* a yals. Since all task force ships were equipped with a washdown system, some difficulty was encountered in mounting the collectors at a position which was above the spray from this system. However, location on the highest platform on the mainmast was satisfactory. 2.3.2 Free-floating Stations One reason for approving this phase of the project was to ascertain the operational feasi- pility of a system of free-floating stations (Fig. 2.3). A system of free-floating stations to measure fall-out over sea areas was first proposed during the early planning for Operation Windstorm, but these tests were subsequently moved to Nevada, and the scheme was never tried. From the start it was realized that such an undertaking presented many problems. As first conceived, the plan called for the use of a raft which would be large enough to support the collection devices and provide a working platform for personnel to make instru- ment adjustments after the raft was in the water. As the time approachedfor establishing definite instrument requirements, information on the number and types of ships which would positively be available for the project was almost entirely absent. Therefore plans were modified to provide for a float smaller than a raft and one which could be placed over the side in a minimum of time without the use of a crane or special rigging. Operationally this plan per- mitted a maximum flexibility since the numberof collection stations which could be placed de- pended almost entirely on the number and speedof the ships available rather than on space and weight limitations imposed by the float. The float finally selected was a standard Navy type 3 Dan buoy (Fig. 3.10). The buoy weighed less than 75 lb when completely assembled with identification and collection devices. The reserve buoyancy of the fldat was about 80 lb. The compact light buoys simplified the problem of their launching and recovery from the sea. The problems involved in launching the buoys so that they would drift to the proper position by shot time and locating them after they had been drifting in the open sea for several days are apparent. It was necessary to assumethat the shot would occur on the day and hour ge, is ft scheduled. Delay of the shot for several hours would not have been too serious; however, postponement exceeding about 30 hr would have necessitated repositioning of buoys or the launching of additional ones. It was assumed that each buoy, when equipped with a sea anchor, could be expectedto drift with the current and notbe affected appreciably by the wind. Available information about the direction and rate of flow of ocean currents in the Marshall Islands area during the months of October and November was extremely limited. Those data which are available have been developed largely from Japanese prewar charts. The best estimate obtained from the Navy Department Hydrographic Office was that the direction of movement was essentially to the westward at a rate of about 17 nautical miles per day. Upon arrival at the site, two buoys were launched to investigate this estimate. One buoy was launched without a sea anchor; its move- ments followed the pattern of the wind direction and speed. The other buoy was launched with a sea anchor about 35 miles due east of the deep entrance to Eniwetok Lagoon and was recov- ered about 5 miles off the Eniwetok reef. The recovery position was not one-quarter mile off a due west line from the launching position. The rate of drift was 18 nautical miles per day. Since this information essentially confirmed earlier predictions, a 270° set and a drift of 18 nautical miles per day were assumed to determine buoy launching positions. It was felt that it might be necessary to launch as early as M—7 day and that recovery search would continue to about M+7 day before being abandoned. This suggestion meant that some of the buoys could be drifting freely for as long as 14 days. The sea areas covered by any pattern of buoy positions would then be extensive. To increase the probability for recov- ering, each buoy was equipped with a standard MX-138A cornerradar reflector. It was mounted at the top of the flagstaff within a special adapter developed by the Mine Sweeping Section of the Bureau of Ships. The radar reflectors were the same type as used in the rubber raft equipment issued to Naval aircraft. The use of the radar reflectors was absolutely necessary if the = ' i ae - Ba. Es weg te om . ee Ka =