Longboats

[David Mack]

 

MrSmelly (who has gone quiet of late) has previously said he has accessed the Northern canals via. Keadby in a 70ft boat.

 

Thorne Lock is the potential sticking point but I believe he managed it. After Thorne much of the North Eastern system is available to you, and worth it too.

Before my time, but Fulbourne at 71 ft 6 in has failed to get through Thorne Lock, although it has been in the chamber from both ends.

[Mick Poyser]

Cassiopeia is gauged at 71' 9" and several people said the gauge is wrong as GU boats are 71' 6", so whilst on dock last year I measured her using a laser and plumb lines. She is actually 71' 9 & 1/2".

She passes through all the shorter BCN locks with no problem except Titford were she has to come down backwards.

[MtB]

Cassiopeia is gauged at 71' 9" and several people said the gauge is wrong as GU boats are 71' 6", so whilst on dock last year I measured her using a laser and plumb lines. She is actually 71' 9 & 1/2".

 

 

Nicely done.

 

Wss this inside or outdoors? I measured the width of my boat docked outside and the slightest breath of wind made the plumb lines swing around so I'm still not 100% confident of my result.

 

Mind you, width is far more critical than length!

[Mick Poyser]

I measured her on Mills dock (Long Eaton) outside. Absolutely no wind that day. Positioned the edge of a brick which on the dock floor on the plumb bob hanging from the stem post, then positioned the lazer to the plumb line hanging down from the counter lower band.

The bostocks at Mills are lengths of railway line on concrete blocks, so was able to point the lazer under them towards the brick. Checked it three timers and got the same result each time.

Also checked her width at each knee across the top band whilst she was still in the water using two 1m spirit levels and a tape measure, but that's another story.

[MtB]

Yes I bet.

 

It aoccasionally amuses me when someone on here asserts it's easy to measure the width of a boat!

[magnetman]

I suppose one could make up a u shaped wooden apparatus using a 10ft scaffold board and some right angle brackets. Measure the inside distance (say 9ft6 or whatever) then hang it over the boat (or place under if drydocked) and measure the distance from each upright to the side of the boat having already marked out the locations to be measured to ensure they are the same distance from an end.

Then take away the measured distances from the 9ft6 or whatever. Or acquire some giant callipers.

I must say I measured the width of my boat by looking it up on the canalplan.org boat list

[David Mack]

I must say I measured the width of my boat by looking it up on the canalplan.org boat list

Which will tell you what you or a previous owner wrote on the licence application form!

[magnetman]

Yes its non critical as it is around 12ft - not to be recommended for narrow boats

I even had a lock keeper telling me narrow boats were 6ft wide recently so definitely wouldn't trust what's on paper unless it was accurately measured and the measurement technique explained..

[Mick Poyser]

The spirit level method needs two spirit levels, one tape measure, two people with a very steady hand and a boat with no cabin on it as you will be measuring over the gunnel. Even when you have all your measurements you still don't know if they are all in a straight line.

[pete harrison]

Cassiopeia is gauged at 71' 9" and several people said the gauge is wrong as GU boats are 71' 6",

This is because "people" confuse nominal dimensions with actual dimensions

[Pluto]

The length of narrowboats was based on the approximate length of the smaller Mersey flats, which worked out at around 69 feet, the length of the box boats which worked on the Manchester Bolton & Bury Canal. Measurement for civil engineering was in its infancy, so a couple of feet was added to the length of locks on 1760s/1770s canals to ensure there was reasonable clearance. By the time of the Canal Mania in 1793, measurement had become more universal, and the length of locks tended to be kept to the minimum needed for the narrowboats of the time, and these are often the locks which are considered short today. The saving in cost compared to the added difficulty in passing the locks must have been considered unnecessary as subsequent canals built after 1800 tend to have long locks with good clearance. The whole problem of lock length was compounded by the independence of each canal company, with no specific dimensions being set nationally. The L&LC locks were based on the then current length of a Yorkshire keel, the A&CN locks being lengthened in the late 1770s to the same dimensions.

[Dharl]

To the OP, might find the link to the table on ABNB as a good guide to size of locks around the system.

 

http://www.abnb.co.uk/submenupages/length.html

 

 

Am sure others can say if this is accurate?

[larkshall]

Purely out of curiosity, what effect does ambient temperature have on the hull dimensions.

 

If a hull is measured in winter, is it smaller than in mid summer?

 

Some of you guys can obviously persuade your hulls through gaps I would baulk at

[MtB]

Purely out of curiosity, what effect does ambient temperature have on the hull dimensions.

 

If a hull is measured in winter, is it smaller than in mid summer?

 

Some of you guys can obviously persuade your hulls through gaps I would baulk at

 

 

Being a bit of a nerd I did the calcs on this a few years back.

 

A 70ft boat changes in length by about millimetre or so IIRC between heavy frost, and a hot summer's day. And still not taking into account the fact that the water it floats in rarely rises to 30 degrees C in summer.