Narrowboat max head height

[magnetman]

In the empty shell the sprayfoam looks a bit old and the wooden battens seem aged which makes me think this may be an uncompleted project. 

 

 

[BoatingLifeUpNorth2]

12 hours ago, magnetman said:

In the empty shell the sprayfoam looks a bit old and the wooden battens seem aged which makes me think this may be an uncompleted project. 

 

 

I think it’s about 25 years old, story I hear, bought new to fit out, vintage engine and all that. This is how far it got, original buyer has sold it back to the original builder, really nice trad tug shell, original condition steelwork as it was built 25 years ago. It would have been expensive when new, solid well built shell. 

Edited January 27 by BoatingLifeUpNorth2

[magnetman]

Don't know the name of this one but that seems to be a mollycroft of sorts. 

 

 

 

[ditchcrawler]

4 hours ago, magnetman said:

Don't know the name of this one but that seems to be a mollycroft of sorts. 

 

 

 

That is the sort of thing I was thinking of when I said raise the roof on an existing boat

[magnetman]

Its common on old caravans and also helps enormously with the light if there are suitable windows. 

 

[Peanut]

Some clessory roofed carriages were used on the London Underground, District Line trains, up until 1972. I remember the nostalgic feeling travelling in them.

[JustAddWater]

I thought I'd give you guys an update on my research.

 

I now think I'm speaking to the right people, they seem to know the subject inside out and are looking into options.  They're a custom builder and their "standard" internal sizing without flooring or paneling is 7ft1inch so this would not work for me.  They are now looking into how this could be changed and the impact of that change on the ability to use all the CRT canals. I'll update the group when I get more info.

 

Also to help me understand the challenge I've created a spreadsheet containing the canal sizing information. I've attached it so you can use it, but you MUST check the data with the source (CRT website) before you use it to make any decisions.  You simply enter your dimensions in meters at the top and it will tell you if there are any issues, some of these canals are very shallow or have crazy height restrictions. 

InfoForSizing.xlsx

[ditchcrawler]

30 minutes ago, JustAddWater said:

I thought I'd give you guys an update on my research.

 

I now think I'm speaking to the right people, they seem to know the subject inside out and are looking into options.  They're a custom builder and their "standard" internal sizing without flooring or paneling is 7ft1inch so this would not work for me.  They are now looking into how this could be changed and the impact of that change on the ability to use all the CRT canals. I'll update the group when I get more info.

 

Also to help me understand the challenge I've created a spreadsheet containing the canal sizing information. I've attached it so you can use it, but you MUST check the data with the source (CRT website) before you use it to make any decisions.  You simply enter your dimensions in meters at the top and it will tell you if there are any issues, some of these canals are very shallow or have crazy height restrictions. 

InfoForSizing.xlsx 27.54 kB · 3 downloads

Please don't rely on CRT information on depth of water or bridge clearance.

[magnetman]

2 minutes ago, ditchcrawler said:

Please don't rely on CRT information on depth of water or bridge clearance.

This is important. 

 

Someone got a barge stuck fast in a lock which had moved slightly and was actually slightly smaller than the published width. It was a wide lock on the K&A but the principle applies elsewhere. There are also places like the South Oxford where rivers join the canal and bridge height varies according to the rain. 

 

If you are considering having a Boat built which is going to get very close to published air draft data I think you will quickly find problems.

 

 

 

 

[ditchcrawler]

1 minute ago, magnetman said:

This is important. 

 

Someone got a barge stuck fast in a lock which had moved slightly and was actually slightly smaller than the published width. It was a wide lock on the K&A but the principle applies elsewhere. There are also places like the South Oxford where rivers join the canal and bridge height varies according to the rain. 

 

If you are considering having a Boat built which is going to get very close to published air draft data I think you will quickly find problems.

 

 

 

 

Also the shape of the bridge and the shape of your boat come into play

[magnetman]

Yes. Thats why I originally suggested a raised centre cabin section similar to a mollycroft on a caravan. Leave the cabin sides the normal height and just provide a central walkway. If done right with little windows it would provide wonderful light into the Boat and mean one could have portholes instead of windows if one so wished without getting a dark cabin. 

 

Still a potential bridge hazard but not as much as a fundamentally altered cabin height. 

 

I expect someone that tall will be used to leaning over a lot anyway to accommodate ordinary day to day things. 

[IanD]

8 minutes ago, magnetman said:

Yes. Thats why I originally suggested a raised centre cabin section similar to a mollycroft on a caravan. Leave the cabin sides the normal height and just provide a central walkway. If done right with little windows it would provide wonderful light into the Boat and mean one could have portholes instead of windows if one so wished without getting a dark cabin. 

 

Still a potential bridge hazard but not as much as a fundamentally altered cabin height. 

 

I expect someone that tall will be used to leaning over a lot anyway to accommodate ordinary day to day things. 

Given that the air draft for a boat properly designed and ballasted is probably only going to increase by 4" or so -- and there are plenty of narrowboats (most of them?) badly ballasted with high bows which have bigger air draft than this -- I think this is making a mountain out of a molehill... 😉 

 

All that's needed is a heavier baseplate/steel ballast to gain a couple of inches under the floor and have the boat sit a couple of inches lower in the water, and a slightly taller hull/cabin (about 6" total), that gives 8" extra internal headroom.

 

Ballast the boat so it's only a few inches bow-up in normal trim (e.g. level with full bow water tank and empty stern diesel tank) and there will be no problems with either air or water draft. It'll also swim through the water better than a "normal" narrowboat -- meaning one which draws a couple of inches less but is ballasted much more bows-up, like most of them are... 🙂 

Edited February 5 by IanD

[David Mack]

All that transcribing of CRT data, of doubtful reliability, seems rather pointless. There are plenty of converted Grand Union Large Woolwich and Northwich boats about with a 3ft cabin on a 4ft 9in hull which navigate almost the entire system without significant problems. Within those dimensions you could easily configure the headroom you want, especially in a new build boat.

Some of the restrictive dimensions are on isolated waterways you will probably never visit with your own boat (e.g. Mon & Brec). Many of the other more significant dimensional constraints are located towards the end of a navigation (e.g. Froghall Tunnel) and not being able to pass will only slightly reduce the extent of waters you can cruise. Only a few are on through routes e.g. Dudley and Standedge Tunnels) and there are many regular craft which cannot pass through these either.

The biggest constraints (in terms of miles of waterway affected) are the width restriction of about 7ft on the Midland canals, which results in two separate wide boat networks in the north and south (three if you include the Nene/Middle Level/Great Ouse and tributaries) and the length restriction of 57-62 feet on the Leeds & Liverpool East of Wigan and some of the Yorkshire waterways, and those have nothing to do with boat draft or airdraft.

[Francis Herne]

I'll echo the comments above that CRT's generic waterway depth/height information is totally worthless.

 

For clearance above water, the Standedge Tunnel limits would be a reasonable target to meet - they're clearly specified and probably the most restrictive on a 'main' route rather than fringe branches.

http://www.penninewaterways.co.uk/documents/tunnel-dimensions.pdf

 

The most straightforward option, as you suggest, would be to simply increase the draught of a standard build by a few inches. Modern boats are shallow by default so it won't stop you going anywhere.

 

On 22/01/2025 at 17:38, magnetman said:

Buoyancy is a significant issue with metal boxes. They want to float. 

Lead ballast might work but it would be very expensive and may cause dissimilar metals problems inside a steel shell. 

 

I have seen one narrowboat with depleted uranium ballast, in the form of small toroids in dozens of plastic tubs. The density was uncanny.

 

 

Edited February 5 by Francis Herne

[Tam & Di]

Gold would be good too. 😀

[IanD]

2 hours ago, Francis Herne said:

I'll echo the comments above that CRT's generic waterway depth/height information is totally worthless.

 

For clearance above water, the Standedge Tunnel limits would be a reasonable target to meet - they're clearly specified and probably the most restrictive on a 'main' route rather than fringe branches.

http://www.penninewaterways.co.uk/documents/tunnel-dimensions.pdf

 

The most straightforward option, as you suggest, would be to simply increase the draught of a standard build by a few inches. Modern boats are shallow by default so it won't stop you going anywhere.

 

I have seen one narrowboat with depleted uranium ballast, in the form of small toroids in dozens of plastic tubs. The density was uncanny.

 

Where on earth did they get it from?

 

I remember a science exhibition many years ago with a bar of depleted uranium sitting on a display, caged at the ends so you could lift it (with both hands) but not nick it. Very strange sensation, you'd have sworn it was being held down by strong hidden magnets or cables with hidden weights... 😉 

[Francis Herne]

5 hours ago, IanD said:

Where on earth did they get it from?

The current owner doesn't know and, I believe, intends to replace it with something more conventional.

 

It's a very unusual boat in several ways. Sadly the previous owner passed away without leaving many detailed notes.

Edited February 5 by Francis Herne

[IanD]

1 minute ago, Francis Herne said:

The current owner doesn't know and, I believe, intends to replace it with something more conventional.

 

It's a very unusual boat in several ways. Sadly the previous owner passed away without leaving many detailed notes.

You're sure it's *depleted* uranium? 😉

[Stroudwater1]

1 hour ago, IanD said:

You're sure it's *depleted* uranium? 😉

A nuclear powered narrowboat may have its attraction? 
 

[agg221]

6 hours ago, Tam & Di said:

Gold would be good too. 😀

For reasons I won't bore you with, I once found myself looking at a small sack of palladium powder, gradually filling up as it left the end of the processing line. I idly calculated that I was looking at about 100kg, which at the time would have had a value of ~£2M. It was quite dense so it would have made good ballast...

 

Alec

[IanD]

Osmium, that's what you want... 😉 

[agg221]

11 minutes ago, IanD said:

Osmium, that's what you want... 😉 

Just don't let it oxidise - osmium tetroxide is evil stuff.

 

Alec

[Phoenix_V]

havent read the entire thread but in case this hasnt been osted before the late Jim Macdonald's Elizabeth

 

[ditchcrawler]

7 minutes ago, Phoenix_V said:

havent read the entire thread but in case this hasnt been osted before the late Jim Macdonald's Elizabeth

 

It didn't look like that last time I saw it unfortunately, I am guessing it was in poor shape when he passed away.

[David Mack]

But does Elizabeth have higher headroom down the middle, or just lower headroom at the sides?