Page 25 - Introduction to Naval Architecture

DEFINITION AND REGULATION 13

produce a universally recognised system for tonnage measurement. It
provided for the independent calculation of gross and net tonnages
2
and has been discussed in some detail by Wilson .
The two parameters of gross and net tonnage are used. Gross tonnage
is based on the volume of all enclosed spaces. Net tonnage is the volume
of the cargo space plus the volume of passenger spaces multiplied by a
coefficient to bring it generally into line with previous calculations of
tonnage. Each is determined by a formula.

Gross tonnage (G7) =

47

V = total volume of all enclosed spaces of the ship in cubic
metres
k 1 = 0.2 + 0.02 log 10V
V c = total volume of cargo spaces in cubic metres
K 2 = 0.2 + 0.02 log 10 V c

D = moulded depth amidships in metres
T = moulded draught amidships in metres
N 1 = number of passengers in cabins with not more than
eight berths
N 2 = number of other passengers
+ =
N 1 N 2 total number of passengers the ship is permitted to
carry.

In using these formulae:

(1) When N 1 + N 2 is less than 13, N 1 and N 2 are to be taken as
zero.
2
(2) The factor (4T/3D) is not to be taken as greater than unity
2
and the term K 2 V C (4T/3D) is not to be taken as less than
0.25GT.
(3) NT is not to be less than 0.30GT.
(4) All volumes included in the calculation are measured to the
inner side of the shell or structural boundary plating, whether
or not insulation is fitted, in ships constructed of metal.