Meaning of "break down"

I was wondering: what is the meaning of the "starboard" and "I can never get those right" in the following comic:
http://images.ucomics.com/comics/ga/2009/ga090723.gif
Thanks in advance

Sailors say "port" and "starboard" instead of "left" and "right". So Garfield is just saying that he has trouble remembering which is which.