of hold to the top of the ordinary floor, gives the coefficient to be used in the Tables. (d) Vessels constructed with a cellular bottom throughout the fore and after holds, but with floors of the ordinary kind fitted for a part of the length amidships under the engines and boilers.In such a case the tonnage of the space between the top of the ordinary floors in the part amidships, and the top of the cellular bottom, if made continuous, should be estimated, and deducted from the registered under-deck tonnage, and the remainder employed in conjunction with the depth of hold to the top of the cellular bottom in determining the coefficient of fineness. (e) Other cases may in practice arise in which the registered under-deck tonnage, or the registered depth of hold, or both, require modification before being used in the determination of the coefficient of fineness, but little difficulty will be experienced in making the necessary correction, if it be remembered that the coefficient sought is the coefficient the vessel would have if framed on the ordinary transverse system. 5. Moulded Depth.-The moulded depth of an iron or steel vessel, as given in the tables, is the perpendicular depth taken from the top of the upper deck beam at side, at the middle of the length of the vessel, to the top of the keel and the bottom of the frame at the middle line, except in spar and awning deck vessels, in which the depth is measured from the top of the main deck beams. In wooden and composite vessels the moulded depth is taken to be the perpendicular depth from the top of the upper deck beam at the side of the vessel amidships to the lower edge of the rabbet of the keel. (a) The form at the lower part of the midship transverse section of many wooden and composite vessels being of a hollow character, as in cases where thick garboard strakes are fitted, the moulded depth in such instances should be measured from the point where the line of the flat of the bottom continued cuts the keel. 6. Freeboard. The moulded depth, taken as above described, is that used in the tables for ascertaining the amount of reserve buoyancy and corresponding freeboard in vessels having a wood deck, and the freeboard is measured from the top of the wood deck at side, at the middle of the length of the vessel. (a) On the same principle, in flush-deck vessels, other than spar or awning decked, and in vessels fitted with short poop and forecastle, having an iron upper deck, not covered with wood, the usual thickness of a wood deck should be dededucted from the moulded depth of the vessel measured as above, and the amount of reserve buoyancy and corresponding freeboard taken from the column in the tables corresponding with this diminished moulded depth: Example.-In a steamer fitted with an iron upper deck, not covered with wood, and having a moulded depth of 19ft 10in, 4 inches, or the usual thickness of a wood deck, must be deducted from this, leaving a depth of 19ft 6in. The freeboard of such a vessel with a coefficient of fineness of 0.76, taken from the column under 19ft 6in, is 3ft 8in, which should be measured from the top of the iron upper deck. (6) In spar-deck vessels having iron spar decks, and in awning-deck vessels having iron main decks, the freeboard required by the tables should be measured as if those decks were wood covered. Also in vessels where 7-10ths, or more, of the main deck is covered by substantial erections, the freeboard found from the tables should be measured amidships from a wood deck, whether the deck be of wood or iron. In apply. ing this principle to vessels having shorter lengths of substantial enclosed erections the reduction in freeboard in consideration of its being measured from the iron deck, is to be regulated in proportion to the length of the deck covered by such erections. Thus, in a vessel having erections covering 6-10ths of the length, the reduction is 6-10ths of 3 inches, or 2 inches. 7. For vessels which trim very much by the stern, through the engines being fitted aft, the freeboard, as ascertained from the tables, if set off amidships would not cut off the amount of surplus buoyancy deemed necessary, and in such cases the suitable freeboard amidships could only be determined after full information is obtained regarding the vessel's trim. 8. The following example will illustrate the general application of the tables : In a steamer of the following dimensions, viz., length 204ft; breadth extreme, 29ft; depth of hold 16'oft; registered tonnage under deck, 682 tons; and moulded depth, 17oft; the under deck capacity in cubic feet is 68,200; by dividing this by 94,656, that is, the product of the length, breadth, and depth of hold, the quotient is 072, or the coefficient of fineness. If we now refer to Table A at 17'oft moulded depth, and trace the line opposite the coefficient o'72 to the column corresponding with this depth, it is found that the winter freeboard given for a first-class steam vessel without erections, whose length is twelve times the moulded depth, is 2ft 11in, corresponding with a reserve buoyancy of 25 per cent. of the total bulk. 9. Vessels of Extreme Proportions.-For vessels whose length is greater or less than that of the vessel of the same moulded depth for which the Tables are framed, the freeboard should be increased or diminished as specified in the footnote to the tables. Thus, if the vessel in the example, clause 8, were 224ft long, the winter freeboard required would be 2ft 11in plus 2in, or 3ft 1in. For steam vessels with top-gallant forecastles, having long poops or raised quarter decks.connected with bridge-houses, the whole extending over 6-10ths, or more, of the length of the vessel, the correction for length should be one-half that specified in Tables A. 10, Breadth and Depth.-In framing the tables it has been assumed that the relation between the breadth and depth is such as to ensure safety at sea with the freeboard assigned when the vessel is laden with homogeneous cargo; for vessels of less relative breadth, the freeboard should be so increased as to provide a sufficient range of stability, or other means adopted to secure the same. II. Erections on Deck.-For steam vessels with top-gallant forecastles having long poops, or raised quarter decks connected with bridge-houses, covering in the engine and boiler openings, the latter being entered from the top, and having an efficiently constructed iron bulkhead at the fore end, a deduction may be made from the reserve buoyancy given in the tables, according to the following scale : (a) When the combined length of the poop, or raised quarter-deck, bridge-house, and top-gallant forecastle is9-10ths of the length of the vessel, deduct 85 per cent. of the reduction in the reserve buoyancy allowed for a complete awning deck, or 85-100ths, of the difference between freeboards in Tables A (after correction for sheer) and Tables C. 8-10ths of the length of the vessel, deduct 75 per cent. of the reduction in the reserve buoyancy allowed for a complete awning deck, or 75-100ths of the difference between freeboards in Tables A (after correction for sheer) and Tables C. 7-10ths of the length of the vessel, deduct 63 per cent, of the reduction in the reserve buoyancy allowed for a complete awning deck, or 63-100ths of the difference between freeboards in Tables A (after correction for sheer) and Tables C. 6-10ths of the length of the vessel, deduct 50 per cent. of the reduction in the reserve buoyancy allowed for a complete awning deck, or 50-100ths of the difference between freeboards in Tables A (After correction for sheer) and Tables C. When the engine and boiler openings are protected only by a long raised quarter-deck, a less reduction in freeboard will be allowed. (6) For intermediate lengths of erections the amount of the reduction in freeboard should be ascertained by interpolation. (c) The above scale of allowance is prepared for vessels having long poops or raised quarter-decks 4ft high or above. For raised quarter-decks of less height, extending over fourtenths of the length, and forming an integral portion of the vessel, the amount of the allowance should be diminished, as shown in the following table: (a) For shorter lengths of raised quarter-deck a proportionate increase should be made. (e) It is to be understood in the application of this scale of allowance for erections on deck to vessels with long poops or with raised quarter-decks, and bridge-houses combined, that the deduction is a maximum deduction, applicable only to vessels of these types in which the erections are of a most substantial character, the deck openings most effectually protected, and the crew are either berthed in the bridge-house, or the arrangements to enable them to get backwards and forwards from their quarters are of a satisfactory character. For other vessels of the same class the amount of the deduction should be fixed only after a careful survey. Also such vessels when employed in the Atlantic trade will require to have specially provided greater freeboard than that given in the tables. (f) A sufficient number of clearing ports as large as practicable, and with shutters properly hung, should be formed in the bulwarks of these vessels, between the forecastle and the bridgehouse, for the purpose of speedily clearing this part of the deck of water. 12. When the erections on a vessel consist of a topgallant forecastle, a short poop having an efficient bulkhead, and bridge-house disconnected, the latter in steamers covering the engine and boiler openings, and being efficiently enclosed with an iron bulkhead at each end, a deduction may be made from the reserve buoyancy given in the tables according to the following scale : (a) When the combined length of the erections is 5-10ths of the length of the vessel, deduct 40 per cent. of the reduction in reserve buoyancy allowed for a complete awning deck or 2-5ths of the difference between the freeboard in Tables A (after correction for sheer and length) and Tables C (after correction for length). 4-10ths of the length of the vessel, deduct 33 per cent. of the reduction in reserve buoyancy allowed for a complete awning deck or 1-3rd of the difference between the freeboards in Tables A (after correction for sheer and length) and Tables C (after correction for length). 13. When the erections on a vessel consist of a topgallant forecastle and bridge-house only, the latter in steamers covering the engine and boiler openings, and being efficiently enclosed with an iron bulkhead at each end, a deduction may be made from the reserve buoyancy given in the tables according to the following scale : (a) When the combined length of the erections is- 3-10ths of the length of the vessel, deduct 25 per cent. of the 14. When the erections on a vessel consist of a short poop and topgallant forecastle only, the former enclosed at the fore-end with an efficient bulkhead, the deduction from the reserve buoyancy given in the tables should be according to the following scale : (a) When the combined length of the erections is3-8ths of the length of the vessel, deduct 8 per cent. of the reserve buoyancy or 10 per cent. of the freeboard required for the vessel flush decked (after correction for length). 3-8ths of the length of the vessel, deduct 6 per cent. of the reserve buoyancy or 8 per cent. of the freeboard required for the vessel flush decked (after correction for length); and so on in proportion. 15. When a vessel is fitted with a topgallant forecastle only, the reduction in reserve buoyancy should be one-half that prescribed by the previous paragraph for the case where, in addition to the forecastle, the vessel is fitted with a poop of the same length. 16. Sheer. The tables are framed for vessels having a mean sheer of deck measured at the side, as shown in the following Table. Length over which Sheer is measured. (a) In flush-deck vessels and in vessels to which clauses II and 12 apply, when the sheer of deck is greater or less than the above, and is of a gradual character, divide the difference in inches between it and the mean sheer provided for by 4, and the result in inches is the amount by which the freeboard amidships should be diminished or increased according as the sheer is greater or less. (b) In vessels having short poops and forecastles, and in those having short forecastles only, the freeboard should be corrected in respect of the excess of or deficiency in reserve buoyancy due to variations in sheer from the standard amount over the length uncovered by substantial erections, as provided in the above table. One-fourth the difference between the mean sheer specified and that measured as described, is approximately the amount by which the freeboard should be modified in respect of sheer. (c) The divisor 4 is to be used when the sheer is of a gradual character, and is not strictly applicable either to those cases in which the sheer is suddenly increased at the bow or stern, or to those in which it does not maintain its normal rate of increase to the ends of the vessel. (d) In all cases the rise in sheer forward and aft is measured with reference to the deck at the middle of the length, and where the lowest point of the sheer is abaft the middle of the length, one-half of the difference between the sheer amidships and the lowest point, should be added to the freeboard specified in the Tables for flush-deck vessels, and for vessels having short poops and forecastles only. (e) Where, as in some instances, vessels fitted with long poops or raised quarter-decks connected with bridge-houses have the deck line rising rapidly from amidships to the front of the bridge, and from that point onwards gradually approaching the normal sheer line, the freeboard may be slightly modified |