Technical and research (T&R) | Bulletins and reports
A method is presented for a more rational determination of service margins for ships. Sources of data and methods are given and areas requiring further research are described. The basic philosophy is the division of the service margin into two parts, a speed margin and a power margin, representing the environmental effects and the deteriorative effects.
Panel H-12 (Planing Boats) of The Society of Naval Architects and Marine Engineers Technical and Research program, in compliance with the Society's charter to place on record the results of research, experience, and information relative to original ship design, reviewed the following report of work sponsored by the Collins Radio Company on stepped hull planing boats. This report is unusual in that it represents privately sponsored scientific controlled experimentation with small craft involving three different hull designs. It is the hope of the Panel that this report will stimulate further effort of this type to the benefit of the small boat industry.
Panel H-13 (Sailing Yachts) of The Society of Naval Architects and Marine Engineers Technical and Research Program sponsored the preparation of this report, which consists primarily of tables of sail force coefficients for systematic variations in sailing yacht rig geometry. These coefficients were determined by a computer program written in accordance with a mathematical model developed by the author and reported in the 1968 Transactions of the Society.
The work reported herein was first proposed to Panel H-7 (Seakeeping) of The Society of Naval Architects and Marine Engineers (SNAME) Technical and Research Program by Webb Institute in 1962 as a study to determine the causes and extent of voluntary slowdowns of dry cargo ships. A SNAME purchase order in 1964 initiated the actual study, ship logbooks were obtained and a small sampling was analyzed.
The work reported herein was initiated at the request of Panel HS-2 (Slamming) of The Society's Technical and Research Program to determine whether. or not impact pressures generated on barge bows, while operating in waves, could be estimated in the same manner as that proposed by Dr. M.K. Ochi for typical ship forebody forms. The incentive for conducting the investigation was provided by the growing importance of offshore barge transportation services and the increasing cost of repairing structural damages caused by barge slamming in rough seas.
To obtain a factual database for aid in accessing the need for additional deep ocean simulation facilities, the National Council on Marine Resources and Engineering Development sponsored a survey of pressure test facilities in the United States, the utilization of these facilities in the recent past, the expected use of these facilities in the near future, and sundry other related data. One of the findings of that survey (which the author led) was that there is a need in the ocean community for publication of an inventory of facilities. This report, an excerpt from the aforementioned survey, fills that need.
This report has been compiled in response to an indicated need for a compilation of technical references on Ferro-cement and concrete as a construction and fabrication material for boats, barges, vehicles, and other structures that operate in the marine environment. Some 270 individual reports, papers, articles, and hard-bound books are to be found in this listing. They have been identified and selected by the members of the Task Group HS-6-4 (Ferro-cement) of The Society of Naval Architects and Marine Engineers Technical and Research Program as being articles of technical interest, with selected articles of historical interest included as well. As much as possible, popular articles without apparent technical merit have not been included.
This report has been compiled in response to an indicated need for a compilation of technical references on Ferro-cement and concrete as a construction and fabrication material for boats, barges, vehicles, and other structures that operate in the marine environment. Some 270 individual reports, papers, articles, and hard-bound books are to be found in this listing. They have been identified and selected by the members of the Task Group HS-6-4 (Ferro-cement) of The Society of Naval Architects and Marine Engineers Technical and Research Program as being articles of technical interest, with selected articles of historical interest included as well. As much as possible, popular articles without apparent technical merit have not been included.
One of the major problems that have developed in the field of high-speed waterborne surface craft, i.e., hydrofoils, planing craft, and air-cushion vehicles, is the lack of a set of standard technical terms to be used in conjunction with these crafts. In an attempt to rectify this situation, Panel MS-l (High-Speed Surface craft) of The Society of Naval Architects and Marine Engineers' Technical and Research (T&R) Program has prepared T&R Report R-17, "Glossary for High-Speed Surface Craft. This glossary is intended to define only those terms primarily associated with these craft and references other glossaries to define terms associated primarily with marine or aeronautical technologies.
After reviewing the methods by which frictional resistance of ships is calculated, this report explores the sources of hull roughness and how roughness affects the speed of ships over a time scale. The report discusses the role of coatings and cathodic protection in controlling roughness and establishes a relationship between the size and shape of roughness and the percentage of increase in hull resistance. Model resistance testing, using fiberglass castings from corroded ship plates is described, with some resultant data given, and related papers on roughness measurement are discussed.
