A system and a method are disclosed for enabling assignment of a responder unit to a user on a water vessel. The rescue system transmits a Short Message Service (SMS) message to a user device on the water vessel, the SMS message comprising a selectable option that, when selected, causes a location of the user device to be shared. Based on a selection by a user of the user device of the selectable option, the system receives a plurality of location coordinates from the user device at a plurality of respective times, each respective location coordinate describing a respective location of the user device at its respective time. The system selects a responder unit to assign to the user based on the plurality of location coordinates and a location of each of a plurality of candidate responder units. The system transmits location information to a responder device of the selected responder unit, the location information based on the plurality of location coordinates.