A system for transferring fluid between two marine tankers, including a first articulated loading arm mounted on the first tanker and a second loading arm or other suitable receiver mounted on the second tanker. The first loading arm is guided into operating contact with the second arm or receiver by laser tracking and ranging equipment, and by a computer which computes the location of the end of the first loading arm relative to the second arm or receiver. After the first loading arm and the receiver are connected together, the computer calculates the position of the outboard end of the first loading arm, compares this position to a set of safe operating boundaries, and provides a warning signal whenever the end of the arm moves outside any of these safe boundaries. When the end of the first arm moves outside a critical boundary the computer provides a disconnect signal which shuts down the loading operation and disconnects the first loading arm from the second arm or receiver.