be shifted so as to enlarge or contract either the coal bunkers or the cargo holds as is desired on a particular voyage. A general or average rule for deducting propelling machinery and fuel spaces is therefore needed. Under the national measurement rules of the United States the so-called "percentage rule" is applied to some vessels and the so-called "Danube rule" to others. The former provides that if the space occupied by the engine and boiler rooms of a screw-propelled vessel is above 13 per cent and under 20 per cent of the vessel's gross tonnage, the combined deduction for propelling machinery and fuel spaces shall be 32 per cent of the gross tonnage. The corresponding percentage rule for vessels propelled by paddle wheels is that if their propelling machinery occupies over 20 per cent and under 30 per cent of the gross tonnage, a deduction of 37 per cent of a vessel's gross tonnage shall be made. The Danube rule, on the contrary, is applied to vessels the engine and boiler rooms of which do not come within the 13 to 20 or 20 to 30 per cent limits. It provides for a deduction of the actual spaces occupied by the propelling machinery plus 50 per cent in the case of vessels propelled with paddle wheels, and plus 75 per cent in the case of screw-propelled craft. A large proportion of all oceangoing vessels are constructed so as to come within the percentage rule, because it usually results in a larger deduction than the Danube rule provides and in a deduction of more space than is actually occupied by propelling machinery and fuel bunkers. The net-register tonnage of American vessels is consequently in many instances an understatement of actual tonnage, and not all vessels are treated alike. The same is true of Great Britain, where the rule originated in 1854 and is still applied. The rule is also followed in Germany and many other foreign countries. Being based upon gross-register tonnage the understatement of tonnage as registered in the United States and in other shipping countries is further increased by the exemption from measurement of various spaces which are in fact available for cargo or passengers. As the special gross tonnage rules applied at the Suez and Panama canals were formulated so as more nearly to disclose the real gross capacity of vessels, so also were the rules governing deductions of spaces not available for cargo or passengers devised with a view to disclosing the real net capacity. Especially was this the purpose in promulgating the "Panama Canal measurement rules," which differ from the Suez rules in some respects. Both the Panama and Suez rules differ from the official tonnage rules of the principal countries in that they discard the percentage rule for deducting machinery and fuel spaces, and substitute the Danube rule with the option of the actual measurement of such spaces in the case of vessels equipped with fixed fuel bunkers. The average deductions made from gross tonnage in arriving at net tonnage during the first 13 months of Panama Canal operation was 30 per cent. The average deduction from gross tonnage under the Suez rules is usually 28 or 29 per cent. In contrast with this the deductions under the national measurement rules of Great Britain and Germany average 39 per cent, of Norway 37 per cent, of Russia and Denmark 41 per cent, and of France 42 per cent. The deduction under the American registry rules, before the recent liberal interpretation of the rules governing superstructures and shelter decks, was about 34 per cent. The deductions from gross tonnage made in accordance with the American measurement rules are further shown in the American measurement certificate reproduced in Form 1. The net-register tonnage of merchant vessels is highly important alike to their owners, to governmental authorities who administer the navigation laws, and to commercial concerns of various kinds. Net-register tonnage is the basis for tonnage taxes and other tonnage dues the world round; and commercial charges, such as those for towage, dockage and wharfage, are also at times based on net-register tonnage. The official statistics of entrances and clearances published by the United States and most foreign governments are stated in terms of net-register tonnage. Time charter rates, when not based on dead-weight tonnage, are based on net-register tonnage; and tolls at some canals, such as the Kiel and Manchester canals, are based in part on this form of tonnage. The incentive to understate net-register tonnage in the various maritime countries has consequently been strong, and when some of them follow that policy it is difficult for the others not to do likewise. The net tonnage ascertained in accordance with the Suez and Panama Canal measurement rules are important, because they serve as the principal basis for the tolls charged at these waterways. Suez net tonnage is the basis for the vessel tolls paid by both merchant and naval craft to the Suez Maritime Canal Company, and Panamá net tonnage is the basis of the tolls paid by merchant vessels and by army and navy transports, colliers, supply ships and hospital ships at Panama. CARGO TONNAGE Quite distinct from the different kinds of vessel "tons" and tonnage mentioned above are the various forms of cargo "tons" and tonnage in terms of which the amount of cargo on board an ocean vessel and its cargo capacity are expressed. Cargo tonnage may be stated either in weight or measurement tons. A weight or avoirdupois ton, moreover, may be a long ton of 2,240 pounds, a metric ton of 2,204.627 pounds, or a short ton of 2,000 pounds. The long ton is of chief importance in the overseas trade of the United States in so far as goods are shipped as weight cargo, and the metric ton in the trade of such foreign countries as adhere to the metric system. The short ton, although commonly used in the shipment of freight by rail in the United States, is only occasionally used in the overseas trade. Much ocean freight, however, is not shipped by weight but in units of measurement tons, usually of 40 cubic feet each. Light package freight is frequently shipped as "measurement cargo," which means that its quantity is stated in measurement tons. It is a paradoxical fact that a vessel may carry a larger number of "tons" of light package freight than of heavy bulk cargo. 2,308 3,639 2,639 3,908 2,831 5,922 3,428 6,860 4,566 4,732 7,178 Grena.. Norwegian 7,341 3,163 5,578 3,047 5,352 3,469 5,427 3,750 3,929 5,266 7,741 5,556 3,994 5,495 4,032 Swedish 3,745 2,858 | 4,130 2,956 5,298 4,001 San Francisco. 1 Formerly British. flag of the United States. 2 British register tonnage. 3 British register tonnage retained after transfer to 4 See column "American Register Tonnage.' The relationship between the various kinds of vessel and cargo tonnages cannot be fairly expressed in terms of an average, because it is influenced greatly by the many different types of vessels operating on the high seas, by the kinds of cargo carried by them, and by the particular gross and net measurement rules in accordance with which the register tonnages are ascertained. A general idea may, however, be obtained from Table No. 6, page 123, which contains concrete data for a number of typical cargo- and passenger-carrying vessels. American shipping includes both "documented" and "undocumented" craft. All self-propelled and sailing vessels operating under the American flag are legally required to be listed and documented by the United States Government at the office of the Commissioner of Navigation. Barges, flatboats and like craft not self-propelled or fitted with sails are not required to be documented unless they carry passengers or are engaged in the trade with contiguous foreign countries; and harbor craft, such as lighters and floats, are likewise not required to be documented. Documented vessels engaged in the foreign trade and the whaling industry are "registered"; those employed in the inland and coastwise commerce are “enrolled"; and those of less than 20 tons measurement are "licensed," REFERENCES BÉRET, V. Étude Sur le Jaugeage (Paris, 1905). Germany (Imperial Department of the Interior). The Measurement of Seagoing Vessels (ed. of 1908, Berlin). Great Britain (Board of Trade). Instructions and Regulations Relating to the Measurement of Ships and Tonnage Under Merchant Shipping Acts (London, 1913). Report by Royal Commission on Tonnage. Reports from Commissioners, 49 (c-3074) (London, 1881). Report from Select Committee on the Merchant Shipping Bill (Tonnage Deduction for Propelling Power) Bill cd-256, London, 1907). |