What type of weapons did the islanders have to fight the German submarines in The Cay?

In "The Cay" by Theodore Taylor, the islanders primarily used outdated rifles and hand grenades to combat German submarines during World War II. Their limited resources and lack of modern weaponry made their efforts challenging, as they relied on these basic arms to defend against the threat from the sea. The story highlights the desperation and bravery of the islanders as they faced a formidable enemy.