A displacement hull is a specific design of a ship's hull that operates on the principle of buoyancy by displacing an amount of water equivalent to its own weight, regardless of the power exerted. Instead of planing on the water's surface like other types of hulls, a displacement hull 'plows' through the water, causing a wave or wake. It is designed to cut through the water by pushing it aside and allowing it to close behind the vessel, resulting in less resistance at lower speeds and more efficient fuel consumption. However, as more power is added, the speed does not proportionally increase due to the exponential growth of hydrodynamic resistance. This implies that vessels with a displacement hull have a maximum theoretical speed or 'hull speed'. These hulls are commonly found in larger, ocean-crossing vessels and provide better seaworthiness and a more comfortable ride in heavy seas.

1. Ocean-going Cargo Ships: Large container vessels have displacement hulls which allow them to displace a significant volume of water, equal to their own immense weight. This kind of hull enables these vessels to cut through heavy ocean waves and maintain balance even when fully loaded with cargo. 2. Submarines: These underwater vessels utilize displacement hulls to balance their weight against the volume of water they displace. This mechanism allows submarines to float on the surface or dive to great depths, maintaining stability and control at all times. 3. Cruising Yachts: Many cruising yachts use displacement hulls to enhance comfort and safety at sea. The hull design enables the yacht to move smoothly through the water, displacing its own weight even when braced against strong winds and waves. 4. Commercial Fishing Boats: These boats commonly use displacement hulls for their ability to provide a smooth and stable ride throughout long fishing expeditions. The displacement hull allows these boats to navigate through rough sea conditions without losing balance or sacrificing speed. 5. Tugboats: These ships, known for their strength and pulling capacity, commonly have displacement Hulls. This type of hull enables the tugboat to maneuver heavier vessels by displacing an amount of water equal to its own weight in spite of the powerful engines it carries.

A fun and fascinating fact about displacement hulls is that they abide by the principle of buoyancy detailed in Archimedes' Principle, which states that an object submerged in a fluid (in this case, water) is buoyed up by a force equal to the weight of the fluid displaced. In simpler terms, a boat with a displacement hull moves through the water by pushing it out of the way, displacing its own weight in water regardless of how much additional power is added. This displacement action causes the characteristic wave or wake that follows behind the boat. Interestingly, the top speed of a vessel with a displacement hull is usually determined by its hull length and shape, not the amount of engine power it possesses. While these types of hulls may not be best for speed, they offer superior sea-handling and more stability at rest, making them a great choice for larger ocean-going vessels like oil tankers, cruise ships, and sailboats!