The hull of a ship gives it its shape and buoyancy and protects the parts and components inside. A ship’s main propulsion engine, generators, boilers, fuel pumps, air compressors, and other such equipment are all located within the hull of a ship. Additionally, the crew and passenger quarters, as well as the cargo carried by the ship, are distributed between its hull and deck. The ship’s stability in water, speed, load-bearing capacity, efficiency, and safety are affected to a great degree by the structure of its hull. Image Credits: Marine Insight. A ship hull has to resist rough seas, stormy winds, rain, and snow. Sea water can be highly corrosive because of the various salts it contains. Because the ship’s hull stays submerged most of the time, it is subject to higher levels of corrosion than other parts of the ship. An estimated 94% of a ship’s life is spent on water. During a ship’s life, as with most of the ship’s infrastructure, its hull has to be maintained and serviced carefully following prescribed intervals. Types of Hulls A ship’s hull is constructed very carefully. The structure and design of the hull are quite complex and critical for the ship’s overall performance and safety on the seas. Hulls of different types of ships vary. Naval architects consider various factors when they engineer a ship’s hull. Image Credits: Marine Insight. For example, the hull of a cruise liner varies from that of a cargo ship in shape and various other features. Most cruise liners have deep V-shaped hulls, while those of cargo carriers are broad, smooth, and continuous [round bilge hulls]. The hulls of war frigates are generally long and narrow for cutting through water at high speeds, stability, and manoeuvrability, while those of commercial car carriers and cargo carriers are box-like with rounded bows to increase the space inside while reducing wind resistance. Modern ship hulls are designed and made with sustainability playing a key role alongside design and structure. Modern hull designs are energy-efficient and eco-friendly, e.g., coatings and paints used to reduce biofouling. Biofouling is when organisms and other deposits form on the hull surface. Besides being corrosive, this acts as a drag on the ship’s motion. Maintenance and service are critical for the efficient and smooth sailing of a ship. Cleaning the ship’s hull removes algae, barnacles, mussels, marine worms, and other deposits [biofouling] that increase the ship’s weight. Accumulation of these deposits causes drag to the ship’s motion and thereby fuel wastage. A clean hull enhances the speed of a ship and therefore fuel efficiency by almost 10-20%. Cleaning a Ship’s Hull Hull cleaning is a complicated and time-consuming process. Ships are usually mandated to be drydocked for maintenance, servicing, and hull cleaning at least twice in 5 years. While dry-docked, the hull of a ship is cleaned and antifouling paint applied. Image Credits: Marine Insight. But hull cleaning is also done underwater when the ship is berthed in port or a service area. Generally, hull cleaning of ships is carried out once every 6 months to 1 year. When a ship is berthed, it is cleaned by divers with specialised equipment or underwater robots. The buildup on hulls depends to a large extent on the type of water the ship sails in. The coating of antifouling paint slows down the metallic corrosion of ship hulls. Remotely Operated Vehicles [ROV] or Robots Remotely Operated Vehicles [ROV] or Robots use high-