Page:EB1922 - Volume 32.djvu/468

446 merchant shipbuilding and given extraordinary powers. The new shipyards were pushed on during 1918, but had scarcely come into active production when the Armistice was signed.

TABLE XIV. Gross Tonnage of Shipping owned in 1910-21 (in millions of tons).

Country

1910

1914

1919

1920

1921

United Kingdom and Colo-

nies

19-0

21-0

18-6

2O-6

22-1

United States

5-i

5-4

13-1

16-0

17-0

Germany ....

4'3

5-5

3-5

0-7

0-7

France

1-9

2-3

2-2

3'2

3-7

Japan

i-i

1-7

2-3

3-o

3-4

Norway

2-0

2-5

1-9

2-2

2-6

Denmark ....

0-7

0-8

0-7

0-8

I-O

Sweden

9

i-i

I'D

I-I

1-2

Italy ....

i'3

1-7

1-4

2-2

2-6

Holland. ....

I-O

i-5

1-6

1-8

2-2

All other Countries

4-5

5-6

4-6

5-6

5-5

Total, World's Shipping.

41-8

49-1

50-9

57-2

62-0

Largely as a result of the efforts of the United States, by the end of 1918 ships were being built at the rate of 7,000,000 tons per annum, against the pre-war record of 3,330,000 tons per annum. In June 1920 the steam tonnage of the world amounted to about 54,000,000 tons, notwithstanding the losses of the war. The total losses had amounted to about 9,000,000 tons of British ships and 6,000,000 tons others, making a total of 15,000,000 tons. Of the total, 2,000,000 tons were due to ordinary marine risks.

FIG. 44.

Motor-Ships. The period 191021 saw immense changes in the means of propulsion. In 191 1 the " Selandia " and " Jutlandia " were launched, and a number of other vessels were being built, in which internal-combustion engines of a more or less experimental character were being fitted. Lloyd's Register reports that by 1914 there were 290 motor-ships of 234,000 tons gross, while in 1921 there were no fewer than 1,447 ships of 1,263,000 tons gross, so that in 1921 there were nearly five times as many motor-ships in existence as there were in 1914, and the tonnage ol these ships was nearly six times as great. In these seven years motor-vessels increased from 47 to 2-1 per cent of the world's tonnage.

Dr. Diesel's master patents expired in 1909 and 1910, and since then many successful types of internal-combustion engines have been established in Europe and in America (see INTERNAL-COMBUSTION ENGINES), and the proportion of motor to steam vessels building rapidly increased. In June 1921 183 motor-vessels of 502,944 tons were under construction, and out of this number 57 of 241,003 tons were being built in the United Kingdom.

Oil Burners. Another very great improvement is in the use of oil instead of coal under steam boilers. Lloyd's Register reports that in 1914 364 vessels of 1,310,000 tons were fitted to burn oil, but in 1921 these had increased to 2,563 ships of 12,797,000 tons, or from 2-62 to 20-65% f the world's tonnage. In the United States four vessels burn oil to every three vessels burning coal. This use of oil fuel has demanded a large increase in the number of oil-tank steamers. In 1914 there were 385 tankers of 1,479,000 tons, while in 1921 there were 861 tankers of 4,419,000 tons, an increase from 2-94 to 7-16 per cent of the world's tonnage.

Electric Drive. It has been the almost universal practice for submarines to be propelled by electric motors when submerged. In a few cases of small surface vessels electric drive had also been used prior to 1910. The earliest recorded appears to be Nobel's tank vessel " Sarmat," fitted with the system in 1904. About 1910 a small vessel named the " Electric Arc " was built on the Clyde to test the method of electric transmission devised by Mavor, using Squirrel cage motors. The experiment was not altogether a suc- cess, but it gave a good deal of experience. Mavor proceeded to America and discussed his ideas with Emmet, and no doubt assisted Emmet in the great undertaking carried out for the American navy in the collier " Jupiter " (now aircraft-carrier " Langley "). The American navy built three colliers at this time of identical dimen- sions, about 20,000 tons displacement, 7,500 H.P., 15 knots full speed, and cargo 12,000 tons. The " Cyclops " has two recipro- cating engines, the " Neptune " has Parsons turbines and a West-

inghouse floating frame mechanical gearing, while the " Jupiter " was fitted with a Curtis turbo-electric generator, running at 2,000 revolutions, giving alternating current at 2,200 volts, and motors driving two propeller shafts at no revolutions. The reported engine room weight of the " Jupiter " is 223 tons, compared with 343 tons in " Cyclops " and 189 tons in " Neptune."

Mavor's next step was to fit up an installation of 1,500 S.H.P. in the " Tynemount," built by Messrs. Swan, Hunter & Co. in 1913. This vessel was 250 ft. long, 1,644 tons gross, and of about 8 knots speed. This system, however, did not admit of development on a large scale.

The next important progress was made in Sweden, where two sister vessels were built, 225 ft. x 36 ft. x 15^ ft., 2,250 displacement, 975 tons gross. Each was provided with 900 H.P. for nj knots. In the " Mimer " triple expansion reciprocating engines were fitted. In the " Mjolmer " Ljungstrom turbo-generators running at 800 r.p.m. were fitted, with two motors of 450 H.P. each, and geared to a single propeller shaft running at 85 r.p.m. It was reported that fuel con- sumption was reduced by over 40%, to -89 Ib. per I. H.P. per hour, and that a saving of 74 tons in weight was effected. A large number of other vessels have since been fitted on the " Ljungstrom " sys- tem. These include the " Turbinia, " of 2,259 tons and 1,020 H.P., built in 1916 in Sweden, and the " Wulsty Castle," of 3,566 tons and 1,500 S.H.P., built in 1918 by Blumer of Sundcrland. It was reported that in 1921 there were 40 vessels building in different countries on this system with the aggregate of 70,000 horse power.

The success of the " Jupiter " was so great that electric trans- mission was adopted by the U.S. navy for a great many of their later ships, even of the highest power. The next great experiment in electrical propulsion was put in hand by the U.S. Shipping Board, who decided to remove the mechanical gearing in 12 vessels and fit an electric drive instead. The first vessel taken was named " Eclipse," the next three vessels " Archer," " Independence " and " Victo- rious." The " Eclipse " is 440 x 56 x 35-2., of 7,589 tons gross and 11,900 dead- weight. The boilers are fitted with Dahl oil burners, steam 215 Ib. and 200 super heated. One turbine of the Curtis Impulse type is fitted to run at 2,000 r.p.m. A three-phased genera- tor supplies current at 2,300 volts. An induction motor is fitted directly on the propeller shaft working at 2,300 volts and running at 100 r.p.m. for 3,000 H.P. The speed may range from 20 to 1 10% of the normal. The result of the trials was very gratifying. The reports as to the first voyage were not quite so good. The other three vessels named had not yet gone on service in 1921.

Another very interesting case is that of the " Cuba," a vessel 310 x 40 x 26-9 of 2,963 tons gross. This vessel has also been fitted with a turbine electric drive by the General Electric Co., Schenec- tady, but in this case a synchronous motor is fitted. Steam of 190 Ib. with 200 super heat is supplied to an 8-stage Curtis turbine, as in " Eclipso" This runs at 3,000 r.p.m. and 1,150 volts. The motor gives 3,000 H.P. at 100 r.p.m. and 1,150 volts, and is fitted directly on the shaft. The trials of this vessel were well reported on. Both vessels are of 1 1 knots speed.

The question of the efficiency and economy of the electric drive was being very much discussed in 1921. On the one hand it was said that the transmission loss of the electrical system was 8% instead of 3% with the mechanical current, but the other ships with electrical current reported very good economy of fuel.

Wood Vessels. In 1914 wood vessels amounted to I % of the total steam tonnage, but owine to the special building during the war it had risen to nearly 4% in 1921. Of this large increase the United States owns one million tons.

The Emergency Fleet programme provided for ordering 1,067 wooden and composite ships, of 3,227,200 tons; but only 607 of 1,948,250 tons, were actually produced. In June 1921 288 cargo carriers remained in the possession of the U.S. Shipping Board, 15 being on active service and 27^5 tied up. The board also had 14 tugs, of which 9 were on active service. Up to this date 21 1 had been sold, 12 of which had been built for service as cargo carriers and 61 as tugs. One had been fitted for carrying oil in bulk. Seventy-four were incomplete when sold. In Aug. 1921 the remaining wooden vessels were reported to be sold to the Ship Construction and Trading Company.

Concrete Ships. Prior to the war a number of small vessels for harbour or river service had been built of ferro-concrete in Italy, Norway and France. During the war a few experimental vessels of small size were built in various places, and the system was adopted to an increasing extent, practically all over the world. As larger vessels were built, the methods received careful consideration, and by proper development vessels up to 7,500 tons dead-weight were successfully produced. The complication of rods and ties in the larger vessels became very great, and sectional or panel systems were introduced, as contrasted with the usual monolith system. The reports as to results varied. The weight of hull was reported to be from 50 to 100% more than for steel, or about equal to wood; while the saving of steel for carrying a given dead-weight amounted to 55 to 66% of the steel ship. This was an enormous advantage during the steel shortage, and a further advantage was the power to build by a new class of labour, giving a greater aggregate of labour for shipbuilding. The most notable vessel was perhaps the S.S. " Faith," built by the San Francisco Shipping Co. in 1918.