Coal canal - evidence it was broad beam?

[magpie patrick]

As many of you know, I'm chairman of the Somerset Coal canal Society. It has long been accepted by us that it was intended that the canal be used by broad beam boats as far as Tucking Mill. However except at the entrance stop lock there is scant evidence on the ground.

 

Even at the entrance stop lock the evidence is mainly only visible when it is totally drained. It has half an invert, with the wall away from the lock cottage coming off from what appears to be the lowest point of a complete invert for a lock twice the beam. I haven't a photo handy and can't find one on the web, but here is a picture of the lock as it is today.

 

 

The gates, when present, hung on the original wall to the right, whilst the left hand wall rises from the centre of the invert.

 

However, other evidence would appear to contradict any passage by wide beam boats. This is the first bridge

 

http://www.flickr.com/photos/43536184@N06/10511955235/

 

Seen here as it was when the canal operated

 

 

Trouble is, with the towpath in place the canal channel is about eleven feet wide. At this bridge

 

 

http://www.flickr.com/photos/43536184@N06/10512158903/in/photostream/

 

We've measured the channel as 12 feet 9 inches and the distance between the springs as 17 feet. K and A boats were up to 13 feet 8 beam so they wouldn't fit through these bridges as they are now but they would if the towpath wasn't there.

 

This has started a debate, which isn't helped by the total lack of evidence that wide beam boats ever did use the canal (nor dare I say it, by the ability of some to construct towering, babel like theories on the flimsiest of evidence). We only know the following

 

• Some major bridges were built of stone but most of less importance were built of timber when the canal opened and replaced around 1845 with masonry structures.
• The entrance lock appears to have been built to wide beam but we don't know it was ever used as such or even why: it could have been to allow two boats at once or it could have been to allow navigation only a very short distance
• The bridges at least as far as Southstoke, where they survive, are not quite wide enough for wide beam boats but if they had no towpath they would be.
• Wide beam was never contemplated through Combe Hay locks.

 

The bridge at Southstoke is not well designed for the horse to go round it as the parapet would catch the rope.

 

My only thoughts are, what happened elsewhere if a canal was built to wide beam and later restricted? Building bridges without a towpath sounds very odd: is it plausible?

 

Thoughts anyone?

Edited October 27, 2013 by magpie patrick

[Burgiesburnin]

Have you any records of the loads carried per boat?

You can then work it back to see if its feasible that the load could have been carried by a narrow beamed boat.

Sorry if this is obvious, just a thought.

[Pluto]

Towpaths for horses only developed in this country (there were none abroad) in the second half of the 18th century as prior to that man power was used. There are quite a few towpath-less bridges on the French canals, and in this country those crossing below locks are often without a towpath, which must have caused some problems in operation. The bridge above the middle lock at Johnsons Hillock has a hook on the face next to the lock around which the towline was placed so a boat going uphill could exit the lock with the horse moving in the opposite direction. Not having a towpath is not that unusual in some respects. One thing to remember is that early canals were far more successful than was envisaged, and that difficulties at bridges would not have necessarily been considered too much of a problem on the tonnages originally envisaged.

 

On the width of locks, the dimensions of the T&MC were changed during construction, so there are several wide bridges on a narrow waterway. Also, I think the wide boats on the T&SC were only around 12 feet wide, and those on the South Wales canals 9 feet wide, so there is a tradition in the south west of non-standard widths for boats.

[Heartland]

It is an interesting suggestion that the canal was once wider at the entrance to the Coal Canal. A similar situation happened at Lifford Stop, Stratford upon Avon Canal.

 

Ray Shill

[Capt Ahab]

It is an interesting suggestion that the canal was once wider at the entrance to the Coal Canal. A similar situation happened at Lifford Stop, Stratford upon Avon Canal.

 

Ray Shill

I have some images of the curved base of the original lock wall of the Lifford stop (Kings Norton) and then the 90 degree base of the new one set on the middle of the wider invert on my blog:

 

http://captainahabswaterytales.blogspot.co.uk/2012/12/kings-norton-open-day_10.html

[magpie patrick]

Interesting responses: Burgies, it's a fair question, I wish I knew the answer, Ray, we have no doubt the entrance lock now has half an invert and also we have documentary evidence of it being narrowed in the 1830's. I suppose anither question arises here - Why. With a fall of 7 inches it was hardly thirsty on water and anyway fell from the lowest level of the coal canal, and the lock keeper could presumably enforce "narrow only" restrictions. Here is a picture of the entrance

 

 

 

As you can see the bridge was quite a lot wider than the lock.

 

Pluto, I suspect the idea that the boats were non-standard is the best bet. The coal canal opened in 1805, and was navigable to Tucking Mill by 1798. In 1805 the K and A was open to Bath but not to Devizes and in 1798 the K and A had hardly started. I seem to recall that for some canals (the Grand Junction?) the size of boats to be used was not known in any detail. It was all a bit ad hoc.

[Heartland]

As to building a canal without a towpath, the Droitwich Barge Canal lacked a towpath until the Worcester & Birmingham Canal Company paid for it to be provided. I think it is also important to add that river navigations (in England etc) also lacked towpaths unless it was specifically provided, and this was usually later (e,g Severn and Trent). Yet there was still a haling path where men might haul the craft.

 

Ray Shill

[Max Sinclair]

Yes this applied to the Severn and Droitwich with bowhaulers walking in the water and all over the farmers crops as shown in the pictures in the towpath Act documents. The towpath was promoted because it disciplined the haulers.

[Heartland]

Regarding the Coal Canal Lock, this subject has been taken up by the RCHS Waterways History Group where Roger Evans has quoted :

http://www.coalcanal.org/features/GuidedTour/T102.php which starts:

This lock was at the junction of the Somersetshire Coal Canal with the Kennet and Avon Canal. Both canal companies had gone to considerable expense to acquire water for their canals and they were not willing to let this valuable commodity flow freely from one canal to the other. Although the level of the S.C.C. was only a few inches higher than the level of the K&A, this lock was installed to separate the canals.

The lock was originally built 14 feet wide, which allowed full-sized barges from the K&A Canal to have access to the lower part of the S.C. C. as far as the flight of narrow locks above Midford. Later it was rebuilt to a width of 7 feet, so as to only allow narrow boats to enter the S.C.C.

The plan [on the web site] shows the shape of the current lock and how it may have been originally built.

Ray Shill

[magpie patrick]

Thanks Ray.

 

I need to be careful how I put this: the text on our website is prepared by the committee member who comes up with elaborate (and sometimes stark staring bonkers) theories to explain every last nut and bolt on the canal. He runs the website (and is not one of our resident historians, unlike Roger Halse and Mike Chapman who are extremely good).

 

I have another theory, one developed whilst cruising the northern Oxford Last week. I noticed that the bridges on this canal are fairly generous, perhaps eleven to twelve feet navigable channel, and that at Barby marina there are one or two wide beam boats moored.

 

Now cast back to 1795 when the first length of the coal canal was being built. There were no narrrow boats on the K and A, in fact there was no K and A actually existing at that time as it too was being built, and whilst they must have known what size the locks would be there were no boats and patterns of usage not yet understood. My thought is that some bright spark building the canal reckoned that the only constiction for boats wider than 7 feet before Coombe Hay would be the entrance lock, so built that wide so that "wider" boats could get up. Of course, when the canals were built, the Coal Canal Boats were narrow and any boat for use on the K and A only was as wide as that canal would take, and too wide for the bridges on the coal canal.

 

I seem to recall that other canals, such as the Grand Junction, were not sure what size boats would be used as the boats didn't exist when the canal was built, and when the SCC was being built othet hybrids were being considered, such as the Dorset and Somerset with it's half length narrow boats.

 

Getting my committee member to put that on the website may be a different matter though...

[Pluto]

Seems the most plausible explanation to me. When looking at canal history, the essential fact is that they were generally local in character and that a national system was not that important to those paying for a canal. Thus, canals tended to be built for boats of an existing local size, or a size to suit local conditions. There were no English-language technical books on how to build canals, other than tub boat canals, until the early 19th century, and thus few standards. You did what was wanted locally.

[Heartland]

Mike has made a valid point. I also think it is important to look back to when the canal was first made and investigate the conditions that then prevailed and also look at surviving records to find the answers, if they exist that is.

 

Comparison with the Northern Oxford is perhaps not the best as parts were altered between Braunston & Napton to suit the Grand Union Widening scheme through to Tyseley in Birmingham. This was done in the early 1930's. A hundred years previous (1829-1834) the Northern Oxford was straightened and widened between Hawkesbury and Napton effectively creating a new canal.

 

It seems reasonable that the Coal Canal junction would be made for craft of K & A size to at least exchange traffic at some point. Perhaps an elaboration on why the reduction to 7ft width was needed. On a related point I recollect from K & A gauging tables both barges and narrow boats were recorded. How common were narrow boats and where did they operate to and from?

 

Ray Shill

[magpie patrick]

Northern Oxford was the canal that inspired my thoughts rather than a good example. It is narrow and yet has wide beams navigating it as far as Barby. Today we have a far greater range of craft sizes than was historically the case and thus this sort of thing happens.

 

Narrow boats on the K and A. I'm working from memory here but I think they were concentrated at the Western End and didn't tend to go to Bristol. Much of the trade at the Western End came from the Coal Canal which was narrow, indeed the Coal Canal Company had it's own wharf above Widcombe Locks. I've seen a picture of a narrow boat below Pulteney Weir but the river was less suited to them and not much coal canal trade went to Bristol: coal in Bristol came from South Wales.

 

The Wilts and Berks connected at Semmington, around ten miles and only one wide lock from Dundas where the coal canal joined. The Wilts and Berks led to the Thames at Abingdon, and we have records of coal being taken from the coal canal to Abingdon and Oxford. The W&B also linked with the Thames and Severn, where narrow boats were common because they would fit the odd sized locks although no other standard size of boat would thanks to the change of gauge at Briscombe Port.

 

I don't think there is much evidence of Somerset coal reaching Reading, so my guess would be that narrow boats would be pretty common between Bath and Semmington, and not uncommon as far as Pewsey. Past Pewsey probably barges predominated. The River Avon always was the preserve of barges as the bulk of trade to and from Bristol went no further than Bath.

 

Hope the logic of all that isn't too muddled

[the grinch]

the Wey and Arun is 12ft wide in the locks. 11'9" barges were used on the canal as far as I know. all our bridges are towpathless

it would seem that 12 - 13' was a common size on the southern canals/rivers

[Ian Mac]

One of the things that we must remember is that when railways came to be built, parliament came up with the concept of the "standard gauge" this is because they had learnt that canals didn't have one and it would have been far better for all concerned if they had had one. They also attempt to enshrined the concept of the carrier being independent of the railway, only the railways fought back against this and limited the concept to private owner wagons.

--

Cheers Ian Mac

[Derek R.]

Was that after Brunel built his Broad Gauge?

[mykaskin]

Surely the reason bridges are often larger than the waterway dimensions is to ease passage for loaded boats. It's surprising how much a Shroppie Bridge reduces your speed as compared to a T&M or Oxford canal bridge.

 

The Bridgewater canal bridges are well over 'gauge' so presumably was thought about very early on.

 

Mike

[matty40s]

...but then why the Shroppie bridges not, as Telford built this much later with grand designs of embankments and cuttings??

[Ian Mac]

Was that after Brunel built his Broad Gauge?

No it was before this is why it was called broad gauge, Brunel successfully argued that a better gauge would be the 7ft and 1/2 inch and built his (Great Western ) railway to that size however he had to convince others to change to his gauge or he (ie the GWR) would have to revert to the standard gauge. Brunel lost that battle and the whole GW system swapped almost overnight to standard gauge.,Although it is a shame, with hind sight as it would have been a far safer gauge and given far more room for future proofing.

[Heartland]

Railway gauges did vary in the early years of the developing British Railway network. However the GWR Broad Gauge did not quite disappear over night. The mixed gauge through Birmingham to Wolverhampton lost the broad gauge in 1869.

 

Ray Shill