Leg 177 began at 1130 hr on 9 December 1997 with the port call in Cape Town. The traditional joint ODP/ODL (Ocean Drilling Limited) annual holiday celebration was held at the Capetonian Hotel the evening of 10 December. This year's festivities were combined with a retirement party for Captain Ed Oonk.
Replacement and repair work on communications, thruster, waste management, power generation, and lifeboat systems extended the port call to 5 full days.
At 1315 hr on 14 December 1997, the port call ended with the last line ashore, and the vessel headed for Site 1088, which is located about 444 nmi southwest of Cape Town. Because of relatively heavy weather, plans to approach the site along a reference seismic profile were abandoned and the approach was made directly using global positioning system coordinates. The transit was accomplished in 56.5 hr at an average speed of 8.9 kt.
A positioning beacon was launched at 2145 hr on 16 December, beginning site operations for the leg. The advanced hydraulic piston corer (APC) coring assembly was deployed and, before spud-in, a temperature measurement was taken a few meters above the seafloor with the APC temperature (APCT) tool in the APC core-catcher (CC) shoe. Hole 1088A was spudded, with the first APC coring attempt at 0930 hr on 17 December. An anomalous pressure bleedoff indication was noted when the corer was actuated, and the core barrel was recovered full of disturbed sediment. These were indications that the bit had been positioned too deep for the spud attempt and/or that the shearpins had failed before the corer reached the seafloor.
The APC was redressed and the drill string was raised 5 m for a second, successful spud-in. A 5.5-m core was recovered, establishing the seafloor depth at 2092 meters below rig floor (mbrf). APC coring continued with azimuthal orientation beginning with Core 4H. APCT measurements were taken every third core. APCT data were adversely affected by vessel heave even though weather conditions had improved somewhat.
After Core 14H at 129 mbsf, the coring line parted at the ropesocket. It was necessary to fish the sinker bars and coring assembly with a second core barrel fitted with a hard-formation CC.
As the corer was being lowered for Core 15H, a ground fault was detected in the top drive. The corer was recovered, and the bit was pulled above the seafloor for the protection of the drill string while troubleshooting was in progress. The electrical problem turned out to be limited to a nick in the insulation of one of the top drive's umbilical cables. Temporary repairs were made to the insulation, and operations resumed after 3 hr of repair time.
Hole 1088C was spudded without the position being offset from Hole 1088B. A seafloor depth of 2093.7 mbrf was indicated by the recovered core. The hole was drilled without coring to 124 mbsf, where continuous coring resumed. After four additional APC cores to 162 mbsf, APC coring was abandoned because of excessive overpull and the requirement to drill around the core barrel to free it. Rotary coring then continued with the extended core barrel (XCB) system to 233 mbsf (Core 13X). At that point, coring operations were terminated at the request of the scientific investigators, well short of the originally projected penetration of about 700 m. The drill string was recovered, the positioning beacon was released and retrieved, and the vessel departed at 2230 hr on 18 December.