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June, 1914 Notes on Chain Cables At the December meeting of the So- ciety of Naval Architects and Marine Engineers, Assistant Naval Constructor John E. Otterson read a paper on "Notes on Chain Cables", abstracted as follows: The above paper contains brief notes as to the history of chainmak- ing, as to the theory of stresses in the chain link; the relative advan- tages of open and stud link chain, of end-welded and side-welded chain; a description of the present hand proc- ess of manufacture; the extent to which machine processes have been developed to date; and notes as to certain experimental work carried on at the navy yard, Boston, looking to- ward the development of a_ satisfac- tory machine process and _ toward the producing of chain of a more uniform and reliable quality. The paper also indicates the advantages to be gained by the proper heat treat- ment of the iron, and points to the necessity of more detailed and ex- tensive study of this question. After reading the paper, Mr. Otter- son said: History of Chain Cables "The history of large chain cables dates back a little more than 100 years, and during that time but little advance has been made in the process of manufacture, so that the large bulk of the high grade chain cable today is made exactly in the same manner as it was made here 100 years ago, namely, by the hand process. That is largely due to the fact that the hand-made chain today is better than machine-made chains In the manu- facture of cables at present we have got to the limit of hand work, we have reached the limit of the size of cable which can be economically made by hand work, and as the size goes up it will be necessary to do a part or all of the operations of making chain cables by machines. Be- cause of the fact that we are looking ahead to the manufacture of sizes of cable larger than three inches, experi- ments have been made at the Boston yard to develop a machine process. Mr. Howard is present. He was the inspector of the chain made at the Navy yard for the Panama Canal commission. I hope that he will take part in this discussion, and prob- ably state the results obtained from his inspection; and if he is in a po- Sition to do so, to include in his discussion some of the notes from his report on these tests, which I think were rather interesting." James E. Howard:--In regard to Material, it occurs to me that the THE MARINE REVIEW best results have commonly been ob- tained with puddled iron, of not too great a degree of refinement. When iron is refined to the extent of al- most reaching the state of puddled steel, then I think there is danger of brittleness being introduced in the manufacture, and in the subsequent use of that iron that brittleness will manifest itself. The fabrication of material into the form of chains puts it into such a shape that there is not a very good distribution of stresses, and probably no chain is used that is not locally overstrained in some of its parts. The effect of overstraining is to cause a sort of accumulation of brittleness. That brings up an impor- tant question in regard to chain ca- ble that we should consider, I think, and that is, while the original tests commonly break at the weld, we know that a great many links, after service, do not break there, but break elsewhere. Having a_ soft and 'tough fibrous iron at the outset, getting that by -- selection of material, we want to keep it so. The proving stress of a chain over- strains it in a degree. That starts, in the same ratio, to increase the elastic limit and tensile strength with increased ductility, so I think it is safe to anneal after proving stresses have been applied, and that anneal- ing to be efficient at all times ought to be repeated. Whenever there is 'a known overstrain of the chain, it would be safe to repeat the anneal- ing. In reference to the chain at the isthmus, that was a recommendation which was introduced, because the case there was so important--to stop a ship at the gates of the locks-- that it would be. prudent to anneal the fender chains after a severe $hock had been received of that kind. Vears of Study Richard M. Watt:--I simply wanted to add to this paper the fact that Mr. Otterson states that it repre- sents several years of exhaustive study on this subject, and that in his capacity as assistant superintendent of the hull division of the navy yard at Boston, he has markedly improved the quality of the output of the chain at that yard, so that his efforts have resulted in the saving of many thousands of dollars to the govern- ment. I believe that that attention, which has so increased the hand out- 'put, will in time develop an entirely satisfactory method or process of power manufacture of chain. Francis T. Bowles:--No doubt we are under many obligations - to the author of this paper for the informa- 245 tion he has given us, and I do not want to appear as too discriminating when I suggest that historical notes on the subject of chain cable are ab- solutely incomplete without any ref- erence to the subject of swivels and shackles. My own interest in the subject of chain cable is entirely con- nected with those things which can- not be properly described in polite language. More Ductile Material John E. Otterson:--I think that the future development of the manufac- ture of chain, as regards the mate- rial, will probably be along the lines suggested by Mr. Howard, and that 'we will go into larger sizes to the use of a softer and more ductile mate- rial. We have recently received a shipment of material of this charac- ter, and while in the straight speci- men it gave rather low test, yet when formed into links the tests were very Satisfactory, the probabil- ity being that the ductile material under deflection flowed more readily and subjected itself to less strains than the harder and more brittle ma- terial. I might say, with the process developed to its present form, and the links turned over to' the chain- makers, that it will be possible for them to increase the output 100 per cent or more. I do not say they will increase it, we will probably have difficulty in making them do it, but it is possible for them to increase it. In regard to the remarks of Admiral Bowles, as to the question of shackles and swivels, I might say that discus- sion of those features has not been included in the paper for the reason that we have not-had as much trouble with the manufacture of shackles and swivels as we have had in the manu- facture of chains, and they are at present manufactured by machine processes. I feel that any. troubles which have been experienced have been more in the testing of these ap- pliances, and when they are put in service they are reliable. . Contract for the construction of a large ice breaking steamer for St. Lawrence river service has' been awarded to Canadian Vickers, Ltd., Montreal, for $998,593. The steamer will be 292 ft. over all, 275 ft. -be- tween perpendiculars, 56 ft. molded beam and 32 ft. molded depth. The machinery will be imported from Ire- land. The Institution of Naval Archi- tects will hold a summer meeting at Newcastle-on-Tyne, July 7-10.