How can owners ensure that charterers will not obstruct the commencement of laytime by preventing a vessel from reaching the loading berth?

Owners can insert a Waiting for Berth Clause in the charter party, or the words "whether in berth or not", "whether in port or not" or another protecting phrase in the Laytime Clause to make it clear that time can count as laytime once the vessel is at the customary waiting place. The following abbreviations are often used for these protecting phrases: w. i. p. o. n. ("whether in port or not"); w. i. b. o. n. ("whether in berth or not"); w. c. c. o. n. ("whether customs cleared or not"); w. i. f. p. o. n. ("whether in free pratique or not").