Swede Ship Marine AB – for Marstrands Hamn, Kungälvs kommun

Quiet hydraulics for an electrified ferry

As part of the electrification of M/F Lasse Maja III, HydTec replaced an ageing, continuously running hydraulic power system with a demand-driven solution. The new system supports the vessel’s vehicle ramps and gates while improving system control, serviceability and compatibility with the ferry’s new electrical architecture.

Challenge:

The existing hydraulic power unit ran continuously, creating unnecessary noise and energy consumption. Electrification reduced the vessel’s general machinery noise, making the hydraulic system more noticeable, while incomplete legacy documentation complicated a safe retrofit.

Delivery

HydTec surveyed the existing installation, recreated the hydraulic documentation and engineered a new power unit with variable-speed pump control, monitoring and redundancy. The scope included manufacturing, workshop testing, onboard piping, integration support, commissioning and hydraulic acceptance testing.

Results

The new hydraulic system completed the defined site acceptance checks, with all recorded hydraulic tests fulfilled and no leakage from the power unit. Demand-driven operation allows the pumps to remain at rest until hydraulic power is required, supporting quieter and more energy-conscious ferry operation.

GO TO RESULTS

A blue and white ferry with the swedish word LINFÄRJA is shown docking to land with water, other boats, and a blue sky in the background.

Initiation

Two men inspecting industrial machinery and piping inside a confined technical space, with one holding a tablet.

Initial assessment

M/F Lasse Maja III operates for Marstrands Hamn and was being converted to a new electrical architecture. Its existing hydraulic system served two vehicle ramps and associated gate functions but relied on older technology and continuously running electric motors. The retrofit therefore had to preserve the vessel’s operational functions while reducing unnecessary running time, supporting the available electrical supply and retaining redundancy and emergency operating capability.

Communication

HydTec coordinated the hydraulic scope with Swede Ship Marine, the end customer and METS, which was involved in the electrical control system. The project required clear interface definitions, I/O information, a functional description and updated hydraulic documentation. Because the existing drawings did not fully match the installation, HydTec also recreated the as-built system to provide a reliable basis for engineering, commissioning and future service.

Process

Technical drawing sheet showing multiple orthographic views and an isometric rendering of a HydTec hydraulic power unit with dimensions, on a white background with grid lines.

Design & Engineering

The engineering started with an onboard survey and verification of actual operating conditions. HydTec evaluated alternative pump and power-supply concepts before selecting a two-pump, variable-speed architecture compatible with the vessel’s electrical system.

The pumps are controlled according to hydraulic demand rather than running continuously. Digital commands from the bridge are processed by the vessel’s control system, while variable-frequency drives regulate motor speed and hydraulic flow. Soft acceleration and deceleration were incorporated to limit pressure transients, noise and mechanical stress.

The design also addressed redundancy, monitoring, interlocking between ramp and gate functions, emergency operation, oil handling and future service access. During the project, the hydraulic drawings were revised to reflect the actual onboard installation, and several legacy safety and functional details were reviewed together with the yard and the control-system partner.

Manufacturing

HydTec manufactured and assembled the new hydraulic power unit around a purpose-built reservoir and a compact dual-pump arrangement. The unit included pumps, motors, filtration, instrumentation, control interfaces and provisions for safe filling and draining.

The equipment was assembled and function-tested before delivery. HydTec also prepared the hydraulic and electrical interface documentation required by the yard, including foundation dimensions, I/O information and the functional description. This reduced uncertainty during installation and allowed the mechanical, hydraulic and electrical work to be coordinated before commissioning onboard.

A HydTec industrial fluid power pump system with two black motors and a blue metal base, packaged inside a wooden shipping crate.

Results

A large blue and dark gray boat or ferry under construction is parked outdoors beside a building and crane, with scaffolding around the hull. A person stands on the wet pavement in the foreground, and construction equipment are visible.

Installation & commissioning

The installation required new hydraulic piping from the power unit to the existing forward and aft valve assemblies in a restricted below-deck space. HydTec planned and installed the pipe routes while Swede Ship supported the vessel-side structural work. Existing valve assemblies were cleaned, checked and adapted before being reconnected to the new system.

HydTec then supported commissioning and hydraulic testing onboard. The site acceptance record shows that the defined checks for fastening, motor rotation, air bleeding, function, leakage, abnormal noise, heat, oil level and maximum pressure were fulfilled. At that stage, the hydraulic functions were tested manually because the final control system was not yet ready.

Follow up & support

After initial commissioning, HydTec continued to support the yard, METS and the end customer with adjustments to gate synchronisation and end-position behaviour. The new demand-driven system behaved differently from the previous continuously pressurised installation, so hydraulic settings and electrical control parameters were refined together. HydTec also evaluated additional improvements for emergency operation, pressure protection and accumulator service.

Quiet hydraulics for an electrified ferry