I am more humble and have a newfound respect for Poseidon, Aoleus, mythology and nautical tradition. I still try to rid people of their oppressive rituals, however, if you buy a boat and wish to rename her, don’t piss off Poseidon. When I step on board, I become a sailor and pay respect to those things that sailors cherish and believe.
A quick perusal of the Internet will provide you many accounts of the ritual to be performed. Here is a brief synopsis of the key elements found.
Please be advised that what follows are summaries of far more elaborate and exact details of the renaming ritual. If you Google the renaming ritual, the two most extensive recounts are those of Captain Pat and John Vigor. Barbara Dyer also has a posting, which she claims will work and avoid the anger of Poseidon. All of these rituals involve friends, rum or champagne and removing all remnants of the old boat name.
Firstly, you must remove all reference to the old name. It is amazing how insidious the name can be. It can show up on various documents, life rings, dinks, sail bags, glassware, leftover shirts and hats, as well as on documentation boards firmly attached to the hull. Carefully look through your nav station, log books, and engine maintenance records as many small bits may contain the name. It is reported that white out is OK to use. Once purged, a good bottle (or a few depending on how many friends you have) of bubbly is needed, some say rum will also work. Various odes, prayers and invocations are available meant to acknowledge, sooth and appease Poseidon and his friends. Champagne is then poured to the North, West, South and East. Of course, any left is to be imbibed by those in attendance, however, do not skimp on Poseidon’s share, as this will PISS OFF POSEIDON. Once this has been completed, it is now all right to bring on items with the new boat name and to re-christen the boat and place her name on the spot of your choice. If you have to schedule the painting of the new boat name before you have the ceremony, make sure the new name is covered until the ceremony is completed. 
One variant says you need to have two rounds of libation for everyone in attendance, plus one more. You must take your boat out into the ocean, or at least out of your harbor or anchorage. Everyone holds a glass full of champagne. Make sure the Coasties are not in sight. The boat owner then backs up the boat and thanks the god of wind (Aoleus) and water (Poseidon) for their kindness and caring for the old boat, using its old name. All then drink a toast to the old boat name. The boat is then put into forward and a second round of drinks is poured. Aoleus and Poseidon are then asked to extend their kindness to the new boat name. This glass is tossed downwind. Some say only the owner needs to do this, then that glass is refilled and the new boat name is toasted. Once ashore, the new boat name can be revealed or affixed. All iterations of the ceremony have a few core elements; an invocation, an expression of gratitude, a supplication, a re-dedication and a libation.
Just remember, don’t use cheap champagne and DON”T PISS OFF POSEIDON.
Don’t forget that you also need a virgin on the bow of the boat to pour out some of the libations.
No, not that kind of virgin … just somebody who’s never been sailing before.