The Canal
The Macclesfield Canal is a canal in east Cheshire, England, one of the six that make up the Cheshire Ring.
It was the last narrow canal to be built in the U.K. and the maximum dimensions for a boat to be able to travel on the waterway are 72 feet long and 7 feet wide. The maximum headroom is 7 feet and 2 inches. The maximum draught is 3 feet and 6 inches.
The canal was built to serve the mills, mines and quarries of the Marple, Poynton, Bollington, Macclesfield and Congleton areas as well as to provide a link from Manchester to the Potteries and Midlands in competition with the Trent & Mersey, Bridgewater route.
It was completed in 1831 and reduced the distance between Manchester and the Midlands by around 25 miles.
Because the canal was one of the last built it very soon came into competition with the railways and in 1846, only 15 years later had been bought by a railway company.
It did manage to survive in commercial use but after the Second World War went into decline until the 1960s.
The canal remained popular with leisure boaters, especially as it formed part of the Cheshire Ring of Canals. It never closed and still remains popular today.
The Locks
The canal is maintained at two levels divided by 12 substantial stone locks in 1¼ miles at Bosley as well as the (originally double) stop lock at Hall Green. The top level is, at 518 feet above sea level, one of the highest navigable levels in the country. The locks drop the level by 118 feet. Bosley locks are characterised by the unique use on a narrow canal of double gates top and bottom. The stop lock has the further oddity of having double gates at the top and a single gate at the bottom rather than the other way round.
The locks also had a side pound next to the lock used to hold water released when the lock was emptied. This arrangement could save 60% of water compared to a normal lock. However they are more difficult to maintain and only achieve this amount of water saving when boats use the locks in alternate directions. When the number of boats on the canal reduced and it was no longer imperative to save water the use of these pounds was abandoned. This
Wikipedia Page has a working diagram showing how the side pound used to work.
Lock gates on the canal have an expected life of between 25 and 30 years and there is a rolling replacement programme in the winter months. These lock gates were refurbished in 2003.
On many locks there are warning signs about making sure the boat does not get caught on the cill. It's not always obvious what this means, but basically the wooden lock top gates do not go to the bottom of the lock but sit on a stone base. When the lock is full and a boat is going down, the cill is not visible. This means that when the water is released from the lock it is possible for the boat to get caught on the cill.
When the lock is empty it is much easier to understand how this works. When I took the pictures of this lock the top chamber was empty and the cill was visible.
This lock has a rack of stop planks next to the top gates. These can be inserted in grooves in the canal sides to cut the flow of water. They are used when there is a leak, or repairs need to be carried out and part of the canal needs to be drained.
Stop planks are stored at strategic positions along the canal, normally next to locks or bridges because they are always built at the narrowest parts of the canal.
This lock is the 10th highest lock of the Bosley flight. There is a metal footbridge over the tail of the lock to give boaters access to both sides of the lock. It is a Historic England Grade II
listed building
with the following description. "Canal lock, 1831, William Crosley engineer. Rusticated red gritstone walls to lock, ashlar to spillway. Semi-circular upper end to lock basin. Stepped quadrant retaining wall to bank west of lock; flight of stone steps to east. Cambered footbridge of cast iron across lock entrance with later plain tubular steel rail. Upper and lower replaced pairs of lock gates of mild steel. Curved wing walls to canal above and below lock. Stone-walled rectangular pound west of lock.".