A dual class vessel is one which is classed by two Societies between which there is a written agreement regarding sharing of work, reciprocal recognition of surveys carried out by each of the Societies on behalf of the other Society and full exchange of information on the class status and survey reports.
- All the ships of "The shipping corportation of India" used to have dual class.
- Out of two, one classfication society was "Indian Registrar of shipping".
- Indian ships were required to have IRS as its classification society but as IRS was then not a member of IACS, ships were forced to have a second classification society which was member of IACS.
- So in this case, these ships would have certificate of class from each classification society.
- In 2010 when IRS became the member of IACS, Indian ships were no more required to have Dual class.
- More than 50 classification societies. But only 12 are IACS members