Just as you wouldn't drive your car without a license plate, current sticker, and registration, your boat must be properly numbered, must have a current state use sticker, and your registration, or "certificate of number", must be aboard. This is a requirement for all mechanically powered vessels, all vessels that travel on federal waters that are navigable, and for vessels that travel on the high seas--virtually every vessel on the water.
Boat numbers must be affixed on the forward portion of both the port and starboard side.
* Numbers should be block letters instead of script.
* Numbers need to be at least three inch in height.
* The color needs to contrast with the hull color.
* The number needs spaces or hyphens between numerals and letters, as: MN 1234 AB or MN-1234-AB.
Also, most states require a current sticker immediately after or before the boat numbers on the port side, generally within 6 inches. While most vessels must be registered, some--like canoes and kayaks, may not have to be registered in your state. Also, fees and the length of registration vary from state to state. Many boaters like to carry their boat papers on a floating key ring handle so they will always have them close at hand.
Finally, if you register your boat in your state of residence, but store it or use in another state, you might have to register your boat in that state, or face a fine. Most states have "reciprocity" laws that allow visitation without having to pay a new registration fee for a few weeks or even a few months, but if your boat essentially resides in another state, you should expect to have to register it in that state.
For instance, if you live in Pennsylvania, but keep your boat in Maryland and boat on the Chesapeake Bay, you can expect to pay a Maryland registration fee. Check with your state, and the state your boat resides in for specific laws. This reference is included in the state law section of this course.