You may be confused by the chronological liberties we have taken with the blogs so far. I apologise. Please let me start this one by putting events so far into context: we bought a boat in Gayton, Northampton on the Grand Union canal, we had a torrid first night on board disturbed by our inverter woes and we then had a tunnel ‘adventure’ at Blisworth – so far all running in order. In the last Blog Pip turned her thoughts to stocking the boat and, as a result, naturally digressed into her toilet calamity – which actually happened in Newbury, on the Kennet &Avon canal.
So what happened in between you may be asking?
Let me take you back to Stoke Bruerne – our destination after ‘surviving’ Blisworth. You may remember we were cruising down from Gayton to meet Jackie and Neil, friends of Pip’s brother Robbie and his wife Sue, who had volunteered to move The Frog down to Newbury for us. The liaison was important for two reasons. Firstly we had not met Jackie or Neil before and secondly, they had never crewed a narrow boat before!
Neil and Jackie arrived and introductions and coffee duly delivered, we set off South. This stretch of the Grand Union was perfect for the task in hand – we were going to go through seven descending locks and then, at a brilliantly placed Winding hole, turn around and do the locks again – but this time ascending – before going back through the Blisworth tunnel and ‘home’ to Gayton. I reassured Neil that I would take us through the tunnel – having foolishly detailed our adventures of the previous day and watched his face turn white. However, it was important he had a chance to go through the locks and that Jackie – who would probably be doing all the hard work – understood how a lock worked (and the precious lock etiquette).
Locks and Lock Etiquette
Many readers will be Boaters themselves and can skip this next section. For those new to canals and possibly our overseas readers, I thought I should explain what a lock is – as they feature very heavily in the life of a cruiser and I didn’t want to assume any prior understanding. So here are the FAQS:
Q: What is a Lock? The British countryside is inconveniently hilly and the history of canal construction is, in part, finding ingenious ways of dealing with this challenge (along with many others). Water flows and the canal’s primary purpose was to facilitate the movement of heavy and large cargoes safely and ‘quickly’ (a relative term in the late 18th century). In order to do this it was important that water flow in the canal was controlled and regulated. When the level of the terrain changed there were various options available to canal engineers: Change course – explaining why many canals meander and follow the contours of the land. This can be the cheapest option but added distance to the journey and ultimately may affect attraction to Toll payers using the canal after construction; Build a tunnel – see my previous Blog on Blisworth. This is probably the most expensive option, has the longest construction time and was the most dangerous during construction. Ultimately, however, it is the least disruptive and most attractive to subsequent commercial users – assuming your Bow Light works; Build a lock – or a series of locks – called a Flight or Staircase. A lock is simply an ingenious way of moving water (and therefore anything floating on that water – like a narrow boat) – from one level to another.
Q: How does a Lock work? This is best described by way of a diagram
So referring to the diagram above. Each lock has a gate (or pair of gates) at either end. The Top gate is at the deeper end of the canal and it follows the Bottom gate is at the shallower end. In between is the ‘Lock Chamber’ – which is where the lifting and lowering takes place. Water flow is controlled in and out of the chamber typically through Ground Sluices, Culverts, or Gate Paddles – or a combination of these. Locks can be single use or wider to allow wide beam vessels or two narrow boats to rise or fall simultaneously (hence two gates).
So a typical cycle is like this: Assuming we are approaching a lock via the top gate and assume the lock chamber is full of water (sometimes it is not and this is where part of the lock etiquette comes in – see later). The top gate should have been left closed and our first task is to open it. As water pressure is equal on either side it should open easily (Pip may disagree as all gates are very heavy (typically made of oak and clearly designed to hold back many tons of water) and the mechanisms are not always well maintained). Anyway I digress. The gate is open and we move the boat in – being careful not to hit the gates or chamber wall (not always achieved!). The top gate is closed behind the boat. It will have become clear that going through a lock is ideally a minimum of a two person job – but many solo cruisers do undertake it – albeit a bit slower. The crew member on the bank then moves to the bottom gate and starts to raise the paddles/open the sluice gates. This is achieved by turning the paddle mechanism using a specially designed tool called a Windlass.
The speed at which gates and sluices are opened also falls under the Lock Etiquette banner (assuming you are sharing a lock with another boat) and will also vary depending upon whether you are descending or ascending in a lock. Descending is less of a concern when it comes to water speed. The water is effectively leaving the chamber and emptying into the canal beneath the lock. Assuming there is no boat moored nearby the gates can normally be opened fully and the descent be reasonably quick. In these situations I always stay on board and control the boat using the throttle – moving gently backwards and forwards as the water flow out of the chamber dictates. This is important as when descending there is a hidden danger beneath the water called a Cill. The Cill extends into the chamber at the foot of the top gates – which are always less deep than the bottom gates (as the water level behind them is higher) and allows the top gates to close onto it and create a good seal. It’s typically concrete and is a risk if your stern is above it as the water level drops. On the chamber wall the position of the Cill is always marked and as long as you pay attention you should avoid grounding out on it. When the water level in the lock chamber matches that outside the bottom gate, the latter is easily opened and you can pass on your way – remembering to stop and pick up your crew member before cruising on! Oh and of course making sure they have closed all the paddles/sluices and pushed the bottom gates closed – unless another vessel is about to use the lock (see etiquette below).
The Cill is obviously not an issue when you enter an empty lock and ascend but the speed of water ingress is!
Let’s explore this more. When ascending you enter an empty chamber through the bottom gate(s). The bottom gate is closed and the top gate paddles/sluices are opened. Sluices normally open into the base of the chamber but are still positioned on either side. Gate paddles open in the gate and can be above the height of the bow of the boat at the start of the ascent – with a risk of flooding the deck if opened too soon. Both of these facts present obvious challenges. As one sluice is open the water ingress will push the boat back and to the other side of the chamber – risking damage to both the boat and the wall if too violent. The faster the sluice is opened the more severe the impact will be. It follows that these processes need to be controlled very carefully. To mitigate the risk, typically the sluices are part opened and ideally opened on the opposite side to the boat first (assuming a double lock width and no other boat is present). This will push the boat towards the wall it is closest to. I should explain where I am at this point. When ascending I always leave the boat, climbing the ladder out of the chamber and take hold of the Centre line (a rope attached to the middle of the boat roof – as opposed to the Bow and Stern lines). On the bank of every lock you will find conveniently placed mooring pins that allow boaters to secure their craft – using the centre line. I don’t tie the boat up – as this will present obvious problems when it rises in the chamber(!). Rather, I hold the line in place, keeping the boat tight to the wall to off set the ‘wash’ effect of the sluices opening and slowly release the line to match the rise of the boat. When the water reaches a certain level the turmoil in the lock subsides and I can get back on waiting for the top gates to open – then I can move off. Sounds complicated I know but there are some great videos on line that bring it to life. In one of our future Vlogs we will ensure we show you The Frog (and Pip) in action.
Lock etiquette is important. It is not just about respect and consideration for fellow boaters. It’s also about respect for the canal network itself and the important consideration of ‘Saving Water’. This concept may seem hard to understand. Don’t we live in one of the rainiest countries on earth? Is water really a problem? The answer is yes its – all year around but especially in the summer months – when it is naturally dryer and many more users are on the network. Water may be abundant generally but not necessarily feeding into the canal network. When they were constructed huge efforts went into building reservoirs and pump houses linking canals to water sources in order to ‘feed’ the canal. Every time a lock is emptied water is moved from one section of the canal to another and continues on its way. This water needs to be replaced. In some canal sections this is straightforward, possibly with a reliable river feed. However, in many it is not and even river levels can run low at times of peak use. For this reason locks are sometimes ‘closed’ for certain times each day as well as placing an onus on canal users to act responsibly when using the lock.
If a lock keeper is on duty, always follow their instructions. You will usually be expected to operate the locks yourself, but under instruction or supervision. Some locks, particularly rivers are always operated by lock keepers. Most locks, however, are self-operated.
If the water is in your favour (e.g: you are approaching a full lock through the top gate), you have right of way; if the water is against you then a boat seen coming towards you has right of way, as they can make use of the water. You may have to wait a few minutes for the oncoming boat to get into a position to use the lock. So you should always look ahead before emptying or filling a lock just for your use. Even if a boat is some way distant – wait until it arrives so they can ‘use the water’. Equally, if you approach a double lock on your own, look aft and see if another boat is coming. If it is wait until it arrives and use the lock together.
Do not be tempted to use lock moorings for overnight stays or moor there for longer than it takes to do the lock as you will be obstructing other users.
If a boat is coming towards you as you exit the lock, leave the gates open for them – this the only time you will do this as leaving the gates open any other time places additional strain on the lower gates and can increase water loss through leakage. Read all signs at the lock carefully. Some older or deep locks have signs that ask you to leave the lower gate paddles open when you leave – again normally a sin. This will have the effect of taking pressure off the gate and should be obeyed. To do this any other time is not acceptable. When mooring overnight in Newbury recently a boat passed us heading down the nearby lock and left the top paddles open. We did not notice but when we moved upstream the next morning boaters moored further up the canal had seen a noticeable drop in the water level with one owner shouting ‘we were hanging off the bank first thing’. A tight mooring rope would cause the boat to tip slightly in these circumstances – not great!
Anyway – I think that is enough on locks. We will return in future blogs with real examples. the next blog we will return to Stoke Bruerne and out first trip out with Jackie and Neil – and you will now have an appreciation of ‘lock craft’ and appreciate Neil’s natural ability on the tiller having never encountered a lock before!