[euroderf]

Slow-but-irresistible force meets movable object.

[samplatt]

All objects are surprisingly movable when they encounter enough mass.

[jaxson60]

To your point, it is mass. Most people don't understand mass on water. At 1 knot the ship would do the exact same damage, topple the support and drop the bridge.

[euroderf]

Motor control and rudder control in a momentumous frame of reference.