Dinghy is a small rowboat or an inflatable rubber life raft: “The tugboat pulled a small dinghy behind it for emergencies.”
Dingy means darkened with smoke and grime; dirty or discolored: “The tenement housing which the author described was dingy with age.”
It also means Shabby, drab, or squalid: “They lived in a dingy room to save money.”
Since the boat was old and poorly maintained, it was obvious that thedinghy was dingy.
