|message Board||EDUCATION RESOURCES||SUNKEN CITIES||RECENT DISCOVERIES||SHIP WRECKS|
|CONSERVATION METHODS||LOCATING THE WRECK||EXCAVATION TECHNIQUES||SHIPWRECK DATA BASE||About This Site|
Glossary of Nautical Archaeology Terms
Airlift: A open tube descends down to the excavation site. Compressed air is pumped from the surface into the lower end of tube thereby creating a suction. Sand, water, and little objects are later sifted and examined on deck.
ANGUS: Stands for Acoustically navigated Geological Underwater Survey
Archaeology: The scientific study of the people, customs and life of ancient times. Archaeologists study buildings, tools, pottery, weapons and other objects in order to find our how people lived in the past when there were few or no written records
Argo: A sled equipped with video cameras that transmits moving pictures of the environment around it.
Circular search: This is an uncomplicated way for divers to search an area of the seabed. The diver begins at a fixed point on the bottom. Secures the search line and then swims a circle with the line stretched.
Concretion: is made up of grains of sand, shells particles, coral and sea plants. This material begins to build up on objects beneath the sea as they start to rust and corrode. After awhile concretion covers the object, preserving it in a hard protective shell. Removing the concretion is a painstaking and tedious operation. Conservators X-Ray the artifact before going to work. They must determine the exsact shape of the object underneath the tough outer casing. After determining the fragility of the artifact the conservator goes to work using special tools to free the artifact from the concretion.
Crow's nest: A platform high up the ship mast, used to spot objects in the far distance.
Conservation: means to preserve an object. The majority of objects recovered from the ocean need to be preserved with special chemicals. If this is not done quickly and properly the artifacts will rapidly deteriorate. The conservator makes the object stable by using special chemical and tools.
Conservator: a person who protects or preserves objects
Decay: During the first stage a underwater shipwreck quickly deteriorates . It often takes decades for a wooden ship and about a century for a steel ship. What remains after that is usually stable for millennia if covered by sand, sediment, coral, or other encrustations.
Decompression sickness: also known as "the bends," an excruciating and sometimes fatal result of nitrogen bubbles blocking the flow of blood at critical junctures.
Dendrochronological : A method dating past events or climatic alterations by a comparative study of growth rings in tree trunks. Nautical archaeologists are able to tell how old a piece of wood is by counting the number of growth rings.
Deepwater side-scan sonar system: A sonar system that surveys a large portion of seafloor but records only somewhat large objects.
Electrolysis: When removed from the sea metal artifacts often contain salt (sodium chloride). The salinity content varies greatly from ocean to ocean and as a general rule the less salt the less destruction to the object. For example the Vasa's artifacts were remarkably preserved because of the low salinity levels and frigid waters in the Baltic sea. The moment objects are taken from the sea and exposed to the open air, the salt and the air begin to react and if left untreated the object literally starts to crumble. Electrolysis is time consuming process that draws salt out of the metal by running an electrical current through it. The more salt the metal contains the longer the process takes. he object stable by using special chemical and tools.
Forward: The front of the ship
GPS: GPS stands for Global Positioning System a system for navigation by satellite.
Hold: A storage space below the deck
Hull: The frame of a ship without it's main structure
Hull Plates: Joined together metal plates that cover the ships hull framing.
Keel : The spine of the ship
Magnetometers: Huge underwater metal detectors.
Marine Geology: The study of the geographical formations and history of the sea.
Midship: The middle of the ship.
Port: The left-side of a ship when facing forward.
Objects: material things; anything that can be touched
PEG: Stands for polyethylene glycol.
Plotter : A computer monitor that examines and displays the path of a search vessel.
Position Fixing: This device allows a nautical archaeologist to know exsact location at sea. When they locate a shipwreck site, they are able to find the exsact same location again.
ROV: Stands for Remote Operated Vehicles. This underwater robot is used as an alternative to divers for difficult and dangerous projects.
SAR: Stands for Sonar Acoustique Remorque. It is able to take pictures by bouncing sound waves off underwater objects.
Side scan sonar: A sonar that is able to look sideways. The signals are sent in a widespread angular pattern down to the bottom of the sea floor. However a calm sea is needed for a decipherable results.
Shipworms: A highly destructive wood eating worm like creature that has two siphons at the posterior end which protrude into the water. Some may reach 60 cm in length and 20 mm in diameter. A ships wood may become completely honeycombed before the infestation is noticed.
Sonar: A device for locating objects under water, similar to radar but using sound waves instead of an electronic beam.
Starboard: Right-hand side of a ship when facing the bow
Stern: The rear of a ship
Survey: The process of thoroughly examining a site and its surrounding area before excavation
Wheelhouse: The covered area on the bridge that houses the ship's wheel
Trawler fishing: A highly destructive form of fishing that is a major threat to many historical shipwrecks.
Treasure hunting: A commercial operation intent on the exploitation of historical wrecks. After treasure hunters plunder a site important and irreplaceable archaeological information is lost forever.
Water dredge: A pump like device used primarily for shallow water excavations.