If I travel outside the EU to the Channel Islands technically I need to fill in this form. Post part 1 before going and part 2 when I return.
I would hope that Spain
has something similar.
Now what happens in practise with thousands of boats ploughing their way across the med each week, well.
However, get caught and it will give Spain's customs
and excuse to go to town if they are feeling inclined. After all if you didn't declare the voyage what else are you hiding? taxes
, boat registration
? I have been on the receiving end of a UK customs
check because I had a new tax free car and the customs officer didn't. A couple hours of my life, under extreme pressure, I won't get back.