The real answer lies in Admiralty Law, in particular the judgement of case of Lord Coleridge on the case of Salt Union v. Wood:
Dormal's ship did go to sea, and did not suffer disaster. Therefor she was a sea-going ship, and so not subject to the Closing.
All that is necessary to repeat the trick is a simple ritual to establish the identification between your vessel and Dormal's Ship. Of course, failure to successfully establish that connection will leave you at sea in a vessel that is not, in fact, a sea-going ship. The Closing will apply, and disaster will strike.