Fletching is the fin-shaped aerodynamic stabilization device attached on arrows, bolts, darts, or javelins, and are typically made from light semi-flexible materials such as feathers or bark. Each piece of such fin is a fletch, also known as a flight or feather. A fletcher is a person who attaches fletchings to the shaft of arrows, fletchers were traditionally associated with the Worshipful Company of Fletchers, a guild in the City of London.
Feather fletching – these are shield cut with barred red hen feathers and a solid white cock.
Plastic fletching (also known as vanes) – this example is parabolic cut with pink hen vanes (the ones put oblique to the bow when nocked on the string) and a green cock (the one – or ones, with even-numbered vanes – put perpendicular to it).
A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation.
Fish get thrust moving vertical tail fins from side to side.
Cetaceans get thrust moving horizontal tail fins up and down.
Stingrays get thrust from large pectoral fins.
Ship propeller