Immediately on the passing of the act, construction began under the direction of Brindley. Upon his death in September 1772, John Varley moved from Clerk of Works to Resident Engineer with Hugh Henshall, Brindley's brother-in-law, appointed in a consultative capacity. He agreed to make inspections every three months. Henshall became Chief Engineer in 1773 and John Varley continued to work on the project. By August 1773, the section between Shireoaks and Worksop was nearly complete, and the company created a works to build boats at Shireoaks. The boats were used to carry spoil from the construction, and also to deliver coal. The canal was effectively open from Shireoaks to below Worksop by 6 April 1774, and to Retford by 3 August. The price of coal to the residents of Retford dropped from 15s 6d (77.5p) to 10s 6d (52.5p) overnight. Hayton was reached on 22 February 1775, and the Norwood Tunnel opened on 9 May 1775. The canal was to be built as a narrow canal, but in 1775, nine shareholders offered to fund the extra cost of making it a broad canal from Retford to Stockwith. Retford Corporation joined them, and each contributed £500, although the additional cost exceeded the £6,000 subscribed. The canal was opened throughout on 4 June 1777, with the lock into the River Trent at West Stockwith completed in the autumn, but the only record of wide-beamed boats using it at Retford is prior to 1799.