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Technical Diving Equipment

The equipment used by technical divers differs considerably from that used by recreational scuba divers. Even when it appears similar, the technical diver will usually either carry more equipment or configure it slightly differently. In this article, we will look at the different equipment configurations used by technical divers, the reason for those differences and also whether there are any lessons recreational divers can learn from these configurations.
Technical Diving Equipment
Published in X-Ray Issue: 38 - Oct 2010
Authored by: Mark Powell | Photography: Mark Powell, Rich Walker and Roz Lunn | Translation:
Download pdf ► Technical Diving Equipment
When combined with a poor choice of equipment placement or a lack of storage space, the diver can end up looking like a Christmas tree with pieces of equipment randomly clipped on and dangling from every conceivable spot.
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Over the years, recreational diving has developed a standard set of equipment configuration. Despite different makes and models there is a consistent set of gear shared by the majority of recreational divers. Buoyancy control is usually provided by a jacket style buoyancy compensator (BCD). The diver’s main cylinder contains the majority of their breathing supply, which is delivered via a primary regulator. A spare regulator or octopus is usually carried to provide a source of air to the buddy, or in the case of a problem with the main regulator. Additional equipment is often carried in the pockets of the BCD or clipped onto it.

Technical divers have quite a different set up designed to deal with a different set of conditions to those experienced by the recreational diver. There are a wider range of styles of equipment configuration, although all of these styles have been developed to address the same key requirements.

Redundancy
The key requirement for any technical diving configuration is that it provides an adequate level of redundancy. Technical diving usually involves mandatory decompression stops, and it may be anything from a few minutes to a few hours before the diver is able to ascend to the surface without risking decompression illness. In this case, the loss or failure of any piece of vital equipment would be a major problem. As a result, the technical diver looks to provide redundancy of equipment so that he can resolve equipment problems whilst still completing the required decompression. Equipment that is required for the safe completion of the dive should always have a backup.

Don’t be a Christmas tree
By adding backups, the technical diver ends up carrying significantly more equipment than the recreational diver. If this is added in a haphazard way, or without consideration of how the configuration will work as a whole, it is very easy for the technical diver to become overwhelmed with equipment.

Many divers carry equipment “just in case” it is needed without ever thinking about what is really required. When combined with a poor choice of equipment placement or a lack of storage space, the diver can end up looking like a Christmas tree with pieces of equipment randomly clipped on and dangling from every conceivable spot.

This dangling equipment can introduce a number of additional risks. Firstly the diver may have so much clutter that when they need to get a specific item of emergency equipment, they cannot find it amongst all the other equipment. Secondly, dangling kit may become lost,
caught in a piece of wreckage or entangled in a line.

Streamline
In order to avoid this Christmas tree effect, technical divers try to streamline their equipment and the placement of it. Contents gauges are clipped on rather than allowed to hang down. Reels, Delayed Surface Marker Bouys (DSMBs) and emergency equipment are stored in pockets rather than dangling on a lanyard. The same principles can be applied by the recreational diver to ensure their kit is streamlines and the Christmas tree effect is reduced.

We all know that human beings are not designed to breathe underwater. For this reason, divers need to take their own breathing gas with them when they dive. It is essential that enough gas is taken to complete the dive. For a recreational diver to run out of air is bad enough, but for a technical diver, it is not an option. If a recreational diver runs out of air on a no stop dive to 20m, they simply have to get to the surface. However, on a decompression dive where the diver may still have 20 minutes of decompression to complete, they are faced with the decision of staying down, completing the decompression and drowning, or going to the surface and risking decompression sickness. This is a choice that should be avoided by ensuring that there is always a sufficient supply of breathing gas.

Twins
The use of a ‘pony’ cylinder may provide enough gas to allow an ascent from recreational depths, but the volume of these cylinders is simply not enough to allow an ascent plus decompression stops from greater depth. This means that a pony cylinder is not sufficient redundancy for technical diving. The use of twin cylinders or twinset is a way of providing this redundancy.

A twinset is usually made up of two identically sized cylinders with a regulator connected to each cylinder. These can vary in size. Twinsets comprising two 7l cylinders are popular with recreational divers who want to have additional redundancy, but for technical diving, cylinders smaller than 10l do not provide a sufficient volume of gas. Twinsets made up of 12l, 15l, 18l or even 20l cylinders are available but, for the majority of technical divers, twin 12l cylinders provide a good balance of weight and gas volumes.

Twinsets can be configured as independent or manifolded. Independent cylinders provide complete redundancy, as there is no link between the two cylinders. Thus, if one cylinder has a problem, the other is completely independent. However, as the two cylinders are independent, the diver has to switch from one to the other in order to balance the gas usage in the two cylinders. Whilst switching regulators should be easily within the skill set of a technical diver and should be a routine action, it can sometimes be forgotten when the diver is in the middle of a problem.

The other option is to manifold the two cylinders together. This involves connecting the two cylinders at the valves by means of a manifold. This has the benefit that the gas from both cylinders can be accessed from the primary regulator. The disadvantage is that, in the case of a problem, the diver must shut down the problem regulator, or isolate the two cylinders by means of a valve in the middle of the manifold, otherwise the gas from both cylinders will be lost. For this reason, it is essential that a diver with a manifolded twinset can carry out a ‘shutdown’ to prevent the complete loss of their gas.

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Technical Diving Equipment
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