The SMART ESM from Rivertrace is a continuous washwater monitoring instrument designed for exhaust gas cleaning systems on marine vessels. It measures the four parameters required by IMO MEPC.259(68) and MEPC.340(77) — PAH, turbidity, pH and temperature — at the inlet and outlet of open-loop, closed-loop and hybrid scrubber systems, providing the continuous data record that scrubber-equipped ships need to demonstrate compliance with MARPOL Annex VI SOx limits and washwater discharge criteria.
Since Rivertrace first launched the SMART ESM for the IMO 2020 sulphur cap, the regulatory landscape governing exhaust scrubber washwater discharge has changed significantly. MEPC.340(77) has introduced stronger monitoring system approval, recording frequency and EGCS Record Book requirements for newer installations. OSPAR Decision 2025/01 has set binding deadlines for the phased prohibition of EGCS discharge in North-East Atlantic internal waters and port areas. Geographic discharge restrictions have expanded to cover 45 countries globally. This article covers the SMART ESM’s current capabilities and its relationship to the full 2025 and 2026 regulatory framework. For the complete regulatory overview, see the exhaust scrubber washwater discharge monitoring explainer page.
| Key thing to remember
The regulatory framework for scrubber washwater discharge has changed substantially since IMO 2020. MEPC.340(77) now applies to EGCS installations from June 2022, with stronger requirements for Administration approval of the monitoring system, data recording frequency and EGCS Record Book documentation. OSPAR Decision 2025/01 introduces binding geographic discharge prohibitions from 2027. The SMART ESM is designed to support compliance with both the current monitoring requirements and the evidence chain that the expanded regulatory framework now demands. |
What Does the SMART ESM Monitor and Measure?
The SMART ESM measures the four washwater parameters required under both MEPC.259(68) and MEPC.340(77) continuously at the EGCS discharge point:
- PAH (polycyclic aromatic hydrocarbons) — measured as phenanthrene equivalent, with a maximum permitted level of 50 µg/l above inlet water PAH concentration
- Turbidity — maximum 25 FNU above inlet water turbidity on a 15-minute rolling basis
- pH — minimum 6.5 or within 2 pH units of ambient seawater pH, whichever is less restrictive
- Temperature — recorded and reported as a supporting parameter for the discharge record
The SMART ESM can be configured for monitoring at both the inlet and outlet of the EGCS, allowing the differential measurement of PAH and turbidity between inlet and outlet that the IMO guidelines require. On hybrid scrubber systems, the SMART ESM supports monitoring in both open-loop and closed-loop operating modes with appropriate alarm and data logging for each mode.
The full technical specification of the SMART ESM is set out in the table below.
| Specification | Detail |
| Parameters measured | PAH (polycyclic aromatic hydrocarbons), turbidity, pH and temperature — all parameters required by MEPC.259(68) and MEPC.340(77) |
| EGCS type compatibility | Open-loop, closed-loop and hybrid exhaust gas cleaning systems |
| Monitoring points | Configured for inlet and/or outlet monitoring as required by the EGCS installation |
| Display | 10-inch touchscreen display with real-time and historical data visualisation — hourly, daily and weekly trend graphs |
| Control system interface | Ethernet connection and 4-20 mA analogue outputs. Modbus protocol support for integration with vessel ICSS or DCS |
| Data logging | Continuous recording at the frequency required by MEPC.340(77); historical data accessible onscreen and exportable for EGCS Record Book and fleet management system integration |
| Remote data access | Automatic email data transmission for remote compliance record keeping and fleet manager oversight |
| Optical path maintenance | Automatic optical path cleaning to maintain measurement accuracy between maintenance intervals |
| Applicable guidelines | MEPC.259(68) and MEPC.340(77) — covers both pre-June 2022 installations and new EGCS installations from June 2022 onwards |
| OEM integration | Broad analogue and digital output selection for integration with all major EGCS OEM designs |
Which Regulatory Guidelines Does the SMART ESM Meet?
The regulatory framework governing EGCS washwater monitoring now comprises three overlapping instruments that together determine what the monitoring system must do, how it must record data and where discharge is permitted. The table below summarises each instrument and the SMART ESM’s status against it. For a full explanation of the difference between MEPC.259(68) and MEPC.340(77), see What Is MEPC.340(77) and How Does It Differ From MEPC.259(68)?.
| Instrument | Date | Applies to | Key requirement | SMART ESM status |
| MEPC.259(68) | 2015 | EGCS installed before 1 June 2022 (unless subsequently modified) | Core washwater parameters and limits. Continuous monitoring required. | SMART ESM meets all MEPC.259(68) monitoring requirements |
| MEPC.340(77) | 2021 — in force from 1 June 2022 | New EGCS installations from June 2022; new installations on existing ships; material modifications to existing EGCS | MEPC.259(68) requirements plus Administration approval of monitoring system; continuous recording at minimum 0.0111 Hz; EGCS Record Book mandatory | SMART ESM designed to meet MEPC.340(77) requirements including continuous data logging at the required frequency |
| OSPAR Decision 2025/01 | 2025 | Ships trading in North-East Atlantic waters (15 OSPAR Contracting Parties) | Open-loop discharge banned in OSPAR internal waters and ports by July 2027; all-mode discharge banned by July 2029 | SMART ESM monitoring and data logging supports the evidence chain required for compliance in OSPAR waters, including mode change and discharge stop records |
How Has the Regulatory Context Changed Since IMO 2020?
When the SMART ESM was first launched in 2018, the primary regulatory focus was on meeting the four washwater parameter limits of MEPC.259(68) ahead of the 2020 global sulphur cap. The compliance question at that time was primarily technical: does the washwater meet the measured criteria?
The compliance question in 2026 is significantly more complex and involves three dimensions simultaneously:
What the water measures
The MEPC.259(68) and MEPC.340(77) washwater parameter requirements remain the foundation. The SMART ESM’s measurement function is unchanged — continuous monitoring of PAH, turbidity, pH and temperature at the specified limits.
Where the vessel is
A washwater discharge that meets all measured parameter values is still prohibited if the vessel is in waters where discharge is banned. Open-loop discharge is already prohibited in Singapore port waters, the Port of Fujairah, Chinese territorial waters for China-calling ships, and parts of the US. OSPAR Decision 2025/01 will extend prohibitions across the North-East Atlantic from 2027. For a full map of current restrictions, see Where Is Open-Loop Scrubber Discharge Banned or Restricted?.
How compliance is documented
Under MEPC.340(77), the monitoring system must be approved by the flag state Administration, must record data at not less than 0.0111 Hz, and all maintenance, malfunction and operational events must be kept in the EGCS Record Book. The SMART ESM’s continuous data logging, automatic optical path cleaning, and data export functions support the evidence chain that MEPC.340(77) requires. For the full documentation framework, see What Records Does a Ship Need to Prove Scrubber Washwater Compliance?.
| OSPAR Decision 2025/01 requires operational preparation now
The 2027 deadline for open-loop discharge prohibition in OSPAR internal waters and port areas is less than two years away. Ships regularly trading through North Sea, English Channel, Irish Sea or Bay of Biscay ports need to assess their compliance options now: fuel switching, closed-loop operation with retained bleed-off, or shore reception arrangements. The SMART ESM monitoring and recording functions support compliance evidence across all operating modes, but the operational decision on how to manage OSPAR waters must be made at fleet management level. |
How Does the SMART ESM Support EGCS OEM Integration?
The SMART ESM was designed from the outset to integrate with the full range of exhaust gas cleaning system designs from OEM partners rather than as a standalone instrument requiring custom integration for each installation.
The integration capability includes:
- A broad selection of inbuilt analogue and digital outputs covering all major EGCS OEM interface requirements
- Ethernet connection with Modbus protocol support for integration with vessel control systems, ICSS and DCS platforms
- 4-20 mA analogue outputs for compatibility with older vessel control system architectures where digital integration is not available
- Configurable alarm outputs for high-parameter alarm and discharge shut-off integration with the EGCS control system
- Data export capability compatible with electronic Oil Record Book and fleet management system API integrations
Rivertrace works directly with EGCS OEM partners to confirm the appropriate output configuration and sample conditioning arrangement for each scrubber system design before installation, eliminating the integration uncertainties that can arise when a monitoring instrument is selected independently of the EGCS supplier.
What Support Does Rivertrace Provide for SMART ESM In-Service Maintenance?
The SMART ESM is supported by the Rivertrace global service network covering all major shipping ports. In-service maintenance requirements include optical path cleaning, filter element replacement, sensor replacement at the manufacturer-specified interval, calibration verification and EGCS Record Book documentation for all maintenance events.
Rivertrace provides:
- Planned maintenance agreements scheduling sensor replacement and calibration verification visits aligned with the vessel’s port call schedule
- Global agent and distributor network with trained service capability and stocked spare parts at all major shipping hubs
- Same-day dispatch from the UK distribution centre for spare parts not held locally
- Technical support by phone and email for in-service fault diagnosis and maintenance guidance
- Service documentation including updated calibration certificates and service reports formatted for EGCS Record Book entry
What Is the Origin of the SMART ESM?
The SMART ESM was developed by Rivertrace and first exhibited publicly at the Sulphur Cap 2020 Conference, Awards and Exhibition in Amsterdam in April 2018, ahead of the IMO global sulphur cap that came into force on 1 January 2020. The product was designed to provide the marine industry with a monitoring instrument that could be fitted across all major scrubber types and integrated into all major EGCS OEM designs as a single unified solution.
Rivertrace has continued to develop and refine the SMART ESM since 2018, incorporating the monitoring system approval, recording frequency and EGCS Record Book requirements introduced by MEPC.340(77) in 2021 and providing updated compliance documentation to support Administration approval processes for newer EGCS installations.
Frequently Asked Questions
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What does the Rivertrace SMART ESM monitor?
The SMART ESM continuously monitors and records PAH, turbidity, pH and temperature at the EGCS washwater discharge point, meeting the measurement requirements of both MEPC.259(68) and MEPC.340(77). It can be configured for inlet and outlet monitoring on open-loop, closed-loop and hybrid scrubber systems.
Does the SMART ESM meet MEPC.340(77) requirements?
Yes. The SMART ESM is designed to meet the monitoring requirements of MEPC.340(77), including continuous data recording at not less than 0.0111 Hz for PAH, turbidity and pH, data export for EGCS Record Book documentation, and Administration approval support. Operators should confirm the applicable guideline for their specific EGCS installation with the flag state Administration.
Can the SMART ESM be used on hybrid scrubber systems?
Yes. The SMART ESM supports monitoring in open-loop, closed-loop and hybrid EGCS operating modes. On hybrid systems, the SMART ESM provides appropriate monitoring, alarm and data logging for both modes of operation.
What is the difference between MEPC.259(68) and MEPC.340(77) for scrubber monitoring?
MEPC.259(68) is the 2015 guideline applying to EGCS installed before June 2022. MEPC.340(77) is the 2021 guideline applying to new installations and material modifications from June 2022. Both require monitoring of the same four parameters. MEPC.340(77) adds Administration approval of the monitoring system, a minimum recording frequency of 0.0111 Hz, and mandatory EGCS Record Book documentation. For a full comparison, see What Is MEPC.340(77) and How Does It Differ From MEPC.259(68)?.
How does geographic discharge restriction affect SMART ESM operation?
The SMART ESM monitors whether washwater meets the MEPC parameter criteria. Whether discharge is permitted in a specific location depends on the geographic restrictions in force at the vessel’s current position. Where discharge is prohibited, the EGCS must be shut off or switched to a non-discharging mode regardless of the monitoring reading. For a map of current restrictions, see Where Is Open-Loop Scrubber Discharge Banned or Restricted?.
How is the SMART ESM maintained in service?
The SMART ESM requires regular optical path cleaning, filter element replacement, sensor replacement at the manufacturer-specified interval and periodic calibration verification. All maintenance events must be recorded in the EGCS Record Book under MEPC.340(77). Rivertrace provides planned maintenance agreements, a global service network and same-day spare parts dispatch to support in-service maintenance worldwide.
What data outputs does the SMART ESM provide for EGCS OEM integration?
The SMART ESM provides Ethernet connection with Modbus protocol support, 4-20 mA analogue outputs, and configurable digital alarm and control outputs. This covers the interface requirements of all major EGCS OEM designs. Rivertrace works with OEM partners to confirm the appropriate output configuration for each specific installation.
Mike Coomber, Managing Director of Rivertrace said:
“We are excited to launch the Smart ESM which is the latest in our innovative range of monitoring products.”