The sail is an item from Freddi Fish 3: The Case of the Stolen Conch Shell.
The sail is first seen when Magenta tries to stop her boat from sinking by plugging it into the hole. When Freddi Fish and Luther are helping the plug the hole, Luther rips her sail by accident. They take the sail to Pierre the Tailor's shop where he sews it back together. After the sail is fixed, they give it back to Magenta and she is able to sail back to the island.