Kennet and Avon - Bridge heights and water levels

[jack4000]

Hi All

 

I've been cruising the Thames and South East canals for a year or so but have decided to head west down the K&A for the summer. I have a pretty tall boat, and with my fixed solar panels I'm at 2.45m/8'1. I'm finding mixed data regarding the bridge clearances in Reading and beyond. CRT say 2.4m max but from experience they're pretty (rightly) conservative, and also water levels vary drastically.

 

Also worth noting that my roof slopes quickly, so arched bridges aren't usually a problem - just max height in the middle.

 

Anyone with tall boats have any experience with the bridges and water levels at Reading? I'm happy to wait for a low water day to get through!

 

Cheers!

 

 

[matty40s]

Are you widebeam or narrowboat?

[jack4000]

Wide - 3.6m. But my max height is only down the middle of my boat for 1.3m and then the walls slope quickly - the profile of a regular trapezium.

[dmr]

Due to covid etc we have not been to the K&A for a while, but from memory one of the lowest bridges is at Hungerford (just by the ssrvices) and thats flat rather than arched and on quite a long pound. What do CRT list as the lowest bridges?

High Bridge (joke name) in Reading can be tricky, its arched but due to flow round the bend you don't always have full control to get into the centre of the arch.

[jack4000]

Hi dmr, thanks for your reply.

 

Yes the bridge you're referring to is Station Road bridge in Hungerford and it is the lowest or equal lowest between Reading and Bath at 2.4m. I can't find a CRT listing of individual bridges but this particular one is mentioned in various places.

 

Thanks for the info about 'High Bridge'. Did you note it to be particularly low in the centre? Or is it more the navigation of it that's the problem? As mentioned above, my issue is height, but from experience a lot of listed heights seem to be safe estimates and with water level changes I sail under a lot of bridges that on paper I shouldn't.

 

 

[dmr]

Canal levels are generally controlled by weirs so unless something goes wrong (as it often does) the water level is fixed. The Hungerford bridge is on a longish pound so would take some draining, and it has many moored boats and a trip boat so you would be unpopular. 😀

If you do a Google on High Bridge Reading, and select images, you will get a few good pictures which show what its all about. Its on the full flow of the River Kennet which can be a dificult river. Doing High Bridge going downstream can be difficult.

[Tony Brooks]

28 minutes ago, dmr said:

Canal levels are generally controlled by weirs so unless something goes wrong (as it often does) the water level is fixed. The Hungerford bridge is on a longish pound so would take some draining, and it has many moored boats and a trip boat so you would be unpopular. 😀

If you do a Google on High Bridge Reading, and select images, you will get a few good pictures which show what its all about. Its on the full flow of the River Kennet which can be a dificult river. Doing High Bridge going downstream can be difficult.

 

Yes, a shallow, single span arch, on a bend. Coming down stream, the current pushes you to the left, so can all too easily hit the underside of the arch. Wide beams would be even more prone to hitting the arch because a narrowboat can aim slightly to the right of centre where as  a wide beam may not.

[Drayke]

Kennet & Avon Canal
Length	87 miles
Locks	104
Maximum boat dimensions	Guide only - weather conditions can affect water levels
Length Width Draught Headroom	21.95m 72ft 4m 13ft 1" 1.1m 3ft 7" 2.4m 7ft 10"

 

I think the lowest bridge is Marsh Farm near Hilperton.

[dmr]

Interesting that its 72foot, I thought it was 70. Pretty sure there are a couple of locks where a pair of 72 foot boats would struggle.

[jack4000]

Thank you all for your insights.

 

Yes the water level should be fixed, but as you say, stuff goes wrong (or wet/dry weather!), and it varies a lot. I'm hoping a few low water days will aid me at some of the tighter bridges.

 

Wow that Marsh Farm bridge looks very low! But if that one is 2.4m then hopefully that means the bridges in Reading are higher and I won't get stuck.

[David Mack]

1 hour ago, dmr said:

Interesting that its 72foot, I thought it was 70. Pretty sure there are a couple of locks where a pair of 72 foot boats would struggle.

I've done it with a 71 ft 6in Big Woolwich sharing locks with a 68 footer. Going up, we had to go in first then push across behind the opposite side closed bottom gate. And we were always second out going down.

[___]

2 hours ago, dmr said:

Interesting that its 72foot, I thought it was 70. Pretty sure there are a couple of locks where a pair of 72 foot boats would struggle.

 

Which should be expected because in combination they'd be 72' x 14' and therefore outside of the published maximum craft dimensions.

 

And if you had a 72' x 13' widebeam you should expect it will fit.

 

[dmr]

33 minutes ago, David Mack said:

I've done it with a 71 ft 6in Big Woolwich sharing locks with a 68 footer. Going up, we had to go in first then push across behind the opposite side closed bottom gate. And we were always second out going down.

So, yes, two 72 footers would not be good 😀. The two short locks are the kennet section, though I think one on Devizes flight is a bit short, and we did struggle once in Crofton bottom sharing with another 70 footer.

15 minutes ago, Captain Pegg said:

 

Which should be expected because in combination they'd be 72' x 14' and therefore outside of the published maximum craft dimensions.

 

And if you had a 72' x 13' widebeam you should expect it will fit.

 

 

Its the length that I questioned, as Im sure it used to be stated at 70 foot. Two narrowboats can easily share the locks, though there are a few where its a really good idea not to have any fenders down. I suspect the 13 foot width limit comes from the bad repair to the entrance to one of the Semington locks a few years ago. Two boats can share but can't go in side by side. I know this. 😀

[___]

58 minutes ago, dmr said:

Its the length that I questioned, as Im sure it used to be stated at 70 foot. Two narrowboats can easily share the locks, though there are a few where its a really good idea not to have any fenders down. I suspect the 13 foot width limit comes from the bad repair to the entrance to one of the Semington locks a few years ago. Two boats can share but can't go in side by side. I know this. 😀

 

Fraenkel has the lock dimensions from Reading to Tyle Mill as 70' x 14' 8" (or alternatively 72' x 6' 6") and from Bull's lock to Hamstead lock as 72' x 14' 3".

 

Only a snapshot because the rest wasn't deemed navigable at the time. It's also difficult to apply Fraenkel because it presumably doesn't set a precedent for the re-opened canal as a whole.

 

My point was that the dimensions don't necessarily work when applied singularly (which is particularly relevant to the OP's question). You suggested something couldn't be done and I pointed out that the published dimensions concurred with your statement.

 

 

Edited March 8, 2023 by Captain Pegg

[dmr]

I can see the short locks in my head but can't remember their names, I will have to get the book out.

We were hoping to go to the K&A this summer but a friend made a recent visit (by road) and said it is now horribly overcrowded (and thats in winter). We spent a lot of time on the K&A and have good memories so Im not sure that I want to go and maybe have a not so good visit, perhaps just stick with the memories and have a look at the Wey instead?

[Tony Brooks]

42 minutes ago, dmr said:

I can see the short locks in my head but can't remember their names, I will have to get the book out.

We were hoping to go to the K&A this summer but a friend made a recent visit (by road) and said it is now horribly overcrowded (and thats in winter). We spent a lot of time on the K&A and have good memories so Im not sure that I want to go and maybe have a not so good visit, perhaps just stick with the memories and have a look at the Wey instead?

 

Please, not in a fatty. Followed one for hours past Byfleet at tickover because he simply could not go any faster and steer a straight course. However, the wide beam hotel boat seemed to have no trouble above Guildford so it may well have been the fatty's skipper. I have a feeling the OPs boat would not get under the railway bridge between Guildford and Farncombe though.

 

I got the impression that the rebuilt Burghfield lock was shorter than the other River Kennet locks.

Edited March 8, 2023 by Tony Brooks

[dmr]

1 hour ago, Tony Brooks said:

 

Please, not in a fatty. Followed one for hours past Byfleet at tickover because he simply could not go any faster and steer a straight course. However, the wide beam hotel boat seemed to have no trouble above Guildford so it may well have been the fatty's skipper. I have a feeling the OPs boat would not get under the railway bridge between Guildford and Farncombe though.

 

I got the impression that the rebuilt Burghfield lock was shorter than the other River Kennet locks.

 

Yes, thats the one, and Sulhamstead is another short one.