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What Types of Underwater Communication Systems are out there?

underwater communication systems - dive alert

Although there are sophisticated underwater communication systems that allow us to speak between divers, they are mainly used in commercial diving because of their price tag and because they require the use of a full-face mask.

For most divers, underwater communication is done through gestures and manual signals.

Underwater Communication Systems; Hand Signals

In the initial OWD course, we already learn basic communication signals. “Are you ok?”, “Everything ok”,” I have problems”, ”I have little air and I need air”. They are usually complemented by other signs, but in the end, these are the important ones when you start diving. When through experience or training you become an advanced diver, you do dives that require more complex communication.

An advanced diver does deeper dives and has to be more precise in indicating the gas remaining in his tank. For this, many advanced divers use the signals used in technical diving indicating the pressure of the tank by numbers using the fingers of one hand. With the palm of the hand facing out and the fingers pointing upwards, to indicate from 1 to 5, and with the palm of the hand facing in and the fingers pointing to the side, to indicate from 6 to 9. The 0 is indicated by making a complete circle with fingers and thumb. This allows you to indicate to your dive buddy the exact amount of air or gas you have left in the tank. This system is also used to indicate depth or time.

There is a set of internationally standardized signs that with small variations are often used in technical diving that come from cave diving. Gestures and manual signals are also used to indicate things like “sediment”, “I have reached my return pressure”, “guideline”, etc…

Underwater Communication Systems - hand signals

Underwater Communication Systems; Light Signals

As an advanced diver, you are not trained to dive in overhead environments, but you probably will perform night dives and with limited visibility that are similar in conditions to those of caves. This is why advanced divers use some cues from cave diving. The primary light is used to communicate, making a circle with the light beam is used both to ask if you are ok and to answer that everything is ok. Moving the light beam from one side to the other indicates that something is wrong and is used to get the buddy’s attention.

In any case, communication in night diving should be done with signals using only one hand and pointing the light beam down or sideways at the signaling hand. It is quite useless to raise a hand to signal during a night dive if at the same time we point the light beam on the buddy’s face, dazzling him. For this, some signals that require the use of two hands have to be modified for night diving.

Underwater Communication Systems; Sound-making Devices

Some divers and guides use sound-making devices to draw the attention of partners and other divers. They can be metal objects that hit the tank or devices connected to the BCD’s inflator that use the air in the tank to produce the sound when pressing a button. These underwater communication systems have the disadvantage that they do not serve to indicate an underwater direction since underwater sounds seem to come from all directions. Therefore, they are only useful when there is good visibility.

Underwater Communication Systems - scuba diving light

In environments with limited visibility, they only serve to verify that the buddy is in the water, but we cannot find him following the origin of the sound. These underwater communication systems connected to the BCD’s inflator have a version for use at the surface that emits a sharp and powerful sound that can reach 1 or 2 km away on the surface. Here they do have a directional value because it can attract the attention of the diving boat’s crew if a diver comes to the surface in trouble, or has been swept away by a strong current and is unable to return to the boat.

Some commercial underwater communication systems incorporate both options in the same device, both for underwater and surface. This device is essential when making drift dives in which the boat leaves the divers in a point with strong current and the divers allow themselves to be carried by the current along the reef and when their air gauge reaches reserve they emerge. The diving boat will have followed them and will pick them up when they surface. Any problem or error can cause a great distance between divers that drift with the current and the boat that is going to pick them up. For this reason, it’s so important to use of these acoustic systems that reach a great distance, of course much more than can be achieved by shouting or using a whistle.

Underwater Communication Systems: Physical Contact.

Again, in low visibility environments, if the visibility is very reduced, the only way to maintain communication with your buddy is through physical contact. Also, from cave diving, there are standardized procedures for communicating in situations of zero visibility. These protocols include holding the partner by the arm and giving hand grips to give the necessary instructions to emerge safely.

In Dressel Divers, you can get trained as an advanced diver and you can learn underwater communication systems and techniques necessary to perform advanced-level dives improving your safety and fun during your dives. If you are interested, contact us.

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