How to navigate canal tunnels safely

As the canal builders became more confident and experienced, they faced geographical obstructions such as hills that would have taken many, many locks to overcome. Instead, they used dynamite and an army of labourers to tunnel through such hills, giving rise to some of the spookiest and most claustrophobic locations on the canals.

These tunnels can be incredibly long; Blisworth is around 2.8 miles for example. Harecastle is 1.6 miles. Standedge (pronounced “Stannedge”), which cuts through the Pennine hills, is simultaneously the longest, deepest and highest canal tunnel in Britain as it’s 5 miles long, 196 metres above sea level and 194 metres below the surface at its deepest point.

Whilst many of the tunnels are two-way for narrowboats – widebeam craft must book passage with the Canal & River Trust otherwise they will block the tunnel to oncoming boats – others are one-way, with a variety of mechanisms for organising who goes when.

Each tunnel will have a CRT notice visible shortly before the tunnel entrance. These are inexplicably printed in a tiny font so you need to be almost upon the sign before you can read it but once you can, it will state the dimensions and – crucially – any rules for how to proceed.

Those rules are particularly critical for the tunnels in which only one boat can pass at a time (else how would anyone know whether they could enter or not?) and, if you have a widebeam boat, for entering any tunnel since you will occupy the entire space, much to the surprise of anyone coming the other way.

The two-way tunnels will, at least to start, feel very narrow indeed but if it’s marked as two way then you can be sure there is – just – enough space for two narrowboats to pass. The key is to slow down to just tickover shortly before you pass the other boat, and keep as tight to the right hand side as you possibly can. And I mean tight – you should be mere inches from the side at most, which will leave a gap of a few inches between you and an oncoming narrowboat. Keep straight and don’t go into neutral as you’ll lose steering.

Banging into another boat as you go through is not uncommon and it can feel like an almighty blow – not everyone slows down as they should or is as much in charge of their craft as they like to think. If you are taking a fibreglass cruiser through this is definitely something to bear in mind as you will come off worst in a collision.

My suggestion would be to follow a (steel) narrowboat through very closely on the basis that they’ll take any impact from an oncoming craft which will then have to have straightened up to get past by the time it reaches you.

It is essential that you have a working tunnel lamp on the bow of your boat so that those coming the other way – particularly on one-way tunnels! – can see you’re coming and know whether to proceed. Tunnel lamps are a standard item on canal boats but do check it’s working before you go in and remember to turn it off once you emerge.

Also check the light is aligned correctly; the idea is to point it upwards and to the right so that it’s illuminating the tunnel wall, rather than pointing straight ahead as that can simply blind any oncoming boaters, particularly with modern LED lamps.

Some one-way tunnels have a timed system for passage (for example, boats going north may enter on the hour and up to quarter past; boats coming south may only enter on the half hour). Others are sufficiently short and straight that you simply look to see if anyone’s coming, and go through if not (or wait, if you can see an oncoming tunnel light). This example shows why it’s crucial to check your tunnel light is working before going into tunnels.

Harecastle tunnel has CRT staff who permit traffic to go one-way or the other way, with both ends working in coordination so that boats are only ever going in the same direction. The tunnel has gates across it to stop traffic going in uncontrolled.

Excitingly, Harecastle gets successively lower overhead as you travel through until you actually have to crouch down while steering in order not to crack your skull on the rocks overhead (fortunately, once you’ve gone past the middle, it gets steadily greater headroom again)

Standedge Tunnel has a system where you must pre-book and your boat will be checked to ensure it will fit the tight dimensions. A CRT guide will also accompany you on the trip through. Going through it takes about an hour and a half.

Blisworth tunnel in Northamptonshire is helpfully very straight so you can generally see the exit the whole time you’re in there, though it starts as just a tiny speck in the distance. Travel time is about half an hour.

Braunston tunnel is not massively long and needs no booking but has several kinks in its path making for an interesting experience when two (long) narrowboats try to come past each other on the curved bits.

All these peculiarities of the tunnels are well documented on the CRT’s website and in the guide books.

The rivers don’t tend to have such tunnels because they are natural waterways that found their own path rather than having one dug by human endeavour.

One final note: it is generally advisable to wear a hat through tunnels as there are often leaky sections where water from the ground above dribbles through!