Description
John Lilley & Gillie Walker SR4 Magnetic Compass Class A
The John Lilley & Gillie (JLG) Walker SR4 Magnetic Compass Class A is a SOLAS-type approved magnetic compass designed to provide the primary magnetic heading reference required aboard commercial merchant vessels. Manufactured by John Lilley & Gillie, a long-established British marine instrument maker within the Walker marine compass family, the SR4 meets the international regulatory and class society requirements demanded of a Class A magnetic compass for SOLAS-regulated ships.
This product page provides a complete engineering, regulatory, and operational overview of the Walker SR4 to support shipowners, technical superintendents, procurement officers, and classification surveyors evaluating the compass for newbuild outfitting, fleet retrofit, or scheduled replacement.
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System Overview & Engineering Architecture
The Walker SR4 is a deck-mounted, reflector-style magnetic compass. Its design philosophy reflects more than a century of British marine instrument heritage, combining traditional magnetic compass engineering with the precision tolerances demanded by modern SOLAS and classification society requirements.
The compass comprises a magnetised needle assembly mounted on a pivot within a liquid-filled bowl, which dampens oscillation and provides steady, readable heading indication. The compass card is read through a reflector prism system positioned above the bowl, allowing the navigator to take bearings from the lower steering position or directly at the compass location.
A Class A compass designation under SOLAS Chapter V Regulation 19 means the SR4 is intended for ships of 150 gross tonnage and above, where it may serve as the primary or backup magnetic heading reference. The instrument is built for endurance in the harsh marine environment, with the bowl assembly engineered to remain stable under vessel motion, vibration, and temperature variation.
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Core Features & Operational Advantages
The Walker SR4 incorporates a number of features that have established it as a respected choice for commercial marine navigation:
- Class A SOLAS Compliance – Designed and built to satisfy SOLAS carriage requirements for primary magnetic heading reference on vessels of 150 GT and above.
- 360° Azimuth Reading – Full graduated compass card allows bearings to be taken on any visible object.
- Reflector Prism System – Enables heading observation from the helmsman’s or pelorus position without parallax error.
- Integrated Corrector Mounting – Supports the fitment of standard magnetic corrector devices (such as quadrantal spheres, heeling error magnet, and Flinders bar arrangements) typically supplied separately.
- Marine-Grade Construction – Corrosion-resistant binnacle and bowl materials suited to wheelhouse, monkey island, or open-bridge installations.
- Liquid-Filled Bowl Assembly – Provides damped, stable indication of heading with minimised oscillation in seaway.
- Spare Parts & Service Support – Through Seanav Marine, operators can obtain OEM spare cards, pivots, jewels, bowl assemblies, and corrector magnets.
- Compass Bowl & Card Assembly – The magnetised needle and graduated card mounted on a central pivot within a sealed, liquid-filled bowl.
- Reflector Mounting – Prism assembly that projects the lubber line and compass card image to the viewing position.
- Binnacle / Mounting Stand – Pedestal or deck stand supporting the bowl and providing attachment points for corrector devices.
- Corrector Device Provision – Standard binnacle positions for quadrantal correctors, heeling error magnet, and Flinders bar.
- Lighting Provision – Integrated or external illumination suitable for bridge watchkeeping at night.
- SOLAS Chapter V, Regulation 19 – Carriage requirements for shipborne navigational equipment, including the requirement for a Class A magnetic compass on vessels of 150 GT and above.
- IMO Performance Standards for Magnetic Compasses – Resolution A.382(X) and subsequent instruments governing magnetic compass accuracy, stability, and construction.
- ISO 449 / ISO 2269 – International standards for marine magnetic compasses, binnacles, and azimuth reading devices.
- IEC 60945 – Maritime navigation and radiocommunication equipment and systems – General requirements (where applicable to associated electronic components of the installation).
- Classification Society Requirements – The SR4 is generally acceptable to major classification societies including Lloyd’s Register, Bureau Veritas, DNV, ABS, and the Federal Transport Authority (FTA) of the UAE, subject to individual class review of the installation.
- Annual Compass Calibration & Deviation Card Update – Swing the vessel and adjust the deviation card, a service offered regionally by Seanav Marine — see Magnetic Compass Calibration & Deviation Card – Seanav Marine India and Magnetic Compass Calibration Service in UAE.
- Periodic Bubble & Fluid Check – Inspect the bowl for air bubbles, fluid discolouration, or leakage; the liquid fill should remain clear and free of particulate.
- Pivot & Jewel Inspection – Check for excessive card friction, sluggishness, or sticking; replace pivots as part of the standard service cycle.
- Binnacle & Corrector Inspection – Confirm correct positioning of quadrantal correctors, Flinders bar, and heeling magnet per class-approved deviation card layout.
- Class Survey Support – Magnetic compass condition is reviewed during annual and renewal class surveys; Seanav Marine can coordinate attendance.
These features make the SR4 a practical choice where a reliable, regulator-accepted magnetic heading source is required as a primary or backup to gyrocompass systems.
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Component Breakdown & Technical Specifications
The principal components of the Walker SR4 magnetic compass installation include:
A formal technical specifications table is provided below for engineering reference.
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SOLAS, IMO, IEC & Classification Society Compliance
The Walker SR4 is designed and manufactured to comply with the relevant international maritime navigation regulations, including:
For vessels flagged in the United Arab Emirates and operating from ports such as Jebel Ali, Port Rashid, Khalifa Port, Port of Fujairah, and Khor Fakkan, the SR4 supports the bridge navigation outfitting required for SOLAS and class surveys.
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Onboard Maintenance & Inspection Standards
Routine maintenance of the Walker SR4 magnetic compass is essential to retain accuracy and regulatory compliance:
Operators in Fujairah may also reference Magnetic Compass Calibration in Fujairah UAE for local service coverage.
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Technical Support & Port Delivery
Seanav Marine supplies the genuine JLG Walker SR4 Magnetic Compass Class A together with OEM spare parts, replacement bowls, pivots, jewels, and corrector magnets. Our technical team coordinates port delivery to Jebel Ali, Port Rashid, Khalifa Port, Port of Fujairah, and Khor Fakkan, as well as major international hubs.
For datasheets, configuration confirmation, spares lists, and port delivery scheduling, please Contact the Seanav Marine Technical Team.
External Reference: Official OEM Product Reference Page
Frequently Asked Questions
1. What class of vessel is the Walker SR4 Magnetic Compass designed for?
The Walker SR4 is a Class A magnetic compass designed for SOLAS-regulated vessels of 150 gross tonnage and above, satisfying SOLAS Chapter V Regulation 19 carriage requirements.
2. Is the John Lilley & Gillie Walker SR4 SOLAS approved?
The SR4 is designed and built as a SOLAS-type Class A magnetic compass in accordance with the relevant IMO performance standards and SOLAS Chapter V Regulation 19 requirements.
3. What type of reading system does the SR4 use?
The SR4 uses a reflector / prism viewing system that allows the navigator to take accurate bearings from the standard compass viewing position.
4. Can the SR4 be installed on an open bridge or does it require a wheelhouse?
The Walker SR4 is suitable for wheelhouse, monkey island, or open-bridge installation, using a pedestal or binnacle mounting configuration.
5. Are corrector devices included with the SR4?
The SR4 binnacle provides mounting provision for the standard set of magnetic correctors (quadrantal spheres, heeling error magnet, and Flinders bar). Correctors are typically selected per vessel and may be sourced through Seanav Marine.
6. Does the SR4 require annual calibration?
Yes. SOLAS and most classification societies require an annual compass swing and updated deviation card. Seanav Marine offers magnetic compass calibration services in the UAE and across Indian ports.
7. Are OEM spare parts available?
Yes. OEM spares including replacement compass cards, pivots, jewels, bowl assemblies, and corrector magnets are available through Seanav Marine.
8. Which classification societies accept the SR4?
The SR4 is generally accepted by major classification societies including Lloyd’s Register, Bureau Veritas, DNV, and ABS, subject to individual class review of the installation. UAE-flagged vessels subject to FTA oversight are supported.
9. Can Seanav Marine coordinate port delivery to UAE ports?
Yes. Seanav Marine coordinates delivery to Jebel Ali, Port Rashid, Khalifa Port, Port of Fujairah, and Khor Fakkan, as well as to other international ports.
10. Is the SR4 suitable as a backup to a gyrocompass?
Yes. The SR4 is commonly used as a magnetic heading backup to the ship’s primary gyrocompass, providing an independent heading source required by SOLAS.
