Silt-out
A silt-out is a dangerous situation when diving in which the underwater visibility is reduced to zero within a few seconds. The problem is particularly common with wreck and cave diving .
causes
Swirling up sediment
The main cause of the so-called silt-out is the swirling up of sediment by the flippers of the divers. This risk arises particularly in the interior of underwater caves or in calm, deep waters, as a lot of loose sediment is deposited here due to the lack of current.
Percolation
Another common reason for a silt-out is so-called percolation . H. the spontaneous detachment of parts of the cave ceiling by water infiltration from above or by the accumulation of air bubbles of the exhaled air inside the cave. The parts that fall onto the surface of the water dissolve in the water at lightning speed and the detached suspended matter can quickly lead to an extreme deterioration in visibility within the cave.
Detachment of rust particles
Especially when entering wrecks, the rising air bubbles of the exhaled air can lead to large quantities of rust particles being detached from the wreck and falling onto the surface of the water, where they are spread over a large area and thus drastically deteriorate visibility within a few seconds.
hazards
In caves and shipwrecks in particular, there is a great risk of getting lost in the event of a silt-out. Furthermore, underwater communication between diving partners, which usually takes place via hand signals, suddenly becomes impossible. Diving with zero visibility is also an enormous physical and psychological burden, as loss of orientation leads many people to panic, fear and thus significantly higher air consumption.
Safety measures
Mental health
In addition to the minimum requirements for recreational diving, which are determined by medical fitness to dive, wreck and cave divers in particular should have a solid personality, physical fitness and inner composure. Only those who are able to keep control of what is happening even in difficult or life-threatening situations can master emergency situations like this underwater with confidence, without putting themselves and their buddy in mortal danger through panic .
Diving training
The most important measure to avoid silt-outs is thorough training. Particularly noteworthy here is the so-called frog kick, in which the diver steps with his fins to the sides like a frog in order to avoid water turbulence towards the bottom. The various diving associations in recent years as part of its Specialty courses numerous exercises have developed to the student divers closer accommodate diving in zero visibility. In addition to diving with a darkened mask, this includes various orientation and partner exercises, as well as a variety of theoretical knowledge.
equipment
Standard in cave and wreck diving is to mark the way to the exit with the help of a continuous guide line, which the diver unrolls from a reel himself and attaches to prominent junctions. In wrecks or caves that have been dived a lot, guide lines are often fixed by local diving centers. Furthermore, the basic equipment of cave and wreck divers always includes a flashlight in order to be able to maintain appropriate communication in the event of a silt-out.
swell
- Thomas Kromp , Hans J. Roggenbach , Peter Bredebusch : Practice of diving . 11., completely redesigned and completely revised. Ed., Delius Klasing, Bielefeld 2009, ISBN 978-3-7688-2662-4 .
- Fred Devos, Chris Le Maillot, Daniel Riordan: Introduction to Guideline Procedures. Part 3: Navigation . In: Quest (2005).