Singapore's Harbour Craft Electrification: What Vessel Owners Need to Know

Singapore's Harbour Craft Electrification: What Vessel Owners Need to Know

Singapore's Maritime and Port Authority (MPA) is actively pushing the electrification of harbour craft as part of the broader Singapore Green Plan 2030 and the maritime sector's decarbonisation commitments. For vessel owners and commercial fleet operators, this represents both an obligation and an opportunity — but converting a working vessel from diesel to electric propulsion is a technically complex project that requires the right yard, the right engineering team, and a clear understanding of what the process involves.

This article covers what you need to know if you are considering or planning a diesel-to-electric conversion for your harbour craft.

Why Singapore Is Pushing Harbour Craft Electrification

Singapore is one of the world's busiest ports. The domestic harbour craft fleet — ferries, launch craft, work boats, crew transfer vessels, pilot boats, and utility craft — collectively generates significant emissions within Singapore's port waters.

The MPA's Sea Transport Industry Transformation Map and subsequent electrification grant schemes have created a clear signal: diesel-powered harbour craft operating within Singapore port limits face increasing pressure to transition to lower-emission alternatives. Electric propulsion, using lithium battery systems, is currently the most mature and commercially viable path for short-range harbour craft up to approximately 25–30 metres.

For operators, the practical drivers are:

• Regulatory compliance with tightening MPA emissions requirements

• Access to government grant schemes incentivising electrification

• Reduced operating costs from lower fuel and maintenance expenditure

• Quieter, vibration-free operation improving crew comfort and passenger experience

What Does a Diesel-to-Electric Conversion Actually Involve?

Converting an existing harbour craft from diesel to electric propulsion is not simply a matter of swapping an engine for a motor. It is a complete re-engineering of the vessel's propulsion and power system, and it requires co-ordination across naval architecture, structural engineering, electrical systems, and class approval.

A full conversion typically involves the following:

1. Feasibility and Design Assessment

Before any physical work begins, the vessel's existing arrangement must be assessed — hull structure, engine room dimensions, weight distribution, and power requirements. The battery system must be designed to deliver sufficient energy for the vessel's operating profile: route length, speed, payload, and duty cycle. This stage typically produces a system specification and arrangement drawings for class review.

2. Battery System Design and Supply

The battery system is the heart of the conversion. For a typical commercial harbour craft, this involves:

• A lithium-ion battery bank sized to meet propulsion and auxiliary power requirements

• A Battery Management System (BMS) that monitors cell voltage, temperature, and state of charge, and protects the system from overcharge, over-discharge, and thermal events

• A Power Electronics Management System (PEMS) managing power flow between the batteries and drive motors

• DC/DC converters and a high-voltage DC bus distribution system

• Integrated fire detection and suppression systems within the battery compartment

Battery systems for commercial harbour craft require class type approval from DNV GL, ABS, or Bureau Veritas (BV) — or a combination where multiple flags require it. The system must also meet Singapore's MPA Merchant Shipping Safety Regulations and Singapore Standard SS 638:2018 for electrical installations.

3. Structural and Civil Works

The battery room must be engineered to accommodate the battery racks within the vessel's hull — accounting for weight, centre of gravity, structural reinforcement, and ventilation. For many vessels, this requires modification to the engine room or the creation of a dedicated battery compartment below the main deck.

This is yard work: cutting, welding, and structural modification of the vessel's aluminium or steel hull, followed by installation of cable runs, cooling systems, and fire suppression infrastructure. Getting this right requires a yard with both structural fabrication capability and marine electrical experience.

4. Propulsion System Installation

The diesel engine, gearbox, and associated fuel systems are removed. Electric drive motors, motor controllers (inverters), and shaft couplings are installed in their place. Depending on the vessel's design, this may involve modifications to shaft lines and stern gear.

For vessels retaining conventional shafts and propellers, the integration between the inverter and the propeller shaft is a critical interface. Waterjet propulsion systems can also be adapted for electric drive.

5. Electrical Integration and Controls

The battery system, drive motors, auxiliary systems, vessel alarm systems, and the vessel's control and monitoring platform must all be integrated into a coherent, class-approved electrical system. This includes:

• High-voltage DC and low-voltage AC distribution

• Emergency shutdown systems with hardware interlocks

• Integration with the vessel's existing navigation and alarm panels

• Communications protocols for system monitoring (Modbus, OPC, or similar)

6. Class Approval and PE Endorsement

In Singapore, a converted vessel requires class approval from the relevant classification society (DNV GL, ABS, or BV depending on flag) and sign-off from a Professional Engineer registered in Singapore for the electrical installation, in accordance with SS 638:2018.

The classification body will require drawing submissions, calculations, and a documented testing programme before they will approve the conversion. This is not a quick process — allow adequate time in the project schedule.

7. Testing and Commissioning

A systematic testing programme is required before the vessel returns to service:

• Factory Acceptance Test (FAT): the battery system is tested at the supplier's facility before delivery

• Site Acceptance Test (SAT): the complete installed system is tested on the vessel at the yard, witnessed by the classification surveyor

• Sea trials: the vessel is operated under load to verify speed, handling, endurance, and system performance

Only after successful completion of all three stages will the class certificate be updated and the vessel cleared for commercial operation.

How Long Does a Conversion Take?

A realistic timeline for a full diesel-to-electric conversion of a harbour craft — from signed contract to vessel back in service — is typically 6 to 12 months. Key timeline drivers include:

• Design and class submission review: 1–3 months

• Battery system fabrication and delivery: 3–6 months (longer for bespoke systems)

• Yard work and installation: 1–3 months

• Testing, commissioning, and class survey: 1–2 months

Projects with a well-defined scope, an experienced yard, and a responsive class surveyor tend to compress this timeline. Projects that encounter design changes, supply chain delays, or incomplete class submissions tend to extend it.

What AES Brings to an Electrification Project

American Equipment Services has been working with commercial vessel operators and major marine contractors in Singapore on vessel electrification projects, including large-scale battery system installations for harbour craft operating within Singapore port limits.

Our Pioneer Sector facility provides the full range of capabilities required for a conversion project:

• Haul-out and drydocking for vessels up to 25 metres

• Structural aluminium and steel fabrication for battery room modifications

• In-house welding and fitting for cable runs, structural supports, and hull penetrations

• Propulsion system removal, installation, and shaft alignment

• Marine civil works for complete system integration

• Commissioning support and liaison with classification societies

We have the experience to manage the interface between the battery system supplier, the classification society, the Professional Engineer, and the vessel operator — which is typically where electrification projects get complicated.

Considering an electrification project for your vessel?

Contact AES to discuss your vessel's operating profile and what a conversion would involve.

📍 2A Pioneer Sector 1, Singapore 628415

📧 sales@amereq.com.sg

[Discuss Your Electrification Project →]