Some scary calculations

An MAIB report (28/2003) clocked a container ship doing 27 knots along the English Channel when visibility was between 50m and 100m (thick fog). The stopping distance for that vessel is 2.4 miles or 50 times the visibility at the time. On land if a heavy goods vehicle drove at speeds at which his stopping distance was even double the visibility we would call it motorway madness and lock up the driver