12 July 2018
Innovative vessel for CEMEX UK is first of next generation of marine aggregate dredgers
Damen has begun work on the construction of the innovative dredging system for the first Marine Aggregate Dredger (MAD). This vessel, which is being built at Damen Shipyards Galati in Romania, is designed to extract sand and gravel from the sea bed at depths of up to -55 metres, including in the challenging conditions of the North Sea. Damen is building the first MAD for Cemex UK Marine Ltd.
The life expectancy of such a vessel is up to 30 years, so it was important to CEMEX that Damen develop them a vessel that was future-proof. The result is a vessel with an advanced focus on safety, performance and sustainability that will ensure its relevance in the years to come. The innovation of the MAD extends to the dredging system that Damen Dredging Equipment has recently started work on in Nijkerk, the Netherlands.
CEMEX asked Damen to develop a system with no inboard dredge pipework, something which has never been done on a vessel of this size before. The thinking behind this was to avoid the possibility of the abrasive dredged material creating wear holes in the inboard dredge pipework on board making it a safer and easier maintenance-friendly system.
“This initial design from Damen Dredging Equipment, considerably reduces the risk of flooding. It has implications way beyond the obvious improvements in safety, not only for the crew on board but also for the maintenance staff, as there will be a reduced requirement for expensive wear parts as well as fast, practical replacement,” says Mark Williams, CEMEX UK Fleet Engineering Manager.
Reduced maintenance is a common theme to be found throughout the dredging system design, explains Frank de Hoogh, DDE Design and Proposal Engineer.
“The modular nature of the dredging system takes care of this. Where maintenance was previously a significant undertaking, it can now be conducted with just the on-board service crane, significantly lowering maintenance requirements and increasing uptime.”
An example of this modularity at work is the screening installation. This is fixed, as opposed to the typical rotating screen towers more commonly used. In addition to being more maintenance friendly, the screening area features an increased capacity courtesy of a larger surface area.
Another element is the dry unloader machine that Damen has developed along with CEMEX and manufacturer PLM. As a concept, Damen has selected the proven principle of a grab unloader, however a lot of work has gone into optimising the design. For example all electronics on the machine are rated IP68 for long term reliability. Another example is the design of the grab which is optimized to maximize efficiency of each discharge cycle.
“Such a system already exists in principle, but this model represents the next step – the next generation – in dry unloading technology.”
Ultimately, Frank says, the MAD benefits from Damen’s role of vessel integrator. “We are responsible not only for the design and build of the vessel, but also for the design and delivery of all on board equipment and its integration with the vessel. This ensures the predictable, reliable performance of the end product.”