Riding the ripples of the Golden Horn, the Mavi Marmara tugs at its moorings in the shipyard where it is being readied to head back into troubled waters.

A flotilla of 15 ships carrying humanitarian aid and activists from 100 countries will sail for Gaza next month, in a second attempt to break the Israeli blockade of the Palestinian territory, organizers announced this week.

Almost a year ago, Israeli naval commandos stormed a previous flotilla sailing to Gaza, killing nine pro-Palestinian activists on the Mavi Marmara, one of six ships in the fleet. The plan to send a new flotilla to Gaza raises the specter of a fresh confrontation between Turkey and Israel.

“Freedom Flotilla II will leave during the third week of June, with ships departing from various European ports,” a coalition of 22 nongovernmental organizations said after a meeting in Paris on Monday.

The Mavi Marmara, which was released by Israel in July, was towed back to Turkey and arrived in Istanbul to a hero’s welcome in December, after which it was taken in for repairs.

Now tied up under the Istanbul skyline for some last preparations, the ship should be seaworthy again by the end of the month, its owners said.

“The Mavi Marmara has become a symbol for the Gaza cause in the whole world,” Gulden Sonmez of the Humanitarian Relief Foundation, the Turkish nongovernmental organization that owns the ship, said in an interview this week. “So we are planning to set forth again with the same ship.”

At dawn on May 31 last year, Ms. Sonmez stood on the observation deck of the Mavi Marmara, shouting orders as Israeli helicopters hovered overhead and commandos boarded the ship. Her colleague Cevdet Kiliclar, who managed the relief foundation’s Web site, was shot and killed while taking photographs “just three or four steps away from me,” she recounted.

Now Ms. Sonmez, who is on the board of the foundation, plans to embark on the Mavi Marmara once again and will be one of 150 activists making the trip.

Within 48 hours of application forms being posted on the foundation’s Web site last week, some 2,000 people had volunteered to partake in the journey, she said.

Although Israel has warned that it will continue to enforce its Gaza blockade, the Humanitarian Relief Foundation does not expect another raid on its ship, Ms. Sonmez said.

“I don’t think Israel will make the same mistake again,” she said. “I think Israel knows that it has isolated itself.”

Not everyone agrees with her.

“If the ship sails, it will be a disaster,” said Osman Bahadir Dincer, a specialist in Middle Eastern affairs at the International Strategic Research Organization in Ankara. “In this atmosphere in the Middle East, we do not need a provocation,” Mr. Dincer said by telephone this week. “This would absolutely be a provocation.”

Relations between Turkey and Israel have not yet recovered from the crisis over the last flotilla. “We are waiting for our basic demands to be met, an apology and compensation,” a senior Turkish official, who asked not to be identified, said this week.

“Since Turkey and Israel are not at war, the Israeli Defense Forces killed innocent civilian citizens of a friendly country.”

A report by the U.N. Human Rights Council found that Israeli interception of the ship on the high seas was “clearly unlawful” and that its treatment of passengers “constituted a grave violation of human rights law and international humanitarian law.”

But the report, published in September, also noted “a certain tension between the political objectives of the flotilla and its humanitarian objectives,” finding that the primary motive of the nongovernmental organizations was political.

“We hope to be able to put this behind us and we have the will to do so,” the senior Turkish official said. “But Israel should move forward as well.”

“Turkey would like to preserve its relations with Israel and once our expectations are met, we will start normalizing our relations,” he said.

For the moment, however, there is little prospect of this, said Mr. Dincer, the Middle East expert. Elections on June 12 prevent Turkey from taking a step forward, while Israel has been hampered by its volatile government coalition, Mr. Dincer added. “Both sides cannot go forward,” he said.

The flotilla crisis last year followed a series of conflicts that had soured relations between the two countries.

Turkey and Israel had long prided themselves for being the only Western-style democracies in the Middle East. But ties began to unravel after the Israeli intervention in Gaza, when the Turkish prime minister, Recep Tayyip Erdogan, stormed off the stage at the World Economic Forum in Davos in January 2009 after an angry exchange with the Israeli president, Shimon Peres. A year later, another quarrel erupted when an Israeli official humiliated the Turkish ambassador by seating him on a lower chair and dressing him down in front of TV cameras.

These incidents are the symptoms, not the cause, of fundamental changes in the relationship between the two countries and within Turkey itself, Mr. Dincer said. “Turkey is no longer the country it was in the 1990s or the 2000s,” when relations with Israel were based on “elite relations” between the military and political leaderships, Mr. Dincer said.

“Turkey is more democratic now, and society plays a much more important role in Turkish politics,” he said, arguing that it was no longer possible to maintain bilateral relations from the top down. “Instead, we must build relations between the two societies, involving civil society and the media and nongovernmental organizations.”

Meanwhile, the Mavi Marmara must not sail, Mr. Dincer warned.

“They have to be stopped, somehow, by someone,” he said about the Humanitarian Relief Foundation, asking that the group consider Turkish national interests. Another attack at sea would fuel attempts to “isolate Turkey from the West,” Mr. Dincer argued.

The Turkish government, while at pains to distance itself from the flotilla, has made it clear that it will not intervene to bar the convoy from sailing.

Israeli allegations that Turkey is behind the flotilla do not reflect the truth, the senior Turkish official said. But in a free society, he added, nongovernmental organizations can do as they like, within legal limits.

“We believe that such initiatives as this convoy will cease only when Israel’s unlawful blockade on the Gaza Strip is lifted, as the situation in Gaza disturbs the conscience of all humanity,” the official said. “It doesn’t seem possible for Israel to reach lasting security as long as the unlawful blockade remains in place.”

Turkey has warned Israel not to attack the ship again, the official said. “Last year, we had notified Israel a multitude of times that it should avoid by all means resorting to force, and act responsibly,” he said. “We are reiterating these warnings once again today.”