Segregated ballast tanks have become compulsory for all crude oil tankers of 20000tons and above, and for all product carriers of 30000tons and above those are built on or after 31/12/1979.
The capacity should be at least such that with just the segregated ballast plus the light ship weight , the vessel will be able to meet each of the following criteria:-
The amidships draft should be at least 2.0 + 0.02 L.
The forward and aft drafts should correspond to the amidships draft above with a stern trim not more than 0.015L.
In any case , the propeller must be fully immersed.
During heavy weather if required the ballast can be taken in cargo tanks.
