The ends of the docking foot apparently had some form of suction and/or magnetism, or other unknown mechanism, which powered a form of tractor beam. The docking feet could be used to clamp onto passing asteroids for mining, or clasp wayward shuttles. Such captured asteroids and shuttles could be accessed from Red Dwarf through a passageway in the center of the docking foot, connecting the main ship to the captured object.
Three million years into the future, the boys from the Dwarf used Docking Foot F, located on the rear lower hull of Red Dwarf, to clamp onto and enter an alien-looking ship that was adrift nearby. ("D.N.A.", Series IV)
After the unpleasant events of that episode, the D.N.A. ship was presumably left adrift, as it was not seen again.
- Although not seen outside the episode "D.N.A.", it is possible that the docking feet were used to tether or bring in other things to Red Dwarf, such as the mail pods (in "Better Than Life", "The Last Day", "Dear Dave"), and various escape pods. ("Justice", "Only the Good...", "Samsara")
- Red Dwarf could also use the front ramscoop to bring space objects of interest aboard, by sucking them into the front of the ship when in scoop range, such as the garbage pod (in "Waiting for God")
- Red Dwarf also had a strong tow-line, with which it used to tow the SS Trojan, instead of using the Docking Foot. This was because Arnold Rimmer didn't want his newly-found brother to see the creaky, rusty old mining ship on which he served. ("Trojan", Series X)
- The Simulant Battle Cruiser had a docking foot, with which the crew of Starbug used to enter the wreck of the battleship. ("Rimmerworld", Series VI) SS Centauri had a docking foot, which the crew in Starbug also used to enter it. (Deleted scenes of "Beyond a Joke", Series VII)