The coastal area at Bude has sand unusually rich in minerals and the poor agricultural land of the locality was found to benefit considerably from application of the sand. In the pre-industrial age, actually transporting it was difficult, even to land relatively close to the coast.
Several schemes were put forward for canals to bring the sand to the countryside, and these proposals did not lack ambition. One scheme gained parliamentary approval for construction in 1774, but financial problems frustrated the proposal.
In 1818, the West Country canal engineer James Green produced a report for canal's backers, and an Act of Parliament was obtained for this more moderate proposal in 1819. After some difficulties in the construction phase the canal was completed and opened on 8 July 1823 Its cost was £118,000.
The main line of the canal runs south east from Bude to a wharf near Launceston, with an easterly branch to Blagdonmoor, beyond Holsworthy. There was a northerly feeder arm leading from a new reservoir at Virworthy, called the Tamar Lake.
There were two conventional locks in the short broad canal section, each with a vertical interval of 5 feet 6 inches (1.7 m). This section terminated at Helebridge, about 2 miles (3.2 km) from Bude, and ordinary coastal barges travelled this far up the canal.
The tub boats were designed to use the main part of the system, and they generally made the transit from the harbour at Bude, or from Helebridge if trans-shipping from coastal vessels there.
After Helebridge there were three inclined planes to the summit section; the whole of the central part of the system was at this level, 433 feet (132 m) above sea level. The main line to Druxton Wharf, near Launceston negotiated three descending inclined planes as it followed the southerly course of the River Tamar.
Having no intermediate locks on the tub boat sections, the canal had to follow the contours exactly between the inclined planes, and this made its route even more circuitous than most canals. However some relatively ambitious viaducts and earthworks were constructed, particularly where side streams and small valleys entered the main watercourse and its valley.
The unusual feature of the canal was the six inclined planes. The tub boats had wheels, and on the inclined planes they were pulled up the slopes with the wheels running in channel rails (like a squat letter "U" in section). There were two sets of rails, one for each direction, but it does not appear that a counterbalancing system was used (in which a boat coming down would balance one being pulled up).
The tub boats were hauled up and let down the inclined planes by chains which were operated in most cases by waterwheels; the transit took five minutes or so. There were standby steam engines at some of the inclined planes. However the Hobbacott Inclined Plane used a different system of harnessing water power: water filled a very large bucket and it was simply the weight of the water that pulled the ascending tub boat up the incline. The bucket operated in a deep vertical shaft, and at the bottom a plug was opened and the water ran to waste along an adit which connected to the lower level of the canal; the descending bucket pulled an empty bucket up in the same operation. The full bucket had to be heavy enough to pull a loaded tub boat up the 1 in 4.5 gradient as well as overcoming friction, and Green calculated that a weight of about fifteen tons was necessary. This was successful, and the bucket raised a boat up the plane in about four minutes, which was about one half of the time taken when the 16 horsepower (12 kW) standby steam engine was used.
The gradients of the planes differed somewhat, with Hobbacott being the steepest at 1 in 4.5 and Vealand being the gentlest at 1 in 8.6.
Today the sea lock is still in working order, and the canal is 'in water' as far as the base of the first inclined plane. The sea lock, though, is the only lock on this section still in working order, so that navigation is not possible along the whole network. Much of the upper section has been ploughed over or has become overgrown, but it is possible to see many remaining signs of the canal's presence, in bridges and wharf buildings. On the feeder branch and on the lower part of the Launceston main line the alignment is indicated on current Ordnance Survey maps. In most cases the alignment is not open to the public, however.
An exhaustive list of locations where the canal's remains can be seen may be found in Harris and Ellis
