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TABLES OF FREEBOARD.
INSTRUCTIONS TO BOARD OF TRADE SURVEYORS.
The Board of Trade have received the report of the Loadline Committee, and the tables and rules annexed thereto.
The Board of Trade accept the conclusions of that Committee as to loadlines as shown in the report and in the tables and rules, and have furnished their officers with copies. Copies can be obtained by the public at large from the agents for the sale of Stationery Office publications, and through any bookseller.
The Board of Trade do not propose that their officers shall detain as overloaded any cargo ship on which the loadline is marked so as to give the freeboard assigned to her by those rules and tables, and which is not loaded beyond the limits prescribed therein.
As proof that the loadline on a ship is marked in accordance with these rules and tables, the Board's staff at the outports will receive the certificate of Lloyd's Register Committee where a loadline has been assigned by that committee, or the certificate of the Board of Trade where a loadline has been assigned by the Board of Trade. In future, the Board of Trade do not intend to assign a loadline for any ship classed in Lloyd's Register Book. In the case of ships not classed, or classed elsewhere, the Board will continue for a time, as heretofore, to assign loadlines on the application of the owner in due course, and accompanied by full particulars of the ship.
The Board of Trade, in making this announcement, desire to point out, for the information of all persons having the command or management of ships, that those rules and tables give minimum freeboards applicable for ships of the highest class only, and that no ships other than ships of the highest class are to be loaded so deeply as those rules and tables admit.
Ships to which a freeboard has been assigned by the Committee of Lloyd's Register, or by the Board of Trade, will, like other ships, be liable to detention, if, having regard to the time of the year, and the voyage, they are loaded more deeply than the rules and tables admit, and ships to which freeboards are not assigned will receive the particular notice of the staff so far as is possible.
Whilst the Board of Trade staft will by this arrangement be greatly relieved of the responsibility for the depth of loading of ships generally, it will be the duty of the Board itself in each case submitted to the Wreck Courts to instruct their solicitor to raise the question of loading whenever it may appear that deep loading may have contributed to the loss of the ship, and it will also be the duty of the Board of Trade if in any such case it should hereafter appear that a ship was loaded more deeply than the tables allow, looking to the age, character, class, and employment of the ship, to make the owner and the person responsible for the loading of the ship a party to the case, and to ask for the opinion of the court on his conduct.
T. H. FARRER, Secretary.
THOMAS GRAY, Assistant Secretary. Board of Trade, Marine Department, August, 1885.
[EXTRACT.) To His Grace the Duke of Richmond and Gordon, K.G., &c.,
President of the Board of Trade.
“1. Whether it is now practicable to frame any general rules concerning freeboard which will prevent dangerous over. loading without unduly interfering with trade.
“2. If so, whether any, and which of the existing tables, with any, and what alterations, or any other, and what tables should be adopted.
"3. How far any such tables can be adopted as fixed rules, and what amount of discretion must be left to the Officers who
have to see that they are complied with." As the result of our prolonged consultations and labours we have unanimously arrived at the following replies to the questions before recited, viz. :
1. We are of opinion that it is now practicable to frame general rules concerning freeboard which will prevent dangerous over. loading without unduly interfering with trade.
2. We have the pleasure to submit herewith tables which we consider should be adopted.
3. We are of opinion that these tables can be adopted, at least for all existing types of cargo vessels, and for some years to come, without the exercise of any other discretion on the part of the officers who have to see that they are complied with, than that which concerns the quality and condition of the ship. The freeboards assigned by the tables herewith are suitable for vessels of the highest class in Lloyd's Register or of strength equivalent thereto, and should be increased for ships of inferior strength.
To the responsible authorities a large discretion must be allowed, viz. : that of applying the tables themselves with reasonable modifi. cations to any very exceptional vessels which may now exist or may hereafter be constructed.
For, careful as we have been to give full consideration to all actual types and sizes of vessels, we cannot but admit that undue interference with trade might occasionally arise were the tables to be applied benceforth to all ships, present and future, without any exception whatever. We are well aware that the discretion which we thus regard as necessary is such as should be exercised with very great skill, care, and judgment, but we see no reason why those charged with the responsible duty of preventing the overloading of merchant ships should not have at their command all needful assistance.
The tables submitted herewith are of the same general form as those hitherto adopted by Lloyd's Register Office, and, like them, involve the reservation above water of a regulated minimum per. centage of the total buoyancy. At the same time these tables secure a sufficient height of deck above water to which the Board of Trade advisers have justly attached much importance. The views of the Board of Trade advisers concerning the value of forecastles, poops, and like deck erections, and the necessity for a liberal amount of freeboard in flush-decked vessels which are
deprived of such erections, have likewise received our careful attention, and have had their due influence upon the tables submitted herewith. The same may be said with reference to the freeboards assigned to vessels of extreme proportions and to vessels of very fine forms. The Board of Trade distinction between winter and summer freeboards has likewise, after the fullest consideration, been adopted.
The tables as now submitted involve only such limited modifica. tions of the freeboards assigned by the latest tables of Lloyd's Register Office as Mr. Benjamin Martell is able to freely accept and cordially concur with. , The same may be said of the extension of the tabular forms by the addition thereto of corrections for changes of length and for voyages in summer and in the North Atlantic in winter.
In the tables submitted the definitions of length, breadth, depth, sheer, round of beam, and freeboard have undergone revision.
The changes introduced have been made for the purpose of simplifying the assignment and marking of freeboards, and although they modify in one or two points the directions of the fourth section of the Merchant Shipping Act of 1873, and may therefore render legislation necessary, the measure required would be of so brief, simple, and non-contentious, a character as to render its passage easy.
It will be observed by the tables that they refer exclusively to cargo-carrying vessels. E. J. Reed (Chairman), W. Denny, Robt. Duncan, James Dunn, Frans Elgar, Thomas Gray, William Gray, James Laing, B. Martell, Digby Murray, T. B. Royden, Thos. Sutherland, Reginald Bingham (Secretary). Explanation of the following Tables of Freeboard for the various
Types of Steam and Sailing Vessels. In the following tables the word Freeboard denotes the height of the side of a ship above the waterline at the middle of her length, measured from the top of the deck at the side, or, in cases where a waterway is fitted, from the curved line of the top of the deck continued through to the side. The freeboards and the corresponding percentages of reserve buoyancy necessary for flush-deck steamers not having spar or awning decks, for awning deck steamers, and for fush-deck sailing vessels, are given in Tables A, C, and D for vessels of these classes and of various dimensions and proportions. "The freeboards necessary for spar deck steamers are given in Tables B. The latter are determined by considerations of structural strength, and they denote the limitations to depth of loading which are thereby imposed upon first-class vessels of this type. The free. boards and percentages of reserve buoyancy thus obtained being in excess of what would otherwise be required, the amounts of such percentages are not given in tables B.
The exact freeboard required for a given ship belonging to any of the classes comprised in Tables A, C, and D, may be calculated by constructing a displacement scale to the height of the deck to which the freeboard is measured, so as to give the whole external volume up to the upper surface of that deck. The percentage of the total volume which is given in the tables as the reserve buoyancy for a vessel of given type and dimensions will be the amount of volume that must be left out of the water. If a water-line be drawn upon the displacement scale aforesaid to cut off the given percentage of total volume, the height of side above this line will be the freeboard required.
In order to simplify and reduce the work that would be involved by the above mode of determining the water-line and the consequent freeboard, that correspond to a given percentage of reserve buoyancy, an approximate method is adopted in the following tables, which enables the freeboard of a vessel to be calculated with a sufficient degree of accuracy for all ordinary working purposes. The use of this method not only saves the time and labour that would be involved by making a complete displacement scale for the whole external volume of a ship, but, what is much more important, it makes the tables easily and directly applicable in cases where such a displacement scale for a vessel is not at hand, or where the data requisite for constructing one is not procurable.
In this approximate method the form of the ship is taken into account by means of proportionate quantities, which are termed coefficients of fineness, instead of by the exact volumes that a displacement scale would give. It is found that the whole internal volume of a ship as measured for register tonnage divided by the product of the length, breadth, and depth, measured as described in the following clauses 1, 2, and 3, gives a fractional quantity or coefficient which bears a nearly constant relation to the quantity that would be obtained by dividing the whole external volume below the upper surface of the deck by the product of the length, breadth and depth. This fractional quantity is called the “coefficient of fineness for freeboard purposes; and it serves the same practical object, when combined with the dimensions of the ship in the manner explained in the tables, as the volume itself would do.
In applying such an approximate method as the above, it is necessary to connect the coefficients of fineness given in the Tables with a standard sheer and round of beam. The standard scales for sheer and round of beam that have been adopted for this purpose are given in clauses 16 and 17 hereafter. Descriptions are also there given of the corrections that should te made for deviations from these standard amounts.
The freeboards given in the tables are for flush-deck vessels in all cases. Such reductions in freeboard as may be allɔwed for deck erections of various kinds and sizes in steamers not having spar or awning decks, and in sailing vessels, are described in paragraphs ir, 12, 13, 14, and 15.
No reduction of freeboard should be allowed on account of deck erections in spar-deck and awning-deck steamers.
Tables A and D give the minimum freeboards for firstclass iron and steel vessels, the strength of which is at least equal to the requirements of the 100A class in Lloyd's Register for three-deck and smaller vessels. The freeboard of all other iron and steel vessels, classed or unclassed, should be regulated by the same stardard; the increase of freeboard required in each case being determined by the limit at which the stress per square inch upon the material of the hull amidships shall not exceed that of the standard class, of the same proportions, form, and moulded depth, when loaded to the freeboards required by Tables A and D. Tables B and C give the freeboards for vessels built in accordance with, or equal to the requirements of Lloyd's Register for the spar and awning deck classes ; and are subject to the conditions just stated for any modifications of strength in excess or diminution of the requirements of their respect tive classes.
1. Length. The length of the vessel is measured on the loadline from the fore side of the stem to the aft side of the stern post in sailing vessels, and to the aft side of the after post in steamers.
2. Breadth. The breadth used in obtaining the coefficient of fineness is the extreme breadth measured to the outside of plank or plating as given in the Register Book, or on the certificate of the ship’s registry.
3. Depth of Hold. The depth used in obtaining the coefficient of fineness is the depth of hold as given in the Register Book, or on the certificate of the ship's registry. This dimension is subject to modification in determining the coefficient of fineness as explained in clause 4.
4. Coefficient of Fineness. The coefficient of fineness in one, two, and three deck and spar-deck vessels, is found by dividing 100 times the gross registered tonnage of the vessel below the upper deck by the product of the length, breadth, and depth of hold." In awning-deck vessels the registered depth and tonnage are taken below the main deck.
(a) It is of importance in the application of the rules and tables of freeboard that the coefficient of fineness deduced from the under-deck tonnage, and the principal dimensions should be a correct index to the vessel's relative fulness of form, and that a change in any of those elements which affect the coefficient, determined in accordance with the rule set forth should be con. sidered, and the necessary correction, having regard to the special circumstances of the case, introduced.
Among the cases that have from time to time come under notice are the following :
(6) Vessel having a cellular botton throughout, or floors of greater depth than those usually fitted.-In such a case the coefficient as determined from the under deck tonnage is in most instances slightly greater than it would be if the vessel were framed on the ordinary transverse system with floors of the usual depth. No general rule can be given for guidance, but it is not difficult, if the depth and slope of the top of the cellular bottom or floor be compared on the midship section with the depth and slope of an ordinary floor, to determine very closely the amount of the correction necessary.
(c) Vessels constructed with floors of the ordinary kind, but with a cellular bottom for a part of the length amidships under the engines and boilers.- In such a case the registered underdeck tonnage is smaller than it would be if the vessel were framed with ordinary foors throughout, the difference being the tonnage of the space between the top of the cellular bottom in the part amidships, and the level of the ordinary floor. The depth of hold is also measured by the Customs officials to the top of the cellular bottom, and this depth is inserted in the register. Under such circumstances, in order to arrive at the coefficient of fineness the vessel would have, if built on the ordinary system throughout, and for which the tables are framed, the tonnage of the volume between the top of the cellular bottom and the level of the ordinary floor should be calculated and added to the registered under-deck tonnage. The tonnage so corrected, used in conjunction with the depth