Written by Kerryn Caulfield, Executive Director of Composites Australia Inc.
Whisper-quiet propulsion in the delicate soundscape of an inland waterway is an asset for anglers, allowing them to move without disturbing marine life that relies on sound for communication and navigation. Unlike traditional combustion engines, electric motors operate with minimal noise, improving catch rates in fish-rich areas while preserving the natural environment. Quiet operation also helps maintain ecological balance, supporting species that depend on an undisturbed acoustic environment. Electric boats offer a practical, regulation-compliant solution for a better fishing experience in regions with noise restrictions or bans on combustion engines.
Specialised marine craft builder Steber International, based in Taree, NSW, has embraced innovation and transformative advancements in boatbuilding since its founding in 1946. The family-owned business was indeed one of the pioneers in adopting fibreglass construction for boats in Australia. The company transitioned from building timber clinker hull boats to Fibreglass (FRP) construction in 1959. Building on this legacy, the company is leveraging the environmental benefits of electric propulsion while pioneering a balanced approach to electric and diesel power. In collaboration with engineering firm Ampcontrol and the University of Newcastle, Steber is driving the development of hybrid diesel-electric systems to enhance efficiency and sustainability in marine transport.
Steber International General Manager Alan Steber said: “Drawing on our expertise in building commercial boats, we set out to develop a prototype to evaluate the commercial viability of an electric propulsion system that offers stealth, reduced emissions, and operational efficiency.”
“An initial 22-foot test rig was launched on the Manning River in Taree in 2021. Trials showed promising results, reaching 20 knots with one person on board and 18 knots with seven. With a 9.5kVA generator and a full crew, the vessel maintained 15 knots for extended voyages.”
Building on the initial project’s success, Steber has developed the scaled-up Steber 43 hybrid. The power is delivered from the combination of an on-board battery system and a standard issue marine diesel engine re-vectored to drive a high-power density electric generator. Two water-cooled 300kW electric motors deliver direct propeller drive, enhancing torque and speed control via fly-by-wire technology.
A specially designed docking mode lowers the propeller speed while retaining complete control over operational range, improving navigation in enclosed waters and docking.
The currently installed 150kWh marine-grade battery system allows the vessel to travel continuously on electric power alone. Approximate electric propulsion ranges between 12 hours at 4 knots, up to 1 hour at 10 knots and .5hr at 13 knots utilising batteries only. The top speed of 24 knots is achieved by using both generator and battery power.
A closed-loop isolated glycol liquid cooling circuit for all major electrical power system components ensures independent flow regulation, component redundancy, and reduced pump size. To simulate vessel operation in northern waterways, the system has also been successfully tested in warm water temperatures up to 33°C.
The Steber 43ft vessel is equipped with Aware Marine remote monitoring software, allowing real-time position and status tracking. This modular and scalable marine electric power system enables tailored performance profiles for both new and retrofitted vessels.
The hybrid diesel-electric propulsion system enables power efficiency, quiet operation and significantly reduced emissions while maintaining a full cruising range. The integration of batteries and an electric motor allows for a reduction in diesel engine size while maintaining equal or higher power ratings.
A key advantage of shifting from fossil-fuel-powered boats to electric propulsion is the lower operational cost compared to the expense of mechanical energy derived from diesel engines.
Alan Steber highlighted the project’s vast potential: “This exciting development has unlimited applications across the marine industry. Fuel savings alone could offset the cost of an electrical upgrade within four years, depending on a vessel’s operating hours. The on-water performance is impressive—there’s no vibration, it’s quiet, and it delivers excellent torque and speed. The hybrid system ensures a smooth, clean and quiet boating.”
“Potential applications include marine park boats, police boats, recreational and leisure vessels, harbour foreshore inspection boats, tourist boats, yacht club tenders and security vessels and more. The ability to operate efficiently on the water while reducing emissions and noise makes this technology a game-changer for the industry.”
Steber Hybrid Specification
- Length: 43ft (13.1m)
- Breadth: 15.6ft (4.7m)
- Max passengers: Up to 20 + 2 crew
- Cargo: Up to 2 tonnes
- Propulsion motors: Ampcontrol 2 x 300kW
- Onboard engine/generator: Commercial diesel/Ampcontrol generator – 350kW
- Onboard battery: Ampcontrol 300kW
- Aux power: Ampcontrol 15kVA
- Max speed: 24 knots
- Economic speed: 15 knots
- Planning mode Electric/Diesel/Hybrid
- Battery: 150kWh
- Fuel: 200 – 1000L
- Water: 100 L
Ampcontrol specialises in developing electrical, electronic and control solutions to support industrial transition to lower-emission operations. Its expertise includes electrification in mining, e-mobility solutions, power infrastructure, renewable energy innovations, lighting, protection systems and communication technologies.
