Permanent magnet technology: a decade of smarter power at sea

When engineers at The Switch began exploring how to apply their permanent magnet know-how from the wind industry to marine propulsion systems, the concept was untested – and the challenges were many. Could a direct-drive generator designed for slow, steady rotation at sea perform as reliably as one built for a wind turbine on land?

What followed was a phase of learning and adapting existing technology to meet the demanding conditions of marine operation – a path that proved far less straightforward than initially expected. 

A new era begins
The first PM shaft generator systems, certified and installed in 2015, marked the start of a new era. By utilizing a vessel’s more efficient two-stroke main engine rather than fuel-hungry four-stroke gensets, the technology delivered immediate fuel savings. However, the real power of PM technology lies in its simplicity. Unlike conventional electrically excited synchronous machines, PM machines don’t need external energy to establish the magnetic field, further improving efficiency, particularly at low speeds.

For shipowners, this also meant a smaller environmental footprint – an advantage that would soon make the technology hard to ignore. 

Efficiency and sustainability come together
In practice, the better fuel economy of PM shaft generators can translate into savings of up to USD 2 million over a typical vessel lifetime. But the benefits extend beyond operational costs. 

As the IMO rolled out stricter efficiency and emissions targets, PM shaft generators have offered a practical way for shipowners to operate more sustainably. The rapid growth of orders since 2020 highlights how the technology has evolved from a niche innovation into a preferred solution for modern ship power systems.

A decade of reliability and growth
Today, The Switch has delivered over 300 machines to vessels worldwide, built by more than 40 shipyards. The fleet has accumulated more than 5 million operating hours – with zero disruption to vessel operations – proving the reliability of this once-radical idea.

The company’s ongoing developments, such as new machine models and enhanced testing capabilities, have continued to strengthen performance and confidence in the technology.

Reflecting on progress
Over the past ten years, PM shaft generators have moved from a concept to a proven technology, delivering both fuel savings and reduced emissions across hundreds of vessels worldwide. As orders continue to grow, The Switch’s experience demonstrates how innovation, combined with careful engineering, can transform the way ships operate at sea. But what does it actually take to bring a new solution into a conservative industry?

Discover the full story behind The Switch’s journey in marine shaft generators in our Talking Point: “10 years in the shaft generator business – A short review.”