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 in consideration of the increase of height of deck in the "well." (1) In flush-deck vessels and in vessels having short poops and forecastles the excess of sheer for which an allowance is made shall not exceed one-half the total standard mean sheer for the size of the ship. (g) No decrease should be made in the freeboard of spar and awning deck vessels, in respect of excess of sheer. 17. Round of beam.-In calculating the reserve of buoyancy, an allowance has been made of one quarter of an inch for every foot of the length of the midship beam for the round up. When the round of the beam in flush-decked vessels is greater or less than that given by this rule, divide the difference in inches by 2, and diminish or increase the freeboard by this amount For vessels with erections on deck the amount of the allowance should depend on the extent of the main deck uncovered. This rule for round of beam does not apply to spar or awning deck vessels. 18. As a general illustration of the way in which the tables should be used in modifying the freeboard on account of erections on deck, extreme proportions and variations in sheer, the following may be taken as an example : A vessel is 234ft long, 29ft broad, and has a moulded depth of 17 oft, the coefficient of fineness being 72. Suppose the vessel to have a poop and bridge-house of the united length of 121ft, and a forecastle 20ft in length, and let the sheer forward, measured at the side, be 4ft 6in, and aft 2ft 1in. Freeboard by Tables A if of the normal length, without erections, and with the normal amount of sheer. The mean sheer by rule is 33'4in, or 6in less than that in the vessel, Freeboard of vessel without erections and with 39 in mean sheer Amount deducted from freeboard for excess of sheer.. Deduct in. 2 12 The length being 30ft in excess of that for which the tables are framed, the addition to the freeboard in respect of the same is one-half of 30-20ths of 2in, or .................. 104 That is 10in to be deducted from 2ft 11in, leaving a winter freeboard of 2ft olin. Corresponding summer freeboard 1ft 10in. 52 TABLE A.-CARGO-CARRYING STEAM VESSELS NOT HAVING SPAR OR AWNING DECKS. For allowances admitted in vessels having erections on deck, see "Explanation." The reduction in freeboard for summer voyages from European and Mediterranean Ports is to be made from April to September inclusive. In other parts of the world the reduced freeboard should be used during the corresponding or recognised summer months. The additional freeboard specified for the North Atlantic trades is to apply to vessels sailing to or from the Mediterranean or any British or European Port, and which may sail to or from, or call at Ports in British North America or Eastern Ports in the United States, north of and including Baltimore, from October to March, Double the reduction to be allowed for voyages in the fine season in the Indian seas, between the limits of Suez and Singapore. Table of Reserve Buoyancy and Freeboard for First-class Sea-going Iron and Steel Steam Vessels (in Salt Water). inclusive. Coefficient of Fineness. 22'0 22.2 2224 2216 22.8 230 Percentage Reserve Buoyancy-(Winter). 2316 23.8 24'0 255 257 25'0 26'2 26'5 ΙΟ 11 6 12 12 ft. in. ft. in. ft. in. ft. in. ft. in. ft. in. ft. in. ft. in. ft. in. ft. in. ft. in. ft. 6 11 O 6 13 ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. ft. 156 162 168 174 180 186 192 198 204 210 216 222 228 234 240 ft. in. ft. in. ft. in. ft. in. ft. in. ft. in. ft in. ft. in. ft. in. ft. in. ft. in. ft. in. ft. in ft. in. ft. in. ft. 4 I 5 I 6 I '70 I 4 I 6 I I 2222NNNN 2222 ABC '9 9 9 I'I 14 1 2 2 2 1'1 I'I I'I 1'2 2 2 3 3 3 3 3 3 34 A. Correction in inches for a change of 10 ft. in the length. B. Deduction in inches for summer voyages. C. Addition in inches for winter, North Atlantic. Coefficient of Fineness. 26'71 27'0 2773 27'5 27'8 28'1 28'3 28'6 28'9 29'3 29'5 298 301 30'4 30.8 32'5 33°2 Moulded Depth and Length. 20 6 21 O 21 6 22 ft. in. ft. in. ft. in. ft. in. ft. in. ft. O 22 6 23 3 Io 3 9 3 11 4 3 114 04 4 4 64 4 4 7 72 3 10 in. ft. in. ft. in. ft. 5 2 6 4 8 6 4 10 9 7 O 74 3 II 4 94 5 7 7 5 7 8 6 10 4 7 4 9 4 II *76 4 4 54 4 4 9 4 11 '78 5 4 I 4 4 4 4 10 5 04 9 9696 7 I 7 6 7 9 4 2 5 7 4 9 4 II *82 5 I 2 4 34 4 5 4 7 5 10 6 6666 II 7 2 7 7 7 10 7 O 7 3 7 7 11 6 10 7 I 7 4 7 7 7 9 8 of 94 4 6 11 5 2 7 2 7 5 4 5 9 5 II 6 6 7 8 10 9 7 O 7 3 7 6 7 9 7 8 I B 24 24 24 2 3 3 3 3 3 32 34 C 34 4 4 4 4 44 44 44 44 43 5 5 5 5 5 A. Correction in inches for a change of 10 ft. in the length. 33°2 Coefficient of Fineness. TABLE A.-(Continued.) Percentage Reserve Buoyancy-(Winter). 34'7 35'0 33'5 33°8 34'I 34°4 Corresponding Height of Freeboard Amidships (Winter), Measured from Top of Deck at Side. Moulded Depth and Length. A. Correction in inches for a change of 10 ft in the length. B. Deduction in inches for summer voyages. C. Addition in inches for winter, North Atlantic. 19. Vessels loaded in fresh water may have less freeboard than that given in the several tables Moulded Depth in Feet. 9 and under 11.. according to the following scale : Reduction in Freeboard. Spar and Without Erections Awning-Deck Vessels. on Deck. 34 61 MEMO. The weight of a cubic foot of salt water is taken in the above table to be 65 lb., and that of fresh water 62.5 lb. For weight of waters see p. 32. |