A common payload rail externally supports a submerged payload from an unmanned marine vehicle. A vehicle interface module has a conforming surface rigidly secured to the unmanned vehicle and feed-through conduits. A functionality module is secured to the vehicle interface module and contains internal interfacing components to minimize or eliminate any modifications to the payload and vehicle. A payload interface module having feed-through conduits is secured to the functionality module and has longitudinally extending rail structures sized to engage correspondingly shaped longitudinally extending receiving means on the payload. The longitudinally extending rail structures are shaped to extend into longitudinally extending receiving means on the payload to arrest lateral displacement between the payload interface module and the payload and at least one securing mechanism on the payload interface module is disposed to engage the payload to arrest longitudinal displacement between the payload interface module and the payload.