I. A person who engages in the business of maintaining or repairing vessels may make application to the department for a general distinguishing number for the boats which he is maintaining or repairing.
II. The commissioner may, if he is satisfied of the facts stated in the application, issue to the applicant a certificate containing the name, residence, and address of the applicant and the general distinguishing number assigned together with such provisions as the commissioner may determine. All vessels being maintained or repaired by said person may, while being maintained or repaired, be regarded as being registered under such distinguishing number, provided the number issued by the commissioner is attached to the vessel.
III. A person to whom such number has been assigned shall not loan the number plates to any person. Such numbers may be used on vessels which are being maintained or repaired by him as part of his business only when such vessels are being operated by the person to whom the plates were issued or a person employed by him. In no case shall such plates be used on vessels for any other purpose.