//SYS21///INTEGRA/BST/VOL2/REVISES 31-7-2001/BSTC14.3D ± 629 ± [590±632/43] 30.7.2001 3:54PM
Major ship design features 629 (iv) Spaces below deck used exclusively for water ballast up to a maximum of 19 per cent of the gross tonnage, including exempted spaces such as the double bottom and capacity below line of ¯oors containing water ballast, oil fuel, etc. (v)i Spaces below the upper deck occupied by propelling machinery. In ships propelled by screws, if the volume of this space is between 13 and 20 per cent of the gross tonnage, the deduction is 32 per cent of the gross tonnage; if the space occupied is less than 13 per cent of the gross tonnage, the deduction is in direct proportion to 32 per cent; if the volume of the propelling machinery is in excess of 20 per cent of the gross tonnage, the propelling power deduction is 1 34 times the tonnage of the propelling space. Happily, this complicated assessment has now disappeared for new ships. The new formula tonnage regulations came into force in 1982 and are applicable to all new and converted ships and, at the owner's request, to existing ships. The formulae now applied to ascertain the gross and net tonnages are as follows: Gross tonnage, GT K1 V
4d 2 N2 Net tonnage, NT K2 Vc K3 N1 3D 10 where K1 0:2 0:02 log10 V V total volume of all enclosed spaces, m3 K2 0:2 0:02 log10 Vc Vc total volume of all cargo spaces, m3 d moulded draught amidships, m D moulded depth amidships, m GT K3 1:25 1 10; 000 N1 number of passengers (in cabins with not more than 8 berths) N2 number of passengers not included in N1 2 4d note that: must not be taken as greater than unity 3D 2 4d K2 Vc must not be taken as greater than 0.25 GT 3D NT must not be taken as less than 0.30 GT if N1 N2 is less than 13, N1 and N2 shall be taken to be zero d is the assigned summer loadline draught or, for passenger ships, the deepest subdivision loadline draught V and Vc are calculated for metal ships to the inside of shell plating and are to include appendages While these new regulations are considerably simpler than the old ones, they still require a great deal of precise de®nition of geometry and phrases such as