Earthrace underwent extensive testing and evaluation to ensure the structures would withstand the loads placed upon her when piercing breaking waves in storm conditions.

According to the team at XC Engineering in Italy, the theoretical loads placed upon Earthrace, and especially the spars, were the highest they have ever seen.

She was designed for 15m (50ft) waves, and to go 7m (23ft) underwater with a factor of safety of 3.  So at 21m underwater the hull would likely implode.  Of course we hoped we'd never get that far underwater.  The most rugged conditions the crew have encountered were 12m (40ft) waves and 80kn winds, which saw the windscreen of Earthrace regularly up to 5m (16ft) underwater.  One crew member described the experience as "by far the most brutal thing I've done."

The hull came through this, and a series of other storms in various oceans and seas, basically unscathed.  It is a testament to the many organisations that worked on the initial desaign and subsequent structural analysis (such as Craig Loomes Design Group and Germanishe Lloyd), that
Earthrace was such an amazing boat!