. This base surge could be seen for three and a half minutes and for longer from the air as it continued to move across the ocean. When the spray dome and base surge had dissipated, a foam patch could be seen spreading from the surface zero water to reach over . The nuclear blast was calculated to be . All fallout stayed within the predicted fallout area with a maximum of . The target ship at was directly hit by the shockwave, vibrating the entire ship and shaking it violently. The Moran merchant marine ship moored at away was immobilized due to shock damage to its main and auxiliary equipment while also suffering minor hull damage. One hour and ten minutes after detonation, a five-gallon water sample was taken directly above the blast location showing . The retrieval team entered a field after an hour and thirty five minutes. Umbrella preparation The second underwater explosion of the Operation Hardtack series was code-named Umbrella. This test was conducted in the lagoon inside Enewetak. This test could be considered a continuation of underwater test Baker, which was conducted in Bikini Lagoon. Explosions in shallow water can create an underwater crater if close enough to the bottom. The target ships from the Wahoo test were towed into the lagoon to be used again for the Umbrella test. The damage from Wahoo was minor in all cases with the exception of the Moran which required extra refurbishing of the hull. These ships had to be washed down and have the measuring equipment replaced before being put into use. The mooring for Umbrella was considerably easier than for Wahoo due to the location and depth of the lagoon. Information gathered from the Wahoo shot directly affected the Umbrella plans with regard to target array placement and decontamination times. The device was placed with a buoy at a depth of . Umbrella blast June 9 saw the second underwater nuclear test of the Hardtack I series. The detonation occurred at 11:15 AM (local time) with clear skies and a wind from the east-northeast. Within one-tenth of a second, the spray dome had broken through the surface. The overall shape of the spray dome resembled a vertical column with the plumes helping create the shape. Within 20 seconds of detonation, the maximum height of the column reached . The base surge reached a distance around downwind,