Hackney Central Mon.18thFeb.1026.
HOW TO NAVIGATE A TRIBUTARY OF A TIDAL ESTUARY ON DIESEL FUMES
Among the many adventures undertaken by Pentargon during her seven year English odyssey were taking tides down estuaries and using the flowing of waters to heel and heft the hulk up an unsuspecting river with the flow and against the odds. The serious side of the game began with an initial visit to Dartford Creek during the Spring of 2015 which involved going down the Thames to Crayford Ness and blundering up Dartford Creek to a safe haven and a stay over.
In an article on the re-opening of Dartford Creek to traffic, the August 2018 issue of "Canal Boat" tersely reported that "a first waterborne visitor, narrowboat Pentargon Springer, was followed by others". Fair comment, but the real truth was more interesting and it is pertinent to share the whole story with you. Pentargon was the first boat in almost forty years known to overnight in Dartford Creek, having tied up alongside at 5.30pm on the 26th April 2015, with FOUR London narrowboat skippers on board. Dartford volunteers had excavated an old mooring bollard from under forty years of neglect to provide a purchase point for Pentargon's lines on that first visit. What was not known was how much pre-planning and surveying had gone on for months prior to the first arrival.
IWA AND OTHER VISITORS
IWA boaters had taken boats up Dartford Creek to the head of navigation and back again on a single turn of tide, scurrying back to The River while they still had water under their heels. However, there is no evidence that anyone had gone to the head of the Crayford Arm and certainly ne'er an admission ever that anyone had stayed over for a tide or two or twenty as Pentargon did on a number of visits that first year.
WHERE WAS PENTARGON WHEN THEY DID NOT NEED HER
Pentargon missed the Dartford Nautical Festival in 2018 as she was engaged in her greatest adventure ever: the biggest waterways ring ever attempted in England (and almost Wales!) by a solo boater. As the Festival got under way with a bevy of St.Pancras worthies and the Thames Barge Decima, Pentargon was on the Staff.& Worcs near Penkridge. A long way to the west of Dartford. She was, that week, at Gailey Wharf being modified by Jamie Ferguson to comply with "ClassD" inland waterways use, prior to joining Sharpness to Bristol some weeks later. Her freeboard was raised to 760mm so she could cope with water where "maximum wave height might reasonably be expected not to exceed 1.6 - 2.0m".
Reports on the methodology used to get the bevy from London to Dartford was noted from the distance with associated amusement that no-one from St.Pancras Cruising Club arranged a briefing from the one skipper who knew the Creek intimately and all its foibles. Nobody outside the Dartford group knew that I had made multiple visits to the Creeks in 2015 and 2016 and had stayed in the Creeks on the boat for a total of five months. And even the principals there had only the vaguest of notions as to what I was up to. It was I who did all the tide surveying, depth sounding and observing of how tide interacts with river. The knowledge was shared on a need to know basis and Condar Broadley brought his sloop right up to a mooring close to the old wharf at Crayford. I'd moored by Steam Crane wharf and above it and had also pitched up on various berms using a lifetime's knowledge of tides and how they work in tidal rivers. I'd explored Crayford Creek in all weathers and at all stages of tide to see what could and could not be done with a 36' narrowboat in uncharted waters.
A SORT OF A SAILORS CV
I was born by a tidal estuary (Colligan River at Dungarvan) , grew up by another , sailing boats from childhood and learning the ways and wiles of tidal estuaries over decades. I even crossed the Shannon Estuary, using the tide, by descending the Ratty River from Bunratty and crossing all the way to the Limerick shore and back. On a blow up inflatable!
At the turn of the century I came to live by the Thames estuary and learned from old codgers, retired rivermen and lightermen, ferry skippers . I'd amassed an enormous fund of knowledge of practical hydrometry on many trips up and down the estuary as a volunteer engineer/navigator on the sail-trainer "Kenya Jacaranda" and later as a volunteer with the London unit of the Maritime Volunteer Service, where I learned the Thames from Teddington to Southend. The old men showed me tricks that have yet to appear on the web or even in books. Maybe I should start writing?
Getting my own boat in 2012, I realised its potential as an Estuary Explorer. It was a very unusual build as narrow-boats go and detailed study brought to light that it had been constructed using ship-building techniques. Dammit it was a ship and it's on the small ships register. (SSR161019) so once I became a boater, I punted a narrow-boat which could go down to the seas I'd come from. It's unique features were exploited to the full in various ascents and descents of the Thames from Teddington or Brentford to Limehouse or Bow using the tides to carry the boat hither and thither.
This article is written to show future skippers how to deal with a river creek on a tidal estuary. The method has been used to transit from Brentford to Bow, to access the semi-tidal part of Barking Creek without using the lock, Dartford Creek of course and Bow Creek . . . in all cases using a 36' Springer with a Lister SR2 running at no more than 900rpm and delivering about 6HP
DESCENT TO DARTFORD
DESCENT TO DARTFORD
The first descent to Dartford was done by exiting Bow Lock at the top of a tide which would flow us down Bow Creek and out to sea. Minimal science was used that day. We had planned for the tide to deposit us at the mouth of the Darent at 11oc, about which time the Tilbury tide gauges would be reading about 3m and dropping. All we had to do was nose the boat into the creek, punch whatever water might be still coming out and drive the boat aground in the channel. The tide then could ebb away and enter its next cycle. Once it had got deep enough, we would be floated off and, as the tide continued to rise, the water flow in the creek would push us upriver. This began to happen about 2pm but of course we were aground again in short order. Bit by bit we proceeded, stopping and starting as time and tide lofted us higher and further inland. It was almost 4.30pm when we came to our last grounding. Just below Bob Dunn bridge is a massive shoal of Kentish mud caused entirely by the water flow under the bridge and the associated venturi.
ASCENT TO DARTFORD
Once through Bob Dunn, the boat began to move forward with less and less stops until we were in sight of the lock and the quay. Here another massive mudbank caused by the lock itself (and forty years of neglect) stopped us awhile. We got in about 5pm but could not breast the cill at the top end. So we tied up and were warmly welcomed to Dartford by the Friends of Dartford and Crayford Creek. The boat crew had had a long day, so they took off for Dartford Railway Station and oystered their way back to London in time for tea. Pentargon and I waited for another hour or so and slipped over the cill as soon as our 24" draft allowed. We were "home and dry" as it were.
THE UPS AND DOWNS.
Take it as given that the bed of a tributary will be higher than the main river.
Take it as given that you go up a tributary on a rising tide. Rather obvious?
Take it as given that the vice is versa and you come down on a falling tide.
However, it is not always obvious that the river itself has its own flow, dependent on how much rain is falling in its basin, or not and (in England) how much water is being nicked upstream, or not. The height of tide appropriate to the Darent is measured at the nearest tide gauge at Tilbury, some five miles downstream or eight if you are at the cill by the lock. Water commences flowing over the cill when Tilbury is reading a REAL 5meters. It took weeks of comparing tidal predictions with real-life measurements to establish this gem in 2015 and since I did not want to get on the collective nerves of London VTS staff at Gravesend by phoning them up frequently, I had to make an aerial tall enough to read their broadcasts or walk almost a quarter of a mile along the river dyke to find a place where my handheld VHF could get a signal. Both methods and others were used at first. There was no published data to fall back on. All the Hufflers were long dead, (and now even the pub is closed!) the last lock-keeper was frail. Yes I got to meet him and his children but the knowledge was gone. Actual figures had to be dug out of nowhere. Even the Royal navy had nothing to offer. They wanted to forget all about Dartford Creek for reasons best kept mum.
RISING TIDES LIFT ALL SHIPS
Similar methodology and tactics established that Pentargon needed 4m at Tilbury to enter the creek without grounding, 5m would run her up to the cill and 5.6m was the minimum that would allow her to scrape over the cill on a rising tide. Fine tuning of the data showed that the tide at the cill happened about 20mins after the tide at Tilbury. Coming and going, showed that it took Pentargon at least half an hour from Crayfordness to Steam Crane Wharf situated on the town side of the lock. Back in the day when all the greaseproof paper in England was made there and Dartford was a thriving town bloated by paper making and pharmaceuticals, the steam cranes lifted the raw material in and the finished paper out.
Tilbury 6.3m was another crucial measure. This was the tide that allowed Pentargon to float onto various berms and effectively dry out under the boat. 6.9m at Tilbury was the highest tide recorded at any time during my stays and in practice anything over 6.2 was rare. This meant that at times when Pentargon was aground she might not be able to come off for months. It did happen once and very nearly prevented her from leaving the Creek late in October of 2016 which might have been a disastrophe.
Another variable for regular users of any of the tributaries is the Thames Barrier. It's in the gift of the Environment Agency to monitor weather and tides and act on such knowledge. About once a month they test the system by closing the barrier, dropping the Barking and Dartford cills and, of course, whenever or if-ever there's a flood threat to London, the order goes out to do it for real and that gets on the news.
THE REAL DEAL
The basic method for getting into Dartford is to approach it from the QE2 Bridge side on a rising tide. If you've come down from London you'll have moored up somewhere (Greenhithe moorings is a good choice as you can listen to LondonVTS half-hourly river transmissions on Ch69) and if you use the actual buoys there, you can stay afloat. I usually just drop an anchor about 50m on the land side of the buoys. Once you know Tilbury has passed 3m rising you can let go and drift gently up the Kent side past Littlebrook Chimney. There is absolutely no reason to cross over. In fact I would never recommend that. You are a narrowboat fogodsake. You have a draft of less than 1m. You are defined as a "pleasure craft" and, if you've done your planning you're on the Small Ships Register [mine is 161019. what's yours?]. And if you are under 42'/12.5m you don't even need a radio although this scribe likes to keep the PLA sweet. Letting the tide drift you up from Greenhithe, you'll approach Crayford Ness about 3/4hr after weighing anchor. The tide will be near enough to 4m at Tilbury and running well in its third hour. Since you are well inshore and in shallow water, you needn't worry about the flow. The Dartford Channel will be very obvious when you get to it from Littlebrook side, whereas it is very difficult to get right if you had come up the Essex side and try to cross at ninety degrees following the book. Trust me on this one, you WILL miss your turn off or have to use mighty power to describe a parabola because you paid no attention to what i have been telling you so far. Let the tide work for you and steer yourself in gently. Dartford Creek is filling and the flow rate is increasing [rapidly] over the next 30mins as you drift along. My own experience of water speeds is that you may get 2kts beteween the barrier and the Crayford turn off and then 1kt up to and beyond Bob Dunn.
You will reach the lock with Tilbury 5m+ and the rule for getting over the cill is to add your draft to 5m. pentargon draws 0.6m so i can pass at Tilbury 5.6m. Most narrowboats have their deepest point over the tiller; certainly Pentargon does, I can stick the bow over the cill from about Tilbury 5.3m and the rising tide will slowly ease me over in its own time.
Hackney Central Sat.16thFeb1525
Hackney Central Mon.18thFeb10.34