VESSEL REVIEW | Voltai – Electric supply boat to be operated in Singapore's port waters

Singapore’s Kuok Maritime Group (KMG) recently placed a new electric supply boat into service.

Named Voltai after a species of electric eel, the 26- by six-metre (85- by 20-foot) vessel was developed by the Coastal Sustainability Alliance (CSA) led by KMG and built by Singapore-headquartered PaxOcean at its PaxOcean Batam shipyard in Indonesia.

KMG expects that the vessel’s electric drivetrain will enable annual fuel cost savings of as much as 40 per cent while the larger size will yield a payload capacity roughly four times that of conventional supply boats.

“Voltai is Singapore’s largest fully electric supply boat and among the first designs recognised by the Maritime and Port Authority of Singapore (MPA) for its energy efficiency and operational readiness,” PaxOcean told Baird Maritime.

“Built for zero-emission operations, Voltai can achieve up to 60 per cent energy savings compared to conventional vessels. Its payload capacity of 40 tonnes or 60 pallets also helps reduce marine traffic and the number of trips required.”

Greater transport capacity compared to earlier local craft

The builder said the owner required a "holistic" solution for lightering operations to achieve the 2030 goals set by MPA for new harbour craft and to help achieve the CSA’s objective of establishing a “next-generation logistics ecosystem.”

“Key achievements include clean, zero-emission operation, high payload and operational efficiency, low total cost of ownership, and alignment with Singapore’s net-zero decarbonisation ambition. The vessel helps to reduce 'scope three' emissions by an estimated 0.5 tonne per ship arrival at the Port of Singapore.”

PaxOcean added that use of the new supply boat would improve delivery efficiency, reduce manpower costs otherwise incurred from operating several conventional vessels, and support compliance with “green port” initiatives.

Voltai is equipped with two 300kW electric motors powered by two 500kWh battery packs. PaxOcean said this setup allows the vessel to cruise at eight knots and achieve a range of 80 nautical miles. An onboard energy management system can meanwhile optimise power usage and help extend battery life.

Real-time remote monitoring to streamline operations

“Unlike diesel engines, the electric drivetrain significantly reduces maintenance requirements and vibration,” said PaxOcean. “The integrated energy management system ensures efficient power usage and helps to preserve the lifespan of the batteries.”

Ampotech supplied the vessel with a solution to connect to the onboard systems such as the batteries and electric motors and transmit data to its fleet management software application. The system tracks vessel movement, energy usage, and available range based on battery status.

The vessel replaces traditional dials and gauges with digital touchscreen monitors that provide real-time system updates to the captain. It also features a ship-to-shore connection that enables continuous remote monitoring. PaxOcean said the live data are mirrored onshore, allowing shore-based teams to track the vessel’s condition and performance.

“This system enables real-time monitoring of performance and supports smarter decisions based on predictive capability of resistance, manoeuvring, and powering data,” the builder said.

Reducing lightering fleet requirements

The vessel also incorporates several technologies that KMG said are aimed at enhancing efficiency. The hull design reduces power consumption by as much as 10 per cent at 10 knots under full load, and the vessel makes use of a digital twin.

Voltai will be operated in Singapore’s port and regional waters, serving merchant vessels at anchorage. Its daily operations will include what PaxOcean termed as consolidated “milk run” deliveries, and this will be made possible with an open cargo deck designed for efficient handling of high-capacity loads.

“With four times the payload capacity, Voltai potentially replaces two to three conventional supply boats,” PaxOcean told Baird Maritime.

For PaxOcean, one challenge in designing the new supply boat was related to achieving zero-emission capability while meeting demanding operational requirements.

“The team had to carefully balance energy storage capacity, power output, vessel range, and payload, all while keeping the design commercially viable and aligned with regulatory and operational expectations.”

Building the vessel within a tight timeline posed another challenge, according to PaxOcean. Construction commenced only after the MPA’s expression of interest of full electric harbour craft was awarded, leaving the company little room to accommodate the long lead times for critical equipment.

PaxOcean said that, despite these pressures, the company remained focused and worked collaboratively to ensure the vessel was completed in time for its debut at Singapore Maritime Week.

“We gained valuable experience in battery integration, energy management, and hydrodynamic optimisation which will reduce future builds’ times, and enhance performance in future electric vessel projects,” PaxOcean told Baird Maritime. “These insights will help shipowners reduce operating costs through real-time performance monitoring and operational planning.”