Pollution prevented

Pollution prevented.
- Daytime. Mediterranean. Calm weather.
- Report No. 92005.

The Chief Officer of an 85,000 DWT. tanker was making an inspection of the vessel, which was at anchor waiting to discharge crude oil. From the main deck he observed a slight trace of oil near the ship's side forward of No.2 port tank. Small drops of oil were coming up to the surface from under the waterline. The Chief Officer donned a breathing apparatus, and dived from a lifeboat to detect the source of leakage. a crack of about 15cm. length was found 5m. underwater. He then took steps to stop any pollution. First by calculating the pressure of water against the pressure of oil in the tank, then transferring the oil to other tanks to drop the level, equalise the pressure and stop the leak.
After discharging the cargo the following day, the ship returned to the anchorage. The Chief Officer trimmed the ship using clean ballast to bring the crack 1m. above the waterline. It was noted that the crack was caused by a heavy blow, possibly from a tug during berthing. The Chief Engineer manufactured a steel plate with a rubber gasket which was fixed over the crack using bolts. For safety the tank was fully inerted, and the bolt holes were made using a slow rotating/perforating machine driven by air. A continuos jet of water was maintained around the work area. The ship was then able to make a further loaded trip to the home port where permanent repairs were carried out in a shipyard.