Before starting the transit to proposed Site WNT-01B (Site 1177), normal operations were interrupted for 3.25 hr so that the hydraulic umbilical of the active heave compensator (AHC), which was leaking, could be inspected. A hole in one of the high-pressure supply lines was found but could not be repaired on board. The ship began the transit at 1700 hr on 29 June. During the transit, the ship stopped for another 2 hr (2000 to 2200 hr) to finish securing the AHC hydraulic umbilical in the derrick. The 70-nmi transit was made in 7 hr. A seafloor positioning beacon was deployed at 0222 hr on 30 June, initiating Site 1177.
The precision depth recorder indicated a drilling depth of 4851.4 meters below rig floor (mbrf). A standard rotary core barrel (RCB) bottom hole assembly was made up and run down to the seafloor. At 1500 hr on 30 June, the driller detected the seafloor by a reduction in drill-string weight at 4844.3 meters below sea level (mbsl) (4856 mbrf). Hole 1177A was then spudded and drilled to 300.2 mbsf (5156.2 mbrf) (Tables T1, T2). Davis-Villinger temperature probe (DVTP) measurements were taken at 50.5 mbsf (4906.5 mbrf) and 120 mbsf (4976.0 mbrf) but did not obtain good data. Hole 1177A was then cored from 300.2 to 833.9 mbsf (Cores 1R to 56R) and recovered 282.74 m (53%).
Coring was stopped after basalt was recovered in Core 56R. The bit was then tripped out of the hole. Once the bit had cleared the seafloor, the drill line was slipped and cut. The seafloor positioning beacon was released and recovered at 0910 hr on 5 July. The bit cleared the rig floor at 1730 hr on 5 July, ending operations at Site 1177.
The transit to proposed Site ENT-10A (Site 1178) began at 1930 hr on 5 July. Typhoon Kirogi was approaching our location from the south and was predicted to pass close to the drill site. Although the weather in the vicinity of the vessel was good, a heavy swell was coming out of the south, causing excessive pitch and roll of the vessel. Because of the deep water at proposed Site ENT-10A (~4554 mbsl), we decided not to deploy the drill string and to suspend operations until the weather would allow safe operations. While the vessel was on standby, 20 stands of 5-in drill pipe were removed from the riser hold, made up, and placed in the middle bay of the pipe racker. The leaking AHC hydraulic umbilical was removed and placed on pallets on the main deck, and the coaxial cable was removed from the vibration-isolated television frame winch in preparation for installation of the new cable during the Yokohama port call after the leg.
At 1045 hr on 7 July, we decided to move the vessel out of the path of typhoon Kirogi and maintain at least a 250-nmi distance from it. The vessel was moved ~98 nmi to the west and looped around behind the typhoon. Because of the loss in operations time as a result of the typhoon, all of the proposed Site ENT-10A objectives could not be accomplished. Therefore, we decided to core at alternate proposed Site ENT-09A (Site 1178) instead.