The medieval port always needed attention to keep it in good repair and up-to-date in order to keep up with the growth in trade and to improve the rate at which cargo could be loaded and unloaded.

In the 1400s and 1500s an extraordinary programme of works on marshes, rivers, bridges, quays and slips was undertaken.

Bridges were re-pointed and arches re-pinned as well as repairs undertaken to the stonework on the New Quay, the slipways at St James's Back, Welsh Back, the Shambles and the Counterslip. Stone was recycled from empty monastic buildings and even gravestones were reused as paving slabs. Trenches were dug to clear mud that silted the waterways and the line of the riverbanks as well as the edge of the Marsh was altered. Piles were driven into the riverbed to reduce its force. All of these works were carried out by hand and much of it required men to stand in water for long periods in all weather conditions.

The cranes on the Back were rebuilt in 1577 by a local carpenter, John Batey. He based his designs on those he'd seen at London's Queenhithe docks. The cranes were sited at the end of the Quay wall and were used for unloading heavy goods and meant that heavier loads could be moved on and off the ships than could be managed by men alone.