I named my boat "Whale Shark," but since I keep it permanently in Mexico, I use the Spanish name "Tiburon Ballena" and had that lettered on the boat. The name came about when I was on a cruise with some friends and we had a surprise opportunity during a dive trip to swim with whale sharks. We were so stoked by it that everytime we saw each other on board, we would yell, "Whale Shark!" It was shortly after that cruise that I bought the boat, and the name just came naturally.
I bought the boat used, but there was no name on it. We still did the christening ceremony.