Egyptian President Anwar Sadat today sailed into this Mediterranean port to an enthusiastic welcome from thousands of Israelis. He immediately plunged into three days of meeting with Prime Minister Menachem Begin in hopes of sparking some momentum in the slow-moving negotiations for Palestinian autonomy in the West Bank and Gaza Strip.

From the outset, Sadat made it clear that normalizing relations with Israel to keep pace with the Israeli withdrawal from the Sinai Peninsual was not necessarily at the forefront of this agenda, as many Israelis had hoped.

"We are also equally determined to spread the umbrella of peace to include the Palestinian people. This is a moral commitment to which we will remain faithful at all times," Sadat said at a dockside welcoming ceremony.

The Egyptian leader's yacht, the Horreya (Freedom), in which King Farouk fled into exile in 1952, docked here at noon after a 20-hour voyage from Port Said, with a rendezvous six miles west of Haifa with 10 Israeli missile boats.

The Horreya, accompanied by three Egyptian warshpips, became the first Egyptian vessel to dock at an Israeli port since the creation of the Jewish state 31 years ago.

Sadat stepped onto the bunting-draped dock as Isreali bands played the Egyptian and Israeli anthems, Israeli supersonic fighters screamed overhead and Israeli guns offered a 21-gun salute.

The arrival lacked some of the electric atmosphere that marked Sadat's historic journey to Jerusalem almost two years ago. This is his eighth meeting with Begin and his third visit to Israel. Nonetheless, tens of thousands of Israelis jammed the sidewalks and rooftops to cheer the Egyptian president.

Officials greetin Sadat included Israeli President Yitzhak Navon, Begin, Foreign Minister Moshe Dayan and virtually the entire Cabinet, leaders of the parliament and Jewish religious leaders.

Navon called Sadat's visit "an additional link in the golden chain of peace now being shaped by our two countries" and said he hoped that the summit would "remove some of the impediments to peace."

Without mentioning the Arab rejectionist states by name, Navon obliquely referred to their attacks on the peace process, saying, "Those elements who walk on the sidelines . . . do not grasp the significance of what is taking place. But they too shall climb on the chariot of peace."

Sadat said it was symbolically significant that the summit is being held in Haifa, a city that historically has been shared by Jews and Arabs. It was also a city of bitter fighting between the two as Israel formed a Jewish state.

Sadat said, in a now-familiar refrain, "Never again will human life be wasted in a futile conflict in which nobody benefits."

Sadat's sea journey here led to extraordinary security arrangements with the eastern end of the Mediterranean cleared of all moving vessels. The only exceptions permitted by the Israeli and Egyptian navies were two American ships, a nuclear submarine and its escorting destroyer, which sailed out of Ashdod harbor to provide an extra protective screen to the convoy escorting Sadat.

Following the docking, Sadat, his wife, Jihan, and their 18-year-old daughter, also named Jihna, were given bread and salt by the country's two chief rabbis in the traditional Jewish welcoming ceremony.

They drove in a motorcade through Haifa's crowded streets to the mountaintop Dan Carmel Hotel where the summit meetings are being held.

In an unexpected move, the Egyptian Navy reversed its decision to restrict its seamen to their ships and allowed them to come ashore for a welcoming party by the Israeli Navy and to tour Haifa.

Besides West Bank autonomy, supervision of the demilitarized Sinai and the sale of Egyptian oil to Israel are expected to dominate the Sadat-Begin talks.

Sadat make it clear before leaving Egypt that the status of East Jerusalem would be raised during the summit, saying in Alexandria over the weekend, "I will insist this time with Begin on a solution for the Jerusalem problem."

But Begin has been equally adament that East Jerusalem, which was annexed by Isreal after the 1967 war, must remain part of Israel.

Sadat is expected to push for an acceleration of talks on election of members of a Palestinian self-governing council, and to urge Israel to encourage West Bank and Gaza Strip Palestinians to join the peace negotiations.