The 257-nmi transit between Sites 1160 and 1161 required 33 hr at an average speed of 8 kt. We made the transit at reduced speed so the active heave compensator hydraulic service loop could be repaired. Site 1161 is the northernmost of three potential sites located during our transit survey between Sites 1158 and 1159 (see "Site Geophysics" in the "Site 1159" chapter). At 1430 hr on 25 December, we slowed to 6 kt and conducted a south-to-north 3.5-kHz survey over Global Position System (GPS) coordinates of this site. At 1530 hr we dropped a positioning beacon about 1 km north of our original GPS coordinates. This position is closer to the middle of the target sediment pond.
After the hydrophones and thrusters were extended and the vessel settled on location, the precision depth recorder (PDR) referenced to the dual-elevator stool indicated a water depth of 5031.4 m below the rig floor. The nine-collar bottom-hole assembly employed at the previous sites was reassembled with a new C-7 four-cone rotary bit and a mechanical bit release. We initiated Hole 1161A at 2330 hr on 25 December and drilled to 116.0 meters below the seafloor (mbsf) before contacting basement. We deepened Hole 1161A by rotary coring from 116.0 to 145.3 mbsf (Cores 187-1161A-2R to 5R) before the hole had to be abandoned because of erratic high torque, rapid penetration, and poor recovery (15%; Table T1). A tracer of fluorescent microspheres was deployed on Core 187-1161A-2R. The drill string cleared the seafloor at 1315 hr on 26 December, and we offset in dynamic positioning mode 200 m north.
At Hole 1161B, we washed through 158.5 m of sediment before contacting basement and retrieving a wash barrel, which recovered a few pieces of basalt. We advanced Hole 1161B by rotary coring from 158.5 to 167.0 mbsf (Cores 187-1161B-2R and 3R, 10% recovery) with the same poor drilling conditions we experienced in the first hole. Rather than attempting to start a third hole at this site, we decided that we had recovered sufficient material at this site to meet our primary shipboard objectives and to move to our next site. We deployed a second tracer of fluorescent microspheres on Core 187-1161B-2R. The drill bit cleared the seafloor at 0045 hr and the rotary table at 0915 hr on 27 December.