January 13, 1986

The Economy The credit markets are prepared for strong economic statistics this week, including sizable gains in retail sales and industrial production for December. Signs of a healthy economy were the catalyst for last week's sharp rise in interest rates. [ Page D1. ]

The United States said today that armed Iranian sailors stopped and searched an American merchant ship for more than an hour in international waters near the Persian Gulf. White House and State Department spokesmen said the incident today on the American freighter, the President Taylor, was ''a matter of serious concern'' but withheld further judgment until after the freighter's captain, Robert Reimann, could be interviewed by United States Embassy officials. American officials said the captain was in Fujaira, a Gulf of Oman port in the United Arab Emirates, where the ship docked after the search by the Iranians, who boarded from an Iranian Navy ship. No Injuries or Loss ''There were no injuries or loss of property in the incident,'' said Bruce Ammerman, a State Department spokesman. A spokesman for the ship's owners, American President Lines, said 43 crew members were aboard. The shipping company said the incident occurred 30 miles south of Fujaira, where it was bound when it was boarded.

The New England Patriots, continuing to exact revenge in the playoffs against teams that defeated them in the regular season, reached Super Bowl XX today by defeating the Miami Dolphins, of all people. The Patriots, who had not won in the Orange Bowl since 1966 and had lost 18 consecutive games there, captured the American Conference championship with a 31-14 victory in which they forced six turnovers. The resourceful New Englanders converted four of the turnovers into scores, giving them a total of 11 out of 16 in the three playoff games that produced touchdowns or field goals. All those playoff games have been on the road, since the Patriots are a wild-card team, and against three of the five teams that defeated the Patriots in the regular season: the Jets, the Raiders, and now the Dolphins. And in the Super Bowl on Jan. 26, they face the Bears, who defeated them by 20-7 in the second game of the season at Chicago. Only one team, the Raiders, has ever won the Super Bowl as a wild-card team. They did it in January 1981, from the Philadelphia Eagles.

International Iran intercepted a U.S. freighter in international waters near the Persian Gulf, White House and State Department spokesmen announced, saying that it was a ''matter of serious concern.'' The American freighter, the President Taylor, was stopped by Iranians who boarded from an Iranian Navy ship and searched the American vessel for more than an hour. The freighter then went on to Fujaira, a port in the United Arab Emirates. [ Page A1, Column 6. ] A black activist was fatally stabbed in South Africa hours before he was scheduled to meet with Chester A. Crocker, the United States Assistant Secretary of State for African Affairs. Pro-Government adversaries reportedly killed Ampie Mayisa, a community leader from Leandra, a township near Johannesburg. The stabbing occurred at his home, which was fire-bombed. [ A1:4. ]

A black township activist was stabbed to death, reportedly by pro-Government vigilantes, hours before he was scheduled to meet today with a high-level American official. The visiting American official, Assistant Secretary of State for African Affairs, Chester A. Crocker, broke with his previous practice in visits to South Africa by touring two segregated townships - Duduza and KwaThema, both east of Johannesburg. Mr. Crocker, who has made regular visits to South Africa, has in the past met only with white Government officials, not their black adversaries. Pro-Government Blacks Blamed Hours before Mr. Crocker visited the segregated areas, however, Ampie Mayisa, a black community leader from the nearby township of Leandra, was found stabbed to death, the police said.