What is "seaboat"

Seaboat \Sea"boat`\ [AS. s[=ae]b[=a]t.]

1. A boat or vessel adapted to the open sea; hence, a vessel considered with reference to her power of resisting a storm, or maintaining herself in a heavy sea; as, a good sea boat.

2. (Zo["o]l.) A chiton.

n. A boat designed for use at sea.