Emily's Easy Job is a season 4 episode.
Plot
Theodore thinks that Emily makes moving ships look so easy that when he is assigned to help her he feels useless. In fact, Theodore thinks that he'll never be as good as Emily, so why bother trying. But when Emily runs into rough water while towing Inverness the cargo ship, Theodore helps prevent the ship from crashing into Owan, the Oil Rig. The young tug realizes that even if he can't do everything Emily can, the things he can do are important.