The YDK Technologies EML 900 (formerly Yokogawa Denshi Kiki EML500/EML550 series) is an IMO type-approved electromagnetic speed log designed for commercial ocean-going vessels. It utilizes Faraday’s law of induction to deliver precise Speed Through Water (STW) measurements without moving mechanical components.

Model Variants

• EML 900-S (Single-Axis): Measures longitudinal speed through water (ahead and astern).

• EML 900-D (Dual-Axis): Measures both longitudinal (ahead/astern) and transversal (port/starboard) speed through water for maneuvering and docking support.

Operating Principle

An electromagnetic field is generated in the water surrounding the hull sensor via an AC coil. As conductive sea water flows past this magnetic field, an electromotive force (EMF) is induced across the sensor electrodes. The signal processing unit converts this voltage potential—which is directly proportional to water flow speed—into digital STW data output to bridge navigation systems.

Key Features & Advantages

• High-Contrast LCD Master Indicator: Features a clear 4.3-inch color TFT display (MLH-533) with custom night-dimming modes and intuitive function keys.

• Multi-Point Speed Calibration: Supports speed linearizer adjustments across multiple speed steps to offset hydrodynamic boundary layer disturbances.

• Low Profile Transducer: Available in standard sea-valve (gate valve) or bottom-tank configurations, enabling underwater transducer replacement without dry-docking.

• Wide Compatibility: Serves as a direct drop-in replacement for older Yokogawa/YDK EML 500, EML 550, and EML 700 series log installations.