Investigators are at a loss to explain how the Modern Express ran into such difficulties.
The crew from the Cido controlled car carrier were evacuated on February 2 as the ship listed 40 degrees in stormy conditions, with initial reports suggesting the listing was down to the cargo having shifted. The vessel then drifted perilously close to the French coast before a tow line was hooked on and the stricken ship taken to the port of Bilbao last week.
Initial investigations in Spain however have surprised many with reports showing the cargo was perfectly stowed.
The news will add fuel to the fire from insurers who have latterly been voicing concern at car carrier designs in the wake of a spate of accidents.