Section 18. No person, without the written consent of the registered owner thereof, shall fill with a beverage with intent to sell the same any vessel registered under the preceding section, or change in any way, or conceal any name or the word ”registered” thereon, or buy, sell, traffic in or dispose of any such vessel. This section shall not apply to vessels purchased from the registered owner; provided, that making a money charge or requiring the deposit of a sum of money under an agreement to refund the same upon the redelivery of the vessel shall not constitute a purchase thereof, within the meaning of this section. Violation of any provision of this section shall for the first offence be punished by a fine of not less than fifty cents for each vessel in respect to which the violation occurs or by imprisonment for not less than ten days nor more than one year, or both, and for each subsequent offence by a fine of not less than one nor more than five dollars for each such vessel or by imprisonment for not less than twenty days nor more than one year.