Archive for category Sidemount

Sidemount Photos

Here are several photos of some of my students in sidemount. These were during classes so while the trim is pretty close to perfect some may be a little off. Also, camera angle can affect how the trim looks. This should give you a general idea of how sidemount cylinders should look, though.

Scroll down to also see some stage cylinder photos and to see how cylinders respond to lower pressures.

Worthington LP85s in proper trim

    Worthington LP85s in proper trim
    Worthington LP85s in proper trim
    Worthington LP85s in proper trim
    Worthington LP85s in proper trim
    Worthington LP85s in proper trim
    Worthington LP85s in proper trim
    Worthington LP85s in proper trim
    Worthington LP85s in proper trim

Faber LP85s in proper trim

    Faber LP85s in proper trim
    Faber LP85s in proper trim
    Faber LP85s in proper trim
    Faber LP85s in proper trim

Faber LP95s in proper trim

    Faber LP95s in proper trim
    Faber LP95s in proper trim
    Faber LP95s in proper trim
    Faber LP95s in proper trim

AL80s in proper trim

    Aluminum 80s in proper trim
    Aluminum 80s in proper trim

Properly trimmed stage bottle (you can barely see the stage in the 2nd photo)

    Stage cylinder in proper trim
    Stage cylinder in proper trim

Pushing one of the cylinders forward

    Faber LP85 pushed forward
    Faber LP95 pushed forward
    Faber LP95 pushed forward
    Faber LP95 pushed forward

Pushing both cylinders forward

    Faber LP85s pushed forward
    Faber LP95 pushed forward
    PST 100s pushed forward
    Faber LP95s pushed forward
    Faber LP95 pushed forward
    Aluminum 80s pushed forward

Some photos of Faber cylinders out of trim

The PST 100 in the left photo is only slightly out of trim. What’s happening is because the cylinder has more weight in a smaller area it trims itself out in a horizontal position. In turn, this pushes the diver out of trim. We dropped the bottom of the cylinder slightly and tightened up the bungees to adjust the cylinder and get the diver back to a horizontal position.

The Faber LP95 in the right photo is down to about a pressure of 1100. When the Faber LP95 gets down to about 1600 it starts to rise up like you see in this photo. This is why it’s important to manage your gas so you end your dive before you reach 1600 psi in these cylinders.

    PST 100s out of trim
    Faber LP95s out of trim

Why Fabers get out of trim at lower pressures

In the left photo is a Faber LP95 at the beginning of the dive. The weight of the gas in the cylinder is heavy enough to keep the cylinder pushed down at the rear attachment point.

In the right photo is the same Faber LP95 later in the dive with 1600 psi. Breathing gas from the cylinder has created a much lighter cylinder. As you can see the cylinder is no longer heavy enough to counteract the bungee and it rotates up so the bottom sticks up above the plane of the diver.

    Faber LP95s full
    Faber LP95s low

Some other issues you can encounter in sidemount

The photo on the left shows a stage cylinder in a poor position. The rigging in this photo is one that has been used by most sidemount divers for a few years. While the stage cylinder can be trimmed out nicely with this rigging at the beginning of the dive when it’s full, it doesn’t stay that way for long. As the gas in the stage cylinder is breathed down the cylinder gets lighter and causes the bottom to rise up.

The photo on the right shows a stock manufacturer’s wing with air in it. The diver is in a dry suit and using AL80s but still needs a little bit of air in the wing to keep him neutral. All of this air goes to the middle of the wing and pushes it up causing the gap you see. There is a way to fix this but it requires sewing in more tabs on this particular wing.

    Bad stage cylinder position
    Wing not properly cinched down

Cold water D ring

This is something we came up with a few years ago for cold water divers. The 2 inch diameter stainless steel ring you see here is useful for divers who wear dry gloves. The ring’s diameter allows the diver to slip a thumb through the center and use it to pull the bungee forward. The diver can then grab the bungee with the other hand and pull it over the valve. The ring also keeps the glove from getting trapped between the bungee and the valve.

Cold water ring

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Sidemount Stage Rigging

Here’s a short video clip of me taking the stage bottle off and putting it back on during an actual dive in Twin Cave.

Rob Neto’s method of side mount stage rigging from Rob Neto on Vimeo.

A few years back several of us were experimenting with different ways of carrying a stage cylinder with a sidemount configuration. Having already done dives in backmount with stage cylinders that method, carrying the stage cylinder below with the clips connected to the chest and waist D-rings, was the obvious first choice. However, this method detracted from the streamlining offered by a sidemount configuration.

Some divers over in the High Springs area were experimenting with mounting their stage cylinders on top so that the stage cylinder lay partially on top of one of the sidemount cylinders and partially on top of the torso. The way these cylinders were being connected to the sidemount rig was with the clips attached to the cylinder with bungee rather than the standard stage webbing. The bottom clip would attach to the butt plate bar and the top clip would attach to the chest D-ring on the same side.

We tried a few different methods of doing this. The first was to attempt to bring the top clip and bungee over the shoulder but that required quite a bit of flexibility, more than what is required to do valve shut downs in backmount. The next option was to try to route the top clip and bungee under the arm. This worked out well. It didn’t require as much flexibility and kept the top of the cylinder cinched down close to the diver’s body. The issue with this method was in keeping the bottom of the cylinder from floating up as the gas in that stage cylinder was breathed down.

With more experimentation it was found that stretching the attachment points on the stage cylinder did a bit to minimize this floating in the bottom of the cylinder but it did not eliminate it completely. The key to minimizing the bottom float is to position the attachment points so the cylinder is pulled down by this stretch. Some people have looked for a standard distance for the attachment points, or actually, where to mount the worm gear clamp that holds the bottom clip, but there just isn’t one. The positioning of the attachment points is dependent on how far apart the butt plate bar and chest D-ring are from each other. People with longer torsos will need to position the lower clip on the stage cylinder farther away from the cylinder neck and those with shorter torsos closer to the neck.

But regardless of where the clip is attached the bottom of the stage cylinder will still become positively buoyant and float up as gas is breathed down. The shorter the torso, the more of a problem this is because the bottom attachment point has to be farther from the bottom of the cylinder. This has caused many sidemount divers conducting cave stage dives to carry the stage cylinder on top during the penetration portion of the dive and to then clip the cylinder underneath during the exit portion so the cylinder rises up into the diver rather than onto the ceiling of the cave. This method does work to keep the cylinder off the ceiling but because the valve and 1st stage are so heavy, the top of the cylinder hangs low. An option to fix this is to add a second bungee loop to the rig that can be used to pull the top of the stage cylinder in close. This is a method I use when doing open ocean decompression dives where I keep my decompression cylinders with me throughout the dive.

One thing I won’t do is stage a decompression cylinder on top. A standard stage cylinder is usually used at the beginning of the cave dive so as you are attaching the stage to your rig you should already have the 2nd stage regulator in your hand and have followed the hose back to the cylinder and confirmed gas and MOD. Once the cylinder is mounted on top it is impossible for most to perform that confirmation of gas without taking the cylinder off. Most decompression cylinders are smaller diameter aluminum 40s. Taking these cylinders and mounting them underneath and using an additional bungee to bring them in closer allows for the proper procedure in gas switches and keeps them very streamlined.

Back to top mounting standard bottom mix stage cylinders. I never liked the fact that the bottom of the cylinder would become positive and increase the chance for contact with the cave ceiling. While this isn’t an issue in taller passages, not all passages are tall enough for that. And an AL80 that is angled off the torso at a 45 degree or more angle isn’t very streamlined. Every stage dive I did I would try to think of better ways of rigging a stage cylinder for top mounting. I’d much rather keep the stage cylinder on top but not at the risk of damaging the cave.

Well, recently I was able to come up with an idea that works very well and keeps the cylinder tucked in close to the body and parallel to the body throughout the entire dive regardless of the amount of gas in the cylinder. I even spent several dives going into sidemount restrictions and was able to keep my stage cylinder attached to me through most of them and still get through the restrictions. It was only the smallest of the restrictions where I had to remove the stage or my right side cylinder to get through.

The problem with the current sidemount stage configuration is that the bottom clip attaches to the back of the sidemount rig. As long as the attachment point is on the back, the cylinder will be allowed to pull up off the back. What I did was move the worm gear clamp holding the bottom clip down a bit. For me, because of my torso length and the distance from my chest D-ring to my butt plate bar the best location for the worm gear clamp with the system most often being used is about 19 inches from the bottom of the cylinder. That’s where my stage cylinder would remain the lowest throughout the dive.

I moved the worm gear clamp down to about 8 inches from the bottom and lengthened the bungee on that clip from almost nothing exposed under the clamp to 8 inches plus the clip.


I also added a D-ring to the right side of my waist strap on my rig.

The final change is to shorten the bungee on the top clip of the stage cylinder as much as you can. This will make it difficult to get the bungee around the valve but the results are worth it.

The best method for clipping the stage cylinder at this point is to drop under water and get horizontal. Take the top clip and attach it to your chest D-ring. Push the cylinder back so it is nestled in between your sidemount cylinder and your torso. Take the bottom clip and drop it between your sidemount cylinder and your hip just below the sidemount cylinder attachment point. Grab the clip when it falls through and under you and pull it across your waist to the D-ring you’ve placed on the right side of your waist strap. Earlier I stated the bungee length I use is 8 inches. You may need to change this to make the cylinder lay on you correctly. The determining factors will be your waist size, your sidemount cylinder size, and the location of the D-ring on your waist strap. You want the bungee to stretch as tight as it can but still make it easy to clip and unclip from the D-ring. Once the bottom bolt snap is clipped to the waist D-ring you are done.

When the bungees are the correct length the stage cylinder will lay on top of your sidemount cylinder and the bottom will not rise up at all regardless of cylinder pressure. If the cylinder does start to rise the most likely issue is you have the worm gear clamp positioned too high on the stage cylinder. The bungee could also be too long. If the stage cylinder rolls off the side of your sidemount cylinder then the bungees are too long. You will need to shorten the bungees a bit so the cylinder gets pulled into the space between your sidemount cylinder and your torso.

I’ve done several dives with this configuration and it is easy to put on and take off and keeps your rig streamlined throughout the entire dive. There is no reason to have to move the stage cylinder in front of you halfway through the dive and you don’t have to worry about the bottom of the cylinder hitting the ceiling. You will notice the left cylinder sits a little lower with the stage cylinder mounted on top of it. That’s okay. With a stage cylinder your profile will be a little higher from bottom to top. It doesn’t matter whether that extra profile is below you or above you, it will be there either way. For those of us who dive sidemount quite a bit, we’re used to having more clearance above us because we don’t have cylinders there so I’ve found it better for me to lose clearance below me rather than above me. If you want your sidemount cylinder to shift forward less then lengthen the bungees on the stage cylinder and it will shift up a little. Have fun trying this new method out and if you have any comments or suggestions please send them. I can’t think of an easier way to do this but that doesn’t mean there isn’t one!

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Trimming out in Sidemount

There’s been some discussion recently on how to trim out in a sidemount rig. The argument has long been whether to trim out using air in your wing or to trim out using weights placed somewhere on your rig, usually around the shoulders. Many of the commercially manufactured sidemount rigs are designed with this in mind, in fact. The original Dive Rite Nomad was designed so the bungees would trap air in the bottom area of the wing to create more lift closer to the feet. The Oxycheq Recon and Hollis SMS100 were designed with 360 wings and the largest area of the wing at the bottom so air would migrate to that area and provide more lift closer to the feet. While this is a good idea in concept, it could lead to a huge mess should the wing fail.

If a wing that is designed to keep the diver in trim should fail, then the trim of the diver will also fail to happen. With no air in the wing, the diver will revert to the position created by the center of gravity of the rig, which is usually lower along the main mass of the body. What this means is without air in the wing the diver will be in a feet down orientation. This may not matter much in open water, but it can make a big difference in a cave, especially a silty one! I’ve experience a couple of wing failures, both in very silty cave passages. Had I depended on my wing for my trim I would have left a silty mess behind me, and in some areas of the cave, left quite a few marks on the floor since the floor to ceiling height would not have accommodated me out of trim without touching something.

I’ve trained and mentored a lot of divers in sidemount diving. I start all of them out without any trim weight at all. We get in the water and I have them get neutral and relaxed. A majority of them trim out at about a 30-45 degree angle with their feet down. This occurs after I have already positioned their cylinders so they are as far forward under the armpits as possible. Any farther forward and the valves and first stages would have to go in front of the shoulders and throw the trim of the cylinders off. Sure, we can try to direct the air in the wing toward the feet to bring them up. This works if the wing isn’t already over half inflated to compensate for the weight of the cylinders (typical in wet suit divers). This also works if the wing is working properly (read hasn’t failed).

My recommendation is to place 1-3 pounds somewhere around the shoulders to bring the diver into a horizontal position. Trim weights don’t fail. No matter how much air is in or isn’t in the wing, the diver will remain in horizontal trim. If the diver is diving dry the dry suit becomes the buoyancy compensator and gets him/her neutral. If the diver is diving wet, then he/she better have a dual bladder rig or an SMB that can be used to get neutrally buoyant (properly place trim will be unaffected). But if the diver is depending on air in that wing to remain neutrally buoyant, a wing failure will likely lead to an out of trim diver.

Most divers need some weight to compensate for the gas being breathed down from the cylinders anyway. The gas being breathed weighs one pound for every 400-600 psi (depending on the cylinder size). A typical cave dive will result in the use of about 2000 psi, which equals 3.5-5 pounds per cylinder for a total of 7-10 pounds of lost “ballast”. But there’s still another 3-4 pounds per cylinder (6-8 pounds total) worth of gas that could be lost or used in emergency situations. Just like you learned in your open water class, you are supposed to be neutrally buoyant with an empty cylinder. We have learned to check for proper weighting at the end of the dive with 500 psi in the cylinder and then add 1 pound to compensate for that 500 psi of gas. This doesn’t change in technical or cave diving. We still need to be neutrally buoyant with empty cylinders. Many divers don’t think about this and are probably positive with empty cylinders, even if only by a few pounds. So adding trim weights will not only trim these divers out but also allow for them to be neutral should they end up still underwater with very little gas left in their cylinders.

So whatever method you decide to use to trim out, at least be aware of the possible consequences. If you’re strictly an open water diver, then it’s not going to matter much either way. But if you do any cave diving at all, then you need to consider what can happen to your trim if your wing fails. While you may be able to get out of the cave, it may not be without doing damage to the cave. So, if nothing else, keep cave conservation in mind.

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Sidemount Cylinders

There seems to be a tendency for newer sidemount divers to think all, or at least most, cylinders are created equal. This isn’t really the case. Cylinders, whether sidemounted or backmounted, will have some very similar results when it comes to different volumes. However, when it comes to buoyancy characteristics, cylinders will vary.

Let’s look choosing your set of sidemount cylinders. Just as in backmounted, manifolded doubles, you must pair match your cylinders. It not a matter of making sure they are the same length – a 1/4 inch difference in length won’t make much difference in sidemount. Rather, it’s the buoyancy characteristics of the cylinders. I had a student that bought a pair of cylinders but ended up buying one cylinder from one location and the other from a different location. With a quick glance, the cylinders appeared identical. The differences did not become evident until during the first dive.

The first dive of my sidemount courses consists of having my students get in the water, getting neutrally buoyant, bending their knees, and relaxing. This way I can look at how their bodies hover and cant and make adjustments to the cylinder rigging so they end up horizontal. This particular student was consistently lower on one side. The rigging was identical on both sides. After we got out of the water, we examined his sidemount rig and the shoulder straps were evenly spaced on the waist strap. Nothing was off kilter and he shouldn’t have been off kilter either. Then I looked at his cylinders. One had a much more defined transition from the body of the cylinder to the neck while the other was a much more gradual transition. I looked at the manufacture dates and they were different. We placed the cylinders in the water with both having very similar pressures and they even sat differently in the water. Their buoyancy characteristics were different enough that they caused quite a significant difference in trim in the water. Lesson learned – pair match your cylinders.

Let’s look at the next mistake often made by newer divers – bigger cylinders will mean more bottom time. This isn’t necessarily true. Often times, bigger cylinders simply mean more drag in the water, which in turn means more effort to move through the water. More effort equates to higher gas consumption. Bigger cylinders could actually mean less bottom time due to this. When I first went back to backmount after a year of strictly diving sidemount I grabbed a set of LP108s. A couple days later I decided to try a different set of cylinders, a set of LP85s. I reached my turn pressure in each set of cylinders at the same location in the cave. That means I used almost 20 cubic feet less on the same dive using the 85s than I did using the 108s. The additional drag and subsequent effort of moving the larger and heavier cylinders resulted in a much higher gas consumption.

The cylinders I prefer for a majority of my diving are LP85s, HP100s, and LP95s. They are all on the smaller sider but provide sufficient gas to do decent length dives. However, even these cylinders are not created equally. Cylinders will have different buoyancy characteristics dependent on the manufacturer. This is the case whether they are the smaller cylinders listed here or the larger cylinders such as LP108s and LP 120s.

Let’s look at the LP95s first. I dive Faber LP95s. I’ve handled PST LP 95s and they are too heavy for my liking. While they are the same dimensions as the Fabers, they do weigh in heavier out of the water and have more negative buoyancy in the water. This makes them a little more difficult to handle, especially when having to remove a cylinder to pass through a restriction. The Faber LP95s are less negative and much easier to handle in the water. LP95s are also shorter than LP85s and HP100s, 2 inches shorter. I bring this up because it does make a difference. The Faber cylinders, because they are neutral when empty, have a tendency to have the bottoms roll up (see photos below) as their pressures decrease. With the Faber LP95s, this doesn’t become noticeable until they reach around 1600 psi. By this time most cave divers are already doing decompression. I did make the mistake recently of staying on my LP95s on the way out of a cave instead of switching back to my stage cylinder. At the end of the dive my cylinder pressures were at 1300 psi and I could definitely feel the cylinders rolling up. I will also take this time to say I do not use Fabers for any type of trimix diving. I did that once and found myself looking for additional weight at the end of the dive. The lower weight of the helium along with heavier undergarments made a difference I wasn’t expecting.

For LP85s and HP100s, I prefer Worthington cylinders. Because these cylinders are 3/4 of an inch less in diameter, they are easier to handle in the water than their LP95 counterparts. The Worthington LP85s and HP100s still end up being slightly more negative than even the Faber LP95s, but it’s a minimal difference that the smaller diameter almost negates. The Faber LP85s and HP100s are even less negative. The issue with this is when they get to about 2200 psi these cylinder begin to roll up along their attachment points. By the time they are at 1600 psi, they are extremely out of trim which in turn makes the diver extremely out of trim. The extra 2 inches in length makes enough of a difference to create this change in them. I’ve had people tell me this isn’t true. Well, maybe they happened to get smaller Faber cylinders that don’t behave as most of their lot do, but every Faber LP85 and HP100 I’ve seen in sidemount configuration does what you see in the photos below. So for me the obvious choice is to use Worthington LP85s or HP100s for the majority of my dives in which I want the smaller cylinders or use Faber LP85s or HP100s when I know my pressure at the end of the dive will be no less than 2000 psi. What I choose isn’t necessarily the best choice for everyone. But if you’re in the market for new cylinders my advice is to try before you buy. Get in the water with the cylinders. Take them on a real dive and to various pressures. And get some photos of yourself from various angles so you can see for yourself what those cylinders are doing.

I hope this information helps you in your quest for buying cylinders. And if you have bought a set of cylinders that aren’t working for you, contact me. Even if they’re Faber LP85s I may just buy them because they do make the best backmounted cylinders for me.

Full Faber LP85s trimmed decently
Well trimmed Faber LP85s

Same diver later in the dive with Faber LP85s with about 1600 psi
Poorly trimmed Faber LP8s

Faber LP85s with about 2200 psi with roll up just beginning – notice how the cylinder is positioned in relation to the cord
Roll up starting at about 2200 psi

Faber LP85s with about 1600 psi showing a significant roll up – notice the difference in the cylinder position compared to the previous photo
Roll up significant at about 1600 psi

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Sidemount Gas Management

I was teaching a sidemount class recently. We started off with the usual gear configuration session. I’m not one of those instructors who tells my students how to configure their gear. What I do is review all the different possible gear configurations and some of the reasons behind them. I’ve had the benefit of having discussed with the designers of some of the sidemount rigs available the reasons behind certain designs. While I may not agree with certain design characteristics for my own rigs, it doesn’t mean there is anything wrong with that configuration. It’s just not what works for me. I like to pass as much information on to my students as possible and have them make their own decisions.

Anyway, after spending a few hours getting gear configured we started discussing regulator configuration. Yes, we cover that as well. There are lots of ways to configure regulators. You can run the hoses around your neck, or straight up to your mouth, or one hose around the neck and the other straight up. The way you run your hoses will affect the way your rig is configured. But no matter how you configure your hoses and your rig, one thing remains the same – gas management.

My recommendation is to keep gas pressures between cylinders no more than 1/6 of total starting pressure from each other. If you start with 3300 psi, switch over 500-600 psi later, or at 2700 or 2800 psi. Then breathe the next cylinder down to your turn pressure (we’ll use 2200 psi here for simplicity). Switch back to the first cylinder and breathe that until turn pressure (2200 psi), turn the dive and keep breathing from that regulator until you get to 1600 or 1700 psi. Switch back and breathe this regulator until the dive is over. This means you will have a total of three regulator switches during the dive. The reason for switching is not to balance the cylinders, although some people will start to feel off balance if their cylinders are more than 600 psi difference in pressure. The reason for switching is in case a gas issue arises.

Some divers, however, don’t think it matters how sidemount cylinders are breathed from. They will breathe one cylinder down to turn pressure, switch to the other cylinder and breathe it down until they exit the cave. Sometimes they will breathe the second cylinder down enough to where they might need to switch back to the first cylinder before getting back to open water. While at first glance this may appear to work, and if nothing goes wrong it does, when things go pear shaped this practice may result in issues.

Let’s look at some examples using the above gas switches. Jim is diving HP100s that are filled to 3300 psi. He begins his dive in a low flow system breathing off of the right side cylinder. He breathes that cylinder to 2200 psi and switches to his left side cylinder. When he reaches 2200 psi on his left cylinder he turns the dive but continues to breathe off that cylinder. When Jim has breathed down the left cylinder to 1100 psi his dive buddy, Kim, who is diving backmount HP 100s has a first stage failure and loses all the air in her cylinders. Jim donates the regulator from his right cylinder to Kim and they continue to exit. However, during the incident, Jim breathed his left cylinder down to 900 psi. Even if Jim’s gas consumption remains the same he is still about 1100 psi from the exit. Remember, Jim and Kim swam 1100 psi in and Jim had breathed 1100 psi from one cylinder and had another 1100 psi to go. If Jim had managed his gas differently he would have enough gas to exit. As it is he is 200 psi short so Jim and Kim will have to buddy breathe the last part of the passage out.

Let’s look at this with Jim managing his gas as recommended above. Jim breathes his right cylinder down to 2700 psi and switches to his left. He then breathes his left cylinder to 2200 psi and switches back to his right. When he reaches 2200 psi on his right cylinder he turns the dive and continues to breathe that cylinder until it gets to 1600 psi. At that point he switches to his left cylinder and breathes that down to 1700 psi when Kim has her incident. Jim still has the same amount of gas. In the first example he had 1100 psi + 2200 psi = 3300 psi. In this example he has 1700 psi + 1600 psi = 3300 psi. The difference is when he donates the regulator from the cylinder containing 1600 psi, he still has 1500 psi left in the other cylinder (assuming he still breathes it down 200 psi during the incident). Now they both have enough to exit safely.

At this point some of you are saying to yourselves that you don’t ever dive mixed teams. Either everyone is in sidemount or everyone is in backmount. That’s fine. And to be honest, I can’t think of an incident in which a properly trained and experienced sidemount diver would need to share air when gas management is done properly so we’ll approach this in a different manner. Let’s look at another example. We’ll take this from the perspective of a self sufficient sidemount diver. But this example will work with two sidemount divers that may happen to share air at the time of the incident.

Joe is diving HP 130s filled to 3300 psi. As Jim did Joe breathes his right cylinder down to 2200 psi, switches to his left cylinder and breathes that down to 2200 psi and turns the dive. He continues to breathe his left cylinder down to 1100 psi. Let’s say Joe continues to breathe his left cylinder. About 200 feet from the exit he starts to feel his regulator breathing harder. He switches back to his right cylinder only to discover the second stage got jammed up with sand in a low sandy restriction he passed through earlier. He tries to purge the sand clear but it’s packed in there pretty tightly so Joe is left without a regulator to breathe from. Joe could go to his buddy and signal out of air, but if his buddy was managing his cylinders the same way he would also be switching to his right cylinder so he wouldn’t have a regulator to donate.

Had Joe and his buddy switched every 500-600 psi their cylinders would never get below 1100 psi so neither regulator would ever start to breathe hard. And it would be less likely that their second stage regulators would be unused long enough to become unworkable. Even with a second stage regulator out for 500-600 psi, it’s possible to get packed with sand a pretty good amount. I’ve had this happen to me to such a point I had to switch back to my other second stage while I worked on clearing the regulator and it had only been out for a couple hundred psi. Fortunately, I was able to switch back, get the regulator clear, and continue my exit uneventfully.

Yes, these examples are of incidents that are not likely to happen. But what incidents are likely to happen? How many cave divers do you know have had an out of air incident? How many do you know have ever been lost off the line? Yet, before every dive we do S-drills (or at least we should) and we all carry safety reels/spools. We prepare for unlikely events and this is just another way to prepare that doesn’t take more than one more regulator switch.

While in the above examples straight thirds was used for simplicity, I do not condone diving to thirds. Diving to thirds is not conservative enough. But that’s another article.

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Sidemount Cave Class

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Armadillo Review

I purchased an Armadillo sidemount rig this year and have been diving it for about six months now. I found a pretty good deal on a used model and jumped on it mainly out of curiosity. The rig I bought is an original Armadillo, not the A2, so this review is on that model. I haven’t been in the water with an A2 or even seen one in person so can’t comment on it.

The original Armadillo sidemount rig, in my opinion, is the best commercial sidemount rig available. It is simple, low profiled, streamlined, and robust. It is also the only sidemount rig I’ve seen that has not, or would not, require any modifications for it to work for me.

The Armadillo comes with the inflator hose already coming off the bottom of the wing and the dump on the top. It was like that when they were first introduced to the market in 2002 and continue to be sold that way today. The Armadillo also comes with adjustable shoulder straps. They can be located anywhere on the waist strap that works for the diver. They are a simple, single piece webbing with no padding. The material used is heavy duty and robust. The rig is reinforced with heavy duty 2-inch webbing along the center and butt plate. The bars used on the butt plate are curved rather than squared. I thought this might be an issue when I first got it because I was in the habit of “locking” my snap bolts along the top of the bars. This hasn’t been an issue with the Armadillo. I still pull my cylinders up toward my shoulders and they stay where I want them just fine.

Even though the rig I bought was used there were no modifications made to it by the previous owners. I have made a total of two modifications to my Armadillo. I added a chest strap, which I only need when I’m carrying stages (most dives), and I fixed the pull dump to the shoulder harness a little more permanently than how it’s shown in the owner’s manual.

The Armadillo does have some drawbacks. The lift is only 33 pounds. So I’m still using my Nomad for my trimix dives because my trimix cylinders are 108s and 121s. My Nomad barely has enough lift for those. The Armadillo definitely doesn’t have the lift for those. That being said, I have been able to dive my Armadillo with 2 Faber LP95s, 2 AL80 stage cylinders, and an AL40 deco cylinder. The other drawback is I can’t use it as a backmount rig so when I’m teaching students in backmount I have to use my Nomad. I suppose I could drill some holes in the center of the back to accommodate backmount but I don’t really see a need for it. Other than that I haven’t found any other drawbacks with the Armadillo for me. And even those two drawbacks aren’t a big deal because I have another rig I can use with larger cylinders and when diving backmount.

While the Armadillo runs a little more than most of the other sidemount rigs on the market, but by the time you get done adding the usual modifications being done on some of the other rigs, you’re paying almost as much for one of those as you are for an Armadillo. The Armadillo isn’t for everyone, but I do encourage anyone in the market for a sidemount rig to try it out before making a commitment.

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Hose Lengths for Sidemount

A common question asked by new sidemount divers is what hose lengths are needed. While at first glance this appears like a simple question there are some things to consider when choosing the correct hose lengths for your new rig. Hose lengths will depend on the types of first stages and second stages you will use with your sidemount rig, how you want to route your hoses, and the type of sidemount diving you plan on doing.

Here’s a list of standard hose lengths you will want to consider. You will need two of each.

Low pressure regulator hoses – 5′ or 7′ if you decide to use a long hose, 15- to 34-inch depending on how you plan on routing short hoses.

Low pressure inflator hoses – 12- to 15-inches long, most common length is 15-inches. (Only one needed if you do not dive in a dry suit.)

High pressure hoses – 6- to 9-inches long.

Let’s look at your first stages and second stages first. Some regulators are better suited to certain positions and hose routings than others. Diaphragm first stages similar to the HOG or Dive Rite models work well in any position. They do work better in some positions because of the angle of the high pressure ports. Piston first stages similar to Scubapro and Atomic Aquatic models tend to work better in certain positions. Make sure you discuss the differences with your instructor or mentor.

You will need to decide whether you want to use a long hose with your set up. If you plan on diving with others and want to be able to donate air, a long hose is recommended. While there are some that advocate trading cylinders in an out of air situation, that is not practical. A long hose is a better option. If you plan on diving smaller passages in which you and your team members must pass in single file, you should consider a 7′ hose as a 5′ hose will not be long enough to allow single file exits.

The more difficult hose lengths to determine are the short hoses. Lengths depend on how you plan on routing the hoses. The options are to route them directly from the first stage to second stage or around the neck. Some second stage regulators can also have the hose come off of either side. This will also have an effect on the hose length. Finally, if you use rotating or fixed angle swivels, you will be able to shorten your hose length by another inch. For hoses that route directly to your mouth, you will need 15- to 22-inch long hoses. The exact length depends on the options just discussed. For hoses that you will route around your neck, you will need 31- to 34-inch long hoses.

The low pressure inflator hose lengths are largely dependent on 1st stage regulator type and which port you choose to use for the inflator hose. As state previously, the most common hose length is 15-inches. This length works well with standards first stages and most any low pressure port. If you have first stages with low pressure ports located on the end of the regulator you will be able to use a 12-inch long hose.

The most common high pressure hose length is 6-inches. This length works well with the SPG positioned in any direction. The 9-inch long hose allows for the SPG to be pulled back a little farther from your face if that is necessary for reading the gauge. It also works better when positioning the SPGs down alongside the cylinders.

If you have a large stock of hoses at home (like many of us do after several years of diving), be sure to bring all the hoses you have in the range listed above. This may save you some money, and room in your dive storage locker, when setting up your sidemount regulators. Make sure you discuss the different options with your sidemount instructor or mentor.

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Second Day in Sidemount

This is what you can be capable of day 2 of my sidemount class (that is if you’re already cave trained).

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Sidemount seems a good first topic to start off with since it’s our primary choice in gear configuration. We began playing around with sidemount a few months before moving to North Florida in 2007 and immediately saw and felt the benefits of diving sidemount over diving backmount. Shortly after moving we took a couple of Dive Rite Nomads for test dives and came back with big grins on our faces and left with less money in our wallets!

At the time the Nomad and the Armadillo were the only two manufactured sidemount systems available. We had researched both and decided to go with the Nomad for a couple of different reasons. The first was the lift. The Nomad ( at that time) had a lift capacity of 50 pounds while the Armadillo’s lift capacity was and is only in the mid 30 pound range. Diving the North Florida caves with steel cylinders, more lift seemed like the best decision. Another issue was the lack of availability of the Armadillo. There weren’t as many dealers carrying the Armadillo, and at some point (I can’t remember whether it was then or sometime later), no one was making or selling the Armadillo. Today it isn’t as readily available as many of the other models.

Three years later and sidemount systems have flooded the market. We now have several different sidemount rigs available to divers. They all have advantages and disadvantages. Some are well suited to cave diving, some are not. In my opinion, none of them is perfect out of the box. But that’s just the nature of sidemount. The current systems widely available to divers are Dive Rite Nomad, Hollis SMS100, Hollis SMS50, OMS Profile, Oxycheq Recon. The Armadillo can still be found in some locations. There are also some privately made harnesses, such as the Razor, but wing choice and attachment is left to the diver. The BAT wing has recently been developed and is being marketed as a wing for the Razor harness system.

As I stated previously, none of these systems is perfect out of the box. I’ve made several modifications to my Nomad and have other modifications I want to make, but have been too busy diving to bother making them yet. While the modifications I’ve made on my rig work for me, they may not work for everyone. There’s a saying, “Get 10 sidemount divers together at a dive site and you’ll see 11 different ways to rig up your gear.” You need to choose what works for you and your type of diving.

One of the things I teach in my sidemount course is all of the possible ways to rig gear and why. I have tried several of them myself. For example, I’ve pointed my SPGs in every direction possible. There are advantages and disadvantages to each of them. One of the key factors in which way you point your SPGs is your valve orientation. I’ve tried a few different valve orientations, too. I finally have things set up in a way that work for me…right now. In six months it may be different. This is what makes choosing a sidemount instructor that has experience sidemount so important.

Over the past year there has been a surge in the number of sidemount instructors. Many of these instructors became sidemount divers and sidemount instructors the same weekend. They have very little experience diving sidemount and may not even dive sidemount outside of classes. Even fewer dive sidemount in caves, the original environment sidemount was conceived for. (I’ll add a blog on the history of sidemount diving in the coming weeks.) Sidemount diving is more than just strapping cylinders to your sides and getting in the water to complete drills. A big part of the course should be setting up the gear before ever getting in the water and then tweaking it between dives to work for you. An instructor who has very little experience diving sidemount isn’t going to be able to help you do this. If that’s all you want the course for, just buy a book and read it. You’ll probably get more out of that. However, if you want to learn how to set up your gear so it works for you and you want to save yourself several dozen dives in trials, find an instructor who has experience and dives sidemount to it’s fullest capabilities. Don’t only ask the instructor, but talk to other divers about the instructor. Unfortunately, there are too many instructors out there that will misrepresent their experience just to get students.

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