Crinan Canal, Lock No. 5, Cairnbaan

A proposal to build a canal which would enable sailing vessels to avoid the dangerous passage round the Mull of Kintyre was first projected in 1771 (en.1). On behalf of the Commissioners of Forfeited Estates, James Watt made surveys of two alternative routes, one across the Tarbert isthmus and the other between Lochs Gilp and Crinan. No further action was taken, but the scheme was later revived and promoted by the 5th Duke of Argyll and the 4th Earl of Breadalbane. At their invitation in 1792 John Rennie made a further survey of the Loch Crinan route and reported on two possible passages, one via Daill and the other diverging from it E of Cairnbaan to pass N of Dunadd and enter Loch Crinan near Duntrune Castle (en.2). In May 1793 the Crinan Canal Company was formed and was empowered to raise a maximum capital of £150,000. Construction-work commenced in September 1794, but it was not until January 1795 that Rennie, in his capacity as chief engineer of the new company, finally decided that the canal would follow the Daill route and would have a depth of 12 feet (3.66m); the locks were to be 96 feet (29.26m) long and 24 feet (7.32m)wide.

Inadequate finances seriously delayed completion of the canal, which was eventually opened in an unfinished state in1801. A section between Oak field and Cairnbaan was destroyed by floods in January 1805, and a new line was cut along the edge of Oakfield Moss. The canal was re-opened to navigation in July 1806 and was declared to be 'finally complete' in August 1809. It was closed again for a year after January 1811 when canal-banks and lock-gates were flooded and badly damaged by the collapse of the principal reservoir in Glen Clachaig. In 1813 Thomas Telford reported that the canal was in 'a very imperfect condition', requiring repairs estimated at £18,251 (en.3). The work was carried out under his supervision in 1816-17, and the canal was again re-opened in November 1817.

The maintenance of the canal, which remains in regular use, has involved a continual need to repair the fifteen locks on its route, especially the sea-locks at each end; to deepen the eastern approaches at Ardrishaig harbour; and to provide an adequate and properly controlled water-supply. The hardness of the whinstone and the softness of the peat moss contributed to the difficulties of construction, especially along the S shores of Loch Crinan where blasting operations resulted in dangerous rocky projections on the landward side of the canal; eleven steamers were sunk on this rock-cut section between 1885 and 1921.

The early history of the canal was also beset with financial as well as technical difficulties. The funds of the original company, burdened with public debts, were exhausted by1812. Effectively from 1817 and formally from 1844 management was vested in the Commissioners of the Caledonian Canal, passing to the Ministry of Transport in1919.

The canal runs from Ardrishaig on Loch Gilp to Crinan Harbour, formerly known as Portree, and is about 14.5km in overall length. It climbs to a height of 19.2m above sea-level, and the summit-reach between Cairnbaan and Dunardry is about 0.93km in length. The canal has thirteen inland locks, including a larger lock, 34.l4m long by 8.23m wide, at the western end above Crinan Basin. This was cut out of solid rock and was intended to give large coastal vessels access to a dry dock, which was never built. The two original sea-locks were also of these larger dimensions; in 1930-2 new sea-locks with improved tidal access were built parallel to them, and the old locks were left to provide additional berthing-facilities. The walls of the lock-chambers throughout the canal are constructed of large blocks of ashlar masonry, in some parts patched or refaced in concrete; The SE face of the chamber of lock 3 at Ardrishaig exhibits large incised masons' marks.

The surface-width of most stretches of the canal varies between about 24.4m and 27.4m, reduced to between only12.2m and 15.2m in the rock-cutting at Crinan. The eastern and western reaches are embanked on their N sides, and a tow-path runs along the embankment. Traces of the direct line that the canal originally followed across Oakfield Moss prior to the breach of 1805 can still be seen between NR853894 and 850896, where the waterway now follows a longer course skirting the hillside to the S. At Bellanoch the S bank follows a natural indentation to form a large bay, and some of the inlets between the bridges at Bellanoch and Crinan Ferry are provided with small rubble-built mooring platforms. There are basins at each end of the canal, and the flight of five locks at Dunardry at the western end of the summit-reach incorporates intermediate circular pounds.

Most of the canal-bridges have been modernised, the oldest surviving structure at the date of survey being the swing-bridge at Oak field (NR 856879), which according to the maker's plate was built by P and W MacLellan at Clutha Iron Works, Glasgow, in 1871 (en.4). The foundations of the chamber of lock 11 at Dunardry (NR 820912) are evidently incapable of supporting the weight of a conventional swing bridge, and a hand-operated rolling cantilever-bridge was installed here in 1900 after temporary use over the sea-lock at Ardrishaig. The bridges are associated with single- or 2 -storeyed keepers' cottages. That at Oakfield (NR 857879) occupies a bankside position and stands above a storehouse, accessible only from the lower (E) side through a wide arched doorway.

Among other canal side buildings, special mention should be made of Canal House at Ardrishaig (NR 851854), the canal manager's house of early 19th-century origin, and the roofless shell of a three-bay boat-shed on the S side of lock 9 (NR 822910), probably designed to accommodate the passenger steamer 'Linnet', which was in service on the canal from 1866 to 1929. An inn at Crinan, and later ones at Cairnbaan and Ardrishaig, served travellers on the canal, and by about the middle of the 19th century the canal offices came to be housed in the plain two-storeyed building on the N side of the harbour square at Ardrishaig.

The round-ended pier flanking the canal entrance at Ardrishaig harbour shows much evidence of reconstruction and extension, and several phases of work are known to have been undertaken on this structure from 1813 onwards. Modern navigational lights are located at the end of this breakwater and in a small hexagonal lighthouse-tower at Crinan Basin. The principal feeder-burn discharges into the summit reach of the canal just to the w of lock 6, where it is traversed by the B841 highway on a single-arched bridge. Overflows onthe opposite bank serve each of the three reaches; the towpath spans a wide overflow near Crinan on a two-arched bridge, while a more rapid discharge of water from the eastern reach at Ardrishaig can be made, when needed, by an automatic off-let, or 'water waster' (NR 856870), designed in 1892 and built probably in 1895 (en.5).

RCAHMS 1992, visited June 1984