|1. Remove the old name from the boat.
2. Have the old name engraved on a key fob or similar item and throw it into the bilge somewhere that it won't interfere with the bilge pumps or other items.
3. Drink a toast to the old name mentioning that "it may be out of sight, but never out of mind".
4. Put the new name on the boat.
5. Drink a toast to the new name and welcome good fortune to all who tread the boats deck.
The above was taken from a post on rec.boats
The Official Superstitious Boat Denaming Ceremony