On the morning of December 16, 1977, the Venoil and the Venpet collided
40 miles off Cape St. Francis, South Africa.
The Venpet was damaged, releasing burning bunker oil
over the starboard deck of the Venoil and into the surrounding water.
The Venoil suffered serious fire damage.
The impact also holed two of the Venoil's tanks.
Both ships were abandoned, and began to drift towards the coast.
The fires on board both vessels went out as they drifted.
Iranian Heavy crude oil has an API gravity of 31.0, and a pour point of -5 degrees F.
Bunker fuel oil is a heavy product with an API gravity that ranges from 7 to 14.
Approximately 155,000 barrels of Iranian heavy crude oil,
and 33,000 barrels of bunker fuel oil spilled from the Venoil.
Approximately 31,000 barrels of bunker fuel oil spilled from the Venpet,
in ballast at the time of the collision.
Of the 219,000 barrels of oil spilled, it is estimated that 25 percent burned.
Overflights on December 17 revealed a slick of emulsified oil 25 miles from the coast and moving west.
The slick moved towards the coast for a week.
By December 24, the oil was in the Plettenberg Bay area,
four miles from the coast of the Tsitsikama Nature Reserve.
A day later the oil moved away from the coast in a WSW direction.
A previously undiscovered slick was found in the area
between Plettenberg Bay and Mossel Bay on December 25.
The slick consisted of patches of emulsified oil in a 100 square-mile area.
The slick moved in a westerly direction.
On December 28, the oil came ashore and, over the next four days,
80 miles of shoreline were impacted.
Most of the area received light oiling,
with the area between the Little Brak and Great Brak rivers
receiving some heavy concentrations of oil.
Oil impacted the river banks, mudflats, sandflats, marshes, and a reef in that area.
Oil also sank in the river and nearby lagoons
as sand became incorporated into the mousse and salinity levels dropped.
Oil reached two miles up the Little Brak River.
Overflights on January 3 revealed that there was no oil in the water
in the area 45 miles from the shore between Cape Agulhas and Port Elizabeth.
Both vessels were taken under tow to prevent their grounding near the coast.
By December 18, the Venoil was 30 miles from the coast, and the Venpet was 47 miles away.
The vessels were towed into the Agulhas Current
so that any release of oil would be carried away from the shoreline.
The Venpet was brought to Algoas Bay for repairs on December 24.
The Agulhas Current carried the Venoil and one tug 250 miles southwest of the coast.
Two tugs were required to tow the Venoil into Algoas Bay, where it arrived on January 1, 1978.
Lightering operations began on January 4 and were completed on January 7. i