TONNAGE MEASUREMENT

GROSS TONNAGE:

1. IT IS A MEASURE OF SHIP’S CUBIC CAPACITY
2. IT IS EXPRESSED IN TERMS OF 1 TON/100 CU FT., OR 1 TON/3M_­³ OF SPACE
3. GRT CONSISTS OF ALL ENCLOSED SPACES WITH CERTAIN EXCLUSIONS

GRT IS MADE OF SUM OF FOLLOWING:

• TOTAL VOLUME BELOW TONNAGE DECK
• CU. CAPACITY OF ALL SPACES IN T.D.
• CU. CAPACITY OF ALL ENCLOSED SPACES ON OR ABOVE UPPER DECK WITH CERTAIN EXCEPTIONS
• EXCESS HATCHWAYS IN EXCESS OF ½ % OF SUM OF a+b+c ABOVE

EXCLUDED SPACES

• TANKS USED EXCLUSIVELY FOR BALLAST.
• SPACES USED EXCLUSIVELY FOR MACHINARY SPACES FOR CREW & OFFICERS.
• WASHING & SANITARY SPACES FOR CREW & OFFICERS
• SPACES USED FOR NAVIGATION, RADIO ROOM, STORAGE FOR BATTERIES, CHAIN LOCKER

The gross tonnage (GT) of a ship shall be determined by the following formula:

GT = K₁*V

            Where: V = Total volume of all enclosed spaces of the ship in cubic meters,

                        K₁ = 0.2 + 0.02 log ₁₀ V

NET TONNAGE:

1. IT IS FOUND BY MAKING DEDUCTIONS FROM GRT
2. IT MAY BE DESCRIBED AS MEASURE OF EARNING CAPACITY OF THE SHIP
3. ALLOWANCE IS MADE FOR PROPELLING POWER
4. MASTER’S & CREW’S ACCOMMODATION INCLUDING WASH ROOM
5. WATER BALLAST SPACES OTHER THAN DOUBLE BOTTOM TANKS
6. SPACES USED FOR NAVIGATION, RADIO ROOM, & STORAGE SPACE FOR BATTERIES & SAFETY EQUIPMENT
7. CHAIN LOCKER
8. WHEN CARGO IS CARRIED BY FOREIGN GOING SHIPS IT IS MEASURED AND ADDED TO NRT

The net tonnage (NT) of a ship shall be determined by the following formula:

NT = K₂ * Vc * (4d / 3D) 2 + K₃ * [N₁ + N₂ / 10]

Vc = total volume of cargo spaces in cubic metres,

K₂ = 0.2 + 0.02 log ₁₀ V

K₃ = 1.25

D = moulded depth amidships in metres

d = moulded draught amidships in metres

N₁ = number of passengers in cabins with not more than 8 berths,

N₂ = number of other passengers,

K2 * Vc * (4d / 3D) 2 Shall not be taken less than 0.25GT

NT Shall not be taken less than 0.30GT