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Title:	Model study of the proposed breakwater system for Roosevelt Roads Naval Base, Vieques, Puerto Rico
Authors:	United States. Mississippi River Commission. U.S. Army Engineer Waterways Experiment Station.
Keywords:	Breakwaters Hydraulic models Vieques Island (P.R.)
Publisher:	U.S. Army Engineer Waterways Experiment Station. Engineer Research and Development Center (U.S.)
Description:	Technical memorandum Synopsis: The study reported herein was concerned with the reduction of wave action, by means of breakwaters, in the vicinity of the Roosevelt Roads Naval Base, Vieques - Puerto Rico. The hydraulic problems involved were investigated on a model which was built to the undistorted linear scale of l to 500, and which included the overbank area of Puerto Rico within the vicinity of the naval shore facilities, the northern part of Vieques Island, and the body of water incorporating the problem area (see plate 1). The study was accomplished at the U. S. Waterways Experiment Station, for the Bureau of Yards and Docks, U. S. Navy Department, during the period from April 1941 to N ovember 1942. In adapting such an area as Roosevelt Roads for use as a naval base, careful consideration had to be given to the location of the breakwater for protecting the area against excessive wave action. The Navy Department desired by means of breakwaters to make Vieques Passage usable as a fleet anchorage and seaplane operating area, and to keep waves and swells within the vicinity of the shore installation on Puerto Rico to a minimum; the proposed project for providing this protection involved the construction of 15 to 20 miles of breakv1ater in water depths varying from around 10 to 60 ft. Due to the magnitude of the project, the then urgency of the work, and the limited funds available, it was necessary to assure that those breakwater sections built would provide a maximum return for the time and funds expended. For the above reasons, the proposed breakwater system was investigated by means of a small-scale hydraulic model. At the time the model study was undertaken, the urgency of the project for war purposes required that the first problem to be solved was that of determining what sections of the entire breakwater system would be required to protect the fleet anchorage area and the seaplane operating area from excessive wave action. The preliminary model tests indicated that the shoals and reefs surrounding Roosevelt Roads were effective in reducing the wave action in the fleet anchorage area to such an extent that approximately 8 miles of breakwaters, which were designed for protecting this area, could be eliminated; therefore, the primary problem involved was that of determining the most effective design and the construction sequence of those breakwater sections to be used for protecting the seaplane operating area. The desired protection for the seaplane operating area was provided by the breakwater design referred to as plan 7 (see plate 10). To protect the shore facilities from southern storms, the breakwater installation known as plan 11 (see plate 14) was found to be the most effective. In addition to the problem of determining the most advantageous construction sequence for the breakwaters protecting the seaplane operating area, it was considered desirable to know the effectiveness of the entire breakwater system against excessive storm conditions, both during construction and after completion. At this stage of the testing program, the Navy Department desired, for strategic reasons, to make Roosevelt Roads a naval base entirely inclosed by breakwaters with the exception of three narrow ship entrances. The comprehensive breakwater installation (plan 12) resulting from the above decision and previous model tests is shown on plate 15. The results of the investigations indicated that breakwater plan 12 would be effective in reducing excessive wave action within the problem areas resulting from extreme storm condition, although the breakwater would provide the desired protection to the major part of the seaplane operating area only during normal .storm conditions. The proposed sequence of constructing the breakwaters protecting the seaplane operating area was found to be satisfactory; however, all breakwater sections immediately surrounding the seaplane area must be installed to provide satisfactory seaplane operating conditions. The current- velocity tests indicated that for normal tide conditions the velocity of the tidal current at the entrances would be increased slightly after the breakwater had been installed, and that the velocity of the tidal currents at the entrances would probably be excessive for severe storm-tide conditions.
Rights:	Approved for public release; distribution is unlimited.
URI:	http://hdl.handle.net/11681/21408
Appears in Collections:	Technical Memorandum