The method of measuring the principal volume in France gives in certain cases a closer approximation than in England and Germany because of the greater number of subdivisions of the length. Moreover, the method of the fictitious bottom line is a more delicate refinement than the method followed in England and Germany, in case the bottom line is irregular. In the case of the ceiling of a concave double bottom where the lowest width is zero the French method is inferior to the English method. The error that results may attain 5 per cent below the real area of the corresponding cross section. (English Commission of 1881.) The French method exempts the volume corresponding to the thickness of the floor joists on which the bottom sheathing sometimes rests. This thickness may reach from 15 to 20 cm. In case of refrigerating walls the deduction of the sheathing from the measurement is generally less than the deduction of the 3 inches allowed, in this case, in England. In this regard, because of the smaller number of subdivisions of the length, the English tonnage gives, in certain cases, an approximation not so close as that of the German and French methods. Because of the number of subdivisions of the length, the approximation of the German tonnage is intermediate between that of the French and that of the English tonnages." The method of subdividing the principal volume at each point of a break in the bottom line is easy and practical to handle. In the case of the ceiling of a concave double bottom the approximation of the English and German methods is better than that of the French methods. This method of measuring the areas of cross section in separate parts in all cases where the old method seems insufficient is apparently becoming more general. The volume corresponding to the thickness of the floor joists on which the bottom sheathing sometimes rests is not exempted from measurement. The deduction of 3 inches from the width in case of refrigerating walls is greater than what is generally allowed in France in this case. The special method of measuring the first width of the principal volume of turret ships is characterized by a No deduction is made in this case. The German method is therefore, on this point, the strictest of the three. 1 Accuracy of tonnage measurements: In Germany all calculations are carried out to the third decimal place, and when the fourth decimal is five or more the third is increased by one. (Instructions to ship survey, art. 26.) Approximation of tonnage measurements: German measurement practice now divides the length into the same number of subdivisions as in England. (Ship-measurement ordinance, art. 6.) The exemptions from measurement of the water ballast spaces are governed by the same rules in the three countries. The approximations of the tonnage measurements are therefore, on this point, in very close accord." The exemptions from measurement of the inclosed spaces on the upper deck likewise conform to the same rules in the three countries. Therefore there can result, on this point, no difference in the approximations of the tonnage measurements. The definitions of the opendeck spaces are a little stricter than in England. Some differences might result therefrom. But it must be observed that with the present subsidy laws an effort is made to avoid open spaces rather than otherwise. Crew space is deducted without any restrictions. The deductions for spaces used in handling the vessel are subject to restriction only as regards the boatswain's storeroom and the sail room, with practically no difference from the English and German rule. 1 See note 2, p. 379. The exemption from measurement of the deck spaces considered open is subject to less strict rules in England than in Germany or in France. This greater indulgence may, in some cases, have as its consequence supplementary exemptions. The deductions for crew space are subject to hygienic conditions. As it never occurs that these are not fulfilled, no difference results. The definitions of the opendeck spaces are more strict than in England. From this there may result, in some cases, less importance in these exemptions. It is proposed to subject the deductions for crew to hygienic conditions.3 The deductions for spaces used in handling the vessel are subject to the condition that these spaces be reasonable in extent and exactly appropriate to their purpose. There results practically no difference from the French rule. 2 Since 1906, and 1908, respectively, water ballast spaces other than double bottom are not exempted in England and Germany. They are measured, and, if used only for water ballast, are deducted. 3 Deductions for crew space in Germany are subject to detailed provisions as to hygienic conditions. (Regulations of July 2, 1905.) FRANCE. The deductions for propelling machinery are subject to the same restrictions as in England only as far as ventilation spaces are concerned. The absence of precise restrictions for the other machinery volumes might, in certain cases, allow their being enlarged beyond what is necessary and thus obtaining, by the application of the "Danubian increment rule," machinery deductions greatly in excess of the real needs of the case.1 The deduction of the actual volume of the coal bunkers might, in certain very rare cases, constitute an important advantage for the French tonnage rules. The deductions for propelling machinery are subject to no precise restrictions. In certain cases considerable exaggeration in the machinery spaces may result from the The deductions for propelling machinery are subject to several restrictions, having as their object.the prevention of the enlargement of the machinery spaces beyond what is reasonable, and also the pre-application of the "Danubian vention of thus obtaining, by increment rule," causing the application of the "Danu- machinery deductions much bian increment rule," deduc- greater than is necessary.1 tions greatly in excess of the real needs of the case.1 However, these restrictions seem to only partially fulfill their object. A commission appointed by the Board of Trade is at present examining the whole question of machinery deductions. Possibly the result will be the establishment of a maximum.2 The deduction of the actual volume of the coal bunkers not being applied in England or in Germany, there might result, in certain very rare cases, a considerable disadvantage as compared with the French tonnage rules 1 It should be added that in the absence of restrictions equally great exaggeration may result from the application of the Board of Trade percentage rule. Ordinarily the Danube rule deducts less than the Board of Trade rule. The Merchant Shipping Act of 1907 fixed a maximum of 55 per cent of the gross tonnage remaining after the general deductions are made. |