Tides refer to the subsequent rise and fall of the sea level which is caused due to the gravitational force of attraction between the earth and the moon.
The high tide refers to the rising up of sea level, and it very much helpful for navigation purposes. A ship can easily sail into the nearest harbor when there occurs a high tide, thereby helping the sailor to reach the nearest land touching place. This is commonly used by the ship sailors.
Thus, Mohammed should have the knowledge of tides, and how both high and low tides are useful for navigation.
