This is the second part of our special articles about Technical Diving.. Read also [Part 1]
The major misconception about technical diving is: Extensive and expensive equipment makes the difference between technical and recreational diving. We strongly feel this is not true. The real “technical” bit of technical diving is in the necessary skills and mindset. In fact, if you do not know how to deal with your equipment, you are actually adding risk instead of creating additional security.
The foundation for these extra skills and mindset is a mayor part of our training called: “Intro to tech” or “Fundamentals”. Both training courses are a basic program that anyone must complete before taking the next step towards technical diving. No matter what level you are or how many dives you already made.
This way every diver knows that every one of his team members has the same procedures for every part of the dive. From the checks before setting up the equipment, the final pre-dive checks on the boat to the actual behaviour during an emergency. Shooting a buoy, the passive and active communication or gas-switch procedures, each team member will perform them in the same way. Therefore each team member will know what is coming and will easily see if something is out of the ordinary. Solving problems underwater is done in the same way. For almost every scenario possible, there is a procedure. These procedures are trained in a controlled environment, over and over and over again. So if the inevitable problem occurs, everybody will react in the same way. The diver in trouble will recognise the behaviour of his helping team members. This way there will be no panic and everyone knows the problem is dealt with in the most efficient manner.
The team will complement each other. Not only in terms of equipment. Many underwater operations can be performed easier and safer with multiple divers doing a specific task, rather than everyone doing something on his own.
Now the promised explanation about our material considerations or silly outfit. The same way as there are standardised procedures for reaction to failures, the setup of the dive-equipment and the placement of everything, we do in a standardised way. Every diver will blindly know what-is-where on themselves, but also on their team member. No excessive item is taken down with us, but certainly not too few either. Everything is smoothly tucked away and yet easily accessible. The name often used for this typical equipment configuration is the Hogarthian style. This type of configuration is proven favourite and named after its “inventor” William Hogarth Main. K.I.S.S. (Keep It Simple Stupid) has been the guiding principle: can the material used endure a beating? Is entanglement with other material possible? Are all other items accessible? Or will the adding of an extra piece of equipment prevent the use of another? The Hogarthian configuration is minimalistic, yet fully-developed for wreck and cave diving alike.
Harness and backplate
All diving equipment is worn, therefore there are no parts dangling around. Everything is tightly fitted around the body of the diver. We use a stainless steel back plate with harness to carry our cylinders. The harness (also called webbing) consists of one piece and has no quick release locks. The reason for no quick release locks is that they can open or fail, which would unnecessarily lead to a preventable problem. Our webbing contains five D-rings: one for the left hip, a crotch and a butt D-ring and one on the right and left shoulder. On these D-rings we can clip all necessary items. Where we clip what items, is predetermined.
The wing provides the buoyancy of the diver and our equipment. The wing comes in various sizes, but must be fit for purpose. When a wing is to large and bulky, deflating it may become more difficult. The use of bungees (elastic straps) on a wing is in our opinion not a good idea as they can easily break and create avoidable buoyancy control problems.
First and second stages
Our first stages are balanced to ensure regulator performance, regardless of cylinder or ambient pressure. DIN connectors provide proper assurance of the O-ring and better hydrodynamics, because no INT bracket sticks out at the back. Therefore we prefer to use DIN connectors.
The routing of the first and second stages is divided into a left and a right post.
This way we ensure that in case of a failure there is always gas available from one of the two regulators.
We breathe from our primary regulator, the “long-hose” that routes from the 1st stage on the right post. The “long-hose” is approximately 2.1 meters long to enable convenient positioning of our team while gas is being shared with a team member in an Out of Gas situation. The “long-hose” is routed under the wing, behind the battery pack, across the chest and around the divers neck into the mouth. Unlike out of gas situations occurring during recreational dives, where the out of air diver goes for your “yellow octopus”, in a technical dive we donate our own regulator if our team member proves out of gas. This way we are sure that the person who needs gas the most, gets an actual working regulator with breathable gas for the given depth. Why the right post and not the left post? Valves could possibly rotate if in contact with the ceiling of a cave or a piece of a wreck. The right valve will always rotate to an open position. Hence the long-hose on the right.
Our backup regulator is routed from the first stage positioned on the left post. Why? Because our primary is already on the right post and we prefer to have two separate first stages. The hose runs closely over our right shoulder and hangs on a piece of bungee cord just below our chin.
The inflator of the wing is attached to the right post and the pressure gauge on the left. Should the left valve be closed accidentally due to contact with the previously mentioned ceiling of a cave of wreck this is easily detected, because the gauge will show the same pressure throughout dive.
The dry suit inflator is connected to our left post, so our back-up buoyancy device is on the opposite post of our wing. However, we prefer to use an argon bottle. This ensures we have two completely separated and redundant buoyancy control devices. Also in case of diving helium based gasses, it gives us the option to inflate our dry suit with either air or even argon to prevent heat loss.
For most of our dives we use two steel 12 liter cylinders, conneted with a manifold, our so called “double 12’s. For some dives we may consider using a double 18. The isolator on the manifold helps safeguard half our gas volume should a non-fixable failure on our regs or manifold occur.
Stage (or deco) bottles are for buouyancy reasons preferably made from aluminium with most common sizes being 40 cft or 80 cft. We prefer for interchangeability reasons to use the same 1st and 2nd stages as the ones we use on our doubles. On both sides of the bottle its maximum operating depth (MOD) is indicated in large numbers.
The gas the cylinders contains in itself is not dangerous, provided it is used at the correct depth.
Part of our approach to technical diving is using standard gasses for given depth ranges.
Our bottom and deco stages can easily be identified by the mentioned large MOD numbers on the bottle, e.g. “60” meters for a Tx18/45 bottom gas (trimix with 18% oxygen and 45% helium); “45” meters for a Tx21/35 bottom gas (trimix with 21% oxygen and 35% helium); “21” meters for an EAN50 deco gas (Nitrox 50% oxygen) and “6 OXYGEN” for our 100% oxygen deco gas. All colour markings are removed from both cylinders as well as first and second stages. We determine and verify the content of the bottle according to the stated MOD (that was confirmed during the pre-dive gas analyses, of course) and not for example on the basis of the colouring on the first stage (which you might have accidentally put on the wrong bottle)
Primary and backup lights
Our primary lights consist of a light head with a separate cannister type battery attached to the webbing at our right hip. For proper communication a focussed beam is required. In this way, clear signals can be given when needed. Our primary lights all have similar ‘strength’, so that all divers are proportionately visible. We use so called passive communication in our diving; if a beam of light of a team member is quietly pointing forward or moving slowly, we know they are ok. No need to actively exchange OK-signals as commonly used during most recreational diving.
We realise there are many possible hazardous situations that can be caused by the failure of a primary light and the absence of a good back-up light. We clip at least one, preferably two, back-up light to the D-rings on our shoulder, stowing them behind an elastic band attached to the harnas.
We strap our instruments conveniently to our under arms; our compass on the left (best location, as we often use our scooters during our dives), our bottom timer on the right side. The bottom timer displays all information we need during our dive: time, (average) depth and possibly ascent speed and a stop-watch function. The dive plan (and a backup plan when appropriate) has been made in advance, when needed verified in a decompression program and most of the times written in the wetnotes for possible in water reference. In our diving a dive computer is not necessary.
We dive tri-laminate dry suits, because the properties of these materials do not alter during the dive. Isolation and buoyancy remain the same under all circumstances. Furthermore, the dry suits we use are fitted with two pockets, one on each leg, and have a so-called telescope torso for comfortable fit.
The distribution of additional diving gear over our pockets is also standardised. Everyone has the same materials in the same place. The right pocket is used for “security / reserve items”: safety spool, spare mask and wet notes, the left pocket is for the “operation items”: primary SMB, spools etc. All this extra dive gear is stored into the pockets on the legs during the dives and attached with a double-ender to bungee cord, so if for whatever reason it falls out of our pockets it won’t get lost.
Masks and fins
The most convenient for us are low volume masks with a simple adjustable neoprene mask strap. Neoprene has the advantage of (almost) never breaking. Our spare mask is a frameless type as it is easiest to store. Our fins are preferably rigid and sturdy, suitable for the various propulsion and positioning kicks needed to manoeuvre with precision. Especially in environments with high risk of silt outs. We replace the standard rubber straps by stainless steel springs.
Metal to metal joints, tie-wraps and carabiners we feel are not a good option to fix materials. We only use boltsnaps that are firmly put in place using easily removable cave-line or double enders. The main difference with other types of clips is that boltsnaps and double enders only open if you want them to.
We are happy to share our choices in our material and configuration as it plays an important part in the fun we have in all the dives we do.
But not the only part. Knowing how to use it properly is equally as, if not more important.
The next issue will be about the first step in learning to use the equipment, the Intro to Tech or Fundamentals course.
We hope to see you at the waterfront and don’t forget to like and follow Team Pitch Blue on Facebook. We are happy to answer possible questions you may have right there.
WORDS By Team Pitch Blue and PICTURES By Case Kassenberg