Section 3. The excise imposed by this chapter shall not apply to vessels described in section eight of chapter fifty-nine and in section sixty-seven of chapter sixty-three; to vessels owned by the commonwealth or any political subdivision thereof; to law enforcement vessels; to vessels under construction; to ferries; to boats, fishing gear and nets owned and actually used by the owner in the prosecution of his business if engaged exclusively in commercial fishing, with a total value of ten thousand dollars or less; nor to other vessels with a value of one thousand dollars or less. Said exemptions shall not subject said vessels and their equipment to any other tax under section four of chapter fifty-nine.