Digging the Buckingham Canal, and a discussion on maximum draft

I left you with a tease yesterday about something interesting I discovered on the Buckingham Canal. The Buckingham Canal? Yes, although this has lain mostly derelict for decades, there is a Buckingham Canal Society dedicated to restoring this branch of the Grand Union from Cosgrove to Buckingham.

This is a section near Cosgrove: the line and profile easy to see. Just add water?

According to Bradshaw* the Old Stratford and Buckingham Branch is 10 miles 6 furlongs in length, with two locks - Hyde Lane Lock and Buckingham Lock. The only navigable section at the moment is a couple of hundred yards' worth at the Cosgrove end. It finishes at a filled-in and mostly destroyed bridge.

I started to walk along the pleasantly rural section when I came across a bunch of people, some in hi-vis jackets, standing in the middle of the canal.

What were they doing? Digging a hole in the canal bed, that's what they were doing!

These were members of the aforementioned BCS investigating where the puddled clay lining began and ended.

The problem was that much of the geology of the area is clay-ey, so that they were having difficulty distinguishing the natural clay from the clay puddle.

Some things were obviously not clay at all!

Want to see down the hole? Oh, all right then! (The colour is a little strange as I used flash, and the bottom looks nearer the top than it really is. See above photos of arm and spade down hole to get an idea of depth!)

I joined in a discussion on maximum draft of laden working boats: consulting Bradshaw again I find I wasn't too far out when I suggested that few boats would draw more than 3' 6"; a workable maximum being 3'. Bradshaw indicates that an unladen narrow boat would draw between 8" and 11"; adding about an inch per ton of load. With maximum loads of between 25 and 30 tons this would give 41" or 3' 5" as the maximum draft. 25 tons on a boat drawing 8" unladen gives 2' 9" draft. For boats actually to be able to move along the canal, of course, a greater depth of water is essential - the deeper the better! Am I right in thinking that many canals were designed to be dredged to 5'?

When eventually restored it will be great to cruise this almost lock-free (depending on how obstacles are overcome) canal. Here's Cosgrove Hall near the start.

I was pleased that one of the team had a supply of recruiting leaflets - I think I'm going to have to join! I have no excuse not to: the chairman of the BCS is Athina Beckett, a former colleague of mine from BBC OUPC days in Milton Keynes.

*Bradshaw's Canals and Navigable Rivers of England and Wales (1904)