Wind Resistance

Air-drag resistance on the above-water area, based on ITTC relative-wind coefficients. Significant on tall ro-ro, container, cruise and PCTC hulls where frontal area is huge; feeds EEDI weather factor fw and operational voyage-routing models.

DesignWind

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

R_\text{wind} = \tfrac{1}{2} \rho_\text{air} V_\text{rel}^2 A_T C_X

Symbol	Meaning	Unit
$R_\text{wind}$	Wind resistance force	kN
$\rho_\text{air}$	Air density (ISA sea-level)	kg / m³
$V_\text{rel}$	Relative wind speed (true wind vectorially added to ship speed)	m / s
$A_T$	Transverse above-water projected area	m²
$C_X$	Wind-drag coefficient - tanker 0.55, bulker 0.60, container laden 0.70, Ro-Pax 0.80+

Source: ITTC - *Recommended Procedures 7.5-04-01-01.1* (wind resistance); Blendermann - *Parameter identification of wind loads on ships* (1994); OCIMF - *Prediction of Wind and Current Loads on VLCCs*

In short

Compute the air-drag resistance on a ship's transverse above-water area using ITTC-style wind coefficients.

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