I read your question and of course, I had to go check. You know what? Tides are complex. Lois is simple compared to them. The most important bit I gleamed from a quick wiki-study: tidal periods are 12 hours, 25 (?) minutes long, so does this mean the time for the high tide varies? I think so. So, I guess, you can get away with it quite easily, especially since the location of their island is unknown.
Michael
PS: My contenders for the ownership:
* Bruce and Dick's love nest.
* Lex and Arianna's Caribbean hide away.
* Arthur Chow's fortress of solitude.
