Yellowstone | Successful partnership between Belgian maritime partners

Conversion in service of strategic offshore wind market

In 2018, DEME decided to investigate how it could expand its capacity in the subsea rock placement market in the short term, focusing on the fastgrowing offshore wind sector in the US, where wind farms are being constructed at sea at a rapid pace. “With a view to a short time-to-market, the decision was made in 2021 to convert an existing vessel,” says Henk, who at the time of the interview is on board the Yellowstone for the final offshore trials of the mission equipment.

The search for a vessel: concept study by Maridea

Maridea, a subsidiary of MULTI. engineering, was tasked with a concept study to determine which types of existing vessels were suitable for conversion, technically, financially and in terms of timing.

After several cycles in which the concept was further refined and after DEME had inspected a number of suitable vessels, the decision was made in 2021 to purchase a bulk carrier. At that point, Maridea started with the basic design for the rock placement vessel in progress. Tim: “Conversions of this size were new for both DEME and for us. But thanks to 3D scans of the technical areas and the 3D models we made of the ship, our teams succeeded in delivering a solid basic design.”
Ruben: “That’s right, MULTI.engineering was on board before and after the purchase of the ship to measure and scan. Also during the further course of the process, I found it to be a real plus to be able to count on their support, not only here, but also on-site.

Challenges during detailed engineering

MULTI.engineering then carried out the detailed engineering, directly on behalf of the shipyard appointed by DEME, PaxOcean in Singapore.
Tim: “That was a challenging period for a number of reasons. In the beginning, it was especially important to coordinate what the shipyard and DEME expected of us. Thanks to continuous consultation and close cooperation with DEME and PaxOcean, we were soon on the same wavelength. The project grew larger than anticipated. At peak times, more than sixty FTEs from MULTI.engineering were involved per week, good for around ten thousand engineering hours per month.”
The size of the project was also unprecedented for Henk. “A dozen DEME engineers were involved in the basic design. During the conversion, that number doubled, and at peak times, around forty DEME employees were on the project at the same time, most of them on-site. Normally, as a project manager, I take care of a large part of the engineering coordination, but there was no room for that now. Especially because we supplied an exceptionally large amount of equipment to the shipyard ourselves for this project.

Those components often had to be installed while the surrounding steel structure was still being worked on at the shipyard. Soon after the start of the project, dozens of external partners were involved. Coordinating and managing that alone was a full-time job.”
Ruben therefore took on the engineering coordination. “This was done in close consultation with the dedicated engineers for things like mission equipment and electrical & automation.”

Proud of the end result

A final difficulty was that the engineering phase had to run almost parallel to production due to the tight deadlines.
Ruben: “That’s typical for a conversion, but far from ideal. It means responding quickly, overlaying 3D models and looking for solutions together with partners. During an on-site conversion, you’re constantly encountering things that are either not on the design drawings or deviate slightly from them in terms of what’s actually been built, but you simply have less flexibility to make changes.”
According to Henk, that’s one of the lessons that can be learned from this project: it’s best to manage a ship for a while and become well-acquainted with it before you start the conversion.
“It’s also a really complex ship, where everything is designed to be very closely combined. Despite a few clashes, all the new constructions and equipment fit together well.

Of course, it took a lot of time, energy and consultation, but the end result is impressive. What I remember most about the intensive collaboration with Maridea/MULTI.engineering is the open communication and the fact that they respond quickly.”
Ruben: “I especially appreciated the short lines of communication. All their engineers were easily accessible to work together to find the best possible solutions.”
Tim: “It was a large and often hectic project. But everyone was in the same situation and did everything they could to make it a success. I continue to find it particularly impressive that two Belgian companies that are practically neighbours have achieved such a great result with a conversion of unprecedented size. That’s something we can be really proud of.