Marport trawl monitoring system installation and service in Busan

NAVION is a worldwide Marport dealer, and trawl monitoring is the work our engineers do most often in Busan. Most jobs run inside a port call: the vessel comes alongside at Gamcheon fishing port or a Yeongdo repair yard, the crew hands over a list of sensors that stopped reporting on the last trip, and the system has to be working again before she sails. We plan Marport installation and repair around that window, not around a workshop schedule.

A full installation starts at the hull. The transducer or hydrophone has to sit where it can hear the gear astern without being blinded by propeller wash, bubble sweep-down or hull-borne machinery noise, so the position is decided against the vessel's fairing, keel line and existing wet ends. We run and label the cable clear of power runs and frequency converters, terminate it at the receiver, and mount the Scala2 PC and display where the skipper can reach them. Retrofits onto an existing wet end are common; before reusing old cable we measure insulation resistance and check the connector for water ingress.

On the sensor side we commission catch sensors, trawl eye and trawl explorer units, door sensors reporting pitch, roll, depth and temperature, spread and symmetry pairs, and headline height sensors. Each unit is configured in Mosa2 for channel, telemetry rate, transmit power and depth or temperature offset, and the channel plan is written down so no two sensors share a slot and the uplink stays clear of the vessel's echosounders and sonar. In Scala2 we build the pages the skipper watches at the haul: door spread and symmetry, headline height and clearance, catch fill, with alarm thresholds set to values the crew chooses.

Most call-outs are not dead sensors. Readings that fade below a certain depth, spread figures that jump, or a catch sensor that only reports when the winches stop are usually acoustic or electrical faults: a corroded pin at the wet end, water in the cable, a hydrophone face fouled with paint or growth, or interference from hydraulics, refrigeration compressors, a shaft alternator or an inverter with a poor ground. We hunt it with the receiver's noise display, running machinery item by item, so a reception problem is separated from a sensor problem before anyone buys a replacement.

Battery and charger handling accounts for a large share of avoidable downtime. We check charger docks and contacts, clean and dry sensor contact pins, inspect end caps, O-rings and pressure housings, and renew seals that are flattened or nicked. Trawl sensor calibration is checked the same way each time: depth against the echosounder and the vessel's draught, temperature against a known reference, spread against warp marks and door geometry.

Verification happens on the water, not on the quay. On the outbound run or a short sea trial we watch every sensor come up, confirm range holds at working depth and through the turn, and check that readings stay stable with the winches and deck machinery running. Before we leave you get the channel and serial list, the saved Scala2 workspace, a note of firmware versions, and a written record of what was found and what was replaced.