Whilst I am not technically qualified on the subject, I understood that as the seabed was such soft, fine sand that it was virtually impossible for it unless it was subject to constant dredging.
As much as I prefer Portsmouth and it IS the home of the Royal Navy
I'm surprised these 'virtual' carriers aren't being planned for Davenport- as were the last big carriers.
IF it isn't TOO far off topic, one of the reasons claimed for the cancellation of the last 'proper' aircraft carriers (remember the Invincible class aren't really carriers at all) by the 1970s government was the cost of dredging in Portsmouth.