in 1895 the decision was taken to expand the keyham steam yard to accommodate the increasing size of modern warships. by 1907 keyham, now renamed the north yard, had more than doubled in size with the addition of no. 4 and no. 5 basins (of 10 and 35 acres respectively), linked by a very large lock-cum-dock, 730 ft in length, alongside three more dry-docks of a similar size, able to "accommodate ships larger than any war-vessel yet constructed". in the 1970s the northern end of no. 5 basin was converted to serve as a new fleet maintenance base, to be built alongside a submarine refit complex for nuclear submarines; an 80-ton cantilever crane, one of the largest in western europe, was installed to lift nuclear cores from submarines in newly-built adjacent dry docks.