Let's say the owner lives right on the border between two States. The boat is Federally documented. It is stored (on land) in one State for part of the year, and also operated in that States' waters for a period. The boat is also operated in the adjacent State's waters for extended periods of time. The exact division of time varies from year to year. When the boat was purchased it was taxed and registered in the first State. In order to avoid any misunderstanding with water police authorities in the second State, the owner wishes to purchase a second registration. So, the boat would now be now registered in both States. Should it be possible to do this without paying tax in the second state. (Registration is relatively inexpensive...the titling process is another story if taxes enter the picture).