Jim watches the dark, heaving ocean for two hours. He’s glad when his coffee time comes. That’s ten minutes of rest he gets after standing watch for two hours. When another lookout comes to the crow’s nest to take his place, he warms up in the mess and then goes to the wheelhouse. There he works for two hours steering the ship. He stands his watch at the wheel.
The wheelhouse is dark, so that the mate can see through the big windows anything that the lookout reports. The only light comes from instruments, such as the compass. Jim watches the compass to make sure he is steering in the right direction. The mate tells him what direction the captain has ordered the ship to go. But the compass can’t be their only guide.
When you guide yourself by a compass on a hike across a wide meadow, you can keep going in a straight line because nothing pushes you to one side or the other. But at sea the wind is always pushing against a ship, making it slip sideways. Currents in the water push, too. The current may be going one way and the wind in another. There are no trees or mountains on the ocean to help seamen know exactly where they are. So they can use the sun and stars as their guides.
Of course, the sun, stars and moon keep moving. But they travel in an orderly way. If a seaman knows the rules about their motion, he can look at them through special instruments and figure out where he is. He can navigate.
More than two hundred and fifty years ago, an American boy named Nathaniel Bowditch went to sea and discovered that sailors didn’t have any good, accurate rules for steering by the stars. He decided to do something about the problem. Before long he had worked out a set of rules that were so good that every man in his crew could navigate—even the cook!
The mate on Jim’s ship has instruments with which he looks at the sun and stars. And he still uses the book that Nathaniel Bowditch wrote so long ago.
Besides the wheel and the compass, there are other instruments in the wheelhouse. One is the engine room telegraph. The mate uses this when he wants the ship to go faster or slower, forward or backward. He moves the handle of the telegraph, and a bell jangles in the engine room. Another telegraph there, exactly like the one in the wheelhouse, shows the engineer at what speed the ship should go. To let the mate know he has received the order, the engineer sends the same signal back on the telegraph, and a bell in the wheelhouse jangles, too.