We accomplished the 256-km transit to Site 1187 (new proposed Site OJ-14A) in 13.5 hr at an average speed of 10.2 kt. The vessel proceeded directly to the Global Positioning System coordinates for Site 1187, and, at 1112 hr on 29 October 2000, we deployed a beacon on site.
The depth objective in this hole was to core into basement until time expired or the bit failed as a result of excessive wear. We spudded Hole 1187A with the rotary core barrel (RCB) at 1920 hr on 29 October. The bit tagged the seafloor at 3803.6 m below sea level. We drilled ahead with a wash barrel in place to a depth of 365.5 m below seafloor, where progress became very slow because of a change in formation. From our interpretation of the seismic profile, we expected to encounter basement at ~410 mbsf. However, we encountered the sediment/basalt interface in the first RCB core (Core 192-1187A-2R) and inferred it to be at 372.5 mbsf, based upon the change in drilling parameters noted by the driller. We continued rotary coring in basement to a depth of 508.3 mbsf, where the bit expired after 65 rotating hours. The failure was manifested by high, erratic torque, indicating that one or more cones had fallen off the bit. The average recovery in basement was 74.3%, and the average penetration rate was 2.4 m/hr. Total penetration into basaltic basement was 135.8 m. Core depths and recovery are given in Tables T1 and T2.
After retrieving the drill string and bottom-hole assembly (BHA), we found that the bit was missing two cones and one cone shank. The two remaining cones had chipped and missing teeth in all rows. After retracting the hydrophones and thrusters and securing the drilling equipment, the crew put the vessel under way to Guam at 0330 hr on 3 November 2000. The 2337-km transit to Guam was completed in 4.5 days at an average speed of 11.6 kt. Leg 192 officially ended at 1700 hr on 7 September 2000, with the first line ashore in Apra Harbor, Guam.