The Act appointed six trustees, rather than creating a company of proprietors; they were empowered to borrow £14,300 and raise a further £6000 by mortgaging the property, if required. The waterway, including the towpath, was to be no more than 18 yards wide, or 20 yards at winding places or where the banks were more than three feet high.
Work started to convert the river into a canal in 1790 with the construction of 16 locks starting at the Ipswich end. The navigation to Stowmarket was expected to be completed within a year, but they soon ran into legal problems with trespassing resulting in dismissals of key personnel, extra costs and the stoppage of construction work. Only three locks were built, these at the Stowmarket end.
John Rennie was called in to sort out the problems. He was new to canal building. His involvement began in 1791 and the canal was opened a little over 18 months after his initial surveys. Rennie wrote a four page detailed report and followed it up with 10 pages of detailed estimates dated April 16th 1792 (which the Trust have a copy of).
Rennie reported that there had been a failure to adequately survey the river and detail the works that would be required to construct the navigation. He estimated the total additional costs to be £12,350 of which £6,600 would be needed for the remaining 12 locks, which he thought could be built for £550 each, and recommended that another Act of Parliament should be obtained, to raise more money. The Act was obtained on 28 March 1793, which authorised the Trustees to borrow an extra £15,000, as the original capital had all been spent. The final cost of construction was £26,263, which was nearly double the original estimate.
The original 1792 John Rennie plan which was on a scroll around 10ft long by 3ft deep (the Trust have a copy) names all the adjoining land owners along the river and details new cuts to be made to shorten and straighten the navigation. The navigation was opened throughout on 14th September 1793. It was just under 17 miles (27 km) long from Ipswich to Stowmarket, rising 90 feet (27 m) through 15 locks of broad construction each 55 by 14 feet (16.8 by 4.3 m). It was suitable for barges with a draught of 3 feet 4 inches (1.02 m).
The Ipswich to Stowmarket navigation in Suffolk (owned by the Stowmarket Navigation Company) was almost certainly the first project to be constructed under John Rennie’s design and direction on his own account as a consulting engineer. The experience helped to develop his expertise and early reputation in bridge and canal engineering.
John Rennie went on to become one of Britain’s greatest engineers and after the Gipping he designed many canals and bridges including the Kennet and Avon canal, both Waterloo and London bridges (the one relocated to USA), London’s East India and West India docks, Chatham dockyard and Bell Rock Lighthouse. He was buried at London’s St Paul’s Cathedral.
Some of the remaining locks and bridges along the River Gipping which were built as part of this are most probably the oldest John Rennie designs still in existence.
