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Chip Log
A chip log, also called common log, ship log, or just log, is a navigation tool mariners use to estimate the speed of a vessel through water. The word ''knot'', to mean nautical mile per hour, derives from this measurement method. History All nautical instruments that measure the speed of a ship through water are known as logs. This nomenclature dates back to the days of sail, when sailors tossed a log attached to a rope knotted at regular intervals off the stern of a ship. Sailors counted the number of knots that passed through their hands in a given time to determine the ship's speed. Today, sailors and aircraft pilots still express speed in knots. Construction A chip log consists of a wooden board attached to a line (the log-line). The log-line has a number of knots at uniform intervals. The log-line is wound on a reel so the user can easily pay it out. Over time, log construction standardized. The shape is a quarter circle, or quadrant with a radius of or , and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speyer Handlog
Speyer (, older spelling ''Speier'', French: ''Spire,'' historical English: ''Spires''; pfl, Schbaija) is a city in Rhineland-Palatinate in Germany with approximately 50,000 inhabitants. Located on the left bank of the river Rhine, Speyer lies south of Ludwigshafen and Mannheim, and south-west of Heidelberg. Founded by the Romans, it is one of Germany's oldest cities. Speyer Cathedral, a number of other churches, and the Altpörtel (''old gate'') dominate the Speyer landscape. In the cathedral, beneath the high altar, are the tombs of eight Holy Roman Emperors and German kings. The city is famous for the 1529 Protestation at Speyer. One of the ShUM-cities which formed the cultural center of Jewish life in Europe during the Middle Ages, Speyer and its Jewish courtyard was inscribed on the UNESCO World Heritage List in 2021. History The first known names were ''Noviomagus'' and ''Civitas Nemetum'', after the Teutonic tribe, Nemetes, settled in the area. The name ''Spira'' i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drogue
A drogue (also known as a storm drogue) is a device trailed behind a boat on a long line attached to the stern. A drogue is used to slow the boat down in a storm and to prevent the hull from becoming side-on to the waves. A boat that has deployed a drogue should not overspeed down the slope of a wave and crash into the next one, nor will the vessel broach. By slowing the vessel, the drogue makes the vessel easier to control in heavy weather and will help to prevent pitchpoling. A drogue works by providing substantial resistance when dragged through the water. An alternative device is the sea anchor, a much larger item than a drogue, which is streamed from the bows. The advantage of the sea anchor is that the bows of a yacht are invariably finer than the stern, thereby giving a safer and more comfortable experience in a storm. Both drogues and sea anchors will have "tripping lines" to aid recovery of the drogue after deployment. An alternative procedure during a storm is simpl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ocean Current
An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind, the Coriolis effect, breaking waves, cabbeling, and temperature and salinity differences. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength. Ocean currents are primarily horizontal water movements. An ocean current flows for great distances and together they create the global conveyor belt, which plays a dominant role in determining the climate of many of Earth’s regions. More specifically, ocean currents influence the temperature of the regions through which they travel. For example, warm currents traveling along more temperate coasts increase the temperature of the area by warming the sea breezes that blow over them. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate for its high latitude compared to other are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Following Sea
A following sea refers to a wave direction that is similar to the heading of a waterborne vessel under way. The word "sea" in this context refers to open water wind waves. In the strict sense, a following sea has a direction of propagation between 15° either side of vessel heading, and has a celerity that does not exceed the velocity of the vessel in the direction of wave propagation. If the wave moves faster than the vessel it is an overtaking sea. If the angle to vessel heading is more than 15° it may be a quartering sea. Usage Sailors use this term synonymously with the points of sail A point of sail is a sailing craft's direction of travel under sail in relation to the true wind direction over the surface. The principal points of sail roughly correspond to 45° segments of a circle, starting with 0° directly into the wind. ... below a beam reach, since the wind direction is generally the same as the sea direction. Therefore, the phrase "Fair winds and following seas," ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Naval Academy
The United States Naval Academy (US Naval Academy, USNA, or Navy) is a federal service academy in Annapolis, Maryland. It was established on 10 October 1845 during the tenure of George Bancroft as Secretary of the Navy. The Naval Academy is the second oldest of the five U.S. service academies and it educates midshipmen for service in the officer corps of the United States Navy and United States Marine Corps. The campus is located on the former grounds of Fort Severn at the confluence of the Severn River and Chesapeake Bay in Anne Arundel County, east of Washington, D.C., and southeast of Baltimore. The entire campus, known colloquially as the Yard, is a National Historic Landmark and home to many historic sites, buildings, and monuments. It replaced Philadelphia Naval Asylum, in Philadelphia, that had served as the first United States Naval Academy from 1838 to 1845, when the Naval Academy formed in Annapolis. Candidates for admission generally must apply directly t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meter
The metre (British spelling) or meter (American spelling; see spelling differences) (from the French unit , from the Greek noun , "measure"), symbol m, is the primary unit of length in the International System of Units (SI), though its prefixed forms are also used relatively frequently. The metre was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately km. In 1799, the metre was redefined in terms of a prototype metre bar (the actual bar used was changed in 1889). In 1960, the metre was redefined in terms of a certain number of wavelengths of a certain emission line of krypton-86. The current definition was adopted in 1983 and modified slightly in 2002 to clarify that the metre is a measure of proper length. From 1983 until 2019, the metre was formally defined as the length of the path travelled by light in a vacuum in of a second. After the 2019 rede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foot (length)
The foot ( feet), standard symbol: ft, is a unit of length in the British imperial and United States customary systems of measurement. The prime symbol, , is a customarily used alternative symbol. Since the International Yard and Pound Agreement of 1959, one foot is defined as 0.3048 meters exactly. In both customary and imperial units, one foot comprises 12 inches and one yard comprises three feet. Historically the "foot" was a part of many local systems of units, including the Greek, Roman, Chinese, French, and English systems. It varied in length from country to country, from city to city, and sometimes from trade to trade. Its length was usually between 250 mm and 335 mm and was generally, but not always, subdivided into 12 inches or 16 digits. The United States is the only industrialized nation that uses the international foot and the survey foot (a customary unit of length) in preference to the meter in its commercial, en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fathom
A fathom is a unit of length in the imperial and the U.S. customary systems equal to , used especially for measuring the depth of water. The fathom is neither an International Standard (SI) unit, nor an internationally-accepted non-SI unit. Historically, however, it is the most frequently employed maritime measure of depth in the English-speaking world. There are two yards (6 feet) in an imperial fathom. Originally the span of a man's outstretched arms, the size of a fathom has varied slightly depending on whether it was defined as a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. Formerly, the term was used for any of several units of length varying around . Name The name (pronounced ) derives from the Old English word ''fæðm'', cognate to the Danish (via the Vikings) word "favn" meaning embracing arms or a pair of outstretched arms. Cognate maybe also via the Old High German word "fadum" of the same meaning.''Oxford English Dict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Units Of Measurement
A unit of measurement is a definite magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can be expressed as a multiple of the unit of measurement. For example, a length is a physical quantity. The metre (symbol m) is a unit of length that represents a definite predetermined length. For instance, when referencing "10 metres" (or 10 m), what is actually meant is 10 times the definite predetermined length called "metre". The definition, agreement, and practical use of units of measurement have played a crucial role in human endeavour from early ages up to the present. A multitude of systems of units used to be very common. Now there is a global standard, the International System of Units (SI), the modern form of the metric system. In trade, weights and measures is often a subject of governmental regulation, to ensure fairness and transparency. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Bourne (mathematician)
William Bourne (c. 1535–1582) was an English mathematician, innkeeper and former Royal Navy gunner who presented the first design for a navigable submarine and wrote important navigational manuals. He is often called William Bourne of Gravesend. In 1574, he produced a popular version of the Martín Cortés de Albacar's ''Arte de Navegar,'' entitled ''A Regiment for the Sea.'' Bourne was critical of some aspects of the original and produced a manual of more practical use to the seaman. He described how to make observations of the sun and stars, using a cross-staff, and how to plot coastal features from the ship by taking bearings using triangulation.G. L'E. Turner, ‘Bourne, William (c.1535–1582)’, Oxford Dictionary of National Biography, Oxford University Press, 2004. Life in Gravesend Before publishing his submarine design, William Bourne was a jurat in Gravesend, England. His name first appears in the first charter of incorporation of Gravesend from June 5, 1562. His na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sailor
A sailor, seaman, mariner, or seafarer is a person who works aboard a watercraft as part of its crew, and may work in any one of a number of different fields that are related to the operation and maintenance of a ship. The profession of the sailor is old, and the term ''sailor'' has its etymological roots in a time when sailing ships were the main mode of transport at sea, but it now refers to the personnel of all watercraft regardless of the mode of transport, and encompasses people who operate ships professionally, be it for a military navy or civilian merchant navy, as a sport or recreationally. In a navy, there may be further distinctions: ''sailor'' may refer to any member of the navy even if they are based on land; while Seaman (rank), ''seaman'' may refer to a specific enlisted rank. Professional mariners Seafarers hold a variety of professions and ranks, each of which carries unique responsibilities which are integral to the successful operation of an ocean-going vesse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
