Throughout the building of offshore wind farms, substation platforms, or cable routes, a guard/security vessel is needed to protect the construction area. The vessel constantly watches the nearby marine traffic using visual checks, radar, and AIS systems. When another boat approaches the site, the guard vessel takes steps to secure the area and inform the approaching vessel on how to pass safely. The requirements for the vessel, including technology and crew, are detailed in the approval notice from the authorities, based on the tasks, area, and amount of traffic. A guard vessel should be able to stay offshore for long periods—up to 30 days or more—and must be very seaworthy and capable of moving quickly.