Marine VHF from late 1940s, ch16 156.8 agreed in Atlantic City 1949. 156.0... Marine, to 158.525= single OR dual: see 160.625 158.5375.PBR, to 160.5375 single OR dual: see 163.0375 ... alarms 160.6... Marine, to 163.025= single OR dual (split -4.6: 156.025-158.4) Marine, to 163 ...