This is the Third Technical Progress Report, from the Ship Structure Committee to the convening authority, the Secretary of the Treasury. It continues the series of technical reports which began with the publication of the Final Report of the Ship Structure Committee?s predecessor, the Board to Investigate the Design and Methods of Construction of Welded Steel Merchant Vessels.

This Ship Structure Committee was formed in 1946 "for the purpose of prosecuting a research program to improve the hull structures of ships by an extension of knowledge pertaining to design, materials and methods of fabrication." Fractures continue to occur in welded ships built during World War II, and many of these ships are still in use. This has led the Committee to continue to direct the bulk of its effort to the solution of the brittle fracture problem in welded ships.

Based on technical and financial considerations, it has been necessary for the Committee to exercise much care in maintaining a balanced and flexible research program covering the fields of design, materials and fabrication; and in the division of effort between "fundamental" and "applied" research. In view of the importance and urgency of the ship cracking problem, the "applied" studies have in general been favored, and have yielded many practical solutions in areas where fundamental understanding may not be achieved for some time. However, it is recognized that "fundamental" research is needed for final solution of the ship cracking problem, rather than the partial solution afforded by "stop-gap" measures.

Progress can be reported on several projects in the Design category which are studying specific ship design details through tests on comparatively small-scale laboratory specimens. Considered as a whole, however, this field is one which has yet to be fully explored; there is, for instance a need for additional information on the behavior of the ship in a seaway. Extensive analysis of the complete Design program by the newly formed Committee on Ship Structural Design of the National Academy of Sciences-National Research Council is expected to result in an integrated program for this work.