What kinds of crimes were committed on the River Thames that it required its own police force?

This picture is the entrance to the London docks. A great many people who worked on the river saw it as a right to help themselves to anything they could. Remembering how hard life was for the poorer members of society in this era, one can understand why. Coalheavers, for example, made it a practice to take two or three bushels of coal with them every time they left the collier they were unloading. It was this kind of stealing the magistrates office was set up to defeat.

The Police Establishment had a number of rowing galleys, each manned by a Surveyor (equivalent rank to today's Inspector) and three waterman Constables under the direction of a Superintending Surveyor. He had his own supervision galley with a crew of four. All Surveyors were empowered both by the crown (an oath taken before the magistrates) and also sworn and issued with an excise warrant by Customs and Excise Service.

Additionally during those two years, many ship and quay guards were also employed on a part time basis. They were visited and supervised by the boat patrols, these constables were employed only when the West India fleets were in the river and being discharged when there was no need for them. They were in time to become the first River Police Special Constables.

The same vigilance which had suppressed thieving had also put a considerable stop to smuggling which 'was an organised system and carried to extraordinary heights by the aid and connivance of many of the revenue officers.' Even 'the almost incredible plunder of Naval stores from the King’s Yards at Deptford and Woolwich had been suppressed to some degree' by the attention on land and water of the Thames Police, whose boats sometimes went as far as Sheerness and Chatham.

They also had to deal with foreign sailors who often became desperately short of funds and were known to plunder and engage in knife fights.

The Thames Police Institution was given another seven yeas of life by Act of Parliament in 1814, and in 1821 an Act for the More Effectual Administration of the Office of Justice of the Peace in the Metropolis and for the More Effectual Prevention of Depredations on the River Thames brought the River Court (but not Bow Street) under the same umbrella as the other seven public offices.

In 1839 Metropolitan Police Courts Act brought all the metropolitan police offices, including Bow Street, into one organisation, changed their description from 'Office' to 'Court', authorised the establishment by Order in Council of other courts, and limited the number of magistrates to 27.

As the result of this and of the Metropolitan Police Act, 1839, the Thames Magistrates ceased to be responsible for the control of the Marine Police, which became the Thames Division of the Metropolitan Police.