From a scientific pespective, sailing is one of the most peculiar modes of transportation ever invented. Powered entirely by the wind, a sailing ship is able to move in a direction contrary to the one in which that very wind is headed. It derives from a balance of forces, some of which you can’t even see.
Consider the case where a captain wishes to take his ship to a harbor in the west, but the wind is blowing towards the east. If he were facing directly into the wind, it would blow him backwards, away from his goal. By facing to the southwest, however, he places his sail at a diagonal to the wind. The wind pressing on this sail tries to push it east, but is opposed by the keel underneath, pressing on the water through which it flows. The only way that ship can move is in the direction it is facing, and so it does.
After a while, however, you find that the ship is headed south of the target, and your southwest progress isn’t getting you any closer to the goal. At this point (or sooner, if you run out of open water), the captain turns to the northwest. Each stretch of diagonal sailing is called a “tack”. No single tack can carry the ship to its intended goal, but taken in sum, she will eventually reach port.
The same principle is true in a well-drafted scene. As an author, we want to bring our protagonist from point A to point B. The antagonist opposes this goal, and introduces conflict. Through the twists and turns of your plot, you tack, carrying the reader ever closer to the end of the tale. And the ever-changing view is what makes your story interesting.
This may, in fact, be the one time when it’s a good idea for your story to be tacky.
Photograph of Sloop Reliance from the United States Library of Congress’s Prints and Photographs division under the digital ID det.4a15401 via Wikimedia Commons.
This is a bit of an oversimplification. Depending on the wind, nearby coastal obstructions, and the need for speed, the captain may choose anywhere from a close hauled point of sail (as close as you can go to facing into the wind without stalling out) and a beam reach (which gains you no progress upwind, but may give you lateral room for another tack), but in general one will select a close reach, which is somewhere in between. As a metaphor, however, I find it sufficient.