That looks line a typical current Alabama
registration (leading "AL" followed by four numbers then two letters), and if I recall, Alabama converted from a 3-digit to 4-digit number about 10 years ago (most boat owners were able to just add a leading zero to make the conversion, "123" became "0123"). If that's all correct, then someone in Alabama went to the trouble and expense of registering it in the past 10 years. It's worth noting, that in Alabama anyway (don't know where else), the boat
registration also covers the trailer that it's on, so no need for a separate
license plate on the boat trailer. All that aside, it would be a show-stopper on land or sea, for sure....