Dualfin

Dualfin refers to any design, device, or concept that uses two fins or fin-like surfaces. The term is used in several domains, including marine engineering, sport equipment, and fictional media. In engineering, dual-fin configurations describe propulsion or control surfaces that employ two independently actuated fins to achieve improved stability, steering, or lift in water or air. In underwater vehicles, twin-fin systems can enable higher maneuverability at low speeds and reduce yaw coupling compared to a single larger fin.

Some swim fins marketed to divers or freedivers use a two-fin or split-fin design, sometimes called dual-fin or twin-fin, claiming greater thrust efficiency and reduced leg fatigue by distributing propulsion across two blades. In cultural contexts, "Dualfin" may appear as a brand name or fictional entity. Some novels or games use the term to denote a creature with two dorsal fins or a technology with paired fins; such usage is generally metaphorical or speculative rather than technical.

Etymology: The term combines "dual" meaning two and "fin" referring to a finned structure. Variants and related concepts include twin-fin propulsion, split-fin designs, and bi-fin configurations, which share the principle of using two fins to influence hydrodynamics.

See also: twin-fin, split-fin, bi-fin. Further reading would include sources on hydrodynamics of multi-fin systems and sport fins with dual-fin designs.