Chapter 2 PROCEDURE 2.1 GENERAL OPERATIONS AND SHOT PARTICIPATION The project participated in two scheduled underwater detonations in the Hardtack series at the Eniwetok Proving Ground (EPG): Shots Wahoo and Umbrella. Operational limitations on accuracy of placement and conflicts with other elements of the total shot array necessitated modification of the idealized station array presented in Chapter 1. AS originally planned, 21 coracles were placed for Wahoo; but, on the basis of Wahoo experi- ence, the Umbrella array was modified to include 26 coracles and one skiff armed and placed by SIO. The coracle stations placed by the project, together with the instruments installed in each, are tabulated against their nominal positions in Table 2.1 and plotted in Figures 2.1 and 2.2. The estimated positions of all elements moving after the detonations are also plotted in these figures; however, throughout the remainder of this report, all coracles and all collections or records obtained aboard them will be referred to by means of the nominal position designa- tors used in Table 2.1 regardless of later position. The coracle stations were supplemented by . additional instrumentation installed aboard all major target vessels and by approximately 70 FFP’s distributed throughout the fixed array. Since climatological averages (References 26 and 27) indicated that surface winds tended to shift to the right during the May-June season, the station array for both Wahoo and Umbrella was skewed to the right of the downwind leg that had been selected by Joint Task Force 7. Deepanchoring was required for all 21 coracle Wahoo locations, whereas only 5 Umbrella locations required such mooring. The remaining Umbrella stations were anchored by standard naval techniques in depths not exceeding 30 fathoms. Experience during Operation Redwing (References 55 and 56) had shown that properly installed deep-anchors could be relied upon for the mooring of skiffs. This fact was most definitely borne out by the Hardtack experience, since only 1 deep moorin 30 failed because of inherent defects, viz, a leaking fiberglass subsurface buoy. No coracles were lost curing the entire operation, although two broke free due to chafing of the surface pennants. All deep moors were placed by the USS Munsee (ATF-107), which had been specially equipped with a Markey hydrographic winch and AN, UQN-1B sonar sounding equipment modified to have a continuous fathometer scale from 0 to 1,200 fathoms. No difficulty was experienced in over- the-side handling of coracles in seas up to Class 5 (winds 17 to 21 knots, waves pronounced and long with white foam crests). An entire deep moor could be placed in about an hour starting from the time of the ATF’s approach. A maximum of six deep moors could conveniently be placed in a normal working day; however, the actual placement of deep moors was controlled by the Task Group 7.3 mooring schedule for placement of the major target elements. The as- sistance of one LCM was required for the placement of coracle moors in shoal waters inside the lagoon. A maxtmum of eight such shallow moors could be placed in a normal working day. After surface currents were measured in the area, placement of the deep moors for Wahoo commenced on 16 April 1958. Placement of deep moors and lagoon anchorages for Umbrella was started on 27 May. Both areas were completely cleared of all remaining mooring components by 12 June. Dwring this 60-day period, the USS Munsee was uSed by the project on nearly continuous assignment. Concurrently with mooring operations, all project instruments were bench-checked and inStalled in coracles at the beach work area (BWA) on Parry Island. For Shot Wahoo, placement 48