ZCZC IA71 141029 UTC APR SWEDISH NAV WARN 069/26 KATTEGAT. MARSTRAND. DUE TO MAINTENANCE WORK VHF CHANNEL 10 AND CHANNEL 16 WILL BE UNRELIABLE BETWEEN 0900 TO 1600 LOCAL TIME ON THE 15TH OF APRIL. APROX PSN 57-53.9N 011-31.0E NNNN