 Iceberg towing drag

Iceberg towing drag is the water resistance that a towing force must overcome to move an iceberg relative to the surrounding water. A quadratic model is $F_D=\frac{1}{2}{\rho }_w{C}_{D}A{U}^2$, where $U$ is the relative speed and $C_D$ must be defined using the same reference area $A$ as in its calibration.

For a form-drag coefficient, that area is commonly the submerged frontal area. A coefficient describing an equivalent basal resistance may instead use an immersed horizontal area. Interchanging the two conventions changes the force estimate. The $U^2$ dependence makes a modest increase in towing speed expensive, and currents can change resistance without changing the iceberg's speed over the ground.