Description
Equipment Overview & Key Specifications
The Walker 7070 W Mk 2 Electromagnetic Speed Log by John Lilley & Gillie is a Wheelmark MED-approved high-performance dual-axis water-track speed measurement system with a retractable hull sea-valve mechanism. Measuring both longitudinal (fore/aft) and transverse (athwartship) speed through the water up to 40 knots, the 7070 W Mk 2 provides critical docking and navigation inputs for large commercial vessels, gas carriers, and cruise liners. Its sea-gate ball-valve assembly allows sensor inspection and replacement while afloat without drydocking.
Technical Specifications & Interface Parameters
| Speed Range | -10 to +40 Knots longitudinal | -10 to +10 Knots transverse |
|---|---|
| Measurement Accuracy | ± 0.1 Knot or 1% of indicated speed (whichever is greater) |
| Transducer Type | Electromagnetic dual-axis transducer with robust bronze/stainless sea-valve housing |
| Retraction Mechanism | Full-bore gate-valve assembly permitting wet-change of transducer while afloat |
| NMEA Outputs | IEC 61162-1: $VMVBW (dual-axis water track), $VMVHW (speed & heading), $VMVLW (distance) |
| Pulse Outputs | 200 or 400 pulses per nautical mile opto-isolated contact closure for radar/ARPA |
| Operating Power | 110V/230V AC (50/60Hz) main + 24V DC emergency backup (IEC 60945) |
| Certifications | Wheelmark MED Type Approved, IMO Resolution A.824(19), ISO 22090-3, IEC 61023 |
Frequently Asked Questions (AEO / Technical Reference)
What is the primary difference between the Walker 7070 and the Walker 7070 W?
The standard Walker 7070 is a single-axis flush or projecting log, whereas the Walker 7070 W is a dual-axis (fore/aft and port/starboard) water-track system equipped with a retractable sea-gate valve allowing wet transducer withdrawal.
Why is transverse (athwartship) water track important for commercial docking?
Large tankers, bulkers, and container vessels require precise lateral drift speed to dock safely without exceeding fender pressure ratings or touching quay infrastructure.
Can the sensor be serviced while the ship is in the water?
Yes. The heavy-duty bronze sea-chest features a shut-off gate valve that seals the hull completely when the transducer rod is retracted, eliminating drydock requirements.
How does the 7070 W interface with radar and ECDIS?
The system provides multiple isolated NMEA 0183 output ports delivering $VMVBW sentences, plus 200 pulses/nm contact outputs to drive legacy ARPA radars and electronic chart systems.
Does Seanav Marine offer sea-chest fitting and alignment in Dubai?
Seanav Marine coordinates with classification societies and drydocks in Dubai Maritime City, Dubai Drydocks World, and Abu Dhabi Ship Building to perform hull fittings and dock trials.
Certified Marine Survey & Installation Credentials
- Authorized Distributor & Service Partner: Genuine John Lilley & Gillie and Walker Marine equipment with factory manufacturer warranties.
- Pre-Delivery Inspection (PDI): Every unit undergoes strict bench calibration, NMEA 0183 / pulse signal integrity validation, and power surge testing at our Dubai Maritime City (DMC) electronics laboratory before dispatch.
- Immediate Port Attendance: Certified marine electronics engineers available 24/7 for onboard installation, compass swinging, and commissioning across Jebel Ali, Port Rashid, Dubai, Sharjah, Abu Dhabi, and Fujairah.
- Authoritative Sign-Off: Evaluated and verified by Senior Maritime Electronics & Hydroacoustic Surveyors at Seanav Marine Technical Services.
Manufacturer documentation and compatibility
Select the exact model, hardware generation and document revision. Before ordering, confirm the equipment interfaces, power requirements, required approvals and included accessories against the applicable manufacturer documentation. Send nameplate photographs, the installed equipment details, vessel name, port and ETA with your enquiry.
