Waterfront Terminology
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ABUTMENT
The foundation structure supporting the inshore end of a pier, trestle or bridge, often acting as a partial retaining wall.
ACCRETION
Deposition of accumulating sediments.
ACQ
A timber preservative called Alkaline Copper Quat, which recently replaced CCA preservative treatment for timber used in US residential markets. At this time ACQ is not recommended for timbers in marine construction, such as pilings and bracing, which may be exposed to marine borers.
ANODE
The positive end of an electrolytic cell. On waterfront structures, the anode is typically a sacrificial zinc, magnesium or aluminum alloy bar fastened to underwater steel to limit corrosion. An anode can also have an external power source to protect the steel with an impressed electrical current.
ARTIFICIAL NOURISHMENT
The process of adding sediment to a beach (usually sand), obtained from another location.
BATHYMETRIC SURVEY
The measurement of water depths, usually with sufficient detail to map the underwater terrain contours.
BATTER PILE
An angled pile used to develop lateral and vertical resistance for a structure.
BEDROCK
Rock of great size and depth in its native location acting as a mass, typically the Earth’s crust. Slang term "ledge".
BENCHMARK
A fixed point (disk, nail or other marker) of known elevation used for reference during a survey.
BENT
A line of piles framed together under a pier or trestle.
BERTH
The water area along the edge of a wharf or pier for vessel mooring.
BITT
A single- or double-post mooring fitting on a ship, pier or wharf to which mooring lines are secured.
BOLLARD
A vertical post mooring fitting typically mounted on a dolphin, pier or wharf, used for securing vessel mooring lines.
BRACES
Horizontal or angled members used on piles or columns to reduce the unsupported column length, and increase resistance to horizontal forces through load distribution. Referred to as cross braces, when angled.
BRACKISH
Water that is part seawater and part fresh water.
BREAKWATER
A structure protecting an area, such as a harbor, from waves. Traditionally a stone rubble berm structure, however it may be a structural wall (solid or permeable), often referred to as a wave screen.
BREASTING DOLPHIN
A structure with a fender system used to resist vessel berthing, and hold a moored vessel, often also fitted with mooring bollards.
BULKHEAD
A vertical wall designed to retain earth, often tied back with rock or soil anchors.
CAISSON
(1) The floating entrance gate to a basin dry dock. (2) A cast in place concrete pile/column, usually of large diameter.
CAMEL
A floating structure placed between a vessel and a dock structure, or between two vessels, designed to distribute contact loads over a larger area.
CATHODIC PROTECTION
An electrical method of controlling steel corrosion within a conducting media (seawater or wet/moist soil). An electrical current is applied to the steel using a connected sacrificial anode, or an external electrical power supply to an impressed current anode, within the conducting media.
CCA
A timber preservative called Chromated Copper Arsenate, which was recently discontinued for preservative treatment of timber, used in US residential markets. CCA continues to be the preservative recommended for timbers, such as pilings and bracing, which may be exposed to marine borers and at this time it is typically available to contractors for use in marine construction (though there may be some additional state and local restrictions).
CHECKING
A longitudinal separation between wood fibers opening along the grain and across growth rings, caused by drying and wood shrinkage. Common in timbers pressure treated with water-based preservatives, but typically not of structural concern in heavy waterfront construction.
CHOCK
A piece of timber (or plastic lumber) between timber fender piles or rub strips, used to prevent lateral movement of the pile/rub strip during vessel contact.
CLEAT
A low capacity mooring fitting with two diverging horizontal horns around which dock lines are wrapped.
CLIP (WIRE)
A wire clip is the U-bolt type of clamp typically used to form an eye at the end of a wire rope. Usually multiple wire clips are needed at each eye to develop the capacity of the wire rope.
CLIP ANGLE
A short length of steel angle bolted or welded between two perpendicular members to form a connection.
COFFERDAM
A temporary structure, typically formed from sheet pile, steel plate or timber, used during construction to enclose an area of riverbed/seabed for dredging or dewatering. Commonly used during construction of bridge piers, where it is often left in place below low water.
COPPER NAPHTHENATE
A wood preservative available to the public and contractors for the field treatment wood that is cut or drilled after preservative pressure treatment.
CREOSOTE
An oil-based wood preservative, derived from coal tar, once commonly used to pressure treat timber waterfront structures.
CREVICE CORROSION
Corrosion of a metal within a crevice, caused by a difference in environment. Usually occurs on partially embedded metal or at non-sealed steel lap joints.
CRIB
A box-like gravity structure formed from connected horizontal members (timber, precast concrete, or stone blocks), which is filled with stone ballast. Cribs may be used to support bridge and pier decks, or may be used as retaining walls.
DEAD WEIGHT TONNAGE
The carrying capacity of a ship at the design waterline, less the empty ship weight. DWT includes cargo, ship fuel, water, etc.
DEADMAN
A concrete block or sheet pile wall, buried in the ground, which is attached a tie rod or cable for anchoring objects, such as bulkheads.
DECAY
Wood deterioration caused by fungi, usually in areas exposed to oxygen and prolonged high moisture.
DELAMINATION
The splitting apart of a material such as concrete into layers, often caused by corrosion expansion of embedded steel.
DIFFRACTION
Wave energy is transmitted along the wave crest to generate waves in a sheltered area, such as in the shadow of a breakwater.
DISPLACEMENT TONNAGE
The weight of water the ship displaces at the design waterline (total ship weight).
DIURNAL INEQUALITY
The daily difference in tidal height extremes, primarily due to changing declination of the Moon. For example; the difference in height between the morning and evening high tides.
DIURNAL TIDE
A tide with one high and one low water in a day.
DOLPHIN
A stand-alone structure, usually consisting of a cluster of piles, a concrete mass supported by a number of piles, or a sheet pile cell, which is used to guide and/or moor vessels.
DRAFT
Maximum depth of a vessel's hull below the waterline.
DRY DOCK
A facility used to remove a ship from the water, either for repair, construction, inspection, or maintenance.
DRY ROT
A loose term applied to wood decay, which required moisture for fungi growth, but now may be dry.
EBB CURRENT
A tidal current (flowing water) caused by a falling tide.
EXPANSION JOINT
A joint in a structure intended to allow for expansion and contraction movement, usually due to changes in temperature.
FAIRWAY
A navigable channel in a harbor or marina.
FASCIA
The vertical exterior face of a pier, wharf, or similar structure, typically used to mount fender systems.
FEASIBILITY STUDY
A planning study intended to evaluate a site for potential development. This study typically includes a site survey and assessment, permitting evaluation, soil, wind, wave and current study, facility layout alternatives, a market survey and cost/benefit analysis.
FENDER
A device placed between a dock structure and a vessel, used to absorb berthing impact energy and provide a wearing surface for the vessel while moored to the structure.
FETCH LENGTH
The horizontal distance, over which the wind might generate waves, usually evaluated for several representative wind directions and water depths.
FLANGE
The portions of a structural member cross-section furthest from the bending axis, which are typically widened to efficiently, resist bending stresses. The term flange is most commonly to the sides of an H-pile or top and bottom of an I-beam or railroad/crane rail.
FLOOD CURRENT
A tidal current (water flow) caused by a rising tide.
FLOTSAM AND JETSAM
Floating waterborne debris.
FOULING
Growth of attached aquatic/marine life on submerged surfaces of vessels and structures.
FREEBOARD
Height of a vessel’s deck above the waterline. Also the height of a structure's deck above a design water level.
GABION
A wire mesh box or mat filled with small local stone. Used to build gravity retaining walls and construct revetments (armor slopes).
GALVANIC CORROSION
A form of corrosion occurring between dissimilar connected metals in contact within an electrolyte, such as seawater.
GANGWAY
A sloping ramp to provide access from a dock structure to a vessel or floating dock from the shore.
GROIN
A shore protection structure built to trap littoral sediment drift (usually perpendicular to shoreline).
GROSS TONNAGE
The volume of all accessible (useable) spaces, in on a ship, converted to an equivalent “weight” using one ton per 100 cubic feet of storage volume. Usually for taxation purposes.
GROUT
A Portland cement mortar, having a consistency of a liquid or paste, typically used for securing anchor bolts in concrete or shimming under structural supports.
HIGHER HIGH WATER (HHW)
The higher of two high tides in any given tidal day.
HYDROGRAPHY
The study of the characteristics of seas, lakes, and rivers, including the water properties and configuration of underwater terrain or sediments.
INSHORE
Term used to distinguish an object from another by its relative closer proximity to the shoreline.
INTERTIDAL ZONE
The zone between high and low water along the shoreline or on a structure.
JETTY
A longitudinal structure (such as a stone berm or sheet pile wall) at or near the entrance to a harbor or river mouth, used to stabilize the entrance channel location and control sedimentation.
KNOT
A unit of speed defined as a nautical mile per hour.
LATITUDE
The location of a place on Earth measured north or south from the equator. One degree of latitude is equal to 60 nautical miles.
LIGHT WEIGHT TONNAGE
The weight or displacement of a ship, excluding the weight of ship fuel, water, stores, people or cargo. Often used as the basis for ship weight in dry docking.
LIMNORIA
Generally categorized as marine borers, Limnoria are small crustaceans (1/8 inch) similar to shrimp, which attack the outer surface of submerged timber. Timber piles attacked by Limnoria are typically deteriorated to roughly an hourglass shape near low water level or just above the mudline. A related species is Sphaeroma.
LITTORAL DRIFT
Sediment moving in the littoral zone, under the influence of waves and currents.
LITTORAL TRANSPORT
The net movement of littoral drift, generally along the beach.
LITTORAL ZONE
A shoreline zone typically between mean high water and -6' MLW.
LONGITUDE (MERIDIAN)
The location of a place on Earth, measured in degrees east or west of Greenwich, England.
LOWER LOW WATER (LLW)
The lower of two low waters (for diurnal tides) in any given tidal day.
LUNAR DAY
The rotation time of the Moon over the meridian of a given place on Earth. The mean lunar day is 24.84 hours long.
MARINE BORER
A general term for marine organisms that bore into timber or concrete.
MEAN HIGH WATER (MHW)
The mean of all high water levels (two per day for diurnal tides), observed over a 19 year tidal epoch (Metonic cycle).
MEAN HIGHER HIGH WATER (MHHW)
The mean of the highest daily high water levels (one per day), observed over a 19 year tidal epoch (Metonic cycle).
MEAN LOW WATER (MLW)
The mean of all low water levels (two per day for diurnal tides), observed over a 19 year tidal epoch (Metonic cycle).
MEAN LOWER LOW WATER (MLLW)
The mean of lowest low water levels (one per day), over a 19 year tidal epoch (Metonic cycle).
MEAN SEA LEVEL (MSL)
The average height of the sea surface for all stages of the tide, measured hourly, over a 19 year tidal epoch (Metonic cycle).
METONIC CYCLE (tidal epoch)
A time period of 235 lunar months, or 19 years 11 days, after which period the relative distances between the earth, sun and moon (which influence the tides) begin to repeat.
MID TIDE LEVEL (MTL)
The elevation midway between mean high water and mean low water. Also called half-tide level, it may not be the same as mean sea level.
MILL SCALE
A black surface oxide layer formed on iron and steel when heated for rolling or forging. Mill scale offers some protection against corrosion, however it may somewhat inhibit the bond of concrete to embedded steel.
MOORING DOLPHIN
A structure on land or over the water that is used to secure a vessel’s mooring lines. Often these dolphins are set back from the breasting line for optimal line angles, and they do not have typically have fender systems.
MUDLINE
A general term often used to designate the seabed, riverbed, lake bed or harbor bottom. The interface between a water body and the seabed/riverbed bottom sediments. May, or may not, imply that the bottom is actually mud.
NAUTICAL MILE
A length unit equal to 6076 feet or 1852 meters (a statute mile is 5280 feet). One degree of latitude is equal to 60 nautical miles.
NEAP TIDE
A tide of decreased range, occurring at quadrature of the moon with the sun. Typically 10% to 30% less than the mean tide range.
NET TONNAGE
A volume measure of the ship space available for revenue earning cargo or passengers.
OCCULTING
A light which is visible for longer periods than it is invisible. (opposite to flashing)
OFFSHORE
A term used to designate the relative location of something in the sea, away from land.
OGEE WASHER
A large cast iron washer used in heavy timber construction to distribute loads and prevent timber crushing at bolt ends.
OVERBURDEN
Soil that is above another strata of soil/rock or an object.
PCB
Polychlorinated Biphenyols, a toxic chemical often found in sediments near industrial discharges. Measured as several different alochors and destroyed by incineration.
PERIGEAN TIDE
Tides of increased range due to the Moon being at its closest point to the Earth.
PERIGEE
The point in the orbital path of a heavenly body where it comes closest to Earth.
PHOLADS
A wood or concrete boring mollusk, resembling a clam, up to a inch in diameter and 2.5 inches in length. U.S. activity is confined to the Gulf of Mexico region. Species Martesia and Xylophaga.
PIER
A deck supported on piles, extending into the water, more or less perpendicular from the shoreline.
PILE CAP
A beam used to connect the top of a line of piles together and support a structure above.
PILE HEAD
The top of a pile.
PILE
A pole, typically of timber, reinforced plastic, steel or concrete, driven or otherwise set into the soil or rock to resist applied vertical and/or horizontal loads.
PIPE PILE
A hollow cylindrical pile with a circular cross-section. Pipe piles are favored for waterfront construction due to their efficient column capacity properties (same radius of gyration in any direction) and smooth, low surface area relative to H-piles, used for superior corrosion resistance.
PIT
A localized area of advanced metal surface loss, often due to paint coating damage, localized loss of marine growth/corrosion scale, metallurgical impurities or a localized corrosion cell on the surface of the metal.
PLUNGING
Crest curls over an air pocket - "tube". Occurs on steep beaches.
POSTING
A method for repairing the deteriorated top of a pile. The damaged top section is cut away and replaced with a post of timber, steel or concrete between the remaining pile and pile cap.
QUAY (pronounced KEY)
A solid man-made vessel landing, generally parallel to the navigable waterway. Large gravity retaining walls along the shoreline that are used for vessel mooring are often referred to as quay walls.
RANGER
A timber deck edge stringer, usually of larger size than the typical interior stringers.
REBAR
Slang for "Reinforcing Bar," for reinforce concrete.
REFLECTED WAVE
The part of an incident wave that is returned seaward after hitting a barrier (particularly a vertical barrier).
REFRACTION
The bending of waves caused by changes in water depth or currents.
REVETMENT
A shoreline slope armored against wave action or currents, by a facing of stone, concrete, etc.
RIPARIAN RIGHTS
The rights of a person owning land containing or bordering a body of water.
RIPRAP
Slope erosion protection formed from stone or concrete rubble, typically dumped and graded over the surface of a prepared shoreline slope.
RUBBING FORCE
The vertical and longitudinal forces applied to a fender system by a moving vessel. These forces are a function of the contact normal force and the fender/ship coefficients of friction (static/dynamic, wet/dry).
SACRIFICIAL ANODE
An anode that provides its own electrical current for cathodic protection of a steel structure by consuming or "sacrificing" itself. These anodes may be formed from various metals and alloys, but often mostly zinc or aluminum.
SALINITY
The total salt content of water, usually expressed in parts per thousand (o/oo). Salinity can be measured indirectly by water conductivity or optical refraction properties.
SCAB
A small piece of timber fastened on the side of a pile as a connection to the pile cap or pile repair post.
SCALE (corrosion)
The iron-oxide by-product from the corrosion of steel, which is deposited on the surface of the steel member above or below water level.
SCOUR
Removal of sediment by waves and/or currents, found especially at the bottom of piles and bridge piers.
SEAWALL
A structure along the shoreline designed to prevent land erosion or damage from to wave action.
SEICHE
A harmonic water level oscillation, which may occur in a largely enclosed waterbody, induced by tides, wind, or seismic forces. The tides are a form of seiche in ocean basins.
SEMIDIURNAL TIDE
A tide with two high and two low waters in a tidal day, with little diurnal inequality.
SHAKE
A longitudinal separation between wood fibers opening along the grain and between growth rings, usually occurring during tree growth.
SHEET PILE
Interlocking structural piles driven into the ground to form a wall, cell or cofferdam. Sheet piles can be timber, reinforced concrete, vinyl, fiber reinforced plastic or steel (hot or cold rolled), with a wide array of interlock or tongue/groove configurations.
SHINGLE
Smooth, well-rounded stone pebbles or cobbles of roughly the same size. The voids between shingle stones are not filled with finer material.
SHOAL (noun)
An elevated portion of seabed comprised of any material, except rock or coral, which endangers vessel navigation.
SHOAL (verb)
(1) To become shallow gradually. (2) To cause to become shallow. (3) To proceed from greater to lesser water depth.
SHOTCRETE
Shotcrete (or gunite) is pneumatically applied stiff concrete/mortar that is blown onto a surface (including vertical and overhead surfaces) without the need for formwork.
SIDESCAN SONAR
An instrument that uses acoustical energy, often around 7.5 kHz, to create a "view" of the seabed surface characteristics, particularly “shadows” from elevated objects, such as shipwrecks.
SIGNIFICANT WAVE
A statistical term defined as the average height or wave period of the one-third largest waves in a given sea (Hs). It is often the approximate height of waves visually estimated by an observer.
SINKHOLE
A hole or void that forms inshore of a soil retaining wall or bulkhead due to the loss of backfill through holes or gaps.
SLACK WATER
The state of a tidal current when its speed is near zero, as when reversing direction.
SPALLING
The chipping or delamination of a surface, usually used to describe loss of concrete due to corrosion of embedded steel.
SPILLING
Bubbles and turbulent water spill down the face of the wave - slow breaking. Occurs on very flat beaches.
SPIT
A point of low land or narrow shoal extending into a body of water from shore.
SPLASH ZONE
The portion of a marine structure subject to intermittent wetting and high chloride exposure (seawater) due to wave action and spray. Typically a zone of high steel corrosion levels.
SPRING TIDE
Tides of increased range (lows and highs) occurring at or near a new or full moon (SYZYGY).
STAINLESS STEEL
Alloy of steel, chromium and nickel offering high resistance to corrosion when exposed to air or oxygenated water (susceptible to crevice corrosion). Grade 316 stainless steel is usually best suited to marine use.
STRINGER
Structural beams spanning between pile caps used to support a pier or wharf deck.
SUBBOTTOM PROFILING SONAR
An instrument that uses acoustical energy at 3.5 kHz or lower, to create a vertical profile section into the seabed sediments.
SURGING
Wave peaks but does not break. Wave slides up the beach with little or no bubbles. Occurs on ledges.
SWELL
Decaying waves that have traveled out of the area where generated. Characteristics are long, regular wave period and flat-sloped wave crest.
SYZYGY
Two points in the Moon's orbit when the Moon is in conjunction or opposition to the Sun relative to the Earth (time of new or full Moon).
TEREDO
A molluscan marine borer, which bores into, submerged timber. Typically found only in water with salinities above about 5 o/oo, this "shipworm" typically leaves a tube of calcium deposits in the timber, which may up to 4 feet long and an inch in diameter.
TIDAL DAY (LUNAR DAY)
The time of rotation of the Earth with respect to the Moon, approximately 24.84 hours (24 hr and 50 min). Thus, high and low tides generally occur 50 minutes later each day.
TIDAL PRISM
The volume of water within an area of study, located between low tide and high tide. This is generally the tidal exchange in a harbor or bay, excluding any net river inflow.
TIE ROD
A steel rod used to restrain a bulkhead or retaining wall by extending inshore to an anchor or buried deadman.
TOMBOLO
A sand or gravel spit connecting an offshore breakwater, shoal or rock with the shore. Usually intertidal.
TRAINING WALLS
Walls constructed to direct the flow of currents and control scoured channel location in a harbor or river.
TREMIE METHOD
A technique for placing concrete underwater through a pipe or hose, where the lower end of the pipe or hose is kept embedded in the mound of fresh concrete to minimize the amount of concrete exposed to the water and potential cement washout.
TRESTLE
A pier-like structure used to provide access between shore and an offshore structure.
TSUNAMI
A long-period wave caused by an underwater disturbance such as a volcanic eruption or earthquake.
TYPHOON
A term for hurricanes in the Pacific or Indian Oceans.
ULTRASONIC THICKNESS MEASUREMENT
Use of ultrasonic sound waves to measure the thickness of a material from one side, calibrated for the ultrasonic speed of the material being measured.
VARIATION
The angle between true north and magnetic north, caused by movement of earth's magnetic poles. Varies by location and is continually changing.
WALE
A horizontal structural beam used to connect or brace multiple piles, or distribute tie rod loads along sheet pile bulkheads.
WARP
To move a vessel by the use of ropes (warps).
WATER DEPENDENT USE
Uses that can only be carried out at the waters edge, such as landing cargo, vessel docking, fishing, swimming, marinas.
WATER ENHANCED USE
Land uses that benefit from viewing or being close to the water, such as restaurants, hotels, housing.
WAVE FORECASTING
The prediction of wave characteristics for a given site, usually based on previously observed or predicted winds.
WAVE HEIGHT
Vertical trough to crest height. A wave breaks when the water depth equals 1.28 His, with a breaking wave height of 0.78 times the water depth.
WAVE HINDCASTING
The use of historical wind data to calculate the characteristics of waves that probably occurred in the past.
WAVE LENGTH
The horizontal distance between similar points on successive waves, measured perpendicular to the crest.
WAVE PERIOD
The time for a wave crest to travel a distance equal to one wavelength, or time required for two successive wave crests to pass a fixed point.
WAVE SCREEN
A type of vertical faced breakwater, usually built with vertical timbers having a close spacing.
WAVE COLLAPSING
Breaking occurs on the lower half of the wave with minimal air pocket.
WEB
Generally the portion(s) of a structural member cross-section parallel to the applied load. The term is most commonly applied to that portion of steel between the flanges of an H-pile or beam.
WEIR
(1) An outflow structure used to control the drainage of water from a pond or dredge material containment area, usually adjustable to vary the water level. (2) A large fixed net trap built along the shore to trap fish.
WHARF
A waterfront structure built more or less parallel with the shoreline, typically used for vessel docking.
WIND SETUP
The vertical rise in still-water level on the leeward side of a body of water, caused by surface wind stresses. A portion of storm surges are often caused by wind setup with onshore winds.
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