Maritime History of the Great Lakes

Marine Record (Cleveland, OH), July 4, 1895, p. 7

The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

_ than one of our lake vessels. + THE MARINE RECOR; BOTTOM REPAIRS. Now we wonder what a New York and purely salt water inspector is getting off relative to lake shipbuild- ing. A man who is trying to build up a register steps re and tells us that we are not building vessels strong nough in their bottoms at the same time the stupid should know that they are already too strong there and not strong enough in the upper longitudinal sections as all lake repairs clearly show. What does our quondam friend want? Has he in mind a plough or some mechanism for dragging up the ground as opposed toa floating body. In a new fangled idea of bottom construction of which Mr. Stuart is the patentee, he says: “The bottoms of these vessels will be 25 per cent. stronger than under the usual construction and wood sheathing in their case would be unnecessary. In run- ning on rocks any vessel will receive more or less dam” age, but from ordinary groundings in rivers and chan- nels, these vessels with their very strong bottom con- struction, receive no damage; should they strike rocks, the damage would be confined to the immediate neigh- borhood of the point of contact, instead of affecting the structure asa whole. As for the danger of total loss, that is practically eliminated in the general construc- tion of these ships, unless it is the result of a collision, against which no vessel afloat is proof.’? Well! Mr, Sinclair Stuart wobbles away off in his statements, for if his patent bottom even gets punctured, as it certainly will, the cost is sure to be 100 per cent. greater to re- pair than it would be under the present system of con- struction. a In this connection a well-known’expert in the design- ing and construction of metal vessels states that “a boat may be constructed of very thin steel plates and bars, and though very light when completed she may be structurally strong, and if of easy proportions may be fit to cross the Atlantic, but that this has little or nothing to do with the essential provisions required to resist violent contact with the ground. The Great Kast- ern, for instance, was structurally the strongest and largest iron steamer ever floated, but her bottom could no more resist grounding, say in the Neebish, When a large vessel sud- denly rests on hard uneven ground the bottom plating will be either fractured or indented, whatever the thickness may be. He says that the bottoms of steel lake steamers are by no means weak, and that except in the transverse section they are stronger than ocean steamers of equal length having the same proportions. He then asks: ‘If a ship’s bottom is proved experiment- ally to be amply strong for any ‘afloat’ stress to which it may be subject, is it necessary or advisable to in- crease the bottom strength for the purpose of resisting rocks or uneven hard ground, which can only be resisted to a limited extent, no matter how closely the floors and frames approximate to the scantlings essential to resist ordinary grounding strains? SPLE seeks to me,’’ he says, ‘‘that it would be better for steamers subject to frequent groundings, to have the lower bottom about as light as itis now, but espe- cially designed with a view to facilitate repairs, for even the lightest, well-arranged and most carefully constructed bottoms have proved amply strong enough to withstand the most intense ‘afloat’ stresses, and as the feature desirable in bottom plating is ductility, which should not be less than 36 per cent., with a mini- mum tensile strength of 58,000 pounds per square inch. “Whereas it seems to be advisable to make the steel for upper deck stringers, sheer strakes and bilge plates at and near midlength and about the locality of the fore end of the engine and boiler space, of high tensile strength, say with an elongation e€qual to from 20 to 22 per cent. ona length of 8 inches, before fractures the remainder of the plating should have great ductility.”’ Furthermore this expert states that he would draw particular attention to the points mentioned in the fore- going and that it would seem that though the bottoms of our lake steamers were made as heavy as the steel belt of an iron clad—when the deadweight (cargo) ability would be nil—they could not even strike the rocks with impunity, for though such bottom plates might not be fractured or even severely indented, the fastening and framing, in fact, the internal structure, would be shattered or strained to destruction, and such injury would probably not be limited to the bottom, but would be transmitted above the bilges and would prob- ably extend over the top sides and decks. “If the upper bottom were made sufficiently strong to float the hull and cargo and the form slightly modified, the wooden ceiling could then be dispensed with. But further, corrosion of the upper bottom goes on as ac- tively, if not more so than does the wear and tear of the lower bottom. Consider these as forming the upper @and lower flange of a hollow girder, the latter being in- tact, while the former is pierced with manholes, does it not appear to the unscientific to make the lower flange, say 10-16 of an inch, as is commonly the case? **Moreover, the lower bottom is the only one of the four large external surfaces of a ship that is not weak- ened by hatchways, gangways or scuttles. “Now if a certain stress .ccannot be resisted, it ¥. seem to be wise to provide means for receiving strain as lightly as possible or to localize the injur: “To accomplish the former desideratum, the bo should be sheathed with elm or oak; this would a’ the initial force of impact and distribute its ener; that in cases of slight grounding the plates woul dom be fractured, and the internal straining woul generally exceed the elastic limit of the fastenin; itis an expensive provision against grounding, a is questionable whether it pays to sacrifice four o inches in draft of water to attain comparative im: ty from grounding injury. i “The alternative plan as I have frequently sta’ to make the lower bottom capable of being more qu and cheaply repaired, and to largely augment the { ness and structural strength of the upper botte that a voyage toa dry dock for repair could be w taken without undue risk with the lower bottom sé ly damaged.”’ Now, it seems to us that the foregoing is more iv with modern lake shipbuilding than any increase | tention to bottom structural ability could possibl All attention has hitherto been directed to the bo: of lake ships and this, too, to the utter neglect o upper works, or nearly so. If we wanta plo machine then let the lake shipbuilder design } thing of that description. On the other hand, if | to be a vessel then let her floatation and seaw qualities come in somewhere and it need not be en, in bottom conglomerations, either, if we don’t wa increase the expense and detention of ship during tom repairs. Ina word, too much attention has given to the bottom structure and too little to upper works. : TT nD LAUNCH OF THE VICTORY. There was successfully launched from the yards ¢ Chicago Ship Building Co., on Saturday afternoo steel steamer Victory, the largest vessel on the ( Lakes. The steamer is 380 feet keel, 400 feet over and 28 feet depth of hold. Her engines will develop horse-power. When drawing 14 feet of water present limit of the Sault Ste. Marie Canal, it has. computed that the Victory will carry 4,000 tons, when the 20-foot channel between the Great Lakes) have been completed next year, she will carry 6,000 when fully loaded. Her cost, complete and read; service, will be about $225,000. In her construction. tons of steel were used and in all about 700,000 r were driven. The Victory will be ready for servi about three weeks and she will go into theiron ore { between Lake Superior and Lake Erie, with occas) trips to South Chicago. Her owners are the Inter-’ Transit Co., which also owns the steamer Kearsi managed from the office of Pickands, Mather & Cleveland, owners of the Minnesota steamship flee Po rr STAGE OF WATER ON LAKE ONTARIO. The present low stage of water in Lake Ontario called out a number of views, which are more or misleading. Accurate information on this impos subject, in so far as Lake Ontario is concerned been obtained from Mr. John Annal, who for 20 y past has had the care of the United States Engineer boats and property at Oswego Harbor, and who has each day during all that time, recorded the readings of the United States Engineers’ water gauge which was established on the stone pier by Mr. J. W. Judson in 1838, and which has since then been the standard for all water levels on Lake Ontario. These daily readings Mr. Annal has sent to the United States Engineéérs’ office, where they are tabu- lated with those of the past 60 years upon graphic charts which constitute a most interesting record of the sur- face movement, in general terms the variations of Lake Ontario are the result of similar variations in all the other lakes from which its waters come. The water level has frequently been lower than now during the 58 years since the gauge was established, but it has never before been as low as now in the month June, when it is always at or about the highest point of the year. Asa regular thing, the lowest time of any year isin February or March. As the spring freshets occur, the lakes rise more or less gradually, between March and June, reaching high water level of the year about June 15th and continuing at about that stage till August, when a gradual lowering takes place until about the end of the year. In only one year—1866—has the water level gone down in the first half of June and then risen again. In that year there was arise of one tis suvyeCl IS Without precedent, and engineers have ~ no established evidence to guide them. ‘This accounts for the difference in opinion of competent engineers; some have scouted the idea that the drainage will lower lake levels, while others have declared that there would be a perceptible decrease in a year, ‘The task of deter- mining the effect exactly and accurately would be al- most impossible. The capacity of the sources of water supply to the lakes have to be determined and they are sO numerous and uncertain that this involves almost untold work and study. One of the engineers of the war department states that the question was a grave one of much importance to the shipping interests of the lakes. In harbors where there is a great depth of water the effect might not be noticed, but in harbors where there is now but a bare sufficiency of water, the level might in time be lowered so as to destroy the har- bor unless artificial means of deepening it were em- ployed. ED OO Oe INLAND LLOYDS’ SUPPLEMENT. Manager McLeod has issued the Inland Lloyd’s sup- plement for July. The steamers Rappahannock and Sacramento, builtand owned by Capt. James Davidson, of Bay City, are the only new boats that are entered since the last. supplement was issued. The net capacity. of each vessel is 1,911 tons ; they are rated Al* and yal- ued, for insurance purposes only, at $145,000.

Powered by / Alimenté par VITA Toolkit
Privacy Policy