Scuba divers cant have a normal voice conversation underwater even though sound travels well in water mainly due to water's elasticity and density.
However, without an electronic system, communication by voice is almost impossible so most of the talking is done using diver hand signals and/or an underwater writing slate.
Waterproof plastic slates are useful for complex communication, making mathematical calculations underwater and map making.
Scuba diver hand signals generally have an advantage over a writing slate when communicating with your buddy. The main drawback to signaling on a slate is the time that it takes to write down the information.
Block slates and multi page wrist slates are commonly used especially by technical divers.
Gaining attention of your buddy is the first step, because he needs to look at you to see your hand signals diving. Depending on the distance between the buddy team, a common method to attract attention while diving is to tap your buddy's shoulder or bang on the scuba cylinder.
What can we use to bang with I hear you ask? Personally, I have a small divers' knife that easily detaches from its pocket and makes a loud rapping sound on the aluminium tank.
Tank bangers and underwater rattles are popular with instructors to gain attention of their students, but you could also use a loose weight, a dive torch or a stone as a last resort.
Communication at the surface often involves signalling with your hands and arms to your buddy, to the crew on the dive boat or maybe someone on the shore. Hand signals for diving are useful close up between a buddy pair down below and also from a distance at the surface.
Inexperienced divers often wave to friends on the boat or shore as a greeting, but in scuba, waving your arms up and down at the surface is regarded as a sign of distress or HELP!
Of course you can also yell or shout for help at the surface, but this can expend a lot of energy which is why all divers should carry a whistle as part of their standard equipment.
The sound made from whistles and horns carry a long way and are usually very loud. Almost all divers also carry some sort of inflatable signalling device that is easily seen from a distance. These are usually brightly colored tubes that alert boats of the divers' presence in the water.
Most dive boat crew members also have signalling devices to get attention from the divers. The underwater recall system is generally used to initiate all divers to return to the surface.
Underwater recall is usually used in an emergency situation and if you hear the recall, you should cautiously ascend to the surface and look to the boat for instructions from the captain.
Avoid swimming towards the boat until or unless you are instructed to do so. Underwater recall systems vary by different boat charters, but the boat crew will normally brief you on their standard procedures for emergency recall.
Scuba diving hand signals are not meant to replace speaking, but they certainly add to the safety and enjoyment of diving. Although divers hand signals are meant for underwater use and occasionally at the surface, it is also possible to communicate by voice underwater.
If you fill a glove with air and seal your mouth inside the glove, very often the spoken words can be heard and understood. I've also tried to speak into the air pocket of my dive mask when it's position slightly lower than normal and encloses the mouth.
These are not standard diver communication procedures and we advise all divers to be familiar with the recommended scuba diving hand signals.
The buddy system works best when the divers stay together and both members are familiar with the hand signals for scuba diving. It's your responsibility to stay with your buddy and follow the rules and review the guidelines and recommendations for each other's dive safety.
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