The engine-room floor. I look for a drop of oil or water that was not there yesterday. Then I check the ropes and start the engine long enough to hear whether it sounds normal. It takes about twenty minutes when nothing is wrong.

A loose belt makes a quick slap. A tired bearing has a low rough sound that follows the speed. But the main habit is simpler: listen before touching anything. The sound usually tells you where to begin.

How different the same water can be. Some mornings the harbor is flat and the ferry leaves without a sound. On others, every rope pulls hard before we have even started. I still look at the water before I look at the clock.