100 Indigenously Designed Addressable Bilge Alarm System for Naval Vessels M Karunanayake 1# , S Nanayakkara 1 and A Bamunusungha Aarachchi 1 1 Sri Lanka Navy, Sri Lanka # chathurkamihiraj@gmail.com Abstract: The primary purpose of an Addressable Bilge Alarm Panel is to provide an early warning of the bilge level of a vessel so that the personal, equipment and valuable resources can be protected and action is taken to remove bilges as soon as possible, all according to a predetermined plan. This study presents aspects of the bilge alarm system onboard Sri Lanka Naval Ship (SLNS) Sagara, by analyzing the existing system based on automation and advanced microcontroller programming using Raspberry Pi3, and ATMEGA 328P microcontrollers. The designed system is an addressable type bilge alarm system that communicates in serial RS 485. The novelty of the designed system are the own data protocol used in RS 485 communication, voice command of specific bilge location and the self designed advanced graphical user interfaces (GUI). In the simulation process, the bilge alarms may be raised automatically by a bilge sensor or manually by a person operating a test button. This response indicates the exact location of the ship on the given blueprint of the touch panel and provides an automatic warning alarm of the bilge location through the ship fitted General Alarming system. The study covers the designing process, implementation, microcontroller and Touch Panel programming, simulation process, testing and commissioning process. The designed system was installed onboard and tested for several months under different sea conditions by experienced Senior Electrical Engineers and Marine Engineers of SLN, then the system was commissioned on 03 rd February 2022. Keywords: Bilge alarm, communication protocol, GUI 1. Introduction A ship either being a merchant or war, the bilge alarm system plays an enormous role to protect the ship by confirming its stability and reducing the risk of marine causalities. It helps to identify any leakages of water, oil or any types of liquid in underwater compartments whether from onboard fitted machinery or ingress water from the sea. To identify the bilges compartment of the ships, reserved with risk markings are fitted with floater or level activated sensors. These sensors are activated with the bilges crossed to their permissible limit and give sensing data to the designed integrated systemThe Officer Of the Watch (OOW) on the Bridge, officer in the Machinery Control Station (Engine Room) and Damage Control Headquarters (DCHQ) of the ship will immediately identify and activate the preventive actions such as bilge pumps operation, emergency repair party initiatives, etc. The overview of the GUI is displayed in figure 1. Specific bilge locations are plotted on the blueprint of the specific ship such that any bilge status is clearly visible in an emergency. Meantime, an audible alarm specifying the relevant bilge location is activated through the ship’s broadcast system so that ship’s crew gets aware of the bilge location remotely.