CanalCuttings - Your FREE Online-world British Inland Waterways, Narrowboat, River Cruiser, Canal Boat Magazine, Info Source and Britain's & Narrowboat Holiday Guide.
Around 850 Pages of Information and Features About Canals, Navigable Rivers and Their Usage - We're not just a Narrowboat World Magazine. The website includes River and Inland Waterways information - UK Inland Waterways Press Releases and Articles Invited.

Changes of Level on Canals

This is Chapter 7 from 'The Canal System of England'

Its growth and present condition, with particular reference to the cheap carriage of goods - 1904 - by H. Gordon Thompson

Attention must now be given to the different methods of effecting changes of level, with their economic aspect.

There are three chief methods of altering a boat's level on a waterway.

The Lock

Kennet and Avon Canal - Caen Hill Locks - Devizes

1. The first, and by far the most common, is by means of the lock, which has been in use for so many centuries. This method is so cheap as regards first cost and so easily worked, that for moderate falls of 15 to 18 feet, where water is plentiful, it is undoubtedly the most advantageous. But the disadvantages of the lock system are :First that for large falls the boats in the lock are apt to be damaged by the rush of water, or by striking against the walls or gates. Second that in deep locks the loss of water is excessive, especially where the traffic is going chiefly in one direction. * (* Saner on Canals.)

The latter is a most important factor where water is scarce.

Large-fan Lock. At the Fourth International Congress on Inland Navigation, a scheme was submitted for a lock of French standard size but having a 66 ft. fall, the total cost of which was estimated at 65,000. The difficulty of the rush of the water was overcome by side chambers at different levels storing most of the water, but the depth used at each operation was over 25 ft., and this would require a very copious supply, where there was much traffic.

On the Manchester Ship Canal and the Weaver, the culvert-openings are distributed along the side walls, but even then, with only a fall of 16 ft., great care is necessary to prevent damage to small craft during the filling of the lock.

The only way of meeting the difficulty of water supply pm S. for for the use of the lock, is by pumping. An efficient pump will raise 1,000,000 gallons of water 100 feet for 20/-. Now, assuming for the traffic from South Staffordshire to London, or vice versa, that water had to be raised by pumps to an aggregate height of 900 feet (which would doubtless be more than would be required, the water for the supply at the present time not being raised one quarter of that height, the balance being obtained from gravitation-supplies), this would give an expenditure for pumping water for the whole journey to London of about 4d. per ton, and if double locks were used the cost would be 2d. per ton of cargo, or 3d. per ton of cargo, assuming that half of the boats returned empty.* (* Salt. Canals and their Improvements Kept. Conf. of Mining Engineers)

The variation in the dimensions of locks on our different canals is a great disadvantage, and it is to be regretted that this variation in size is not tabulated or even mentioned, in the returns in the Blue Book of the Board of Trade.

Inclined Planes

Below is a picture supplied by the Foxton Inclined Plane Trust

2. Another method of effecting changes of level is by inclined planes. the use of inclined planes. The most extensive use of planes,* (* Saner on Canals) is on the Oberland Canal in Germany, where there are five in succession, with lifts varying from 45 to 80 feet. The boats are only of 60 to 70 tons burthen, with flat bottoms, and are not kept afloat, but rest on a grid for nearly their whole length. This system does not appear to be applicable for larger craft, as the weight of the cargo, especially if in bulk, would set up severe strains upon the sides of the boats when taken out of the water. The cost of these inclines averages 5,140 each.

At the Fourth International Congress referred to previously, a design was brought forward for an incline of about 100 feet to take French Standard boats, and the cost was estimated at £60,000, an expense quite out of proportion to the comparatively small outlay for the lock.

Disadvantages of inclined planes

Other disadvantages of inclined planes are briefly:

(1) The large amount of space necessary.

(2) The great wear and tear of the chains and ropes.

(3) The damage done to the boats by striking the sides of the trough. Advantages The one important advantage is doubtless the great saving of water.

Hydraulic Lifts

3. Vertical Hydraulic Lifts are also in use. The Anderton Boat Lift was the first of these was built in 1875 at Anderton, between the River Weaver and the Trent and Mersey Canal, under the direction of Mr. (now Sir) E. Leader Williams. The boats remain afloat in a water-tight trough, and are raised 50 feet with a loss of only 6 inches of water, one trough ascending as the other descends.

Disadvantages - The great objection to such lifts is their first outlay of and the cost of maintenance; the Anderton lift with troughs 75 feet by 14.5 feet cost £5,000, and the maintenance averages £6,500 per annum. The great advantage of Advantages. this method, however, is the great saving of time and water, and as this latter is a matter of the most vital importance in a district where the water supply is poor, this method is one which bids fair to be adopted, in order to effect the changes of level in future canal construction.

Economy of Systems

The question of the economy of the different systems for effecting changes of level points to the lock system as changes of level, the cheapest. Assuming that 30 hydraulic lilts could be made to take the place of the proposed locks on the route from South Staffordshire to London, and that they could be worked @ 0.20d. per ton (the figure given by Mr. Saner who had over 10 years experience of the Anderton . lift), this would represent 6d. per ton for lifts to London as against 3d. per ton for pumping.* (* Salt, Canals Kept. Conf. of Mining Engineers, p. 114,) The lift system, also requires the attention of several skilled men, entailing extra expense. Whilst it may be said that locks are wasteful of water, and that this waste must be made up by pumping, there is this advantage over a mechanical arrangement, that in times of large rainfall no cost is incurred in supply. Locks are infinitely less likely to be stopped by any defect in the arrangements for their working, than are hydraulic lifts or inclined planes, they are less costly to construct, no skilled labour is required to work them, and some authorities declare that they can be worked as expeditiously or more so, than any mechanical appliance.