The Woolwich Ferry did run a quite limited service at the start of this week. I discussed it very briefly in the sidebar news update whilst another blog Murky Depths also covered it too. On Monday morning I was alerted by a single tweet on the fact the ferry had run. It was subsequently found it had run two limited service periods. These were Sunday late afternoon just a few crossings before its advertised closure time. Also Monday morning about 9am onwards. Today its not running nor tomorrow and the rest of the week – expect very possibly at times of lower tides.
Why does the ferry have a delay in restarting its services? And why are there limited services at certain times only? Its all simple as will be explained. First the issue with the ferries is one of docking. They can of course dock and the magnetic mooring system does work. However the new ferries are trying to emulate a system built for the 1960s ferries. There are modifications of course otherwise the issue is the new system doesn’t exactly allow the ferries to dock easily.
Dame Vera Lynn on the Woolwich side.
Ferry staff have told me the problem is indeed the docking system. I visited the ferries today and met a couple of the staff. From what I understand plus some reasoning of my own its to do with how the old and new arrangement works. The old arrangement was built exactly to fit the 1960s ferries whilst the new and modified arrangement is one for the the 2018 built ferries but doesn’t work properly.
I have shown this view before its from Twitter and shows the pontoon (the furthest one depicted in the picture) that goes under the terminals. Source: Twitter
This is my interpretation of what is happening – its just a discussion, its not fact based however I believe it reasonably describes what’s happening (this is backed up by a video showing the difficulty trying to moor the new ferries against the new piers.)
With the old ferries it was an ideal system. Their bows went right beneath the piers. The rounded bow fitted underneath the piers like a hand in a glove. The holding position was essentially at the front of the ferry and the ferry slid into position.
The new boats are much longer and they have flat sides and bows. Essentially what the new boats are trying to do is fit two absolutely flat surfaces together – their own bows and the edge of the floating pontoon/piers. The holding surfaces are both at the front and on the side. So what seems to be happening is two sets of straight surfaces at 90 degree angles are trying to fit together.
The flat surface of the pontoon the new ferries are trying to dock against without any sort of interface present…
No matter how well, how skillfully the boat is brought in its not going to work well. There are also the tides to consider, its a very fast current here. (its not fast in terms of flow but in terms of eddies and surges because its tidal, if one does not know what the river is doing its going to do the unexpected – and quickly.)
Thus when the boat is brought in towards the piers and the fitting looks good, the boat’s momentum as well as the currents will move the boat out of line. It means the captain keeps having to compensate and make each manoeuvre smaller until it can achieve a perfect fit and the magnetic mooring equipment can come into play.
The other problem is the magnetic mooring equipment doesn’t reach out far enough to catch the boats as they come in, the boats have to go right in and fit perfectly into the arrangement before they can be caught by the automated mooring system.
Its like trying to bring a rectangle block around on an arc and fitting it perfectly into a 90 degree corner. No matter how excellent one makes an approach with their rectangular block its rarely going to be a perfect fit first time. Conversely no matter how well the boat swings out as it crosses the river its arc is probably not wide enough plus the momentum of the ferry itself and the flow of the river will also be a problem – boats rarely do exactly what one wants so there has to be a considerable amount of leeway and the new system just wants a perfect fit!
The old ferries simply swung round as they crossed the river and then slid into holding position, their rounded bows making the process much easier and I have included these two pictures to show how they docked.
The old ferries had six contact points against the piers (besides those alongside the boat itself) four of these contact points ahead of the bows are shown.
The position of the contact points ensured the old ferry was held exactly in position regardless of the situation – meaning it could not start to slip back out into the river.
As has been said before the new ferries are are contacting a flat surface to another flat surface with no means of suitable interface at all as the picture below shows. (The recess is for the anchor its nothing to do with the docking.) If it was a rounded bow like the old ferries (or even a pointed bow) it wouldn’t be a problem.
Ben Woollacott’s stern (which also doubles as a bow as the boats are bi-directional.)
In the case of mooring other vessels, boats, schooners, yachts, ships whatever, its just a question of throwing the ropes ashore and tying these to bollards effectively bringing the vessel to a stop hard against a quay. Its a time honoured way of making sure craft stop – and stay where they are supposed to be.
Another view of Ben Woollacott’s bow showing its flat across its breadth and curves down to the keel. No interface of any sort….
The new ferry has got to match with the front perfectly before it can match the sides perfectly and only when that happens can the magnetic mooring equipment come into play. There’s nobody to throw ropes to to help bring the boat in squarely! It probably means there is either a design or interface issue at stake. I couldn’t say if it was simply one that had been overlooked or whether it was one the designers should have forseen, I mean, they have their computers and predictions and they are the experts, not me!
Expanding a little more on the mooring issue, if one looks at the few chain ferries still in use (this example is because chain ferries are almost always rectangular shaped) are supposed to dock quite perfectly either side of the river however they almost always crash and bang into the quay because their momentum wants to continue forward – or the currents affect the boat’s steer, and its hitting the quay and then bounces off. Its at that point the ferry operator then has to adjust each set of chains separately in order to pull the boat squarely onto its mooring. Although chain ferries have their uses they are not exactly convivial!
The approach roads have been resurfaced and new lanes and markings introduced – as well as electronic signs and lights on the approaches.
The new ferries dont have any chains, or ropes, to pull them in squarely. The other problem of course is when the propellers are reversed to slow the ferry down the thrust invariably pushes the ferry away from the piers. Short bursts of the propeller has to be used of course to achieve corrections but again the set up is not so easy as on the old ferries. I don’t think they could use the props to thrust the ferries into the piers because it would cause them to crash and that would not be acceptable. With the old ferries once they acquired contact with the piers they could put the boat in full forward and it would stay there.
With the new boats the flat surfaces constitute a bounce point thus the prop and steer adjustments have to be much lighter. The other factors, current, backwards thrust, loadings, wind direction, undertows etc all conspire to spoilt these fine adjustments. It hasn’t been said yet however I can see these boats struggling in very strong winds because their shape means they will act somewhat like a sail.
It would be completely different if ropes were being used to tether the ferry. Since the ferry is relying on an almost perfect manoeuvre its a bit like asking for the impossible.
There are other factors too such as load and distribution and tides and currents and undertows plus the fact the ferry sticks a third of the way out from the end of the pontoons which means there is little in terms of mooring estate. I know from experience a mooring location which is much shorter than the vessel itself is very often going to be a problem. Although I did write these in more detail originally I decided to exclude most because it complicates the descriptions a bit too much.
The pontoon underneath the terminals has some rubber matting however I don’t think its sufficient to grip the boats in place – not enough surface area ratio to the boat.
The problems leads me to think there may have to be some slight modifications to the bows of the ferry and the piers, like some sort of interlocking system to hold the ferry in place while it adjusts in order to fit the longer side against the magnetic mooring piers. I cant think of any apt descriptions so I’ll just use Tower Bridge as a rough example! This, like most movable bridges, has an interlocking system which holds the spans in place as they meet each other and keeps them in position. Otherwise the bridge would be all floppy and it wouldn’t stay in place – exactly the problem with the new ferry. It needs an interlock of some sort to catch it and keep it in place otherwise its just going to be ‘floppy’ and attempts to dock it take up valuable time.
The construction of the ferries in Gdansk as evidenced by this link shows they do not have anything of the sort I am describing such as interlocking systems or a different connector of some sort (like a pair of super strong steel lugs that fit into a hole in the floating pontoon.)
Ironically as this picture shows when the new ferries are berthed out of use they are tied to the piers! The magnetic mooring dolphins are then retracted out of use.
It may be another reason why the operators are sticking their limited services to lower states of the river. The flow of the river is generally going to be lighter, and there are less powerful eddies which may make the docking somewhat easier to do. The limited services that have run so far have only been done when the tides are lower and a check of the tide tables proves this.
The slowness of the new system means it takes too long to make one crossing. The staff confirmed to me it was very slow trying to moor the ferries in position. As long as it is like that they cant really run a proper intensive service like every ten minutes or even less under the old system because its quite time consuming trying to get the boats into position and there also is the loading and unloading of vehicles to consider.
One of the captains of the old ferries, David Watkins, had said bringing the boats in was rather like cracking an egg. It had to be done right. It didn’t have to be perfect because the piers helped but there was still a certain method to it. With the new boats its obviously got to be absolutely perfect! Its probably akin to cracking a egg on a nano scale!
One of the staff said they were hoping a service could start from next Monday (14th January) but its dependent on the problems being resolved.