Flying boat Do-18 was projected as the marine reconnaissance aircraft of the mean range, and simultaneously as a civil mail seaplane for the company "Lufthansa ".
   First four prototypes of the machine were took aloft in March, 1935, but civil boats has been constructed only 6, the others 148 machines with production deliveries to "Luftwaffe" since 1938 .
   The basic military modifications - Do-18D with diesel engines "Jumo-205D" (600 hp), (75 machines in three versions), improved version Do-18G and six-seater educational boat Do-18H (71 machine of both types).
   Subsequently most part Do-18G has been reconstructed under project Do-18N in a saving airplane.