Definition
A sharp longitudinal ridge or corner formed where two surfaces of a hull or fuselage meet at an angle, most commonly along the sides of a seaplane or flying boat hull. The chine deflects spray downward and outward during water operations and helps define the hydrodynamic shape of the hull.
Plain English
A long, sharp edge running along the side of a seaplane's hull where the bottom and side meet. It throws spray away from the aircraft when taking off or landing on water.
Context Anchor
Seen in seaplane float and hull construction, preflight inspection, and descriptions of water taxi, takeoff, and landing behavior.
Derivation
From Old English 'cinu,' meaning a crack or fissure, later used for the backbone or spine of an animal. In boatbuilding it came to mean the angled edge running along a hull's length — the same idea carried over to seaplane hulls.
Why Pilots Care
Affects water spray control, directional stability, and how efficiently the hull rises onto the step during takeoff.
Grounding Statement
Picture a seaplane float moving through water: the chine is the long edge that helps water break away instead of climbing up the side.
Intuition Check
Do not confuse chine with chin. In aviation, a chine is not a body part or a nickname for the aircraft nose; it is a lengthwise edge on a hull or float.
Example Sentence 1
Spray flew outward along the chine as the floatplane accelerated across the lake.
Example Sentence 2
After beaching, the pilot checked the chine for cracks or wear from repeated contact with the ramp.