Because there is no way for divers to vocalize their needs or thoughts to each other when underwater, SCUBA divers must be able to convey information to each other and the boat crew in a way that everyone can understand. Unless equipped with underwater radios, divers must use some type of signal to transmit information, such as how much air they have left in their tanks, or if there is danger present. Before heading out a dive, the dive master should give a rundown of what your signals will be, and they can vary greatly between dive operations. There are several signals, however, that are virtually standardized enough that all divers should know them. Here are our top 5.
The most commonly used and universally recognized diving sign is the “okay” hand signal, made by forming a circle with the thumb and forefinger. The okay signal is generally used when first entering the water to let the boat know you are safely in, or responding to a dive buddy’s okay signal below the surface. Another time the okay signal is frequently used is upon surfacing, to let the boat crew know you are alright.
Air Pressure Check
When diving in groups, not all people consume air at the same rate and divers should be continually mindful of the air supply of their diving partners. To ask how much air a buddy has left, one diver holds up their own air gauge. The partner replies by pressing one finger to the arm for each 1,000 PSI and one finger up for each 100 PSI of air pressure left in their tank. For example, if the diver being asked has 1,400 PSI left, they press one finger to the arm, and then hold up four fingers. Note: this is a general system; some dive operations will have their own signals.
With proper technique and attention to detail, you should be able to complete your dives without running out of air. However, there are any number of situations that can cause air tanks to run low besides poor air consumption, such as leaky hoses or other equipment malfunction. The hand signal for low air is to hold a clenched fist over the center of the chest. This should be done when your gauge reads 500 PSI or less. When a SCUBA diver signals they are running low on air, others must immediately prepare to share their air supply — not just their buddy.
The signals for going up or down are often misconstrued by new divers as a “thumbs up – yay!” or “thumbs down – boo!” , but they are in fact directional signals most often used by the dive master. However, you may also use the thumbs up signal if you are having any kind of trouble and want to call the dive; simply try to communicate what is wrong to your buddy and use the thumbs up signal to indicate that you are going up. Make sure your intention to ascend is known at least by your buddy, if you cannot alert the dive master!
Used when the dive master desires to stop the ascent, the hand signal for leveling off is made by waving the hand side-to-side with the fingers spread and palm of the hand held downward. This is used most often during safety stops while ascending to allow a SCUBA diver’s internal pressure to stabilize. Try to stay at virtually the same depth as your dive master during the safety stop.
Top image via Official U.S. Navy Imagery