Hard Up m a Clinch. Seaman's expression that means being in a critical and difficult position.
Harfield's Compensating Gear. Steering gear in which an eccentric-ally-mounted pinion actuates a toothed rack shaped to conform to eccentricity of pinion. At small angles of helm the long radius of pinion gives quick movement: at large angles of helm the small radius of pinion gives decreased speed but increased power.
Harmattan. Dry and cool NE wind over NW Africa.
Harmonic Analysis. The separation of component tides of an undulation and the determination of their individual values and incidence. These values are considered as being due to action of hypothetical tide-raising bodies.