Mammoet’s Rønne Cranes Feed Svanen Without a Quay Rebuild

Mammoet’s two MTC1600 cranes lowered Windanker’s 2,150-tonne monopiles into the sea at Rønne without reinforcing the quay. Van Oord’s installation vessel Svanen stayed on station in the German Baltic and took each pile from tugs. The same pair of cranes later ran a 78-pile line at that port for Baltic Power.

Two Cranes Were Built to Match Svanen

A crawler big enough to equal the vessel would have needed more yard space than Rønne could spare, and it would have punched the quay too hard. Mammoet, the Dutch heavy-lift firm, built a different machine: the MTC1600 terminal crane, rated at 1,600 tonnes on its own and 3,200 tonnes as a pair.

Stefan de Vries, Mammoet’s project manager on the job, said the firm wrote a new crane design because monopile foundations were growing faster than the kit around them. The first plan was a combined 2,800 tonnes. His team then asked to match Svanen so the shore limit and the ship limit were the same number, a 400-tonne increase.

Initially, it was planned that the cranes would lift 2,800 tonnes, but we suggested their maximum capacity match that of the Svanen, to ensure consistent limits across the project. So, we increased their combined lift capacity to 3,200 tonnes.

Stefan de Vries, Project Manager, Mammoet

Ballast on each MTC sits farther from the boom’s pivot than it does on a large crawler, so ground pressure falls and the load spreads. That is why Mammoet could say no civil work to reinforce the quay was required. Crane lifting also beat a roll-on, roll-off cycle, which would have brought Svanen alongside and left it idle while the deck was ballasted.

The 21 Piles Came in Seven Shipments

Windanker is Iberdrola’s 315 MW farm in the German Baltic, about 45 kilometres northeast of Rügen, sized by Van Oord to supply some 315,000 households. The Dutch marine contractor installed all 21 Windanker monopiles by 4 December 2025, calling them the largest it had put in the seabed.

The units were made in Spain by Navantia Seanergies and Windar Renovables and shipped to Rønne in seven batches, three piles per voyage. Mammoet recorded the heaviest at 2,150 tonnes and about 87 metres long. Van Oord put the diameter at 10 metres. Ninety axle lines of self-propelled modular transporters, fitted with Mammoet’s XXL monopile transport system, lifted each tube off its seagoing grillage and drove it into the yard.

THREE BALTIC CAMPAIGNS AT RØNNE

Those first two campaigns put 99 monopiles through the same Danish quay with the same crane pair. Baltica 2 then added a 111-pile scope on the same waterfront.

Crawler Cranes Would Have Forced a Quay Rebuild

The bottleneck on XXL foundations is rarely the open sea. It is a port that was never designed for a 2,150-tonne tube and a crawler whose tracks would overload the slab. Rønne had the berth and the storage land. It did not have a reinforced heavy-lift pad for that class of crawler.

Mammoet’s answer was to stop treating the quay as a ship berth and start treating it as a lift. After storage, an LR1750 crawler only had to fit plugs in both ends so each pile would float. The transporters then rolled the sealed tube in front of the two MTC1600s, which set it in the water. Tugs towed it to Svanen, which was already in the field with a clear hook.

That split of labour is the cheap part of the chain. The expensive asset is the installation vessel. Every hour it spends waiting on a quay is an hour it is not driving steel into the Baltic. Feeding it from the water, from a port that did not need a rebuild, is how Windanker’s piles actually moved.

How a Monopile Leaves Rønne

The shore sequence is the same idea on every campaign, with small changes in axle count and bund material. Windanker used sand bunds; Baltic Power used gravel. The XXL saddles unfold hydraulically to cradle the tube, then the extra jacking stroke drops it into a deeper indent so the bund can be lower and shorter.

THE SHORE SEQUENCE

• Lift off the ship: SPMT axle lines take the pile off its grillage and drive it into the yard.
• Park on bunds: Extra stroke lets the tube sit in a deeper indent while using less sand or gravel.
• Seal both ends: Plugs go in at a capping station, then the pile is tested so it will float.
• Lower into the harbour: Two MTC1600 cranes put the sealed tube in the water at the quay.
• Tow to the vessel: Tugs run it out to Svanen, which stays on the field instead of coming alongside.

On Baltic Power, Mammoet said that method can turn any quay into a heavy lift terminal for load-in and load-out. The claim is operational, not architectural. The cranes arrive, lift, and leave. The quay does not have to be rebuilt around them.

Baltic Power Turned the Setup Into a Line

Windanker was 21 piles. Baltic Power was the stress test: 78 monopiles up to 1,680 tonnes, 86.3 metres long and 9.1 metres across, barged in threes to Rønne and unloaded on 78 axle lines, three sets of 26. Mammoet’s case on that job is the first time it describes the MTC1600 on site as a pair working like a factory.

The foundations went 23 kilometres offshore from the Polish towns of Choczewo and Łeba. Orlen and Northland Power’s farm is rated at 4 TWh a year, about 3 percent of Poland’s electricity demand. Transition pieces were marshalled in the same port, lifted with an LR1800 crawler rather than the MTC pair.

Mid-project, the shore team changed how barges were emptied. The MTC1600s were lifting piles so cleanly that they took over unloading from the SPMTs. Direct lifts meant less time fully ballasting each barge, because the weight no longer had to roll across the deck. That is the production-line proof the Windanker kit was not a one-off stunt for a 21-pile German farm.

Jaap van der Riet, Mammoet’s commercial manager, tied the shore cranes to the ship from the first talks. “When we were in discussions with Van Oord, it wanted to upgrade the Svanen to have a 3,000t lifting capacity, so the vessel could install XXL monopiles in the Baltics,” he said. “To further support that, we said we would develop cranes and systems that matched this capacity.”

Svanen’s Taller Gantry Set the Lift Limit

The vessel and the quay were redesigned as one system, even though the work sat in different yards. On 11 December 2023 Van Oord said it would extended Svanen’s gantry by 25 metres, with a 1,200-tonne A-frame section that took the ship to 125 metres tall. The same programme was meant to raise hook capacity from 3,000 tonnes toward 4,500 tonnes, with a stronger gripper and room for a larger hammer. The rebuilt Svanen was due back in the third quarter of 2024. Low draught was the Baltic reason for keeping this hull rather than replacing it.

Those three lift numbers are not the same thing. Van Oord’s 3,000-to-4,500-tonne programme is the vessel. The 3,000-tonne figure van der Riet cited is what Van Oord wanted on the hook for Baltic XXL piles. The 3,200-tonne pair on the quay is the shore match Mammoet actually built. Windanker’s 2,150-tonne units sat inside all three.

FROM SHIP REFIT TO ELECTRIC YARD

1. 11 December 2023: Van Oord announces the Svanen gantry, hook, gripper and hammer upgrade.
2. 2024: Mammoet’s XXL monopile transport system debuts; the rebuilt Svanen is due back in the third quarter.
3. 4 December 2025: Van Oord completes all 21 Windanker monopiles in the German Baltic.
4. June 2026: Mammoet publishes the Baltic Power marshaling case, 78 piles on the same Rønne crane pair.
5. 24 September 2026: An electric SPMT trial moves a 1,700-tonne Baltica 2 pile 815 metres at Rønne.

Mammoet had already fitted Svanen’s new A-frame in 2024. The marshaling gear on the quay is the land half of that refit.

Electric Transporters Are Already on That Yard

The next campaign at Rønne is Baltica 2, the Ørsted and PGE farm off Poland. Mammoet’s scope with Van Oord covers 111 monopiles of 1,700 tonnes each. In September 2026 the firm ran what it called the first electric-powered monopile marshaling move in live conditions: 815 metres on three electric power packs driving three 26-axle SPMT sets, finished without a recharge.

For a layout like Baltica 2, Mammoet put the diesel saving at 25,000 to 30,000 litres, or about 70 tonnes of carbon dioxide. The MTC1600s on that job have power packs that can take batteries or a grid feed, and they can run at limited capacity from an SPMT electric pack if shore power is short. The cranes still drop next-generation piles straight into the water, which also cuts the ballast work that comes with a roll-on load-out.

Rønne itself has been pouring concrete on a separate track. Phase 3 works in 2025 added more than 100,000 square metres of project space and a 280-metre quay, and the port said that package doubled how many offshore wind shipments it can handle at once. That is a harbour expansion. It is not the crawler pad Mammoet refused to build. The cranes still earn their keep by keeping ground pressure down on whatever berth they are given.

The piles Iberdrola ordered as 21 monopiles at the Fene shipyard are now in the German seabed. The machine that put them in the water is still on the same Danish quay, feeding the next Baltic farms, including one trial already run on batteries.

Frequently Asked Questions

When Did Mammoet’s XXL Monopile Transport System First Appear?

Mammoet’s XXL monopile transport system debuted in 2024, a year before the Windanker marshaling run at Rønne. Foldable hydraulic saddles and jacking spacers are the core of it, and the Baltic Power job used an extra 0.6 metres of stroke so larger tubes could sit in deeper bunds without a taller gravel pile.

Who Built the Windanker Monopiles and Which Turbines Sit on Them?

Navantia Seanergies and Windar Renovables built the 21 foundations at their joint factory in Fene, in A Coruña, Spain, under a 2024 order that was the alliance’s second monopile contract for Iberdrola and its fourth of that type. New 15 MW turbines were specified for those piles, with Windanker due to come online in 2026 as part of Iberdrola’s Baltic Hub.

How Far Is the Windanker Site From Land?

Van Oord places Windanker in the German Baltic about 45 kilometres northeast of the island of Rügen. The marshaling port is Rønne on Bornholm, so each sealed pile still had a tug run from a Danish quay to a German field after the MTC1600s put it in the water.

Did Rønne Expand the Port While These Piles Were Moving?

Yes, but on a separate civil programme. Phase 3 of the port’s own works, finished in 2025, added more than 100,000 square metres of project space, a 280-metre quay and a new roll-on ramp, and the harbour said that package doubled concurrent offshore wind shipments. Mammoet’s claim of no quay reinforcement refers to crawler-scale ground works for the MTC1600s, not to that wider expansion.

Where Were the MTC1600 Cranes Load-Tested?

On Baltic Power, load testing ran at a quieter corner of the Rønne site so the live quay could keep working, after which each crane was moved to the lift area in one piece. That is the practical difference from a large crawler, which has to be built up on a prepared pad before it can pick a 1,600-tonne load.