There are many different ceremonies for re-naming your boat — you can look them up online or ask your local boating community which they prefer. Typically, though, you must first remove all traces of the old name. This means removing the name from the hull, burning the old log books and paperwork, and requesting that the gods to forget the old name. Then, you re-christen the boat with alcohol, normally good champagne. First offer half to the water, from east to west, and then some to the boat, and some then some for you and your first mate to toast the new vessel. Another, less desirable, option is to have a virgin urinate over the bow [source: Eyers].
In the new naming ceremony, sailors are to address Poseidon, god of the sea, who supposedly holds the name of every vessel ever launched recorded in the Ledger of the Deep. In this ceremony, ask for safe passage, fair winds and calm seas for your future voyages. One common script goes like this [source: United States Vessel]:
Oh mighty and great ruler of the seas and oceans, to whom all ships and we who venture upon your vast domain are required to pay homage, I implore you in your graciousness to take unto your records and recollection this worthy vessel hereafter and for all time known as “(vessel's new name)”, guarding her with your mighty arm and trident and ensuring her of safe and rapid passage throughout her journeys within your realm. In appreciation of your munificence, dispensation, and in honor of your greatness, we offer these libations to your majesty and your court.”
You are also to address the mighty powers of the four wind gods - the great Boreas, Zephyrus, Eurus, and Notus - pouring champagne out as you face each of them: north wind, west wind, east wind, and then south wind.
"Oh mighty rulers of the winds, through whose power our frail vessels traverse the wild and faceless deep, we implore you to grant this worthy vessel (vessel's new name) the benefits and pleasures of your bounty, ensuring us of your gentle ministration according to our needs."
There's a lot that goes into renaming a boat if you want to ensure good luck and avoid ending up at the bottom of the ocean, according to the superstition and lore of the boating world. Better to be safe than sorry, in our opinion.