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Definition: A bilge keel is a long, longitudinal fin fitted along the curved section of a ship’s hull, at the turn of the bilge, to reduce the vessel’s rolling motion caused by waves and improve stability.
Detailed Description:
- Purpose:
- Stability Enhancement: The primary function of a bilge keel is to dampen the rolling motion of a ship, thereby improving stability, especially in rough seas.
- Comfort and Safety: By reducing roll, bilge keels enhance the comfort of passengers and crew and reduce the risk of cargo shifting, which can be crucial for the vessel’s safety.
- Design:
- Shape and Material: Typically a flat or slightly curved fin made of steel or other durable materials. It runs longitudinally along the hull.
- Positioning: Located at the turn of the bilge, which is the point where the bottom of the hull meets the vertical sides of the ship.
- Function:
- Hydrodynamic Effect: As the ship rolls, the bilge keels increase hydrodynamic resistance to the rolling motion by creating drag in the water. This resistance dampens the roll and stabilizes the vessel.
- Non-Active: Unlike active stabilization systems such as fin stabilizers, bilge keels are passive and rely solely on their shape and positioning to reduce roll.
- Installation:
- Welding: Bilge keels are welded to the hull during the construction or retrofitting of the ship. They need to be securely attached to withstand the forces exerted by the water.
- Length and Size: The size and length of bilge keels can vary depending on the size and type of the vessel. Larger ships may have longer and more prominent bilge keels.
- Applications:
- Commercial Vessels: Commonly used in cargo ships, tankers, and passenger vessels to improve stability during voyages.
- Naval Ships: Applied in naval vessels to ensure stable operations and improve the effectiveness of onboard systems and crew comfort.
- Advantages:
- Cost-Effective: Bilge keels are a relatively simple and cost-effective method to enhance stability compared to active stabilization systems.
- Maintenance-Free: Since they have no moving parts, bilge keels require minimal maintenance once installed.
Summary: Bilge keels are long, longitudinal fins fitted along the curved section of a ship’s hull at the turn of the bilge. They reduce the rolling motion of the vessel, enhancing stability, comfort, and safety. Bilge keels are a passive, cost-effective solution widely used in various types of ships.
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