An ordinary scale measures force, not mass: as soon as the deck heaves, the reading fluctuates with it. A marine scale measures the motion of the ship and calculates it out of the weight, so you read a stable, correct value even at sea. WPL Industries builds them in Geldermalsen, the Netherlands, from 316 stainless steel: the M2 for fishing and offshore, from 6 to 400 kg, and the M3 for research and sampling, from 300 g. A number of versions can be supplied verified.
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11 variants
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11 variants
Why an ordinary scale does not work at sea
A load cell measures the force that a load exerts on the platform. On shore that force is constant; on board it rises and falls with the acceleration of the deck. In a swell, an ordinary scale therefore shows too much one moment and too little the next, and never settles. Filtering alone does not help: a weighing then takes too long and the average is still wrong on a tilted deck.
A motion-compensated scale measures the motion itself as well as the load and uses it to correct the reading, inside the scale and without you having to do anything. The result is a stable reading, a short stabilisation time and a correct weight, even in rough weather. How motion compensation works exactly, and what to look for when choosing and mounting a scale, is explained in the knowledge article marine scales: reliable weighing on a moving ship.
M2: for fishing, on-board processing and offshore
The M2 is the bench scale for heavy-duty work: sorting, packing and labelling the catch on board, and weighing on drilling platforms and work vessels. It is made entirely of AISI 316 stainless steel, water-resistant and finished with smooth, rounded edges, so it can be hosed down quickly after the shift.
We supply the M2 in four platform sizes, from 250 × 300 to 450 × 600 mm, with a capacity of 6, 15, 30, 60, 200 or 400 kg. Each capacity weighs in two steps: 6 kg in 1 and 2 g, 60 kg in 10 and 20 g, 400 kg in 100 and 200 g. The wall bracket for the indicator is included; a column is optional.
M3: scientific weighing on research vessels
The M3 is made for anyone who needs to weigh small quantities accurately at sea: biological sampling on fisheries research vessels, individual specimens, gonads, stomach contents and subsamples. It is made of 316L stainless steel and reads from 0.1 g on the 300 g model - a resolution at which other marine scales fall back on coarser steps.
The M3 is available with a 120 × 120 or 275 × 275 mm platform and a capacity from 300 g to 15 kg. An optional draught cover is available for the small platform size: on an open deck or near ventilation, air movement alone is enough to unsettle a reading in tenths of a gram. With the carrying case and the 12 V battery, you can take the scale from station to station.
Connecting, logging and labelling
The R10 indicator of the M2 has USB, RS-232 and Ethernet, and can be extended with Bluetooth and a WiFi module with data logger. This lets you connect a label printer to label boxes and products directly while weighing, or send the weights to catch management software, a network or Excel.
With the Weightcontrol software, which runs in the scale itself, every weighing is recorded automatically. You open the data in a browser on a laptop or tablet, without any extra program, and export it as PDF or CSV, or retrieve it via the API. For labelling there is a label printer in a stainless steel housing.
Verified for trade use, or with a calibration certificate
If the weight determines a price or an invoice - catch sold by weight, processed product that goes ashore by the kilo - a verified scale is mandatory. A number of M2 and M3 versions can be supplied verified from the factory, with the green M mark and a seal; the initial verification is carried out by the manufacturer. State in your enquiry that you weigh for trade use, with the platform and capacity you have in mind.
For research and quality control, a calibration report is usually sufficient. It records the repeatability, eccentricity, indication errors and measurement uncertainty, in accordance with the European guideline EURAMET cg-18. Read more about calibration on our page about verification and calibration.
Choosing the right version
Choose the platform first, then the capacity. The platform must fully support the base of your largest tub, box or sample holder, without anything else touching it. Then choose the capacity that covers your heaviest load with some margin, not the largest one available: the lower the capacity, the finer the readability.
If in doubt, or if you need a non-standard size, call or email us. We are happy to advise on the location on board, the mounting and the connection to your systems, and we agree any non-standard version with the manufacturer.
Frequently asked questions
What is motion compensation on a scale?
In addition to the load, the scale measures the motion of the ship and removes it from the reading. This lets you read the actual weight while the deck heaves, pitches or rolls, with a stable reading and a short stabilisation time.
What is the difference between the M2 and the M3?
The M2 is the bench scale for fishing, on-board processing and offshore, with a capacity of 6 to 400 kg. The M3 is the scientific precision scale for research vessels and sampling, with a capacity of 300 g to 15 kg and a readability from 0.1 g.
Can a marine scale be supplied verified?
Yes. Several versions of the M2 and M3 can be supplied verified for trade use, with the green M mark and a seal. This is necessary as soon as the weight determines a price or an invoice. For research, a calibration report is usually sufficient.
Can I label fish boxes straight from the scale?
Yes. The M2 drives a label printer via USB, RS-232 or Ethernet, so every box gets a label as it is weighed. A label printer in a stainless steel housing is available.
What is the wind cover on the M3 for?
Air movement exerts a small force on the pan and the sample. At a readability of tenths of a gram, that makes the reading unsteady on an open deck or near ventilation. The wind cover shields the weighing area from draughts.
Who makes these scales?
WPL Industries from Geldermalsen, a Dutch manufacturer of industrial and marine weighing equipment. WPL develops and builds the marine scales itself and supplies them worldwide. Weighing Experts supplies them in the Netherlands and Belgium, with advice, installation and calibration.