Fluke

The flat, triangular blade or arm of an anchor designed to dig into the seabed and provide holding power.

The term “fluke” in a marine context primarily refers to the pointed, flat parts of an anchor that are responsible for securing the vessel to the seabed. Flukes are engineered to penetrate and grip various types of seabeds, such as sand, mud, or clay, ensuring the anchor remains firmly in place. The design and size of the flukes are critical to the anchor’s effectiveness, as they determine how well it can hold under strain from wind, waves, and currents. Traditional anchors, such as the Admiralty pattern, feature large flukes that pivot around a shank, while modern designs like the Danforth or plough anchors have fixed or semi-fixed flukes optimised for specific seabed conditions. 

The fluke’s efficiency is influenced by factors such as its angle, surface area, and the material of the seabed. For example, wide, flat flukes are ideal for soft mud or sand, where they can dig deeply, while narrower flukes may be better suited to harder seabeds. Proper deployment of the anchor, including ensuring the flukes are correctly oriented to engage the seabed, is essential for achieving a secure hold. Additionally, the term “fluke” can also refer to the tail fins of marine mammals like whales, but in the context of recreational boating and marine terminology, it is most commonly associated with anchors. Understanding the role and design of flukes is fundamental for safe anchoring practices and maintaining vessel stability.