Electromagnetic logs indicate water speed. Sensors in the ship hull use Fleming's rule.
There are two types of sensors (fore-and-aft) and dual-axis sensors (fore-and-aft and starboard-and-port). In addition, various types of sea valves are available for installing sensors on the bottom of the hull. The sensor head extruded from the bottom is either 7mm or 50mm long type.

EML500 : This type is suitable for general merchant vessels, and accepts both flush-mountable and dual-axis sensors.
EML50 : This type is compact and can be mounted in many different ways.

The electromagnetic log system is configured as shown below and is suitable for a wide variety of vessels.

System Name			Hull Type	Sensing Axes	Sensor Size	Remarks
EML500	-	HS1	Single bottom	1	35 mm dia.
	-	HD1	Double bottom	1	35 mm dia.
	-	HV1	Single bottom	1	70 mm dia.
	-	FA1	Single bottom	1	48 mm dia.
	-	HV2	Single bottom	2	70 mm dia.
	-	FA2	Single bottom	2	48 mm dia.

LT501 Master Unit
This unit consists of a terminal block and a signal processor.
Microprocessor and LSI based circuitry and the absence of moving parts ensure high reliability.

LR523 Master Indicator
This unit works as the control and display unit of the system.
The electromagnetic sensor can be backed up if the ground speed is supplied from a GPS receiver.

LR524/525 Analog Speed Indicators
These units are analog indicators for reading the vessel water speed. The LR524 is for a single-axis sensor, while the LR525 is for a dual-axis sensor.
There are six choices for the indicator speed range.

Various Sensors (LS501/531/541/542/571/572)
These sensors are used in the EML500 series.
The sensors have built-in preamplifier for stable and long-distance transmission of the current signal.

Flush-mounted Sensors
The 48mm or 70mm diameter sensor is flush-mountable and therefore suitable for highspeed vessels.
(The figure shows the sensor mounted on the bottom of a vessel.)

Electromagnetic Log System