Ol' Ironsides is a former ship that only appears in the episode "Karate Star."
Ol' Ironsides is posted on one of the sides of the boat. It is displayed in a bluish color from an angle, yet when the camera shows a close-up of SpongeBob, it appears to be along the lines of a purple color. A steamer appears at the top of the boat.
There are two visible windows on the front and right side of the steering room. The screws used to construct the boat are clearly visible.
Once Patrick chops the boat in half, the inside can be clearly seen. Wooden walls and flooring can be depicted after this process, yet no furnishing or decorations appear in the boat. The floor of the steering room is not visible due to it being on a higher level. The inside does show signs of aging, showing it is an older steamer boat than others that have appeared.
Role in episode
This ship is inspected by SpongeBob to be "solid as a rock." Patrick tries to chop it, but seemingly fails. However, the boat begins to wobble and, finally, snaps into two large pieces.
Old Ironsides was actually the nickname of an American frigate used to fight in the War of 1812. It gets its name from accounts of British sailors that cannonballs seem to bounce off of the ship and it is made of iron.