What is the name of the ship made from dead men's nails?

The ship made from dead men's nails is Naglfar.

In Norse mythology, Naglfar is a vast vessel constructed from the fingernails and toenails of the dead. Its name is usually translated as “nail-farer” or “nail-ship.” The Prose Edda warns that leaving a dead person’s nails untrimmed would help provide material for the ship, so the vessel would take longer to complete if nails were properly cut and buried.

Naglfar appears in accounts of Ragnarök, the prophesied destruction and renewal of the world. When cosmic bonds break and the seas rise, the ship is released from its moorings and travels toward the battlefield Vígríðr. The jötunn Hrym is named as its captain in the Prose Edda, while the Poetic Edda associates it with hostile forces arriving for the final conflict.

A common mix-up is Skíðblaðnir, another famous Norse ship. Skíðblaðnir belongs to Freyr and can carry all the gods while folding up small enough to fit in a pouch. Naglfar, by contrast, is the ominous “nail-ship” of Ragnarök.