So, you just bought a new boat and the name doesn't suit you. There is a specific set of guidelines for changing a boat's name, but these simply uphold thousands of years of sailing tradition and superstition. You don't need to fill out any forms with the DMV or any other entity because your boat's official identification is its state-assigned registration number. And that doesn't change.
Appeasing the Gods
The guidelines date to the ancient Greeks and Romans. According to mythology, various gods of the air and sea kept log books with names of each vessel and their deeds on the high seas. So, whenever a new ship was built and commissioned, she would be presented to the gods for entry into their logs. It would not be good for the sailors on board if Poseidon looked up one day and found a ship sailing in his domain that was not logged into his books.
Scratching Out the Old Name
Since Poseidon (Greek) or Neptune (Roman) would have the ship's name in his log, sailors wishing to change a vessel's name should petition the god(s) to strike the old name from the roster and add the new name.
First, remove anything and everything labelled with the vessel's old name. According to tradition, even something as simple as a key chain with the old name should not be left on the boat. Replace any life preservers or anything else that has the old name on the boat. Be sure not to bring anything with the new name on it until everything with the old name has been removed.
Once everything with the old name has been removed, you can paint the new name and bring on board any cushions, key chains, signs or other trinkets or gadgets with the new name.
The New Name
Once the changeover is complete, you must petition the deities to accept your boat's new name.
Dan Meadows of Nor'easter Magazine suggests you buy a bottle of champagne and stand on the bow. Open the champagne and pour a little into the water. Say something like "Poseidon/Neptune Great Ruler of the Sea, I ask you to strike the (old name) from your rosters. Pour a little more champagne into the water and say: Great Neptune/Poseidon, Lord of the Oceans Ruler of the High Seas, I ask you to add (new name) to your rosters and keep her in your favour. Then pour a little more champagne into the water. Finally, for an extra measure of luck, Meadows recommends offering champagne to each of the four winds. So walk around your deck, pouring a little champagne into the water on the north, south, east and west sides. After doing everything to appease the deities, you may enjoy the remaining champagne yourself.
What you actually say and whether you address Neptune or Poseidon does not matter. But Meadows says that flattery never hurts when trying to appeal to deities. Boat name changing ceremonies are meant to be a celebration; so have friends on hand to help drink the champagne.
So, you can change your boat's name without incurring the wrath of the gods. Just be sure to eliminate all traces of your boat's previous moniker before putting on the new one. Then be sure to invite some friends over to help you appease the deity of your choice and have good time.