Search patterns Flashcards
What factors govern the choice of seabed search patterns?
Factors include underwater visibility, nature of the seabed, currents, size and shape of the area, available craft and equipment, and state of the sea.
How should ropes be handled underwater to avoid entanglement?
Ensure minimal length of rope is free in the water at any one time and never throw coiled rope into the water.
what should divers do to avoid entanglement when using lifelines or surface-supplied breathing apparatus?
Arrange equipment carefully to reduce potential areas for entanglement and discard non-essential equipment. Cease all activity and assess the situation if entanglement occurs, and notify the attendant if necessary.
What are lifeline directional signals used for?
Lifeline directional signals are used for communication in poor visibility or when divers are working further apart.
What are semi-circular or sweep searches used for?
semi-circular or sweep searches are common search patterns where the diver moves in a semi-circular motion over the seabed, progressively moving further away or closer to a central datum.
What is the purpose of circular searches and how are they set up?
Circular searches allow systematic coverage of an area. A fixed central point is established, and a length of rope (search-line or snag-line) is connected to the central position. A circular sweep is made until a marker peg is encountered.
What are the advantages and limitations of semi-circular searches?
Semi-circular searches are quick and easy to set up, useful for covering large areas. However, they cannot be used in areas with obstructions or uneven bottoms.
What is a jackstay search and how is it conducted?
A jackstay search involves laying ropes along each side of the search area. Divers swim towards each other while observing the terrain, using the ropes as reference points and guides.
How can snag-line searches be used to locate objects?
Two divers and a weighted snag-line are used to swim over the area. If the object is large and the bottom featureless, it should be snagged and quickly found.
What are the considerations when choosing a search pattern?
Factors such as object size, visibility, bottom conditions, and available resources influence the choice of search pattern.
What is the purpose of lifeline signals in underwater searches?
Lifeline signals are used to communicate between the diver and the attendant in conditions of poor visibility or when working at a distance.
How should a diver handle entanglement if it occurs during a search operation?
The diver should cease all activity, assess the situation, and notify the attendant using lifeline signals. If the entanglement cannot be cleared, the standby diver should be sent in for assistance.
What are the advantages of parallel searches in search operations?
Parallel searches are suitable for shorelines, piers, or edges where the attendant can walk alongside while the diver swims in a straight line. This technique offers better efficiency and coverage compared to semi-circular searches.
How can grid or jackstay searches be conducted in underwater search operations?
Grid or jackstay searches involve laying ropes along each side of the search area. Divers swim towards each other while observing the terrain, using the ropes as reference points and guides.
What are the advantages and limitations of circular searches in underwater search operations?
Circular searches allow for systematic coverage of an area but can be challenging when the bottom is covered with obstacles or debris. They are relatively easy to set up and useful for covering large areas.
How can semi-circular searches be conducted in underwater search operations?
In semi-circular searches, the diver is controlled by the attendant and swims on a taut line over successive areas of the bottom. Turns should be made outside the line to prevent slack and ensure an efficient search pattern.
