Deck carriers: new market, alternative or the future?

Deck carriers have been around for many years, moving hull blocks between shipyards in South Korea and China. Now the wind industry has brought plenty of new opportunities prompting a number of carriers to invest in this ship type. 

“I think we were the front runners in Europe,” Andreas Rolner, co-founder and Managing Director of United Heavy Lift, said in a recent interview with Project Cargo Journal, when speaking of the deployment of this ship type for the transport of wind turbine components. The company has taken over the module carrier Vestvind (Vir Varenya) built in 2016 and brought the vessel into the European market.  “At the time we could already see the growing wind market for large foundations and we could compete with the tug and barge. Insurance-wise, they are a lot cheaper, they are a ship type, twice as fast as a barge and just in general, a safer type of transport, and we proved the concept back then,” Rolner said.

The success of the concept prompted the company to build two deck carriers of its own design for a long-term contract with Vestas and to start its cooperation with Guangzhou Salvage. The cooperation has run to an end in mid-2023. However, at the start of 2024, the company formed a new cooperation with Dongbang Transport Logistics (Dongbang), signing a Memorandum of Understanding (MoU) to combine their expertise in heavy lift vessels and heavy transport vessels.

But it is not just the United Heavy Lift that is exploiting the advantages of deck carriers for the transport of wind turbine components.

Growing interest

Recently, a significant number of carriers have started showing interest in this vessel type, especially for the transport of ever-growing wind turbine components. “I actually think this is a completely new market,” Rolner said. In terms of intake capacity, these types of vessels are pretty much unbeatable, which not only spurred the interest but also the deployment of these vessels.

“They simply have the deck space to take it on,” Rolner said. “Whether it is foundations, jackets for offshore wind, or monopiles they are unbeatable and often are the only option out there to transport these components,” he said.

At the start of 2023, DNV responded to the growing demand for this specialised type of vessel and created a new class notation for deck carriers to accelerate the classification of this important emerging ship type.

Read more: Embracing biofuels is the practical option on the path to decarbonisation

“The Deck Carrier ship type notation defines specific requirements for these vessels,” explains Jan Rüde, Ship Type Expert MPV, Hull Structure and Outfitting at DNV. “It covers typical features, such as a front deckhouse, a large, open deck space, the absence of a cargo hold, and strong hull and deck reinforcements.”

Jost Bergmann, Business Director MPV & General Cargo Ships at DNV, further noted that deck carriers themselves offer a cost-effective option for project cargo too large or heavy for traditional heavy-lift vessels. Their simple design allows for lower construction costs, making them a valuable addition to a heavy-lift operator’s fleet.

The drawbacks

With the fact that a deck carrier is simpler in design compared to a traditional multipurpose heavy-lift vessel, why isn’t there a widespread ordering spree?

“There are specific constraints for operation when loaded, such as acceleration limits, maximum wave height and weather conditions,” Rüde said. Additionally, deck carriers typically sail at lower speeds than traditional heavy-lift vessels, resulting in longer transit times. The increased acceleration forces experienced by cargo during transport can also subject it to greater stress compared to heavy-lift vessels.

Going up in size, and adding the semi-submersible feature to this type of vessel means the vessels become more thirsty and a lot more expensive, hampering the attractiveness for carriers. However, SAL Heavy Lift recently chartered two modern semi-submersible deck carriers Zhong Ren 121 and Zhong Ren 122 on a long-term basis, showing that there is demand even for these types of vessels. “The demands and requirements of our clients – especially in the offshore wind sector – are becoming increasingly extensive and complex. These two new additions give us the opportunity to meet and possibly even exceed these requirements. Customers will benefit from more choices and better solutions,” Martin Harren, CEO of SAL Heavy Lift and the Harren Group said.

Another drawback according to Rolner is the fact that there are not too many sister vessels in the segment. “Typically you will have two or maybe even a one-off vessel. So if there is a delay on a project and you need to have a second vessel or a replacement ship, often you have to redo the complete engineering because it is a completely different vessel,” Rolner said. “You may think, well it is the same ship, just a deck carrier, what is the difference, but every vessel is unique.”

The heavy-lift multipurpose side offers more redundancy. United Heavy Lift’s F900 fleet for instance offers 19 identical vessels. So the deck carrier is a very capable alternative to the traditional heavy-lift MPP fleet and carriers are investing in this type of vessel. Earlier this year, Mitsui O.S.K. Lines’ unit, MOL Drybulk, placed an order at the Chinese Taizhou Sanfu Ship Engineering yard for the construction of a coastal deck carrier which will mainly be used to transport components for offshore wind turbine foundation components.