Why one Mulberry harbour survived the Channel storm

Why was the American Mulberry harbour destroyed by the storm while the British harbour survived?

The decisive differences were geography and exposure: the beaches, seabeds, depths, and installation conditions were not the same even though the harbour design was broadly shared.

Both harbours used broadly the same design components and similarly trained assembly teams. Their sites nevertheless differed in wind exposure, water depth, seabed material, slope, and the way the structures could be placed. Those conditions make the American harbour's destruction and the British harbour's survival an engineering-site problem rather than a simple design contest.