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56 Naval Architects Meet (Continued from Page 14) launching of the airplane carrier LEXINGTON. When needed, informa- tion of this character is invaluable. The problems in connection with the launch of the LEXINGTON were quite different from those at the launch of the airplane carrier SARATOGA, a paper on which was presented last year by Mr. Rigg. The two papers taken together therefore present a great deal of valuable data on the methods of launching exceptionally large and heavy vessels. The LEXINGTON it is stated in Mr. Wakeman’s paper is the largest ship, in weight, ever launched in this country; and only two heavier vessels have ever been launched in the world, these being transatlantic liners. The length over- all of the LEXINGTON is 880 feet; the length between perpendiculars is 850 feet; breadth molded at bulge, 105 feet 354 inches; breadth molded at flying deck 105 feet 8 inches; depth molded to flying deck at center 74 feet 3 inches. The launching weight of the ship in long tons was 25,517 and the weight including the cradle was 26,897 long tons. 4. “Analysis of the Standardization Trials of the U. S. Battleships Mary- land, West Virginia and Colorado,” by Capt. William McEntee, C. C., U. S. N., council member. It was the purpose of Captain Mc- Entee in this paper to explain dis- erepencies between the results cal- culated and deduced from model basin data and the actual results obtained _ during the standardization trials of the completed vessels. This partic- ular case presented anexceptional op- portunity for such analysis due to the fact that the MARYLAND and WEST VIRGINIA are sister ships. One of the conclusions made by the author was that the results of the comparison probably warranted the conclusion that for relatively low powered ships at least, the power required for their propulsion can be estimated from self- propelled model tests with greater ac- curacy than the power can at pres- ent be measured on the full sized ship during her trials. This paper caused a lively discus- -sion, Admiral Tawresey who read the paper for the author and who as head of the board of inspection and sur- vey conducted the _ standardization trials took exception to some of the author’s deductions. Other contributed remarks’ severely criticised model basin methods and supported the ac- curacy of the full size trial data. The fact remains, however, that Cap- tain McEntee in his very thorough and able analysis points with sup- porting evidence to the possibility of error in full size trial data. 5. “An Investigation of the Be- havior and of the Ultimate Strength of Rwveted Joints Under Load,” by Commander E. L. Gayhart, C. C., U. S. N., member. Commander Gayhart has contributed a paper of real practical value. It represents a report on tests carried out at the direction of the bureau of construction and repair. Professor Hovgaard of the Massachusetts In- ‘of many vessels MARINE REVIEW stitute of Technology collaborated in the planning of these tests which were carried out under the author’s direct supervision at the bureau of standards. The work was directed . primarily to the study under tensile forces of slip phenomena and stress distribution in riveted joints. Varia- tion of rivet spacing was investi- gated as was also the effect of using rivets of a grade softer than the material of the plates. Many inter- esting conclusions were reached as to the advantages of arrangement, spacing and material in rivets. 6 “Corrosion,” by W. Bennet, member. Such serious difficulties have been experienced by corrosion in compara- tively new ships and especially in tankers that the matter has become one of prime importance for the classification societies and insurance companies. Mr. Bennet’s investiga- tion covering a long period of time, therefore represents a valuable con- tribution to the marine _ industry. This study is of particular interest to owners of new vessels who natural- ly are seriously concerned as to their ultimate life and in measures to prevent rapid deterioration. The au- thor states that whether the serious wastage and corrosion recently found on the rivet points on the bottom is due to electro- chemical action consequent to their scrubbing over muddy bottoms at Gulf ports, to over-heated or over- calked rivets, to the action of polluted rivers, to the composition of the rivet steel and plating, to unduly long periods between drydocking, to in- sufficient or inefficient cleaning and painting. or as is probably nearer the truth, to a combination of causes including all of these and _ possibly more, the very greatest care and forethought is necessary in both the selection of suitable material and the work of building them into the hull of the ship. Mr. Bennet calls attention to an investigation made of the steel of the LEVIATHAN and some _ English steel which had been attached to her stem. Though Mr. Bennet does not state so in his paper this investiga- tion was initiated by MARINE REVIEW. The condition of the steel in the hull of the LEVIATHAN and of the attached English steel, when this vessel dry- docked in 1923 for the first time in: five years was called to the attention of Professor Jack of the Massachu- setts Institute of Technology who turned over the information given to him by MARINE REVIEW to Prof. G. B. Waterhouse. Samples of the stee! were procured for Professor Waterhouse on the initiative of MARINE REVIEW and due to the splendid co-opera- tion of Admiral de Steiguer, then commandment of the Charlestown navy yard. Doctor Waterhouse at the re- quest of the editors of MARINE Rpr- VIEW, prepared after an _ investiga- tion extending over a period of a year, an exclusive article on his work which was published in the August 1924 number of that publication. It was from this article Mr. Bennet quoted in his reference to the LEvI- ATHAN steel. 7 “The Strength of Propeller Shaft Struts,” by Lieut. W. P. Roop, GC: C..°U. 8. Ne visitor. December, 1926 The author summarizes his paper by the statement that a propeller shaft bracket is much better dis- posed for strength when the strut arms enter the boss radially instead of tangentially. The subject has been covered in this paper both from some- what of a theoretical point of view and also by many practical examples. Some interesting photographs are shown of strut fractures, also dia- grams of struts and forces involved. 8. “The Flettner Rudder,” by Olav Overgaard, member, and J. Living- ston, visitor. The authors have quite thoroughly described and illustrated the Flettner rudder. The Flettner rudder was origi- ally intended for airplaines and about 500 of these craft have been equipped. It was first tested on a European merchant vessel in 1921 and proved successful. Since then over 100 ves- sels have been equipped of which 25 are large seagoing ships and the remainder tramp steamers and barges up to 3000 tons. The principle of the Flettner rudder is that the main rudder which is partly balanced is free to rotate about its own axis and is steered by the fin or secondary rudder which is also partially bal- anced. The main rudder stock is hollow and enters the hull through a stuffing box and it extends to the main deck where the weight and thrust are taken up by a suitable thrust bearing. 9. “Engineering Aids to Naviga- tion,” by Commander Stanford C. Hooper, U. S. N., visitor. In this paper the .author has en- numerated and explained modern aids to navigation. He particularly points to the enormous assistance rendered the science of navigation by the phenomenal development in radio and sound apparatus and its uses. His discussion is particuarly directed to the use of such apparatus in’ assist- ing a vessel in making a safe and expeditious passage from one port to another. The author covers in his paper a brief general history of the development; description of how the appartus is used as an aid to navigation and the extent of use of apparatus and instances of results obtained. The paper is_ illustrated by many diagrams and several photo- graphs. 10. “Considerations Governing the Selection of a Fleet for the Upper Mississippi River,’ by Brig. Gen. T. Q. Ashburn, U. S. A., visitor. In this paper General Ashburn gives the results of studies made to build a suitable fleet of river boats for service on the upper Mississippi from St. Louis to the Twin Cities in the open season of the year, and for service on the lower Mississippi or the Warrior river during the winter. The problem was to design a fleet of towboats and barges which could operate successfully as a common car- rier and which could be constructed for the sum of $600.000. The distance on the river is 768 miles with a de- pendable eight months’ channel of 4 feet and a current varying from nothing to eight miles an hour. After a thorough inspection of the route in conjunction with the naval architects Cox and Stevens and Thomas R. Tarn and after much study it was finally decided as 4 working basis