Welcome to the Cave Diver's Forum.
  • The Rising Popularity of Side mounting

    (and why you should consider a long hose)
    by Jay Wells

    Side mount diving (SM) is not just for breakfast anymore. Traditionally divers in the United States have used a SM configuration for several reasons. In Florida style caves it was developed as a means to reach lower and tighter places by SM pioneers such as Woody Jasper and Lamar Hires. It is also very popular in Great Britain, Europe, Mexico and the US as a method to reach sumps in dry caves or entrances requiring long treks horizontally or vertically. Hauling a set of doubles for long distances and lowering or raising them on vertical faces is impractical and can result in a dearth of sherpas when confronted with the task.

    In general a SM diver uses two independent tanks and regulators which are connected to the body via a harness. Each tank is connected at two points. The bottom of the tank is connected to the harness near the divers hip/kidneys and the top of the tank is connected to the harness via a bungee/cord at the top of the right shoulder such that the tank valve hangs under the arm.
    At that point all similarities end. In SM diving, the end justifies the means. Some sump and cave divers rely only on a dry suit/wet suit for buoyancy if it is possible or likely to crawl along the bottom. Cavers in Britain have used this method before SM was used in the US. In bigger caves where one may swim through large sections a wing is added for redundancy and trim. It is this style which seems to have become very popular in Florida by divers who are not always looking for tight spots and it is this style I would like to examine in this article.

    There are several reasons for it’s rising popularity. Smaller divers find it easier to transport tanks individually to the water. The same goes for older divers or divers with leg or back problems. Other divers like the “independence” of independent tanks. Having two independent gas supplies with the valves, regulators and hoses in plain view and easy to reach is very reassuring. It allows a solo diver easy access to any problems occurring in that area and eliminates the need to carry a “buddy bottle” as solo BM divers do. Some solo SM divers still carry an extra bottle to further increase their safety.

    Teams of SM divers are more self reliant. This is important in very restrictive caves. The loss of a regulator or an air leak is much less stressful and does not require immediate action from a team member which is important in tight areas. The diver can quickly determine the problem and switch to another tank if necessary. Other team members can be alerted and tanks can be swapped between divers if required. Exiting the cave becomes quicker and simpler as touch contact is not needed.

    Another reason for it’s popularity is the amount of information now available on the internet and the “off the shelf” equipment developed. A diver can purchase a system such as Dive Rite’s Transpac II or an Armadillo and get off the shelf items to configure it for SM.

    This eliminated a lot of the experimentation done by early SM divers and allows a faster and easier progression to comfortable SM diving. It still does not replace the benefits of taking a good SM class from a knowledgeable instructor however.
    And let’s not forget the cool factor or the hardware factor. Cave divers look for a new challenge and enjoy modifying their own equipment. Each SM diver configures their equipment slightly different so the customizing options are almost endless with lot’s of great ideas popping up.

    My SM configuration –

    ---------insert pic here ---------

    I wanted to keep my BM and SM configurations very similar because I do switch back and forth and I am very comfortable with the way my regulators are situated for BM diving.

    I use a 7 foot hose on my right tank. The method I use in SM is to bend the hose into two U's, the shorter inside the longer. I use two inner tube bands to keep it secure on the inside of my right tank. The free end is just long enough to reach my mouth and give me freedom of movement. This in effect is 'Bungeeing' the hose, I have had no problems pulling it free, but I haven't found a better method.
    With a seven foot hose on the right, I use a 39" hose on my left, put it around my neck and use a standard necklace like a BM diver. My regs look just like my BM configuration.

    My Gas management –
    I test my left reg before entering the water and again before entering the overhead. I start with the right tank and breathe it down 1/6 and then switch to the left tank and breathe it to 1/3, back to the right tank and breathe it to 1/6 to turn. At maximum penetration my right tank never has less than 1/3 of my gas in it for sharing purposes. If I am in a SLC (sh***y Little cave) or nasty environment, I test or switch to the idle reg more frequently in case of debris, etc.

    OOA Situation- Mixed team

    Let me preface this by saying that it is very unlikely for a BM diver to completely lose their air supply using a manifolded set of doubles with an isolator, but it can happen and air sharing is the most critical emergency skill .
    It is more unlikely for a SM diver using independent tanks to completely lose their air supply. I am only stating this to place the emphasis on the independence of SM divers and that in mixed team diving the BM diver may be more likely to need to share air, so it is important that a team of mixed divers has a clear understanding of emergency procedures.

    Generally when I dive with a mixed team of two or more BM divers in the team, the attitude is that the best solution is to keep the BM divers together. If they have an OOA situation, they can go to each other and do the standard drill. The SM diver can survive the loss of one tank /reg if they have followed a good gas management plan. In the event that the SM diver needs to share, the standard drill can be used.

    For redundancy and safety I think the best solution is to have a SM diver with a 7 foot hose In the event of an OOA emergency the drill for the SM diver to donate would be just like the BM way. I believe this should also be the case if there is a lone BM diver with a SM or several SM divers. It could be said that the right reg is not always being used, and is therefore not reliable. Under a proper plan, the right reg has been used recently and is in plain view of the SM diver. Is there a chance that the reg won’t function when you donate it? I think it is more likely that the necklace reg on a BM diver won’t work. It’s likely that the majority of BM dives occur without the diver ever breathing off the necklace reg in the overhead. A SM diver uses both regs on every dive.

    Another solution with a lone BM diver is to have that person carry a stage and not exceed the pen limits of the available gas. This allows the BM diver to be more independent, but it fosters the attitude that the BM diver is not really a part of the team. The same can be said when a single SM diver teams with two BM divers and is not part of the gas management plan of the two BM divers. The use of a long hose by the SM divers allows all gas management and emergency procedures to be treated as if the team were all BM divers following normal protocol. This is a distinct advantage over having different gas management or emergency procedures among the same team.

    OOA Situation, SM divers.

    Again,I think the best solution is to have the a SM diver with a 7 foot hose. In the event of an OOA situation the response would be just like the BM way. If I am not breathing it, it is on my right shoulder d-ring. In the event of an OOA situation, 99.9% of the time I will see the other diver approaching and hand them the reg, just like on BM. I think this is important, especially in tight areas. Probably the worst case would be in a very tight area. In this case the 7 foot hose would be essential in getting the air to the other diver. The SM divers can switch tanks when they get to an open area if they choose.

    Donating/switching tanks is a tough call. Swapping steel tanks takes careful thought. The divers can end up in an unbalanced situation which may cause more problems. Bracing against the ceiling will keep you from flipping over or flopping to one side, but then you have to handle a negatively buoyant tank. Settling on the bottom may make the actual swapping of the tank easier, but it may result in positive buoyancy and a silt nightmare. Still, it is probably the best method for swapping tanks. It is important that the two SM divers work together to swap tanks. Ideally, a clean rocky base would be the best place to switch. But why switch? If the SM divers are equipped with a 7 foot hose on the right tank, there is no need to switch, just perform the standard drill. The speed you gain in exiting independently would be more than offset by the time and energy it would take to switch.

    I believe that in an OOA situation, a team that is not ‘sharing’ can exit much faster than a team doing the standard drill. Especially on scooters or through restrictions. This raises an important question. Is speed of exit more important than maintaining touch contact and reassurance with the OOA diver?

    My philosophy is the exit determines the method. If you can comfortably exit using the standard OOA drill, do so. This method is tried and true and divers can perform it with their eyes closed (literally) and in their sleep.
    The shortcomings of this method occur when the OOA situation occurs at max pen and it may take more gas to exit sharing air than it did to get to max pen or you have to pass one or more restrictions.

    These are some examples:

    A long exit without any help from the flow.

    By exiting in touch contact you will be slower and the anxiety level will be higher possibly causing increased air consumption. Swapping tanks is probably a better choice for speed of exit, if you can swap tanks efficiently.

    You need to pass a number of restrictions to exit. -

    My favorite common example of this is Cow Springs. A lot of people back mount in there and I am not convinced that they consider the consequences of exiting on BM’s sharing air. You can certainly get a lot of help from the flow on the exit. But consider if the OOA event occurs past Not My Fault. That will be a challenge when passing through. Then you get to the lower restriction. Have any of you thought about how you would go through sharing air? I am confident I could grab almost any BM buddy pair, get them in the cave and tell them to exit the restrictions sharing air without planning it beforehand and most would fail. Videoing it would be interesting. Very few buddy teams would make it out, and even those would make a pretty interesting video.

    In this scenario two SM divers on a long hose should choose to swap tanks before passing the restrictions as they would have difficulty sharing air through the restrictions.

    For very tight passages where tanks have to be removed a standard configuration with two short hoses is probably still best as the extra long hose could come free from the tank. However, the next time you are diving with a mixed team of SM and BM divers or you are in a team of SM divers, ask if anyone has considered using a long hose.