Canal Carpentry

In this, the third of a series exploring the traditional aspects of canal maintenance, we look at canal carpentry where the heaviest extremes of woodworking are to be found.

In 1967 I left my trade as a joiner to start work on the Marple Section of British Waterways Board (BWB) “on the bank” where, among other things, I steered the now famous President, though she was diesel-powered then.

Bosley Flight restoration

Eventually, a vacancy came up for a section carpenter which the inspector asked me to apply for. He then made me a permanent foreman and told me to make the restoration of the Bosley Flight on the Macclesfield Canal my priority. The Marple section had not been allowed to have a carpenter for some years and so, understandably, the locks were in poor condition – proof, if needed, that BW’s intention had been to close not only the Ashton but the entire Ashton, Peak Forest and Macclesfield system.

No new paddles had been made for some time, so I set to with a will, producing them in batches in the fine old workshop overlooking Marple Junction. Paddles tend to bow slightly owing to water pressure, causing friction against the iron paddle frame, so the convex side needs to be dished or hollowed slightly with an ancient woodworking tool known as an adze – rarely seen nowadays and dangerous in unskilled hands. Three carpenters came and went while I was at Marple, none of whom could use one. The paddles were of elm, which, after being made, were left to saturate in a nearby water trough.

The narrow locks of the Bosley Flight are most unusual in having twin or mitred top gates. There has been much speculation as to why this should be the case, and even engineers do not know. The gates, being angled back into the chamber, reduce the amount of water needed to fill it and this, I feel, is the answer.

Many gates had worn off their fit resulting in lock ponds (pounds) emptying overnight. The answer here was to cut a groove right around each gate and attach an oak liner – a process known as “lining out”. The final fit could be obtained by daubing the quoin with red raddle, as used by sheep farmers during the mating season, and planing the resulting mark on the liner until either the gates fitted or the chippie’s patience ran out. In fact, it is possible to obtain a very good fit by this method. All gates leak, of course, but a canal with too many badly leaking gates is a sure sign of a canal being poorly run.

Unscheduled stoppages

Everything was in such a parlous state that the lock-keepers and myself would arrange our own unscheduled stoppage in order to carry out running repairs, even though it was strictly against the rules. Traffic was much lighter then, of course, and we were never caught except by the local length foreman, Jack, who was aghast that we had stripped all the defective planking from a top gate prior to replacing it.

Some gates were past repair and so we started a replacement programme, beginning with the bottom gates of Lock 12. A railway bridge prevented our using a crane, so all lifting had to be done with a threelegged device that the historian L.T.C. Rolt wrongly described as a sheer legs, though, in fact, it was a three-leg derrick. The old gates were loaded into a boat and the new ones lifted and lowered each side of the gatewell to await fitting. We then drained the canal, which still left more than 2ft depth in the gatewell, which needed to be pumped out before work could begin, and to do this we fitted a stank board on either side (see illustration). A stank board consists of a set of boards ledged together at the middle and ends with the lower edge curved to match the shape of the invert. The boards are hammered into a layer of clay, not truly upright but inclined towards each other and secured with wedges before being made watertight with clay plastered up the sides.

We could now pump the gatewell out, revealing the sills still in perfect condition, as well as both pintles leaded into the gatewell floor upon which the gates rest. Lock gates are kept in position and pivot upon a simple pintle-and-socket arrangement, which can be fitted either way round. Nevertheless, it is much better if the pintle is fitted in the gate heelpost and easier to replace since it is not unknown for them to fracture. We then fitted each gate in place, the men hauling mightily back on a rope while I fitted the massive U-shaped collarband through the anchor straps. Everything else could then be bolted together including the balance beams, which can be something of a misnomer since they do not normally act as a full counterbalance unless unusually long or heavy.

Nearly all the lock gates I fitted were oversized to some degree. The answer here would be to trim the mitres with an adze before propping them together and sawing down the joint with a two-handed saw. Lock gates are said to last around 25 years, though it depends upon the quality of the timber used, especially oak which can be inferior if not carefully selected.

Slowing progress

Two weeks would be allowed for lock stoppages during my earlier days and we could install a new set of gates well within that time, for they are not really so difficult to fit despite their awesome size. However, as time went on the period allowed for stoppages was greatly increased – the reason given being that a considerable backlog existed. As carpentry foreman, I carried a fair amount of responsibility for getting everything done, but progress fell from a trot to a saunter despite my best efforts, because there was no longer any sense of urgency. It occurred to me that long stoppages suited BWB because it resulted in it saving a vast amount of water. A flight of locks needs to have a flow of water running down it in order to balance everything up, regulated by a device known as a penstock. At stoppage time off went the penstock, off went the reservoir feed and BWB was saving a great deal of water, as well as that used in passing craft through the flight.

The length of stoppages has always been a very emotive issue for boatowners, and something which I feel the present administration should examine more carefully.

James Hewitt (left) making a template for a new top gate for the Marple Flight. Note the pair of bottom gates waiting to be fitted.

An adze – an ancient woodworking tool still used occasionally on the canals.