Ship Design Codes used by the U.S. Maritime Commission

The ship design classification system used by the U.S. Maritime Commission employs the structure:

C4-S2-A4

where

represents

C   

ship type, as shown in the first table below

4   

ship size, as shown in the first table below

S   

propulsion system, as shown in the second table below

2   

passenger capacity and number of propellers, as shown in the second table below

A   

sequential letter indicating the specific design for this type of ship

4   

sequential number indicating the specific revision to this design
Code Ship Type Size Code
1 2 3 4 5 6 7
Length on Waterline (ft)
B Barge up to 100 100 to 150 150 to 200 200 to 250 250 to 300 300 to 350 350 to 400
C Cargo Ship up to 400 400 to 450 450 to 500 500 to 550 550 to 600 600 to 650 650 to 700
G Great Lakes Cargo Ship up to 300 300 to 350 350 to 400 400 to 450 450 to 500 500 to 550 550 to 600
H Great Lakes Passenger Ship up to 300 300 to 350 350 to 400 400 to 450 450 to 500 500 to 550 550 to 600
IB Integrated Tug-Barge up to 200 200 to 300 300 to 400 400 to 500 500 to 600 600 to 700 700 to 800
J Inland Cargo Ship up to 50 50 to 100 100 to 150 150 to 200 200 to 250 250 to 300 300 to 350
K Inland Passenger Ship up to 50 50 to 100 100 to 150 150 to 200 200 to 250 250 to 300 300 to 350
L Great Lakes Bulker (Laker) up to 400 400 to 450 450 to 500 500 to 550 550 to 600 600 to 650 650 to 700
LG Liquid Gas Carrier up to 450 450 to 500 550 to 600 600 to 650 650 to 700 700 to 750 750 to 800
N Coastwise Cargo Ship up to 200 200 to 250 250 to 300 300 to 350 350 to 400 400 to 450 450 to 500
OB Oil/Bulk/Ore Carrier up to 450 450 to 500 500 to 550 550 to 600 600 to 650 650 to 700 700 to 800
P Passenger Ship up to 500 500 to 600 600 to 700 700 to 800 800 to 900 900 to 1000 1000 to 1100
Q Coastwise Passenger Ship up to 200 200 to 250 250 to 300 300 to 350 350 to 400 400 to 450 450 to 500
R Refrigerated Cargo Ship up to 400 400 to 450 450 to 500 500 to 550 550 to 600 600 to 650 650 to 700
S Special Purpose Ship up to 200 200 to 300 300 to 400 400 to 500 500 to 600 600 to 700 700 to 800
T Tanker up to 450 450 to 500 500 to 550 550 to 600 600 to 650 650 to 700 700 to 800
U Ferry up to 100 100 to 150 150 to 200 200 to 250 250 to 300 300 to 350 350 to 400
V Tug up to 50 50 to 100 100 to 150 150 to 200 200 over  
  Notes:
Larger ships have size codes that are incrementally larger.
Liberty ships were EC2, the E being for Emergency. 
Victory ships were VC2, the V being for Victory. 
  
Code Propulsion System Notes: 
S Steam The letter code alone indicates a single-screw ship that carries 12 or fewer passengers.
M Motor The suffix T indicates a twin-screw ship that carries 12 or fewer passengers. 
SM Steam and motor The suffix TR indicates a triple-screw ship that carries 12 or fewer passengers. 
SE Turbo-electric The suffix QR indicates a quadruple-screw ship that carries 12 or fewer passengers.
ME Diesel-electric The suffix 1 indicates a single-screw ship that carries more than 12 passengers.
G Gas turbine The suffix 2 indicates a twin-screw ship that carries more than 12 passengers. 
GE Gas turbine-electric The suffix 3 indicates a triple-screw ship that carries more than 12 passengers. 
N Nuclear The suffix 4 indicates a quadruple-screw ship that carries more than 12 passengers.