The big difference between a sailing robot and practically every other kind of moving robot is this: the sailing robot can’t just move in whatever direction it likes. Why exactly? Because of the very thing that powers it: the wind.
The wind is our only source of energy. It gives us hope, it gives us life. But we are also at its mercy. When it blows where we don’t want it to, we must adapt.
[caption id=”attachment_448” align=”alignnone” width=”1500”] (Source: http://www.cruisingoutpost.com/2014/01/points-of-sail/)[/caption]
The picture above very politely describes the lingo used for the different angles a boat can be relative to the wind, among other things. Let’s elaborate a little more.
There are altogether six reference points of sail, or terms, for the direction our boat is facing relative to the wind; close hauled, close reach, beam reach, broad reach, and run. The terms are listed in sequence from where the boat is directly facing towards the wind, or upwind, to directly facing away from the wind, or downwind.
The simplest mode, no surprise, is when the wind’s blowing exactly right behind us, or when we’re sailing downwind. In non-plebeian-speak, this is known as a run. In a run, the sails are filled to the brim with wind, they work like big bags.
A better speed can be achieved closer to the wind: Then the sails get a shape similar to a wing, making you speed on quicker than you can say “WE’RE GONNA CRAS-”
But the real routing challenge is that we can not go upwind! So if we want to go directly in the direction from which the wind is blowing, we have to move in zig-zag lines, a procedure called ‘tacking’. And since our race will be going around a triangle, we will spend at least one side of the triangle doing exactly that!