Maudslay's Lambeth works began to specialize in the production of marine steam engines. The type of engine he used for ships was a side-lever design, in which a beam was mounted alongside the cylinder. This saved on height in the cramped engine rooms of steamers. His first marine engine was built in 1815, of 17 h.p., and fitted to a Thames steamer named the "Richmond". In 1823 a Maudslay engine powered the "Lightning", the first steam-powered vessel to be commissioned by the Royal Navy. In 1829 a side-lever engine of 400 h.p. completed for HMS "Dee" was the largest marine engine existing at that time.