Gunboats are types of boats armed with a turret. A model of one is present in Crash Bandicoot: The Wrath of Cortex, but is never used in the game itself. It might have been present in a level that was deleted from the game, or was to be present in one of the levels that is still in the game but got cut. These might have been piloted by Lab Assistants, or one of Cortex's minions/allies (namely Tiny Tiger, N. Gin, etc.).