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NOAAS Ronald H Brown.
A research vessel (RV or R/V) is a ship designed and equipped to carry out research at sea. Research vessels carry out a number of roles. Some of these roles can be combined into a single vessel, others require a dedicated vessel. Due to the demanding nature of the work, research vessels are often constructed around an icebreaker hull, allowing them to operate in polar waters.
DREDGER
The Geopotes 14 lifting its boom on a canal in The Netherlands. (gēopotēs is Greek for "that which drinks earth")
Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location. This technique is often used to keep waterways navigable.
It is also used as a way to replenish sand on some public beaches, where sand has been lost because of coastal erosion. Dredging is also used as a technique for fishing for certain species of edible clams and crabs, see fishing dredge.
A dredge is a device for scraping or sucking the seabed, used for dredging. A dredger is a ship or boat equipped with a dredge. The terms are sometimes interchanged.
The process of dredging creates spoils (excess material), which are carried away from the dredged area. Dredging can produce materials for land reclamation or other purposes (usually construction-related), and has also historically played a significant role in gold mining. Dredging can create disturbance in aquatic ecosystems, often with adverse impacts.
WARSHIP
Magdeburg, a German Braunschweig class corvette (2008)
A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more manoeuvrable than merchant