Interview Tillen: Interchangeable and transferable knowledge is key

When a wind farm is being built the news reports concerning it mention mainly only the major parties involved. Behind these large companies, however, is a chain of suppliers, each of which has made an important contribution to the project in its own way. Tillen B.V. is such a company.

From its premises in De Meern, near Utrecht, the Dutch mechanical and structural engineering company Tillen provides lifting and handling solutions for various sectors, including the wind sector. The company celebrated its 15th anniversary last year. Windpowernl visited the company and spoke with owner Ivo van Donselaar about how the company has developed from a side business to an established engineering specialist that has already provided many large companies with specialist lifting and handling tools and/or designs and advice.


Tillen bv was founded in 2007 by Van Donselaar, Tim Huele and Roberto Rotgans. At the time they worked in the evenings, weekends and holidays, as they still had full-time jobs. In the years that followed, the men built up the company’s name to such an extent that the work was starting to take up more and more of their time. In 2011, the turning point was reached: they had to make a choice on how to proceed. Van Donselaar didn’t feel like continuing to do it on the side, and the other two partners, for various reasons, didn’t feel like committing themselves full- time. In late 2011, Van Donselaar bought out the other partners and continued, initially from home, on his own, having already secured a work supply for several days a week for a year. After six months, he rented an office and got help from an intern. More employees soon followed, including Tim, his previous partner.

Useful tools for lifting and handling optimisation

Tillen mainly designs on behalf of a customer. These customers are active in different segments but all from a lifting and handling technology background. Most of the designs are used indirectly or directly in the offshore wind sector, says Van Donselaar. Products range from secondary steelwork to handy tools for ship and crane builders and cable installation companies, as well as the somewhat larger constructions like cable carousels and baskets and offshore access systems. Sometimes this involves completely new designs and other times optimisation of existing tools.

In one case, the design has since become a product. It concerns micro-shelters and trailers for a client supplying bird radar systems. The micro-shelters ensure that the radar systems can be transported efficiently, easily installed on site, and then, during use in all weather conditions, provide protection for the electrics and air conditioning that power the radar system and keep it functioning properly.

Tillen has since been able to supply 11 units of these. The company is also working on an entirely proprietary design. This involves a modular tagline system. Van Donselaar: “This is a development where we can temporarily attach a pair of hoisting winches in the mast foot with a beam, so you can stabilise the load but also steer it in two directions. With this improved control you can safely install loads at higher wind speeds and thus improving installation lead time. The advantage is that you don’t have to weld anything to the crane structure, and so no additional certification is needed. Moreover, the system is light and compact. When the project is finished, you also remove the components in no time.”

For their activities, Tillen has three main teams: a team of four design engineers, a team of five structural engineers, and a team of four CAD engineers for detailed design and drafting. “From the moment the assignment is accepted, we first start thinking about the concept and discuss the approach together. Then we evaluate whether the concept is matching the intended function and make any further adjustments if required. Next, the designers assess what is required to make the construction robust and fit for purpose. They then outline the functions while structural engineers work on the calculations in the background. Eventually, the design is worked out in drawings. For third parties, we often also do an independent, engineering strength calculation. In those cases, only our calculation team are working on it.”

All photos: © Tillen

Loyal employees

Van Donselaar aims to employ people on a long-term basis. So far, he is succeeding quite well. The intern who helped him in the beginning then became a permanent employee and remained loyal to the company until last year. Most of the people found Tillen themselves, came in through the network or, like the first intern, came in via a graduation internship and stayed. This is a deliberate choice explains van Donselaar. “There is simply a shortage, it would be a shame if you have to let someone go who suits your business activity. So, you need to invest in people.”

In addition, the type of work also plays a role, says Van Donselaar. Self-employed people often have sufficient technical knowledge and can, in addition, be updated on the work floor. However, everything must be done in a similar way so that it is easily interchangeable and transferable, because that is ultimately the goal. “Our working method is really not that spectacular but we have to be consistent,” he explains, “Each project is set up in such a way that we can be flexible with scaling in our dimensions for quite a long time. That way we can continue with the design while simultaneously making the calculations. But we all have to use the same techniques. So those models are a bit more complex anyway, the way we set them up. Then it is preferable to have people stay for the long term. When we get young freshly graduated people, we place them first in the group working on models and drawings. Precisely to master that method. At the same time, they already see a lot of constructions and details passing by and can see how we work, until, at some point, they can do it themselves.”

And that is where the challenge lies with self-employed people. Van Donselaar: “A person has been trained and knows all the ins and outs of the project, but then the time comes when only simple work remains which can also be handled internally. Then you can no longer spend the costs on the project. If you then cannot continue with the person on another project, the logical step is often to say goodbye to each other. When this person leaves, they take with them the experience and knowledge about the project they worked on.” According to Van Donselaar, it happens with some regularity that after one or two years, a customer still has a question about a project, for instance to continue working on the design. At that moment you no longer have that amount of experience and knowledge to hand.

Despite having been quite successful so far in getting the right people, this has become increasingly difficult, Van Donselaar also observes. Particularly young people are now simply waiting to be approached. After all, the sought-after technically skilled people already know during their studies that they will find a job. They are already often approached there, or at job fairs, by companies but also mostly by recruiters and large secondment agencies. In doing so, Van Donselaar notices that young people who have just graduated tend to make their choice based on the best offer. Questions like, where do I feel most at home, where do I think I can grow, which company’s products or activities appeal to me most, often play a secondary role. He also understands this, as studying is also increasingly expensive these days, but he does think it is a shame that young people make important decisions on a few Euros.

“That’s a little less the case with the more experienced people but at some point they themselves know where they need to be. That makes it harder to find them.You then have to go and call them yourself and hopefully you get lucky,” Van Donselaar says.

Open, flat culture

How does Tillen manage to keep its employees engaged? Van Donselaar: “We try to create a very open flat culture, where everyone can always address each other. Moreover, we talk with our people several times a year. In these talks, we evaluate where someone stands and where he or she wants to go, among other things; after all, that can change over time. We have also drawn up a job matrix and a competence matrix. If someone aspires to a different job, they can immediately see which competencies they need to meet and where they might have room for improvement.”

In doing so, Tillen also tries to be a flexible company for its employees. Before the COVID-19 period, Tillen was already facilitating working from home. That is not for everyone but fortunately Van Donselaar has nothing to complain about his employees’ commitment and discipline. Rather, he sometimes must slow them down not to do too much. “The great thing is that they really work together well. They also seek each other out outside work, for example for a BBQ or to play sports,” he proudly tells.Yet another example of this flexible attitude is when a colleague wanted to go on a two-month round trip with his father and wanted to take unpaid leave for it. But sometimes someone just gets a great offer elsewhere. In that case, Van Donselaar still looks together at the possibilities for possible advancement within Tillen. However, the conclusion is sometimes that you have to let someone go.

Long-term cooperation with partners

The long-term collaborations are also reflected in the relationships with external partners. Tillen does not build anything in- house themselves, nor is that the ambition, Van Donselaar says. Although, he would like to have his own workshop for small orders. Here they could have small constructions built and inspected, and clients could come over to watch the progress. For the large constructions, however, Tillen enjoys the freedom to choose by whom and where they are built. This way, it does not always depend on the price and availability of one company. Moreover, each company with whom they work has its own specialism.

Tillen has been working with a number of companies for many years now. On the day of the interview, we were invited to join on a visit to one of those companies, metal construction specialist Voscon BV in Vlaardingen. This company builds the housings of the aforementioned micro- shelters for the radar systems for Tillen. Van Donselaar: “Voscon is very good at this kind of construction. But we now also have a number of tenders running for several thousand-tonne lifting beams and lifting frames.You need a different supplier for those kinds of constructions.”

Working with multiple partners also has the advantage that you can switch faster if you need to carry out ad hoc assignments. And that happens with some regularity. “This market segment is fairly ad hoc.
Lifting and hoisting is very often a neglected child. A company has arranged an object and a ship to transport it. And then they suddenly realise that the object also needs to be brought on board and secured. Then they come to us, for example. When that happens, it’s nice to have partners who can act swiftly,” Van Donselaar elaborates.

Future plans

Finally, where does Van Donselaar see Tillen standing in a few years’ time? “At one point we went through a Business Savvy programme with OpenBook Works: where are we now, what do you think the company is known for, and where do you want to go? We discussed this first with the team leaders and then with the team members. Everyone has their own personal ambitions, of course, but we all came up with overlapping ambitions: we want to grow in knowledge and size, but the atmosphere must remain the same – we want to continue to enjoy going to work. So not much bigger than 25 to 30 people. We want to be seen as specialists, with just slightly bigger projects in terms of complexity and size, and maybe we will have our own workshop. What is especially nice to see is that everyone wants to work for each other, for the project, and to grow and learn – that is really a great thing. It is also quite unique: you are working in an informal setting but in a hugely professional way.” •

This article appeared in the spring 2023 edition of Windpowernl magazine. Read the full magazine here.

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