Slamming is the impact of the bottom structure of a ship onto the sea surface. It is mainly observed while sailing in waves, when the bow raises from the water and subsequently impacts on it. Slamming induces extremely high loads to ship structures and is taken into consideration when designing ships. Slamming is not strictly limited to ships but is observed in watercraft as small as kayaks. [1] For trimarans and catamarans, slamming can occur when an ama slams back down into the sea after being lifted clear by wind or wave action. Slamming can also occur for multihull vessels when the sea strikes an area that is normally above water level and join the vessel's hulls together.
Slamming can occur in relatively mild sea conditions if the vessel is prone to pitching, which is more likely to occur aboard vessels where the bow and stern sections are both narrow.
A hull is the watertight body of a ship, boat, submarine, or flying boat. The hull may open at the top, or it may be fully or partially covered with a deck. Atop the deck may be a deckhouse and other superstructures, such as a funnel, derrick, or mast. The line where the hull meets the water surface is called the waterline.
A ship is a large vessel that travels the world's oceans and other navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity and purpose. Ships have supported exploration, trade, warfare, migration, colonization, and science. Ship transport is responsible for the largest portion of world commerce.
Naval architecture, or naval engineering, is an engineering discipline incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process, shipbuilding, maintenance, and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation (classification) and calculations during all stages of the life of a marine vehicle. Preliminary design of the vessel, its detailed design, construction, trials, operation and maintenance, launching and dry-docking are the main activities involved. Ship design calculations are also required for ships being modified. Naval architecture also involves formulation of safety regulations and damage-control rules and the approval and certification of ship designs to meet statutory and non-statutory requirements.
An icebreaker is a special-purpose ship or boat designed to move and navigate through ice-covered waters, and provide safe waterways for other boats and ships. Although the term usually refers to ice-breaking ships, it may also refer to smaller vessels, such as the icebreaking boats that were once used on the canals of the United Kingdom.
A semi-submersible platform is a specialised marine vessel used in offshore roles including as offshore drilling rigs, safety vessels, oil production platforms, and heavy lift cranes. They have good ship stability and seakeeping, better than drillships.
Rogue waves are huge and unpredictable surface waves that can be extremely dangerous to ships and isolated structures such as lighthouses. They are distinct from tsunamis, which are often almost unnoticeable in deep waters and are caused by the displacement of water due to other phenomena. A rogue wave at the shore is sometimes called a sneaker wave.
A sea anchor is a device that is streamed from a boat in heavy weather. Its purpose is to stabilize the vessel and to limit progress through the water. Rather than tethering the boat to the seabed with a conventional anchor, a sea anchor provides hydrodynamic drag, thereby acting as a brake. Normally attached to a vessel's bows, a sea anchor can prevent the vessel from turning broadside to the waves and being overwhelmed by them.
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water. Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".
Springing as a nautical term refers to global (vertical) resonant hull girder vibrations induced by continuous wave loading. When the global hull girder vibrations occur as a result of an impulsive wave loading, for example a wave slam at the bow (bow-slamming) or stern (stern-slamming), the phenomenon is denoted by the term whipping. Springing is a resonance phenomenon, and it can occur when the natural frequency of the 2-node vertical vibration of the ship equals the wave encounter frequency or a multiple therefrom. Whipping is a transient phenomenon of the same hull girder vibrations due to excessive impulsive loading in the bow or stern of the vessel. The 2-node natural frequency is the lowest and thereby the most dominant resonant mode leading to hull girder stress variations, though in theory higher vibration modes will be excited as well.
MV Derbyshire was a British ore-bulk-oil combination carrier built in 1976 by Swan Hunter, as the last in the series of the Bridge-class sextet. She was registered at Liverpool and owned by Bibby Line.
Capsizing or keeling over occurs when a boat or ship is rolled on its side or further by wave action, instability or wind force beyond the angle of positive static stability or it is upside down in the water. The act of recovering a vessel from a capsize is called righting. Capsize may result from broaching, knockdown, loss of stability due to cargo shifting or flooding, or in high speed boats, from turning too fast.
A 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 bulbous bow is a streamlined flaring or protruding bulb at the bow of a ship just below the waterline. The flare or bulb modifies the way the water flows around the hull, reducing drag and thus increasing speed, range, fuel efficiency, and stability. Large ships with bulbous bows generally have twelve to fifteen percent better fuel efficiency than similar vessels without them. A bulbous bow also increases the buoyancy of the forward part and hence reduces the pitching of the ship to a small degree.
The bow is the forward part of the hull of a ship or boat, the point that is usually most forward when the vessel is underway. The aft end of the boat is the stern.
A vessel's length at the waterline is the length of a ship or boat at the level where it sits in the water. The LWL will be shorter than the length of the boat overall as most boats have bows and stern protrusions that make the LOA greater than the LWL. As a ship becomes more loaded, it will sit lower in the water and its ambient waterline length may change; but the registered L.W.L is measured from a default load condition.
A linkspan or link-span is a type of drawbridge used mainly in the operation of moving vehicles on and off a roll-on/roll-off (RO-RO) vessel or ferry, particularly to allow for tidal changes in water level.
Seakeeping ability or seaworthiness is a measure of how well-suited a watercraft is to conditions when underway. A ship or boat which has good seakeeping ability is said to be very seaworthy and is able to operate effectively even in high sea states.
Shipwrecking is an event that causes a shipwreck, such as a ship striking something that causes the ship to sink; the stranding of a ship on rocks, land or shoal; poor maintenance, resulting in a lack of seaworthiness; or the destruction of a ship either intentionally or by violent weather.
A submarine pipeline is a pipeline that is laid on the seabed or below it inside a trench. In some cases, the pipeline is mostly on-land but in places it crosses water expanses, such as small seas, straits and rivers. Submarine pipelines are used primarily to carry oil or gas, but transportation of water is also important. A distinction is sometimes made between a flowline and a pipeline. The former is an intrafield pipeline, in the sense that it is used to connect subsea wellheads, manifolds and the platform within a particular development field. The latter, sometimes referred to as an export pipeline, is used to bring the resource to shore. Sizeable pipeline construction projects need to take into account many factors, such as the offshore ecology, geohazards and environmental loading – they are often undertaken by multidisciplinary, international teams.
This glossary of nautical terms is an alphabetical listing of terms and expressions connected with ships, shipping, seamanship and navigation on water. Some remain current, while many date from the 17th to 19th centuries. The word nautical derives from the Latin nauticus, from Greek nautikos, from nautēs: "sailor", from naus: "ship".