If you only sail on a lake, you can skip the tide section, but if you plan to sail on the coast, estuaries and rivers, you need to know how tides work and how they will affect you. Tides come in (flood) and go out (ebb) twice in every 24 hours.
Tides are caused by the gravitational pull of the sun and moon. There are two spring tides and two neap tides every month, which is the time it takes the moon to go round the earth.
潮汐是由太阳和⽉亮的引⼒引起的。每个⽉有两次⼤潮和两次⼩潮,也是⽉球绕地球⼀周的 时间。
When the sun and moon are in line, you get the highest high tides and the lowest low tides.