Until September, 1990, after the closure of the Wear's last shipyard's, the port's dredging fleet played a key role in maintaining adequate water depths for shipping.
But, as early as the late 18th century, innovative dredging techniques had been employed to open up the shallow harbour to larger vessels.
It is generally accepted that Britain's first dredger operated by steam power was a "bag and spoon" dredger
introduced on the Wear in 1796.
Authoritative sources differ in their descriptions of the engine type, with some describing it as a "bell-crank" engine, while others refer to a "beam engine" having a steam cylinder of 128 inches diameter and three-foot stroke.
The engine was built by Boulton & Watt of Soho, Birmingham, and supplied to John Grimshaw, a leading rope-maker on Wearside.
It was fixed into a boat measuring 60 feet long by 20 or 22 feet wide and used to operate the spoons, which lifted silt from the river bed.
Previously, these had been worked by manual labour.
Described as being in the form of a truncated cone, each spoon had a closed narrow end with a spade bit being fixed to the open end.
They were made from leather hide with an iron rim.
It is also claimed that the first bucket-ladder dredger driven by steam was designed for cleaning and deepening Sunderland Harbour.
This curious-looking machine entered service in October, 1811 and comprised a powerful steam engine, which drove a continuous belt of iron buckets fixed to chains.
After being filled with sand, gravel and mud from the river bed, the buckets were consecutively emptied into a spout from the top of a shaft.
Up to 55 tons of spoil could be dredged within a 35-minute period.
Readers might be interested to know more about the 60-foot diameter caisson intended for use as a foundation for the roundhead of the unfinished New South Pier (On the Waterfront, April 19).
Archive photographs show that the steel structure was built at Pallion by William Doxford and Sons in 1914.
Although work on the pier was abandoned on the outbreak of war, the River Wear Commissioners evidently still hoped to resume construction once hostilities had ceased.
In 1919, despite the caisson being reported as available for completion of the pier, construction work remained at a standstill.
The caisson continued to be maintained, however, with its exterior being cleaned and painted on SP Austin and Son's pontoon in 1926.
It was again docked on the pontoon during 1931.
Prior to World War Two, after lying disused in Hudson Dock for some years, the caisson was towed to the beach at the South Outlet and cut up for scrap.
