A voyage by sailing ship from Surabaya to Jakarta in the western monsoon is also difficult, especially when the wind blows violently.12 It would be safer to take advantage of every slight veering of the westward wind. Vessels should avoid the disadvantage of high seas and easterly currents. Upon the approach of a gale, it is necessary to take shelter in a harbor, since such bad weather does not last long. Most of the shipping routes along the north coast of Java are unsafe in this monsoon