In May, several ships intent on breaking the Israeli blockade of Gaza departed from Cyprus and Turkey; the Rachel Corrie, named for an American killed by an Israeli bulldozer in 2003, departed from Ireland. Now another vessel, carrying Jewish human rights activists, will keep the pressure on Israeli authorities to end or further mitigate restrictions on the movement of food, medical supplies and building materials into Gaza. It will set sail sometime in July from an undisclosed Mediterranean harbor. “Our purpose is to call an end to the siege of Gaza, to this illegal collective punishment of the whole civilian population,” said the expedition’s organizer, Kate Leiterer. “Our boat is small,” she said, “so our donations can only be symbolic”: schoolbags, musical instruments, art materials and medical supplies.