDI – As a sidemount instructor, what advice would you like to share with divers who are considering the course/style?
Pete – The first thing they should do is try it before they get involved in anything else. There’s a lot of events and demos for divers to actually get the gear on in water, so they can get a feel for the equipment. I strongly recommend that they take a course because it’s not difficult to dive with, but it is about gear management and gas management while you’re making the dive. You just don’t buy it, slap it on and go; it has to be fitted to an individual’s body shape for a proper wear.

SDI – Once the diver has committed to trying sidemount, do they have a learning curve when transitioning from backmount to sidemount?
Pete – Yes, there is a learning curve, and that curve is getting the gear configured to your body shape and learning to manage the equipment in the water as well as managing your gas consumption. Diving is both a mental and physical sport. Some people pick up on it right away and feel very comfortable with the configuration, and others have to change the way they swim in the water, since a frog kick is the preferred method of locomotion underwater and they have always been doing a butterfly, so mastering the frog kick and the equipment is the most important learning curve.

SDI – You recently taught an SDI headquarters’ staff member, Taylor. Can you tell me a little bit about that?
Pete – Taylor did great during the course; her trim was good, her fin kick was good, she handled it well, she did all the drills properly and took her time. The major skill in sidemount diving is the ability to handle your gear by yourself. There is no reason for a sidemount diver to have to have someone help them get dressed, that’s all part of the class. She learned how to get dressed on the surface and in the water as well as de-kitting on the surface and in the water. That’s the major thing about sidemount diving, you’re not supposed to need a caddy, so-to-speak, to help you get dressed and in and out of the water.

SDI – If I want to try sidemount, where would I go to learn more?
Pete – Demo Days are a great place to learn more. Most dive centers and manufactures will have demo days so divers can try out new equipment. Dive Rite and TDI are partnered up this year at several locations, one being at Dutch Springs on June 8, 2013.

SDI – Last year SDI/TDI and Dive Rite teamed up with Buddy Dive Resort in Bonaire for a week of tech dive demos, presentations and training. Was sidemount included in the camp?
Pete – Yes it was, and we will be doing it again this October, 2013. Bonaire was a blast! We had a pre-dive briefing and then off to the water. We demonstrated how to get dressed in the water while floating on the surface. Then with a sidemount instructor, they went on a guided dive, so they got the experience of actually diving sidemount. And for those who were qualified as instructors, we helped them work toward their instructor level.

SDI – If you could rectify one myth about sidemount diving, what would it be?
Pete – The first thing you have to understand, sidemount diving was propelled to where it is today by the consumer, not the manufacturers. This is what the people wanted. They saw the advantages, they tried it and they enjoyed it. The only thing I can say this is akin to is if you are a skier, and if you remember about 30 years ago when the snowboards started showing up on the slopes, everyone said it was a fad and it wasn’t going to stick. Now, it’s an Olympic sport.
Sidemount diving is viewed upon the same way. You can see people discussing it, saying it’s not necessary, its only mission specific, but what it comes down to is that this is something that somebody wants to do and they make the active decision to dive this way and that’s why it took off, because they liked it.

SDI – Whats next from sidemount?
A – Sidemount is just a different way of carrying your gear. So to make it simple, the sport diver with a single sidemount may want to make that jump to deep dives, requiring decompression diving with a double sidemount, wearing two tanks. And after that, the next step would be technical sidemount, where you might be doing mixed gas dives, carrying 2 cylinders or you may be up to four or more because you’re doing trimix dives that require switching to different breathing mixtures.

SDI – That leads me to my next question: is 2 tanks technical diving?
Pete – No, technical diving isn’t what you’re wearing; technical diving is what you’re doing. Some people like the 2 tanks even though they are not doing deco, but they are planning 2 dives that day. Wearing both tanks on the first dive is all about gas management so they have enough gas in both tanks to make the second dive without changing their rigging.
Individuals considering solo diving may look at sidemout diving as one of the best configurations to go with because you have full control over your equipment. In terms of gas management, if you have any problems with your hoses or regulators, you can actually see what you’re working with.

SDI – And finally, is sidemount your preferred configuration for diving?
Pete – Yes. If I’m not diving the rebreather, I prefer to dive sidemount.

For more information on sidemount diving or to find an SDI sidemount instructor near you, visit us at https://www.tdisdi.com/sdi/get-certified/sdi-open-water-sidemount-diver/

Contact SDI TDI and ERDI

If you would like more information, please contact our World Headquarters or your Regional Office.

Tel: 888.778.9073 | 207.729.4201

Email: Worldhq@tdisdi.com

Web: https://www.tdisdi.com

Facebook: www.facebook.com/SDITDI