The gearing provided some additional technical problems. Smith geared the engines to the propeller via spur-wheels and pinions, the largest of which was toothed with hornbeam (a white timber traditionally used for gearing in windmills).[18] The gearing arrangement proved to be very noisy, and the ship's stern was subject to considerable vibration in operation. Smith planned to reduce the noise by the use of spiral gears,[19] but it is unclear whether this modification was ever carried out.