In order to use a unified base for the application of tonnage
measurement of segregated ballast tankers, Administrations are recommended to accept the
1 The ship is certified
as a segregated ballast oil tanker as stated in paragraph 5 of the supplement to the
International Oil Pollution Prevention Certificate and the location of the segregated ballast
tanks is indicated under paragraph 5.2 of that supplement.
2 Segregated ballast tanks are those tanks exclusively used for the carriage of
segregated water ballast, as defined in regulation 1(17) of Annex I of MARPOL 73/78. The
segregated ballast tanks should have a separate ballast pumping and piping system arranged for
the intake and discharge of ballast water from and to the sea only. There should be no piping
connections from segregated ballast tanks to the fresh water system. No segregated ballast tank
should be used for the carriage of any cargo or for storage of ship's stores or material.
3 In the International Tonnage Certificate (1969)
under "Remarks" an entry is made for the tonnage of segregated ballast tanks in oil tankers as
"The segregated ballast tanks comply with regulation 13 of Annex I of the
International Convention for the Prevention of Pollution from Ships, 1973, as modified by the
Protocol of 1978 relating thereto, and the total tonnage of such tanks exclusively used for the
carriage of segregated water ballast is ........ The reduced gross tonnage which should be used
for the calculation of tonnage based fees is ....................."
4 The tonnage of segregated ballast tanks mentioned above should be
calculated according to the following formula:
x V b
= 0. 2+ 0. 02 log
V (or as tabulated in appendix 2 of the International Convention on
Tonnage Measurement of Ships, 1969)
V = the total volume of
all enclosed spaces of the ship in cubic metres as defined in regulation 3 of the International
Convention on Tonnage Measurement of Ships, 1969
total volume of segregated ballast tanks in cubic metres measured in accordance with regulation
6 of the International Convention on Tonnage Measurement of Ships, 1969.