JD6W/M Electromagnetic Log

Return to list

Product Details

1. Product Overview

1.1 Main uses for construction

The JD6W/M electromagnetic log is a marine navigation device used to continuously measure the speed of a vessel relative to the water during motion and automatically accumulate the distance traveled. It can provide real-time ship and voyage information to various user devices.

1.2 Working Principle

According to Faraday’s law of electromagnetic induction, when a conductor moves in a magnetic field, an induced electromotive force is generated. Since seawater is a continuous conductor, the electromagnetic sensor functions essentially as an electromagnet that generates a constant magnetic field. The sensor is submerged from the bottom of the ship into the seawater. As the ship moves relative to the water, an induced electromotive force is generated. This induced EMF is then fed from the sensor’s electrodes into a signal-processing circuit, where it is processed and analyzed to obtain velocity information.

Figure 1: Block Diagram of the System Configuration

The basic system configuration consists of: one main display, one signal processing enclosure, one speed indicator, and one electromagnetic sensor. If a planar sensor is selected, one water gate unit will be provided; if a rod-type sensor is selected, one pneumatic lifting device will be provided.

2. Main performance indicators

Power supply
Requirements	AC 220V ±10% 50Hz ±5%, 150W
Performance
Speed measurement range	-10- +35 kN
Accuracy	t0.2kn (for the water layer)
Navigation calculation accuracy	10.1%
Single-flight range	0–9999.99 nm;
Cumulative flight range	0-99999.990 m;
Interface
Serial interface	6-channel AS485 interface for external speed output

Serial number	Instrument Name	Model	Note
1	Signal processing enclosure	JD6W/M- 1
2	Main display	JD6W/M-2
3	Speed Indicator	JD6W/M-3	Can be additionally equipped
4	Planar sensor	JD6W/M-4
5	Water Gate Pavilion	JD6W/M-5	Compatible with planar sensors
6	Rod-type sensor	JD6WM-6
7	Pneumatic lifting and lowering assembly	JD6W/M-7	Compatible with liver-type sensors

Installation requirements for the pitot tube electromagnetic sensor:

a. To ensure the instrument functions properly, when using a flat-sensing sensor, a flow guide should be installed around the portion of the sensor that extends outside the vessel to smooth the water flow.

b. The sensor cable should be installed in a location at the bottom of the vessel where it is less affected by water flow, and it must ensure that the cable does not become exposed above the water surface even when the vessel has its minimum draft and maximum roll.

c. The sensor installation should have a deviation of no more than ±1° from the ship’s keel line;

The sensor attachment should not be exposed to strong magnetic fields, and within a 5-meter radius ahead of it, there should be no protrusions that could disturb the water flow, as well as no prominent water inlets or drainage holes.

6. Basic Supporting Plan

Depending on the type of sensor used, the Feng device comes in two basic configurations: a flat-sensor configuration and a measuring-rod configuration.

6.1 Planar Sensor Supporting Solution

Serial number	Instrument Name	Model	Unit	Quantity	Note
1	Signal processing enclosure	JD6W/M-1	Taiwan	1
2	Main display	JD6W/M-2	Taiwan	1
3	Speed Indicator	JD6W/M-3	Taiwan	1	Can be upgraded to 2.
4	Planar sensor	JD6W/M-4	Taiwan	1
5	Water gate valve	JD6W/M-5	Taiwan	1

6.2 Measuring Rod Matching Solution

Serial number	Instrument Name	Model	Unit	Quantity	Note
1	Signal processing enclosure	JD6W/M-1	Taiwan	1
2	Main display	JD6W/M-2	Taiwan	1
3	Speed Indicator	JD6W/M-3	Taiwan	1	Can be upgraded to 2.
4	Rod-type sensor	JD6W/M-6	Taiwan	1
5	Pneumatic lifting component	JD6W/M-7	Taiwan	1