Final answer:
Motorboats and boats powered by electric motors must be registered to comply with the legal requirements set by maritime authorities, allowing for proper identification and regulation.
Step-by-step explanation:
All motorboats and boats powered by electric motors must be registered. This is a requisite by law in many jurisdictions to ensure that boats are legally recognized by a governing body and can be identified in the case of emergencies, accidents, or violations of maritime laws. The process of registration typically involves assigning a unique identifier to the watercraft, paying a fee, and displaying the registration number prominently on the vessel. Insurance, while often highly recommended or required in certain areas, is not the correct answer to this question, nor are painting and tying down, which are more related to maintenance and safety practices rather than legal requirements.