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The offshore wind industry is under increasing pressure to install larger and heavier turbines more efficiently. This means jack-up vessels need higher jacking capacities to support the increased loads safely. Traditionally, capacity is increased by scaling up the jacking system. GustoMSC took a different route, rethinking how loads are distributed within the rack and pinion systems that raise the vessel on its legs, to increase capacity within the same platform footprint. The result is asymmetrical Rack & Pinion (ASYM R&P) Technology.

Aron Charité, the mechanical engineer who came up with the concept and led its development, explains how the idea evolved into a validated technology.

‘The larger and heavier the jacking system, the fewer turbines and the less installation equipment the vessel can carry per trip, increasing transport costs,’ explains Aron. It also limits the vessels' flexibility for future projects. ‘We were trying to find a way to increase the capacity of a rack and pinion jacking system without simply making the entire system larger and heavier.’

Rethinking the standard

Rather than reinventing the technology, the idea was to get more capacity out of the same space, drive force, and materials. If successful, this could increase the amount of equipment the vessel can carry without adding weight. Aron’s previous experience at an independent gearbox repair company led him to question one part of the jacking system in particular: the gear teeth.

‘In that role, I saw an enormous variety of gear damage and became familiar with a wide range of technical solutions,’ he says. ‘I understood that the gear teeth were a critical point in the jacking system. The jacking system’s symmetrical tooth profile was designed to handle loads equally well in both directions, even though most of the load acts in only one: lifting the platform and holding it in place. I started to consider whether an asymmetrical tooth profile, optimized for the main load direction, could distribute the stresses more effectively, which would allow for heavier loads.’

Building confidence through analysis

Turning the idea into a workable design was far from straightforward. ‘Changing tooth geometry could affect the interaction between the rack and pinion, the load distribution, and the amount of sliding and wear,’ explains Aron. ‘We therefore needed simulations, controlled comparisons, and ultimately full-scale testing before we could have confidence in the concept.’

The team started small, simulating a single rack tooth. ‘The effects on the rack tooth had not yet been assessed at the level of detail we needed, so we introduced an additional comparison step: a symmetrical rack tooth with a different pressure angle that could roll against the same pinion tooth, under the same forces and operating conditions. That allowed us to isolate the effect of changing only the rack tooth geometry. Demonstrating that this could improve the stress distribution was an important early milestone, and it helped create a shared understanding among colleagues across the different engineering disciplines.’

At first, the team’s sole aim was to reduce the stresses in the teeth. But as the design evolved, the analyses produced an unexpected result. ‘In conventional asymmetrical gearing, the flank with the larger pressure angle is normally used for the primary load direction,’ says Aron. ‘Our analyses showed, however, that the smaller pressure angle produced a better stress balance in our application, which allowed us to file a patent application.’

Innovation through collaboration

The test campaign called for innovation of its own. MaxEdge, a computer and data acquisition system, continuously monitored and recorded key parameters, allowing the team to follow the test remotely and check that the values stayed within their defined ranges.

‘Real-time data processing allows us to investigate an event as soon as it occurs and identify whether it was related to the rack and pinion, the lubrication system, the hydraulics or another part of the test setup,’ explains Aron. ‘Combined with the test machine’s control and safety systems and the automated lubrication system, this allowed the test to run continuously, 24 hours a day, in a controlled and repeatable way, without constant manual intervention. The nozzle supplier also used the campaign to test new nozzle versions in a realistic environment.’

Performance and perspective

The results exceeded expectations, confirming that ASYM R&P performs as intended under representative operating conditions. The new geometry makes more efficient use of the force between the rack and pinion and allows the surrounding structure to be made lighter. In the validated design, this saves approximately 100 tones, leaving room for more turbines and installation equipment.

Behind these results lay another achievement. ‘I’m most proud of how we learned to make a complex engineering concept accessible and convincing to others,’ says Aron. ‘Once people understood that the drivetrain torque stayed the same while the new geometry produced a better stress balance and a higher jacking capacity, the development began to feel like a no-brainer. That clarity helped to convince both internal stakeholders and potential clients.’

Aron also reflects on what the journey taught him. ‘One of the main lessons is the importance of listening carefully to concerns from colleagues and other departments. Rather than dismissing those concerns, it is important to find out why they are being raised. Sometimes the best way forward is to introduce an intermediate step that allows everyone to learn together.’

Looking ahead

The development of ASYM R&P shows that even a proven technology whose tooth geometry had remained largely unchanged for decades can still be improved by questioning one of its fundamental design assumptions.

For the wider offshore wind industry, the potential is significant. ‘ASYM R&P Technology enables existing and future jack-up vessels to accommodate larger turbines more effectively,’ says Aron. ‘That gives vessel owners and operators more flexibility in how they prepare for and execute offshore wind projects, and can help reduce transportation and project costs. And this development is only the first step: the asymmetric tooth profile creates additional design freedom for further improvements in load transfer, stresses, wear and the surrounding structure. Testing of these further improvements has already begun.’