canal guide quoting 'head room'

[mantis]

Hi

In the Collins guide it states, for example,  'head room' of 6'9" on a canal.  In yacht, 'head room' would mean the interior head room and the exterior size is referred to as Air Draft.  Am I correct in assuming that for canal boats 'head room' means the exterior dimension of a boat from the water line to the tip of the roof - ie what you need to know to fit under a bridge?  if the canal guide says 'head room = 6'9"' then that the limit of the lowest bridge?

thanks

[Martin Megson]

Hi,

Yes, in that context headroom is the same as air-draft. 

 

[DHutch]

Sounds like it.

Marine terms are often not used as rigorously in canal circles as in bumpy water. Lines/warps/etc all become rope, and people use left and right, front back, etc.

Daniel

[mantis]

thank you!  Nice and simple :-)

Another question if I may hijack my own thread...

should it say somewhere - or where should I look, for the maximum beam that can traverse a certain section?  ie, where do I go to find out if a 12' wide beam can go from Limehouse to Hertford?  or are all locks on these sections (Grand Union, Hertford) good for up to 14'?  I'm obviously missing that bit of information somewhere, but it's not clear to me in the guide or the charts I've been looking at.

thanks again!

[howardang]

5 minutes ago, DHutch said:

Sounds like it.

Marine terms are often not used as rigorously in canal circles as in bumpy water. Lines/warps/etc all become rope, and people use left and right, front back, etc.

Daniel

Not to mention Windlasses, Ceilings etc. 

 

Howard

[Neil2]

2 hours ago, mantis said:

Hi

In the Collins guide it states, for example,  'head room' of 6'9" on a canal.  In yacht, 'head room' would mean the interior head room and the exterior size is referred to as Air Draft.  Am I correct in assuming that for canal boats 'head room' means the exterior dimension of a boat from the water line to the tip of the roof - ie what you need to know to fit under a bridge?  if the canal guide says 'head room = 6'9"' then that the limit of the lowest bridge?

thanks

You have to be careful with canals though, if for example a bridge or tunnel is described as 6' max height, it doesn't necessarily mean that your boat of just under 6' air draught will clear it.  Simply because the curved bridge/tunnel profile might not match the cabin profile of your boat.  This is an issue really confined to the narrow canals and I doubt it was ever a problem in the  days when boats had very pronounced tumblehome, but in the modern era where narrowboat builders try and maximise cabin space we have taller boats with more boxy profiles.  

I know boats have been refused passage through Standedge tunnel on this basis.  I've also met boaters who dread going through Harecastle because there is very little margin for error in the middle section.  It's also an issue if you're one of those with a cruiser stern boat that insists on cruising with a pram cover up.    

Harecastle has a helpful profile guage at the entrance, as does the notorious Froghall tunnel, but I'm struggling to think of any other examples.  Even at Standedge they use a portable guage.  It would be helpful if every canal had a guage at each end to indicate whether boats can pass under low bridges/tunnels.  The Leeds/Liverpool canal would certainly benefit from one because of Foulridge tunnel. 

[Chewbacka]

3 hours ago, mantis said:

thank you!  Nice and simple :-)

Another question if I may hijack my own thread...

should it say somewhere - or where should I look, for the maximum beam that can traverse a certain section?  ie, where do I go to find out if a 12' wide beam can go from Limehouse to Hertford?  or are all locks on these sections (Grand Union, Hertford) good for up to 14'?  I'm obviously missing that bit of information somewhere, but it's not clear to me in the guide or the charts I've been looking at.

thanks again!

This may help you https://canalrivertrust.org.uk/media/original/32433-waterway-dimensions.pdf

It's a 6 page PDF of canal dimensions and size restrictions.

Edited August 16, 2017 by Chewbacka

[mantis]

thanks very much - excellent resource.

 

[Hudds Lad]

49 minutes ago, Chewbacka said:

This may help you https://canalrivertrust.org.uk/media/original/32433-waterway-dimensions.pdf

It's a 6 page PDF of canal dimensions and size restrictions.

It does list the Hudds Narrow from Aspley to Standedge as having a draught of 246ft which, being a local, I can assure you is not accurate

[Martin Megson]

19 minutes ago, Hudds Lad said:

It does list the Hudds Narrow from Aspley to Standedge as having a draught of 246ft which, being a local, I can assure you is not accurate

Maybe it passes over a very deep well 

[David Mack]

6 hours ago, mantis said:

thank you!  Nice and simple :-)

Another question if I may hijack my own thread...

should it say somewhere - or where should I look, for the maximum beam that can traverse a certain section?  ie, where do I go to find out if a 12' wide beam can go from Limehouse to Hertford?  or are all locks on these sections (Grand Union, Hertford) good for up to 14'?  I'm obviously missing that bit of information somewhere, but it's not clear to me in the guide or the charts I've been looking at.

thanks again!

Map of wide and narrow waterways at http://www.jim-shead.com/waterways/mwp.php?wpage=Inland-Waterways-of-England.htm

Edited August 16, 2017 by David Mack

[Tony Brooks]

I think what Neil2 says needs emphasising, especially for anything other that a narrowboat. The ridge arch or the slop of the deck on a flat "arch" bridge or even how a bridge sits in relation to the canal may well mean the airdraft of a boat would need to be lower than that stated. I understand that some bridge abutments have moved over the years thereby forcing boats to one side of the bridge hole. This limits the available airdraft for wide beam boats but much depends upon the boat's profile. Then there is the water level on river navigations. A boat may pass under certain bridges for several months of the year but may not when the level rises.

My advice is to treat any such dimension as a very rough guide until you have physically checked.

[Machpoint005]

21 hours ago, howardang said:

Not to mention Windlasses

Our are called " 'andles ".