Windage area
The projected lateral area of a ship above the waterline, the wind force it develops, and why it dominates canal handling for container ships and car carriers.
Windage area is the projected lateral area of a ship above the waterline, and it decides how much force a beam wind puts on the hull. It is the parameter that separates the handling problem of a laden tanker from that of a container ship stacked high or a car carrier with a slab side.
In open water a large windage area costs leeway and fuel. In a confined channel it costs control: the wind force acts through a centre of effort well above and often well forward of the pivot point, and in a canal there is no room to absorb the resulting swing. Casualty investigations into canal groundings return to it repeatedly, alongside squat and bank effect.
The full article will cover how windage area is calculated and where it is published, the force and moment it develops in a given wind, its interaction with pivot point and with tug assistance, the transit restrictions authorities impose in wind, and its treatment in casualty analysis.