Technical Specifications for Ships

built under the Merchant Marine Act of 1936



The following analysis provides a description of all types of vessels designed and built by the United States Maritime Commission under the Merchant Marine Act of 1936. In addition to such basic types as the C1, C2, C3 (Cargo), Victory , Liberty, and T2 (Tanker) types, all specialized designs that were created to serve the diversified war and peacetime transportation needs of the nation, are shown.

Since many designs were modifications or conversions from standard designs, only design characteristics or standard designs are generally shown. Design characteristics are for identification purposes and are not warranted as those of any particular vessel.

A description of the classification system of letters and numbers used to outline characteristics of all Maritime Commission designs will be find next.

In the following pages various terms are mentioned which give the factual data of each vessel. Definitions of these terms will also find next.

(from Vessel Design & Characteristics, Office Chief of Transportation, Washington D.C. 1 June 1948)

Index of Vessel Designs

Design Design Design Design Design Design
B1-A1 C2-G C3-S-A3 L6-S-A1 S2-S2-AQ1 V2-M-AL1
B1-B1 C2-S C3-S-A4 L6-S-B1 S3-M2-K2 V2-ME-A1
B1-C1 C2-T C3-S-A5 S3-S2-BP1 V3-S-AH2
B3-F1 C2-SU C3-S-BH1 N3-M-A1 S4-S2-BB3 V4-M-A1
B4-BX1 C2-SU (R) C3-S-BH2 N3-S-A1 S4-SE2-BD1
B5-BJ1 C2-S-A1 C3-S1-BR1 N3-S-A2 S4-SE2-BE1 VC2-S-AP1
B5-BJ2 C2-S-AJ1 C3-S1-A3 VC2-S-AP2
B5-BJ3 C2-S-AJ2 C3-S1-B1 P1-S2-L2 T1-M-A1 VC2-S-AP3
B5-G1 C2-S-AJ3 C3-S1-N2 P2-S1-DN3 T1-M-A2 VC2-M-AP4
B7-A1 C2-S-AJ5 C3-S-DX1 P2-S2-R2 T1-M-BT1 VC2-S-AP5
B7-A2 C2-S1-AJ4 P2-SE2-R1 T1-M-BT2 VC2-S1-AP7
B7-D1 C2-S-B1 C4-S-A1 P2-SE2-R3 T1-M-BK1
C2-S-E1 C4-S-A3 P2-S2-R9 Z-EC2-S-C2
C1-A     (Diesel & Turbine) C2-S1-DG2 C4-S-A4 P3-S2-DL2 T2 & T2-A Z-EC2-S-C5
C1-B     (Diesel & Turbine) C4-S-B1 P4-S2 T2-SE-A1 Z-ET1-S-C3
C1-M-AV1 C3-Cargo (Diesel & Turbine) C4-S-B2 P6-S4-DS1 T2-SE-A2 Z3-EC2-s-C1
C1-M-AV8 C3-P & C C4-S-B5 T2-SE-A3
C1-ME-AV6 C3-A (P & C) R1-M-AV3 T3-M-AZ1
C1-MT-BU1 C3-E C5-S-AX1 R1-S-DH1 T3-S-A1
C1-S-AY1 C3-IN (P & C) R2-S-BV1 T3-S-BF1
C1-S-D1 C3-M Cargo Passenger R2-ST-AU! T3-S-BZ1
C3-P (P & C) T3-S2-A1
C2-Cargo C3-S-A1 EC2-S-C1 S1-BG1 T3-S2-A3
C2-F C3-S-A2 EC2-S-AW1 S1-M-A1

Classification System for Maritime Commission Designs

The system will be based on three groups of letters and numbers which will endeavor to outline characteristics of the vessel. The first group "prefix" will indicate the type of vessel, such as cargo, passenger , etc., and its approximate size. The second group "intermediate" will indicate the type of machinery, and number of screws and the third group "suffix" will indicate the paticular design of the type of vessel and modifications of the same.

Example : C2-S-AJ1

For the first group (see Table 1) a letter will be used in conjunction with a number. Please note example above as an illustration; the "C2" stands for a cargo ship between 400 and 450 feet ong.

The second group will be outlined in Table 2 with the appropiate symbols with a number. Continuing the classification , our example would now be "C2-S" standing for a single screw cargo ship, steam machinery, of a lenght between 400 and 450 feet.

It can be seen from the above that there may be many variations of length and form in the range 400 and 450 feet and hence it is necessary to have a design letter that will fix the particular vessel under consideration. A third group is, therefore, used and the design letter will remain fixed regardless of any change that may be made. The design letter of our example is, therefore "AJ" in this third group indicates the original arrangement of this particular design . This number can be varied to reflect changes of a major nature such as addition of passengers, conversion  to troopship, etc. An example is as follows: Let us assume that accomodations for 50 passengers were added to this particular vessel. As this would be a major change, the third group would become "AJ2". Since accomodations for more than 12 passengers had been added this second group would become "S1", and as these accomodations were for less than 100 Passengers, the first group would not change. Our complete designation would then be C2-S1-AJ2. Since we already have, and may have many more, "C2" vessels it is important to point out here that any verbal abbrevation (nickname) of this particular design should b2 "AJ" and not "C2".

The Prefix

The first or "prefix" group indicates (a) the general class of vessel (cargo, passenger, refrigerated, tanker, etc.) and (b) the lenght-range within which the design falls. The symbol in this group are assigned in accordance with the folowing table:

Table 1

Letter Class of vessel Lenght Designation ( Feet)
Single Other than Emergency & Victory types 1 2 3 4 5 6 7
C Cargo-Unltd.Ser (under 100 passenger) Under 400 400-450 450-500 500-550
P Pass.-Unltd.Ser (over 100 passengers) Under 500 500-600 600-700 700-800 800-900 900-1000 over 1000
B Barge under 100 100-150 150-200 200-250 250-300
L Great Lakes Ore & Grain under 400 400-450 450-500 500-550 550-600 600-650
N Coastwise Cargo under 200 200-250 250-300 300-350 350-400 400-450 450-500
R Refrigerator under 400 400-450 450-500 500-550
S Special under 200 200-300 300-400 400-500 500-600 600-700
T Tanker under 450 450-500 500-550
V Towing Vessels under 50 50-100 100-150 150-200
Z conversion (for conversion of established types "Z" is prefixed to original designation, but with new final number in some cases
Double Emergency & Victory types
EC Emergency Cargo (Liberty Ship under 400 400-450 450-500 500-550
ET Emergency Tanker (used with prefix "Z" for conversion of Liberty Ship to Tanker design).
VC Victory Cargo under 400 400-450 450-500 500-550

The following older designs (except the last four) accord with table 1 but they do not accord with table 2, in as much as they were  given their identification before the present scheme of self-descriptive symbols was fully developed:

C1-A C2-SU Reefer C3 (P & C) Turbine
C1-B C2-T C3-P (P & C)
C2-Diesel C2-Turbine C3 Turbine
C2-F C3-A (P & C)
C2-G C3-Diesel Navy Yard AOG
C2-Modified C3-E Passenger
C2-S C3-IN (P & C) Passenger & Cargo
C2-Seas Shipping C3-M Tankers, 28
C2-SU C3-(P & C) Diesel

In the preceding list of older designs the letter or word following the hyphen are simple distinguished characters. All of the remaining and newer designs have more fully self-descriptive designations as shown in the Exampe.

Intermediate Letter or Group

Following the "prefix", the intermediate letter or combination indicates the type of power machinery and pro-pulsion, and whether passenger accomodations, if any, are provided for 12 or more persons, or more than 12. These symbols can be interpreted by references to the following table:

Table 2

Type of machinery No.of propellers Under 12 passengers Over 12 passengers
Steam Single S S1
Motor Single M M1
Turbo Electric Single SE SE1
Diesel Electric Single ME ME1
Gas Turbine Single G G1
Gas Turbo-Electric Single GE GE1
Steam Twin ST S2
Motor Twin MT M2
Turbo Electric Twin SET SE2
Diesel Electric Twin MET ME2
Gas Turbine Twin GT G2
Gas Turbo-Electric Twin GET GE2
Steam Stern Wheel SW S0
Motor Stern Wheel MW M0

The Suffix - - Identification of Design

The third group, or "suffix", supplies the exclusive identification of the particular design, and indicates the approximate time when the design originated. The alphabet letters are assigned in series; therefore, if there is but one letter, this indicates that the design originated earlier than one having two letters. Likewise, a single letter that is near the beginning of the alphabet indicates an earlier date than one near the end of the alphabet. As between two designs, each of which has two letters, the same date relationship obtains between their first letters, than their second letters in relation thereto. (There are occasional irregular designations, of which the date does not accord with the above scheme).

The figure following the letters in the suffix indicates that it is either  (a) the original design of that particular alphabet designation or (b) a modification thereof. The original design is invariable numbered "1". Thereafter modifications, if any, are numbered "2", "3", and so on - - "2" indicating the first modification, and so on.


Full Scantling Ship - A ship with three decks in which the frames hold the same dimensions to the upper deck.
Shelter Deck Ship - A ship having a very light upper deck in the sides of which are open ports to the second or main deck.
Flush Deck - An unbroken deck fore and aft, where no wells or erections extend across a vessel.
Stem or Bow - The foremost steel bar in a vessel
Stern - The afterpart of a vessel
Lenght over all - The distance from the foremost part of the stem to the aftermost part of the stern.
Beam - The width of a ship athwartship
Depth - The depth of a vessel from the top of the keel to the top of the deck beams at the side of the freeboard deck then depth is measured to the bulkhead deck.
Draft Loaded - The depth of water necessary to float a vessel fully loaded.
Tonnage: - Merchant vessels:
Gross Tons - The entire internal cubic capacity of the ship expressed in tons of 100 cubic feet to the ton, except certain spaces with are exempted such as:Peak and other tanks for water ballast, open forecastle bridge and poop, access of hatchways, certian light and air spaces, domes of skylights, condenser, anchor gear, steering gear, wheel house, galley and cabin for passengers.
Net Tons - Obtained from the gross tonnage by deducting crew and navigating spaces and allowances for propelling machinery.
Register Tons - Register tonnage is applicable to both gross and net, in other words it can be expressed as gross register tonnage or net register tonnage.
Deadweights Tons - The Difference between the displacement light and the displacement loaded in tons of 2,240 pounds
Displacement, Light - The weight of the ship excluding cargo, fuel, ballast stores, passengers, crew, but with water in the boilers to steaming level.
Displacement, Loaded - The weight of the ship including cargo, passenfer, fuel, water, stores, dunnage and such other items necessary for use on a voyage, which brings the vessel down to her load draft.
Cargo Deadweight Tons - The number of tons (2,240 pounds per ton) which remain after deducting fuel, water, stores, dunnage and such other items necessary for use on a voyage from the deadweight of the vessel.
Grain Cubic - The maximum space avaiable for cargo measured in cubic feet, the measurements being taken to the inside of the shell plating of the ship or to the outside of the frames and to the top of the beams or under side of deck plating. In other words, if a bulk cargo were loaded such as grain, it would flow in between the frames and beams and occupy the maximum space avaiable.
Bale Cubic - The space avaiable for cargo measured in cubic feet to the inside of the cargo battens, on the frames, and to the underside of the beams. In a general cargo of mixed commodities the bale cubic applies. The stowage of the mixed cargo comes in contact with the cargo battens and as a general rule does not extend to the skin of the ship.
Measurement or Ship Ton - Calculated as 40 cubic feet, volumetric or space meassurement. (Abbreviated M/T). See Bale Cubic - example, a vessel having capacity of 10,000 M/T has a balle cubic of 400,000 cubic ft.
Weight Ton - Calculated as a long ton (2,240 pounds) (abbreviated W/T)
Liquid Cargo - Conversion factors:
Item °API Cu.Ft./ton Bbls./ton
Fuel Oil : Bunker "C" 15.0 37.23 6.630
Diesel Heavy 18.8 38.23 6.808
Gasoline* 60.0 48.679 8.670
Cargo Oil 25.9 40.00 7.124
1 Bbl. - 42 U.S.Gals. - 5.615 cu.ft....
* Capacity of tankers if based on their cubic capacity in barrells with tanks 98% full, loaded to Summer load.line.