What does Scylla do to ships?

Scylla is the name of a small channel opposite the great whirlpool Charbydis. It's purpose is trap and destroy sailors attempting to avoid the whirlpool.

Reported by several sources (exp. Stesichorus) Scylla is a great sea monster with four eyes, six completely separate heads and necks, each mouth with three rows of shark teeth. She has twelve octopus legs, a cat's tail , and a waist circled by dog's heads.

She gets near a ship as they attempt to avoid Charbydis and as they pass each of her six heads grabs a sailor and eats them. According to the Circe in The Odyssey one can ask Syclla's mother to control her to the point where she'll only pounce once, but that's all you can do.