Posted on March 6, 2024
The development of Damen’s Offshore Carrier vessel (DOC) was sparked by a desire to increase efficiency. The concept was born when Damen hit upon the idea of combining the tug and pontoon conventionally used in offshore transportation, in a single vessel.
Almost immediately, a range of advantages presented themselves. Such a vessel would significantly widen the weather window for offshore operations and be able to maintain better speeds and course stability. It would also offer considerably reduced fuel consumption.
The vessel would feature a hull shape that would reduce slamming to a minimum and a large, unobstructed deck space for transporting large, heavy offshore equipment. As Damen began to develop the DOC design, a further benefit became apparent; flexibility.
Versatile vessel
It’s hard to imagine a platform as versatile as the DOC. The basic, standard design can be tailored to meet a wide range of specific requirement and put to use in diverse operations across multiple markets.
Examples include the transportation of cargo, installation, RoRo, pipelaying, rock dumping, deep sea mining, and other specific mission equipment. It was the platform’s suitability to cable laying, however, that first caught the attention of Damen’s clients, as the company’s DOC Product Specialist and Naval Architect Rolf Sluman explains.
“Van Oord approached us when they were looking to build a cable lay vessel. They were interested in the DOC because we were already at an advanced stage with the development. The basic engineering was complete and, as such, they would be able to take delivery at short notice of the vessel they named Nexus.”
Going to ground
A second order quickly followed for another cable layer, this time from Maersk Supply Service. This vessel, the Maersk Connector, had its own set of specific requirements. Chief amongst these was the ability to go aground fully loaded.
To facilitate this, the vessel was installed with a ballast system consisting of two dedicated grounding pumps each with a 1000m3/h capacity and two normal ballast pumps each 1000m3/h, enabling it to land quickly, and in a controlled manner.
“With this, the vessel is able to operate at extreme shallow draught, getting very close to shore. This presents a number of benefits. For one thing, it offers a degree of protection for the cable with no need to create an additional connection. It also means that the installation can take place using one vessel, with no need to call upon a second, shallow draught support vessel. Ultimately, this saves considerable time and money during operation.”
The next generation
Currently, Damen is working on the next generation of DOC vessels – what Rolf refers to as the DOC 2.0. The aim of the upgraded vessels is to incorporate lessons learned in the initial construction projects, as well as new technologies that have come to maturity in the meantime.
“For example, we’re looking to optimise the tank configuration. This will offer increased and improved stability. With this, a vessel of the same size as the current generations of DOC vessels will offer increased loading capacity.
“We’re also looking at expanding the range. Wind turbine components, for example, are getting bigger all the time. We foresee a need in the future for larger versions of this type of vessel.”
The route to sustainability
This is not the only way in which the DOC is being prepared for the future. Damen is also incorporating the latest technological developments in order to meet its, and its clients, sustainability ambitions.
“We’re developing a vessel that is prepared for the use of alternative fuels. There is continual progress in this field right now and operators investing in a newbuild vessel want to ensure its relevancy for the long term. We’ll also be incorporating batteries so that the next generation of DOC can reduce fuel consumption and emissions with peak shaving and spinning reserves,” says Rolf. “Our aim with the next generation is to offer a vessel that not only meets the needs of today, but also of tomorrow.”
