Sailing Downwind
When the wind is in your back, and you maneuvre from reach to broad reach, you should constantly loosen gradually your sails, so that you still use them effectively. When the wind blows on each side of the sail, it generates both pushing and pulling power. Everything beyond a broad reach with the wind from more than 150 degrees off your bow, there is a change. At certain point the sails lose their aerodynamic lift and start to behave only as wind catchers to push the boat along. This is called downward sailing. The boat is much freer than in any other course. It is also unstable, and there is a danger of involuntary jibes. So you have to be on the alert; all the crew needs to be instructed in advance how to react if such things happen. Contrary to the common belief, and the saying "I wish you tail wind!", the downwind course is the slowest of all. As it was explained earlier, you are driven not by the true, but by the apparent wind. Even on a windy day, if you turn downwind, you will notice that the wind seems to drop, and you - to decrease speed. This comes directly from the ratio between the true and the apparent wind - the faster you go, the less and less wind there is to push you. (and eventually you reach dead run).
To get the most you can from your sails, keep them square (at 90o degrees) to the apparent wind. This is simple as long as you sail below a broad reach. But if you head further, then it becomes tricky. The jib grows blanketed - the main sail cuts its wind. If this happens, you'd better pull the jib and draw it to the other side. Now you are sailing wing-and-wing (some people call it 'butterfly'). This situation is hard for the helmsperson because he should be concentrated to keep the both sails full, and this is delicate business. Make sure to secure the shrouds - the boom should be in control at any times, because if it hits them hard, it may break them and you don't want this - shrouds are very important to the mast. Again, like in the tacking, everyone should be careful about their heads - and even more so, because the boom may suddenly involuntarily and very forcefully go to the other direction.
A good tip is to watch your masthead telltale - if the wind goes across the stern, or the end of the boom starts to lift, then the jibe is inevitable. If you want to prevent it - turn quickly on (windward direction), or simply make it a controlled jib.
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