anchor made of two railroad wheels, a 1! g7ton -a.vel, a wire clamp (SIO drawing A-832, X dimension = 0.144 inch with a tolerance of + 0.000 to — 0.002 inch), a length of °4)-inch- dinmeter cable determined by the depth of the moor (guaranteed ultimate tensile strength 3,300 pounds), a Second wire clamp, 15 feet of 7 i¢-inch-diameter wire rope, a second 1!,-ton swivel, w subsurface float of net buoyancy determined by the depth of moor, 300 feet of ‘Q-inch nylon line with 5- by 9-inch plastic floats as required. No attempt was made to insulate the various components of the moor electrically. The deep moor is described in greater detail in Reference 73. Since litue advantage could be gained through applying deep-anchoring techniques to the shallow anchorages required for placement of coracles within Eniwetok lagoon, all such coracles were moored to Navy Dan buoys by 150-foot pennants. This type of mooring is a standard Navy procedure requiring no special theoretical considerations. The major components of the moor from the bottom up were: a 25-pound Danforth anchor, 30 feet of 3y-inch chain, a 15-pound concrete clump, 5 feet of 3 ,-inch chain, a length of 3 .-inch-diameter wire rope dependent upon depth, anda standfrd Navy Dan buoy. 2.3.2 Properties and Placement of Coracles. Operational experience with the coracles is reported in detail in Reference 73 and is, therefore, reviewed only briefly here. About an hour was required for installation of a complete deep moor, starting from the time of the ship’s approach run ona desired location. Coracles could be handled over the side, using the ATF Ship’s boom if proper precautions were taken to protect the coracle from swinging against the side. The accuracy of coracle placement was principally limited by the accuracy of the ship’s navigating equipment at short range. For Wahoo, the placement accuracy for stations within 10,000 feet of surface zero was approximately +300 feet. Stations beyond 10,000 feet could be placed within an ellipse with a 600-foot minor axis and a 1,000-foot major axis parallel to the downwind leg of the array. The obServed coracle excursions were within the calculated limits. No variation with tide was discernible. The direction and extent of the observed excursions, however, appeared entirely random; therefore, recalculation of the point of contact with the bottom to effect more accurate station positioning was not poSsible. For Umbrella, an accuracy of +200 feet was obtained for all positions. The coracle locations reported in Table 2.1 and plotted in various figures throughout this report were determined from an analysis of photomosaic maps made at approximately H-1 hour and H+1 hour for Wahoo and by means of a Series of pre- and postshot radar fixes for Umbrella. Although 11 coracles for Shot Wahoo were found drifting, their positions during the time of principal interest did not change more than about 300 feet. The drift rates for coracles dragging their moors may be estimated from Wahoo recovery data presented in Table 2.6 and the observed drift rates presented in Figure 2.16. Estimated positions for drifting coracles are plotted for the first 6 hours after zero time in Figures 2.1 and 2.2. During Shot Wahoo, roughly 70 percent of the deep moors failed. Of the 20 moors in position at the time of detonation (2 were without coracles), only 7 at the more distant locations survived. The relatively slow drift rates observed indicated that most of these coracles were dragging the greater portion of their mooring cable; therefore, it was presumed that failure occurred near the bottom. At no time was there any evidence of dragging anchors. Because of limitations on time, only one broken moor (DL 12.0) was completely recovered. Inspection of the cable revealed a pure tension break at a depth of 5,000 feet with no sign of kinking, corrosion, or abrasion. Failure of the moor at DL 18.3 was undoubtedly caused by damage incurred prior to the shot, during a collision with one of the target vessels as it was being towed into its final position. The reasons for failure of the remaining moors cannot be precisely determined because of the lack of detailed information. Strain on the cable due to waves or submarine avalanches caused by the detonation do not appear sufficient to have caused failure. At locations closer than 3,500 feet, the violent upwelling of water after the detonation may have created radial currents along the surface of sufficient magnitude to cause failure. The drag due to the coracle alone in a current of 10 knots would be 3,500 pounds. However, on 72 vl a AD -