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Air Resistance

In calm weather, air resistance is, in principle, proportional to the square of the ship’s speed and proportional to the cross-sectional area of the ship above the waterline. Air resistance normally represents about 2% of the total resistance.
For container ships in head wind, the air resistance can be as much as 10%. The air resistance can, similar to the foregoing resistances, be expressed as
R🇦 = C🇦 × K, 

but is sometimes based on 90% of the dynamic pressure of air with a speed of V, i.e.:
R🇦 = 0.90 × ½ × ρ(air) × V 2 × A(air)

where ρ(air)air is the density of the air, and A(air) is the cross-sectional area of the vessel above the water.

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