Description
System Overview & Engineering Architecture
The Walker 7070 Mk2 Electromagnetic Speed Log represents the second-generation evolution of the well-established JLG Marine electromagnetic speed log family. Manufactured by John Lilley and Gillie (JLG), a UK-based marine instrumentation house with a multi-decade heritage in electromagnetic sensor design, the 7070 Mk2 is engineered to provide SOLAS-compliant longitudinal (forward/aft) and transverse (port/starboard) speed-over-ground measurement for commercial shipping, naval auxiliaries, and specialised workboats.
Electromagnetic speed logs operate on the Faraday principle of induced voltage. As the vessel moves through the earth’s magnetic field and through the conductive seawater medium, the relative motion generates a measurable EMF across electrodes embedded in a flush-mounted or through-hull sensor head. The Walker 7070 Mk2 retains the JLG-proven electromagnetic sensor geometry and refines the analogue signal-conditioning chain to deliver stable speed data under a wider range of hull coating, fouling, and ambient electromagnetic noise conditions.
The Mk2 variant introduces an updated digital processing module, modernised NMEA 0183 / NMEA 2000 interfacing, and a revised grounding and isolation architecture to mitigate stray shaft and hotel-load interference — a recurring challenge on large commercial vessels with extensive Variable Frequency Drive (VFD) systems. The result is a robust dual-axis speed log platform trusted by operators seeking long-term, class-surveyable bridge instrumentation.
Core Features & Operational Advantages
The Walker 7070 Mk2 Electromagnetic Speed Log is engineered around several operational principles that have defined the JLG Walker product line:
- Dual-axis speed measurement — simultaneous longitudinal and atherees ground speed indication.
- SOLAS Chapter V compliance — meets IMO requirements for speed and distance measurement on compliant vessels.
- Class-approved sensor technology — designed to satisfy the performance testing regimes of major classification societies.
- Refined Mk2 signal processing — improved noise rejection over the original 7070 platform, particularly in electrically noisy environments.
- Modern bridge display integration — compatible with standard marine MFDs, ECDIS, and voyage data recorder (VDR) inputs via NMEA protocols.
- Proven JLG electromagnetic sensor head — flush-fitting design with documented long-term in-service reliability.
- EM sensor head (fit-through-hull or flush-mount configuration) — the electromagnetic transducer assembly containing the electrode array and pressure-rated housing.
- Junction box / sensor interface unit — provides the first stage of analogue signal conditioning and electrode bias.
- Digital processor unit (Mk2 electronic module) — performs speed calculation, signal averaging, and protocol conversion.
- Bridge display unit / repeater — operator interface for speed indication, calibration status, and fault diagnostics.
- Serial / NMEA interface cabling — for distribution to ECDIS, VDR, radar, and integrated bridge systems.
- Installation hardware, grounding kit, and calibration documentation — including class-society-required test certificates.
- Sensor head inspection at each dry-dock — visual check of electrode condition, marine growth, and anti-fouling coating integrity.
- Electrode cleaning and re-calibration as required by class survey cycles — typically aligned with the special survey period.
- Junction box and processor unit functional test — annual or survey-triggered verification of NMEA output to ECDIS and VDR.
- Cable and grounding integrity check — particularly important on vessels with retrofit variable frequency drive (VFD) installations.
- Bridge display calibration verification against a known reference (log over measured distance, or GPS SOG correlation in deep water with negligible current).
For operators comparing the Walker 7070 Mk2 against Doppler and alternative electromagnetic platforms, the Seanav Marine technical article Single Axis vs Dual Axis Speed Log: A Complete UAE Maritime Guide for Accurate Vessel Speed Measurement provides a useful engineering comparison.
Component Breakdown & Technical Specifications
The standard Walker 7070 Mk2 delivery package comprises the following principal line items:
Operators considering adjacent or comparative products can review the SKIPPER EML1200 dual axis speed log, the Marinelite EML9000 Electromagnetic Speed Log, the SKIPPER DL21 dual and single axis speed log, or the Doppler-platform SKIPPER DL2 Doppler Speed Log and Marinelite DL9000 & HDL9000 Doppler Speed Log for technology comparison purposes.
SOLAS, IMO, IEC & Classification Society Compliance
The Walker 7070 Mk2 Electromagnetic Speed Log is designed for installation on SOLAS-regulated commercial vessels where Regulation V/18 (Navigational systems and equipment) and the related IMO performance standards for shipborne speed and distance measuring equipment apply. Operators trading under DNV, ABS, or Lloyd’s Register class should verify the specific type-approval certificate and test report applicable to their vessel’s keel-lay date.
For vessels calling at Jebel Ali, Port Rashid, Khalifa Port, Port of Fujairah, or Khor Fakkan under the Federal Transport Authority (FTA) flag administration and UAE flag/class requirements, the speed log installation must be reflected on the ship’s Record of Equipment and supported by the original type-approval documentation retained onboard for PSC inspection.
Seanav Marine supports UAE operators with class-compliant retrofit execution — see our Bridge System Upgrade Dubai | Vessel Retrofit Solutions UAE | Seanav Marine and Vessel Retrofit Solutions Dubai UAE | Bridge Electronics Upgrade service pages for typical project scopes.
Onboard Maintenance & Inspection Standards
Routine maintenance of the Walker 7070 Mk2 Electromagnetic Speed Log follows standard JLG Marine service intervals and class-society survey expectations:
Operators requiring service support may engage Seanav Marine for Marine Speed Log Repair Service in JNPA or via our global Marine Speed Log service provider service pages.
Technical Support & Port Delivery
Seanav Marine provides commercial quotation, technical specification review, and class-society-aligned logistics for the Walker 7070 Mk2 Electromagnetic Speed Log. Port delivery is available to UAE hubs including Jebel Ali Port, Port Rashid, Khalifa Port, Port of Fujairah, and Khor Fakkan, with bonded export options for vessels transiting onward to Indian Ocean and Red Sea trade routes.
For formal quotation, class documentation review, and delivery scheduling, please Contact Seanav Marine Technical Team.
Authoritative Reference:
Frequently Asked Questions
1. What is the measurement principle of the Walker 7070 Mk2?
The Walker 7070 Mk2 operates on the electromagnetic (Faraday) principle — measuring the EMF induced across electrodes in a sensor head as the vessel moves relative to the earth’s magnetic field through conductive seawater.
2. Does the Walker 7070 Mk2 measure both longitudinal and transverse speed?
Yes. The Mk2 is a dual-axis electromagnetic speed log providing simultaneous longitudinal (forward/aft) and transverse (port/starboard) speed-over-ground data.
3. Is the Walker 7070 Mk2 SOLAS-compliant?
The system is designed for installation on SOLAS-regulated commercial vessels under Chapter V Regulation V/18 for shipborne speed and distance measuring equipment. Operators should verify the specific type-approval certificate applicable to their vessel.
4. Which classification societies recognise the Walker 7070 Mk2?
The platform is designed to satisfy the performance and survey regimes of major classification societies including DNV, ABS, and Lloyd’s Register. Specific type-approval documentation must be verified against the vessel’s keel-lay date and class notation.
5. What differentiates the Mk2 from the original Walker 7070?
The Mk2 generation introduces an updated digital processing module, refined signal-conditioning chain, and revised grounding/isolation design to improve noise rejection — particularly in vessels with VFD-driven hotel loads and shaft generators.
6. What bridge systems can the Walker 7070 Mk2 interface with?
The Mk2 processor supports standard NMEA 0183 and NMEA 2000 distribution to ECDIS, VDR, marine radar, and integrated bridge MFDs.
7. What maintenance does the Walker 7070 Mk2 require at dry-dock?
Sensor head inspection, marine-growth removal, electrode condition check, anti-fouling integrity verification, and functional re-calibration in line with class survey requirements.
8. Can the Walker 7070 Mk2 be retrofitted to existing vessels?
Yes. The Mk2 platform is widely used as a class-compliant retrofit. Seanav Marine supports retrofit execution under our Bridge System Upgrade service scope.
9. Is UAE port delivery available?
Yes. Seanav Marine coordinates port delivery to Jebel Ali Port, Port Rashid, Khalifa Port, Port of Fujairah, and Khor Fakkan.
10. How do I obtain a formal quotation for the Walker 7070 Mk2?
Submit your vessel particulars and class requirements via the Seanav Marine contact form at https://seanav.org/contact or by email to service@seanav.org.
