A Royal Navy engineer, Metcalf, suggested an alternative system in 1903, where two cables were used, and the cable tension was maintained with the use of a steam ram. Trials were held in 1903, which demonstrated an optimal operating speed of 10 knots with a transfer rate of 54 tph. Although it was a superior system and met with a formal endorsement from the Admiralty there is little evidence that such equipment was employed by any navy. In May 1905, the U.S. Navy tested an improved Miller-Lidgerwood rig using the "Marcellus" and the battleship near Cape Henry. These coaling tests achieved 35 tph while steaming at seven knots, which fell short of expectations.