"SECTION 197. Stamp Tax on Charter Parties and Similar Instruments. - On every charter party, contract or agreement for the charter of any ship, vessel or steamer, or any letter or memorandum or other writing between the captain, master or owner, or other person acting as agent of any ship, vessel or steamer, and any other person or persons for or relating to the charter of any such ship, vessel or steamer, and on any renewal or transfer of such charter, contract, agreement, letter or memorandum, there shall be collected a documentary stamp tax at the following rates:

"(a) If the registered gross tonnage of the ship, vessel or steamer does not exceed one thousand (1,000) tons, and the duration of the charter or contract does not exceed six (6) months, Five hundred pesos (P500); and for each month or fraction of a month in excess of six (6) months, an additional tax of Fifty pesos (P50.00) shall be paid.

"(b) If the registered gross tonnage exceeds one thousand (1,000) tons and does not exceed ten thousand (10,000) tons, and the duration of the charter or contract does not exceed six (6) months, One thousand pesos (P1,000); and for each month or fraction of a month in excess of six (6) months, an additional tax of One hundred pesos (P100) shall be paid.

"(c) If the registered gross tonnage exceeds ten thousand (10,000) tons and the duration of the charter or contract does not exceed six (6) months, One thousand five hundred pesos (P1,500); and for each month or fraction of a month in excess of six (6) months, an additional tax of One hundred fifty pesos (P150) shall be paid.