System and methods for determining relative position and relative motion of objects

A ship system, comprising:

• one or more optical targets for disposal on an object;
• a target tracking device for disposal on a vessel, the target tracking device being configured to track the one or more optical targets, and the target tracking device comprising a camera configured to take one or more images of the one or more optical targets;
• and
• a controller that is configured to receive data from the target tracking device, calculate a relative motion between the target tracking device and the one or more optical targets using the data received from the target tracking device, and control the vessel using the relative motion.

An offshore crane system, comprising:

• one or more optical targets for disposal on a first vessel;
• a target tracking device for disposal on a crane disposed on a second vessel, the target tracking device being configured to track the one or more optical targets, and the target tracking device comprising a camera configured to take one or more images of the one or more optical targets;
• and
• a controller that is configured to receive data from the target tracking device, and control the crane using the data received from the target tracking device.