1.1.Area with special order of navigation is closed periodically. The time of the area closure is broadcast as PRIP not less than 3 days in advance and repeated each next scheduled time until the area is opened to navigation. When the area is announced closed to navigation all vessels and craft are strictly prohibited to enter it and vessels in the area should leave it by the time indicated in PRIP.

2.Mean sea level for the period 1940-1955 is 28.0 m below the Kronshtadt gauge zero point. Updated depth corrections are daily broadcasted in hydrometeorological information (METEO). In order to determine the actual depths for the day of navigation, charted depths should be updated using the indicated correction with a corresponding sign.