Marine Weighing Glossary

Accuracy class

A classification of weighing instruments by metrological performance. Non-automatic instruments under OIML R 76 and the EU NAWI Directive fall into classes I (special), II (high), III (medium) and IIII (ordinary). Read more

AISI 304

A common austenitic stainless steel with roughly 18 % chromium, 8 % nickel and no molybdenum. It resists general corrosion well but is more prone to pitting in chloride-rich seawater than 316 grades. Read more

AISI 316L

The low-carbon version of 316 stainless steel, with at most 0.03 % carbon. Lower carbon limits carbide formation during welding, so corrosion resistance is preserved in and around welds. Read more

AISI 316

An austenitic stainless steel with about 2 % molybdenum added to chromium and nickel. Molybdenum improves resistance to pitting and crevice corrosion by chlorides, which is why 316 is widely used in marine equipment. Read more

API

Application Programming Interface: a defined set of requests and responses through which software reads data from, or sends commands to, another system, such as requesting the current weight or taring a scale. Read more

Apparent weight

The force a load exerts on a scale that is itself accelerating. When a vessel accelerates upwards the load presses harder and the reading rises; a vertical acceleration of 1 m/s² changes an uncompensated reading by about 10 %. Read more

Automatic catchweigher

An automatic weighing instrument that weighs discrete loads, such as packs or pieces of fish, without operator intervention. Graders, checkweighers and weight labellers are types covered by OIML R 51 and the MID. Read more

Batching

Combining individual pieces into packs or boxes that reach a target weight. Batching software chooses pieces so each batch meets its nominal weight with as little overweight as possible. Read more

BLE

Bluetooth Low Energy, a short-range wireless standard designed for low power use. It suits linking a scale to a tablet or phone, but range should be tested inside steel ship compartments. Read more

Block freezing

Freezing fish or fillets into rectangular blocks between the refrigerated plates of a plate freezer. Block weights are checked because blocks are sold and further processed by weight. Read more

Calibration

Establishing, under specified conditions, the relationship between a scale's indications and calibrated reference weights, including the measurement uncertainty. Calibration differs from adjustment and from legal verification. Read more

Capacity

The maximum load (Max) a weighing instrument is designed to weigh. A capacity comfortably above, but not far above, the heaviest load normally gives the most useful resolution. Read more

Catch certificate

A document required under the EU IUU Regulation (EC) No 1005/2008 for imports of fishery products, validated by the flag state, confirming that the catch complied with applicable laws and conservation measures. Read more

CE marking

A marking by which a manufacturer declares that a product conforms with applicable EU harmonisation legislation. On regulated weighing instruments it is accompanied by the supplementary metrology marking. Read more

Checkweigher

An automatic weighing instrument that weighs packs, usually while they move on a conveyor, and classifies or rejects them according to whether they fall within set weight limits. Read more

Condition factor

An index that compares a fish's weight with the weight expected for its length. Fulton's condition factor relates weight in grams to the cube of length in centimetres, and values around 1 are typical for many species. Read more

Creep

A slow change in a load cell's output while a constant load remains in place. Creep matters when loads stay on a scale for long periods, such as bins or tanks. Read more

Crevice corrosion

Localised corrosion in narrow gaps, such as under gaskets, bolt heads or deposits, where trapped liquid loses oxygen and becomes more aggressive. Hygienic designs avoid such crevices. Read more

CSV

Comma-separated values: a plain-text table format in which each line is a record and fields are separated by commas or semicolons. CSV files open directly in spreadsheets and import into most databases. Read more

DATRAS

The ICES database of trawl survey data, holding haul, length and biological sampling records from many countries in a common exchange format, with weights stored in grams. Read more

Eccentric load

A load placed away from the centre of the platform. A well-built scale shows the same weight wherever the load sits; the eccentricity test checks this with test weights at several positions. Read more

EHEDG

European Hygienic Engineering & Design Group, a consortium of equipment manufacturers, food companies and research institutes that publishes guidelines and certification for hygienic design of food processing equipment. Read more

ERS

Electronic Recording and Reporting System: the system through which EU fishing vessels record logbook, transhipment and landing data and transmit them electronically to the flag state's authorities. Read more

Ethernet

The standard wired technology for local area networks. A scale with Ethernet can send data to computers, databases and printers anywhere on the vessel network. Read more

EURAMET cg-18

EURAMET Calibration Guide No. 18, the European guideline for calibrating non-automatic weighing instruments through repeatability, error of indication and eccentricity tests, with measurement uncertainty and certificate content. A cg-18 calibration reports errors and their uncertainty; it is not a legal verification. Read more

FAO major fishing area

One of the statistical regions defined by FAO for reporting catches, such as area 27 for the Northeast Atlantic. Areas and their subdivisions identify where fish were caught in documents and on labels. Read more

Fillet yield

Fillet weight as a percentage of the weight of the raw material it came from, such as round or gutted fish. Weighing both input and output of filleting is the basis of yield control. Read more

Giveaway

Product packed above the nominal or declared weight. Giveaway costs money on every pack, so processors use accurate weighing and batching to reduce it without creating underweight packs. Read more

Glazing

Coating frozen fish with a thin layer of ice by spraying, brushing or dipping in chilled water, to limit dehydration and oxidation. For food sold in the EU, declared net weight excludes the glaze. Read more

Gonadosomatic index

Gonad weight as a percentage of total or gutted body weight. It rises as fish approach spawning and is used alongside visual staging to classify maturity. Read more

Grader

A machine that weighs individual pieces and sorts them into weight classes, typically by directing each piece to an outlet. Weight graders count as automatic catchweighers when used for regulated purposes. Read more

Gravity zone

An area within which gravitational acceleration is treated as constant when adjusting weighing instruments. Gravity differs by about 0.5 % between equator and poles, so a scale adjusted in one zone can read differently elsewhere. Read more

GS1

A global not-for-profit standards organisation that manages barcodes and identification keys, such as GTINs and GS1-128 logistics labels, widely used to identify products, lots and pallets in seafood supply chains. Read more

Gutting

Removing the internal organs of fish, usually soon after capture to preserve quality. Gutted weight is lower than live weight, so conversion factors are applied when reporting catches. Read more

Heave compensation

Another name for motion compensation, used mainly on ships and boats: the marine scale corrects its reading for the vertical movement of the vessel, so the displayed weight stays stable at sea. Read more

Heave

The vertical up-and-down movement of a vessel caused by waves. Heave produces vertical accelerations that change the force a load exerts on a scale, so it has the largest direct effect on weighing at sea. Read more

Hopper

A container mounted on a scale to collect loose product, such as small fish or fillets, for batch weighing before it is emptied into a box or onto a conveyor. Read more

Hysteresis

The difference between readings for the same load reached by increasing and by decreasing the load. Low hysteresis means the result does not depend on the loading history. Read more

ICES

The International Council for the Exploration of the Sea, an intergovernmental marine science organisation that coordinates research surveys, publishes survey manuals and provides scientific advice on North Atlantic stocks and ecosystems. Read more

IP66

Ingress protection rating meaning dust-tight and protected against powerful water jets from any direction, as defined in IEC 60529. Read more

IP67

Ingress protection rating meaning dust-tight and protected against the effects of temporary immersion in water, tested at up to 1 m depth for 30 minutes under IEC 60529. Read more

IP68

Ingress protection rating meaning dust-tight and protected against continuous immersion, under conditions agreed between manufacturer and user that are more severe than those for IP67. Read more

IP69K

A protection rating defined in ISO 20653 for resistance to close-range, high-pressure, high-temperature water jets, as used in intensive washdown cleaning in food processing. Read more

JSON

JavaScript Object Notation, a lightweight text format for structured data built from key–value pairs. Web APIs widely use it, including for exchanging weight records between scales and software. Read more

Label

In seafood handling, a printed tag on a box or product showing information such as species, weight, catch area, date and lot code, used for sales and traceability. Read more

Landing obligation

The EU rule in Article 15 of the Common Fisheries Policy regulation requiring catches of species subject to catch limits to be kept on board, recorded, landed and counted against quota, with defined exemptions. Read more

Legal for trade

Describes a weighing instrument that meets legal metrology requirements and may be used where weight determines a price, fee or legal obligation, such as selling fish by weight. Read more

Length–weight relationship

The curve linking a fish's weight to its length, fitted to fish that were individually measured and weighed. Weight rises roughly with the cube of length, so a fish 10% longer is about a third heavier. Read more

LEO

Low Earth orbit, typically below about 2,000 km altitude. Satellite constellations in LEO offer lower-latency data links than geostationary systems and are increasingly used for vessel connectivity. Read more

Linearity

How closely a scale's readings follow a straight line from zero to capacity. Non-linearity shows as errors that vary with load, even when zero and span are correctly adjusted. Read more

Live weight

The weight of fish as caught, before processing. When fish are gutted or filleted on board, logbook quantities are converted to live-weight equivalent using conversion factors. Read more

Load cell

A transducer that converts force into an electrical signal. Most electronic scales use strain-gauge load cells, whose metal element deforms very slightly under load. Read more

Logbook

The master's record of fishing activities and catches, including estimated quantities per species in live weight. EU catching vessels must keep it electronically. Read more

Lot

In EU fisheries rules, a quantity of fishery or aquaculture products of one species and presentation, from the same geographical area and the same vessel, group of vessels or aquaculture production unit. Read more

M marking

The supplementary metrology marking: a capital M and the last two digits of the year it was affixed, inside a rectangle, placed next to the CE marking on instruments conforming with EU metrology directives. Read more

Margin of tolerance

The permitted difference between a logbook estimate of catch on board and the quantity landed or found at inspection. In the EU it is generally 10 % per species, or 20 % for species up to 100 kg. Read more

Maximum permissible error

The largest error, positive or negative, allowed for an instrument's indication at a given load. For legally controlled scales it is expressed as a number of verification scale intervals, such as one or one and a half intervals. Read more

MID

The EU Measuring Instruments Directive 2014/32/EU. Its annex MI-006 covers automatic weighing instruments, including automatic catchweighers such as graders and checkweighers, when used for regulated purposes. Read more

Minimum conservation reference size

The smallest size at which a species may be retained for direct human consumption under EU rules. Catches below it are recorded as a separate logbook entry. Read more

Motion compensation

The capability that lets a marine scale show correct weights on a moving vessel by compensating for the effects of vessel motion, tilt and gravity. Its performance is judged by testing the scale at realistic accelerations and tilt. Read more

NAWI

Non-automatic weighing instrument: a scale that requires an operator during weighing, for example to place the load or accept the result. In the EU such instruments are regulated by Directive 2014/31/EU for uses like trade. Read more

NMi

Nederlands Meetinstituut, a Dutch organisation that tests and certifies measuring and weighing instruments, including conformity assessment work under the EU metrology directives. Read more

Notified body

An organisation designated by an EU Member State to carry out conformity assessment under a directive, such as type examination of weighing instruments. Its identification number follows the CE and M markings. Read more

OIML R 51

The OIML Recommendation for automatic catchweighing instruments, which weigh discrete loads automatically, such as checkweighers, weight graders and weight labellers. It sets metrological requirements and test methods. Read more

OIML R 76

The OIML Recommendation for non-automatic weighing instruments, which need an operator during weighing. It defines accuracy classes, verification scale intervals, maximum permissible errors and test procedures. Read more

OIML

The International Organization of Legal Metrology, an intergovernmental body that publishes model requirements for measuring instruments, called Recommendations, which many countries use as the technical basis of national law. Read more

Otolith

A calcium carbonate structure in the inner ear of bony fish that grows in layers, allowing age to be estimated. Otoliths are removed during biological sampling and weighed, if required, in laboratories. Read more

Pitch

Rotation of a vessel about its transverse axis, raising the bow while lowering the stern and back. Pitch causes vertical accelerations that grow with distance from the centre of rotation, so scales far forward or aft are disturbed more. Read more

Pitting corrosion

Localised corrosion that creates small, deep cavities in a passive metal surface, usually triggered by chlorides. On stainless steel in seawater, pits can go deep while the surrounding surface looks intact. Read more

PREN

Pitting Resistance Equivalent Number, a corrosion-resistance index calculated from a stainless steel's chromium, molybdenum and nitrogen content. Grade 316 typically scores in the mid-20s and 304 around 18–20, because 316 contains molybdenum. Read more

Raising factor

The multiplier that scales subsample results to a whole catch category, usually category weight divided by subsample weight. An error in either weight changes every raised value. Read more

Readability

The smallest step a scale's display shows, also called the actual scale interval. Readability is not accuracy: a scale can display 0.1 g steps while its real error is larger. Read more

Repeatability

The ability of a scale to give the same result when the same load is weighed several times under the same conditions, usually expressed as a standard deviation or range. Read more

Roll

Rotation of a vessel about its longitudinal axis, from side to side. Roll tilts weighing platforms and, away from the centreline, adds vertical accelerations that disturb scale readings. Read more

RS232

A long-established serial communication standard for point-to-point links. Many scales, printers and survey data systems still use RS232 to send weight data over short cable runs. Read more

RSW

Refrigerated sea water: seawater cooled by mechanical refrigeration to chill catch in tanks, common on pelagic vessels. Chilled sea water (CSW) is the equivalent cooled with ice. Read more

Sea state

The condition of the sea surface, commonly given on the WMO sea state code from 0 (calm, glassy) to 9 (phenomenal) according to wave height. Higher sea states mean larger vessel accelerations during weighing. Read more

Stability

The condition in which a scale's reading has stayed within a set tolerance for a set time. A stability indication tells operators and software when a value can be recorded or printed. Read more

Strain gauge

A thin resistive foil bonded to the elastic element of a load cell. As the element deforms under load, the gauge's resistance changes proportionally, usually measured with a Wheatstone bridge circuit. Read more

Subsample

A representative part of a catch category that is measured or sampled in detail. Its results are scaled up to the whole category using the ratio of category weight to subsample weight. Read more

Surge

Fore-and-aft movement of a vessel along its longitudinal axis. Surge mainly produces horizontal forces, which affect weighing less directly than vertical motion but can shift loads on a platform. Read more

Sway

Sideways movement of a vessel along its transverse axis. Like surge, sway mainly generates horizontal forces rather than changes in the apparent weight of a load. Read more

Tare

The weight of a container, tray or packaging, or the scale function that subtracts it so the display shows only the net weight of the product. Read more

Traceability

The ability to follow a product through catch, processing and distribution by recording lots and their movements. EU rules require lot information to accompany fishery products through the supply chain. Read more

USB

Universal Serial Bus, the common interface for connecting devices to computers. On scales it is used for direct PC connection, data export and connecting printers. Read more

Verification scale interval

The mass step, for example 1 g or 10 g, on which a legally controlled instrument's accuracy class and permissible errors are based. It is fixed by the manufacturer and may equal the readability or be larger. Read more

Verification

In legal metrology, the examination and confirmation by an authorised body that an instrument meets legal requirements, usually followed by marking or sealing. Re-verification intervals are set nationally. Read more

VSAT

Very small aperture terminal: a satellite communication system using a compact dish antenna, traditionally via geostationary satellites, that provides data and internet links for vessels beyond coastal mobile coverage. Read more

Washdown

Cleaning equipment by spraying it with water, often with detergents and disinfectants. Washdown-proof scales need sealed enclosures, smooth surfaces and materials that tolerate daily cleaning in wet, salty conditions. Read more

Well boat

A vessel with wells in which circulating seawater keeps fish alive during transport. Aquaculture uses well boats to move smolts, transfer fish between sites, carry out treatments and deliver fish for harvest. Read more

WELMEC

European cooperation in legal metrology between national authorities. WELMEC guides, for example on non-automatic weighing instruments and gravity zones, help apply the EU weighing directives consistently. Read more

Wi-Fi

Wireless local area networking based on the IEEE 802.11 standards. On board, it lets scales, tablets and computers exchange data without cables within range of an access point. Read more

Wind cover

A shield around a small weighing platform that keeps moving air away from the sample. It matters at readabilities around 0.1 g, where even gentle draughts disturb the reading. Read more

Yaw

Rotation of a vessel about its vertical axis, swinging the bow to port or starboard. Yaw has little direct effect on vertical force but is part of the combined motion a marine scale must tolerate. Read more

Zero tracking

An automatic function that corrects small, slow drifts of the zero point while a scale is empty. It works only within narrow limits, so it does not hide genuine loads placed on the platform. Read more

ZPL

Zebra Programming Language, a widely used command language for label printers. Label layouts with fixed text, variable fields and barcodes can be stored and filled with weights at print time. Read more