FURUNO, DS-85 DOPPLER SPEED LOG

The Furuno DS-85 is a marine Doppler Speed Log (SDME – Speed and Distance Measuring Equipment) used on ships to measure speed through water (STW) and distance traveled. It is IMO-compliant and designed for merchant vessels, fishing vessels, and workboats.

The DS-85 uses the Doppler effect principle:

A 2 MHz ultrasonic transducer sends acoustic beams into the water
The signal reflects off particles in the water (plankton, bubbles, microstructures)
The frequency shift of the returned signal is measured
This shift is converted into:
- Ship speed through water
- Distance traveled

It uses a dual (pair-beam) system, sending signals fore and aft to improve accuracy and reduce errors from vessel pitching and movement

Technical Specification

📡 General system

Type: Doppler Speed Log (SDME – Speed & Distance Measuring Equipment)
Principle: Doppler ultrasonic measurement (speed through water)
Frequency: 2 MHz
Beam system: Dual (pair-beam system)
Compliance: IMO / IACS UR E27 / IEC standards approved

🚢 Performance

Speed range:
-40.00 to +40.00 knots
Speed accuracy:
- ±1% or ±0.1 knot (whichever greater)
Distance accuracy:
- ±1% or ±0.1 nautical mile
Distance log range:
- 0.00 to 999,999.99 NM (through water)
Operating depth requirement:
- Measurement taken > 3 m below keel

🖥️ Display unit

Screen size: 4.3-inch LCD
Resolution: 480 × 272 (WQVGA)
Type: Color LCD display
Brightness: ~600 cd/m²
Display modes:
- Digital speed
- Analog speed dial
- Distance run

🔌 Electrical / Power

Power supply:
- 100–115 VAC or 200–220 VAC
Power system integration: Network-powered remote displays supported

📡 Interfaces & connectivity

Serial interfaces: IEC 61162-1 / IEC 61162-2
LAN: Ethernet (100Base-TX)
USB: Maintenance port
Outputs: AIS, ARPA radar, autopilot integration supported

⚓ Transducer system

Frequency: 2 MHz high-frequency acoustic transducer
Beam type: Dual-beam Doppler system
Installation depth: hull-mounted below boundary layer
Optional parts:
- Ball valve system (DS-854)
- Tank and transducer assemblies (various cable lengths 10–40 m)

📦 Physical / installation

System components:
- Display unit (DS-8500)
- Distribution unit (DS-8510)
- Transceiver unit (DS-8520)
Cable distance: up to 400 m between units