Two boats have courses that intersect. Assuming they do not collide first, after one hour they would be at the ends of the colored line segments (the locators) and would then continue with the same speed and direction.
To avoid a collision, take a bearing on the other boat, for instance by lining it up with a piece of equipment on the side of your boat. If the angle does not change over time, you will collide! So change course or speed.
To experiment, you can drag the locators to get new courses.