the river was affected by silting which restricted trade despite the construction of various sluices and barriers from 1142 onwards, when the first sluice was built below boston. other sluices were erected at boston in 1500 and at langrick in 1543, but navigation was again difficult on both the river and the fossdyke by 1660. in 1671 an act of parliament was obtained for the improvement of the navigation. in 1743, john grundy, sr. and his son john grundy, jr. were commissioned to produce a detailed survey of the river. they produced an engraved map in 1743 and a printed report, running to 48 pages, in the following year. the main recommendation was a new cut to eliminate the "prodigious meandering course" of the channel above boston. although the estimated cost of £16,200 dissuaded the landowners from taking action at the time, the report formed the basis for improvements in the 1760s.