"Delaware regulations provide that a vessel is deemed to have its state of principal use in Delaware if it is to be used, docked, or stowed on the waters of Delaware for
over 60 consecutive days.
Vessels registered in the State of Delaware are accordingly issued with a credit card sized ‘State of Delaware Registration Certificate’, the reverse of which states the state of principal use is Delaware.
It is therefore possible for a foreign jurisdiction to declare the Delaware registration of a vessel
to be invalid on the basis that a state registration is not valid for cruising outside US waters and/or the vessel is not used principally within Delaware waters.
If a vessel’s registration is declared invalid then the vessel itself is effectively stateless and in contravention of international maritime law."
http://oceanskies.com/delaware-yacht...ion-a-warning/