A pneumatic seacock retrofit is provided for convenient closing of all or a portion of the seacocks, whether as a matter of every day convenience or for use in an emergency, in which all of the vessel's seacocks can be pneumatically closed at the same time, leaving the possibility of selectively overriding seacock closure, with all control valves operating to provide a momentary pulse of air to the rotary actuators and then return to a neutral position, leaving the actuators free for further control. Moreover, an operator is free to manually close a valve in the event that the pneumatic system fails.