Japanese Use of Military Barges, WWII Tactical and Technical Trends, No. 43, January 27, 1944 (Lone Sentry)

The following account of the Japanese military barges has been drawn from official sources and is believed to be reliable.

a. As Supplementary Shipping

According to one report, the deficiency in Japanese military cargo tonnage caused by the sinking of merchant shipping is being made up to some extent by the use of motor-driven barges of very considerable sea-going capacity. The activities of barges in the area of the Solomons, Bismarks and New Guinea indicate that these capacious, shoal-draft craft are being used to transport and supply troops in areas that cannot be reached by cargo vessels because of excessive loss from aerial attack. Such barges can easily be run into shallow coves and creeks, where a little camouflage together with the natural cover make them extremely hard to detect from the air during the day. With suitable overhead screening, even open beaches can be used. In areas where our air forces are active, most of the actual operations are conducted at night. It seems probable as the destruction of Japanese shipping goes on, that the 6,000 barges which were believed to be in service last spring will continue to be augmented, and ever more widely employed for supply, reinforcement and evacuation.

b. Characteristics of the Large Landing Barge (Daihatsu)

While a number of types of barges are used by the Japanese army, it is thought that the enemy will concentrate on the large landing barge, see accompanying illustrations. The usual type of barge is about 49 feet long and 12 feet wide, with the conventional pointed bow, although some of the same size and general construction have a double bow to support a landing-ramp.

Usually, the construction is reported to be of wood--teak, Oregon pine, or whatever local varieties are available. Apparently steel or composite construction -- wood on a steel frame -- is also used. Plating of 5/8-inch steel may be applied to protect personnel. At any rate, the boats are simple, sturdy, easily built, seaworthy and cheap. From information received, it is inferred that the cargo capacity is about eleven short tons. They would carry 10 horses, or a light tank, and an automobile, or 70 fully equipped men exclusive of a barge crew of seven, which presumably, includes some sort of a machine-gun, or AA-gun crew. A 60-horsepower gasoline or heavy-fuel motor installed aft gives a speed of 8 knots, equivalent to about 9 miles per hour. Although not decked over, such barges are capable of covering considerable distances of open sea and present a logistic factor that must be taken into consideration.

[Japanese Landing Craft and Barges, World War II]
JAPANESE LANDING CRAFT

Incidentally, it is probable that the Japanese are employing all the Chinese junks they can get. These vessels are, in spite of their odd appearance, particularly well adapted for the treacherous waters of the shallow China coast. An ordinary junk may well be heavily built, about 100 feet long, 30 feet wide, and almost square in cross-section, with a bottom that curves up like a chair rocker from mid-ships to the almost square bow and high after-deck. Due to their peculiar shape, the cargo capacity is unusually large -- a junk as described may carry upwards of 200 tons on a seven-foot draft. Under sail, they may be seaworthy and reasonably fast, say, 180 miles per day with ordinary winds and cargo. However, they are extremely difficult for western sailors to handle because of their peculiar construction, rigging and behavior. In Japanese service, they may be equipped with motors. The influence of junk construction may be noticed in the appearance of the Japanese barges, particularly about the bow.

c. Operational Organization

The Japanese army has regiments of shipping engineers (Sempaku Kohei), who operate in details of from 20 to 140 per transport vessel, control the loading and unloading of the ships, and operate the barges on ship to shore, or on coastal or inter-island runs. Evidence points to the fact that they are well-trained and efficient.

d. Capacity in Unopposed Landings

From Japanese sources it appears that unopposed, 45 large barges, 20 small, 6 armored barges and three of an unknown type unloaded 6 vessels of 4,692 personnel, 66 guns, 20 horses and 140,800 cubic feet of supplies within 20 hours of dropping anchor. The boats were ready to launch upon anchoring; the order of unloading was; (1) infantry, land-duty personnel and antiaircraft unit; (2) medium field artillery; (3) other units, horses, baggage and materiel. The armored barges were for protection against American forces; the three barges of unknown type may have been tank landing craft. As the 20 small and 45 large barges had capacities of 30 and 70 men respectively, or a total of 3,750, about 80 of the total personnel could have been transported to the beach on the first trip. While the personnel was successfully landed and antiaircraft batteries were in action the following morning, three ships were sunk by air and artillery attack and much cargo was lost.

e. Capacities for Troop Movement

Japanese tests to establish the possibilities of barges for troop transport indicate that with the use of benches and tents, cooking facilities on board, and some type of guns mounted for protection, barges could cover 50 nautical (56.5 land) miles in seven hours. The cargo weight figures, based upon estimates of 200 pounds per man including crew of seven and other weights as given in TM 30-480, Handbook of Japanese Military Forces, work out as follows, on a "yardstick" basis for purpose of estimate:

Table 1

Troops
Personnel       Additional
Equipment       Weight
(Short Tons)

Rifle Co 50 none 5.61

MG Co 40 3 MGs 4.84

Inf Bn gun unit 40 2 70-mm How's 4.95

Inf Regt gun unit 35 1 75-mm gun 4.73

Mtn Arty unit 35 1 75-mm gun 4.73

Rapid fire gun unit 28 2 37-mm gun 4.18

Lt Arm car or tankette unit 15 1 tankette 5.39

TM 30-480, Handbook of Japanese Military Forces, gives the personnel of a Japanese regiment as 3,332 and lists the weapons. Table 2 below indicates their possible distribution in barges.

Table 2

Weapons       Personnel       Large Barges
LMG's and small arms 2,600 52
24 HMG's   320 8
6 70-mm How's   120 3
4 75-mm guns   140 4
12 37-mm guns*     168      6
3,348 73

A comparison of the weight-carrying capacity of a barge -- 11 tons (10 long tons) -- and the data in Table 1, indicate the barges were loaded to only about half capacity. Considerable quantities of rations and ammunition could consequently be carried in addition to the personnel and weapons in Table 2. For the movement of barges a distance of 300 sea miles (345 land miles) the Japanese would probably use a one-night stage of 70 miles, which is reasonable, considering a period of darkness of 12 hours, and a barge-speed of nine miles per hour. It may therefore be concluded that:

(a) A convoy of 73 large barges can move a Japanese infantry regiment and a substantial amount of rations and ammunition a distance of 70 nautical miles (80 land miles, approx) per night for several nights, with proper day concealment and fuel supply.

(b) A fleet of 37 large barges seems to be sufficient to transport a Japanese infantry regiment about 34 miles in 36 hours including two nights.

f. Capacity for Ration Transport

Enemy data indicates an allowance of 3.06 pounds of food per man per day. It may then be inferred that a barge with 11 tons capacity (10 long tons -- 22,400 lbs.) contains rations for 6,200. A barge system capable of delivering three large barge loads per day is sufficient to supply rations for a Japanese triangular division of 18,000 men. An average Japanese schedule for a 300 sea-miles (345 land mi) barge run would be six days, and the round trip probably 15 days. Allowing for barges to transport motor fuel to staging stations, it may be concluded that 50 large barges can supply normal rations to a triangular division at a distance of 300 sea miles, or 345 land miles.

g. Capacity of Japanese Barges for a Troop Movement of 300 (sea) Miles

The Japanese estimate that for the transport of a force of about 1,000 men a distance of 300 sea miles without support other than reconnaissance planes, the following applies:

(1) Transport Used

A detachment of Shipping Engineers equipped with the following:

         2 Special large landing barges
         40 Large landing barges
         15 Small landing barges
         2 Armored boats

With this convoy not overloaded, the data indicated that an infantry battalion of 750 and about 300 shipping engineers, or a total of 1,050 were to be transported. The shipping engineers were equipped with small arms -- rifles and machine guns. This total included the machine-gun company with eight 7.7-mm machine guns, two each 20-mm rapid fire guns, 37-mm antitank guns, 70-mm howitzers, 75-mm guns and 75-mm mountain guns. There are indications that most of these guns were set up in firing position, which would give the convoy a rather respectable firepower. The total weight of ammunition carried was 78 metric, or 85.5 short tons, together with 25.3 short tons of rations -- hard bread for eight days and regular rations for 12. The water allowance, 1.05 gallon per man per day, was 27.5 short tons. An allowance of 2.2 tons of fuel per day was made for the large barges, but figures for other craft are not available. The total fuel load was 115 metric (126.5 short) tons. Such an allowance would be insufficient for a return trip and would permit but little maneuvering.

The tonnage load of the convoy was as indicated below--

          Short tons

Personnel (1,050)   115.5

Guns    11.0

Fuel   126.5

Rations    25.3

Water    27.5

Ammunition    85.8

     Total   391.6

Assuming the capacity of a large barge without reserve fuel at 11 short tons, and that of a small barge at 4.4, the capacity of the convoy exclusive of the special and armored barges is 40 large barges, 440 tons; 15 small barges, 66; total, 506 tons. Since the actual load was 391.6 tons, approximately, the barges were loaded to about 77 percent of capacity.

As the number of days required for a 345-mile trip is stated as 15, including two or three days for servicing every five or six days, it is highly probable that the time allowed for a one-way trip was from 6 to 10 days. Supporting this assumption are the facts that the water allowance was sufficient for six days, emergency rations for eight. Standard rations were stowed for 20 days with 10 days rations for consumption after landing.

It may then be concluded that the Japanese believed the craft listed were sufficient for the self-sustained transport of 1,050 men, their machine guns and heavy weapons, with 163 pounds of ammunition per man, rations for 20 days and water for six, over a distance of 300 nautical (345 land) miles in from 6 to 10 days.

*The ordinary regiment would probably have only six of these guns.