DISCOVER Magazine #7

On the road again

Published in category: Offshore Wind

An update from Damen’s  Fender Research and Development team 

First and foremost, Damen is well known as a builder of ships. But what is less known by many is the extent of the company’s R&D activities. These are concentrated efforts by teams of experts that are constantly working towards safer, more efficient vessels with longer, more productive lifespans.

Here, we meet up with Design and Proposal Engineer Brian Mewis and Project Engineer Kees van Oosten from Damen’s R&D team. Their task? To develop the optimum bow fender for Damen’s Fast Crew Supplier 2610 – the vessel that’s fast becoming the industry standard for the offshore wind industry. Keeping in mind safe, efficient and cost effective offshore access. “As yet no fender manufacturer can meet the tough demands of the larger vessels in the offshore wind market,” opens Mr Van Oosten. “We are, in collaboration with a number of external specialists, picking up the issue ourselves.”

Controlled testing

“We perform our own in-house testing here in Gorinchem – that’s on a 1:5 scale,” explains Mr Mewis. “We simulate vessel impact against a boat landing platform mounted on a turbine foundation structure by using a 600 kg weight on a swing (see figure 1).

Systematic_measurements _with_various_fenders_and_foam_compositions

Figure 1: Systematic measurements with various fenders and foam compositions, carried out by means of the Damen test setup, giving insight in impact characteristics.

By pulling the swing further back we can simulate higher impact forces.” The team also measures the vertical forces involved in a vessel ‘landing’ – these are measured in friction tests (see figure 2). The amount of friction being relative to the forward thrust of the vessel.


Figure 2: Measurements with different load conditions giving insight in the friction and deformation of different materials.

The testing process is not limited to the controlled and safe environment of landbased facilities though. “For the last 18 months we have been collecting data with measurement devices placed on one of our client’s vessels,” informs Mr Van Oosten. “We have measured every impact upon the fender and coupled this with information about wave height, wind, current as well as the speed and direction of impact.” These data have proved invaluable in the development process. “We now know exactly what happens and when it happens. This has really helped us define the design criteria which we converted into a new innovative design.”

Customer feedback

The stream of incoming information doesn’t stop there. “We also get a lot of customer feedback through our Services Department,” continues Mr Mewis. “When a customer orders a new fender, we of course want to know what happened to the old one. Crushed and deformed fenders are one of the main problems.”

The team has experienced some difficulties in maintaining a steady supply chain for fenders. “This is a dynamic development process. We need to implement the knowledge that we gain today in tomorrow’s fenders. As soon as we have developed the optimum fender, we will be able to order for stock,” adds Mr Mewis.

Further examples of customers’ input concern the importance of colour (especially important in low-light conditions) and the variation of friction during use (and therefore decreased vessel stability) between vessel and turbine. Naturally, Damen couples this valuable, real-life, information with its own in-house data.

State of the market

Looking to the future, the team is ready for the next phase of the R&D programme. “This market is constantly changing. The demands are getting tougher with bigger vessels going further out to sea. Customers want a large operational window, with minimum downtime. Our next step is testing the new developed fender – this will give us a comprehensive insight to our work so far,” concludes Mr Mewis. Watch this space for the next results.

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