to show narrowboat skippers how to deal with a river creek on a tidal estuary.
The boat used was a 1973, 36' Springer with a 1968 Lister SR2, running at 1100rpm, delivering 6HP to the prop, translating to 2kts over still water.
The method was developed on the Thames from previous experience as a volunteer engineer/navigator on a sail training ship based on the Thames
... the method was used to access Barking Creek without using the 'municipal' lock, to enter and explore Dartford/Crayford Creek over two Summers ... and Bow Creek with its access to Bow Locks ... and in 2017 to navigate solo from Sharpness via Portishead to Bristol
Background to Pentargon's skipper ... "Born in Ireland by a tidal estuary ... grew up by another tidal estuary ... where I sailed dinghies from childhood ... reared family by the Shannon estuary ... learning the ways and wiles of tides and estuaries, crossed the Shannon Estuary in 1990 using tides to descend the Ratty River, proceeding to the further shore and returning on a rising tide, using a leaky blow-up inflatable!
In 1999, I came to live by the Thames Estuary and expanded my estuary lore, befriending old rivermen, lightermen, ferry skippers and, indeed, anyone who would talk with me. They all seemed to recognise 'one of their own' or at least someone who spoke the same language as them. I found them easy to listen to and easy to learn from. I amassed an enormous amount of river lore from assorted old codgers on many trips in the Estuary, especially as a volunteer on the sail-trainer Kenya Jacaranda.
Later as a 'stoker' with the London Unit of the Maritime Volunteer Service I learned the urban Thames from Tower Bridge to Teddington, and the seaward reaches to Southend, including why the Barrier will not save London and what depth the water will be on Mile-End Road when it does fail.
The old men showed me tricks played by Old Father Thames which have yet to appear on the web or even in books. Getting my own boat in 2012, I realised its potential as an Estuary Explorer.
Pentargon is an unusual build as narrow-boats go and a detailed investigation brought to light that she was constructed using ship-building techniques ... and so, having became a boater to explore the ditches of England, I could also go down to the seas I'd come from again.
And I did! Pentargon was and is registered as a 'small ship' (SSR 161019) and her unique features have been exploited to the full in various ascents and descents of the Thames from Teddington or Brentford to Limehouse or Bow, using tides to carry the boat hither and thither upstream initially before venturing the other way! Then in 2017, during the longest solo ring ever completed on Britain's Inland Waters, the estuary experience was put to the ultimate test on the Bristol Channel.
"Rivercreek" was inspired by Martin Ludgate's article "Up the Creek" (Canal Boat, August 2018), where he credited Pentargon for kick-starting the use of Dartford Creek as 'a leisure destination for 'intrepid canal boat skippers'.
Among many adventures undertaken by Pentargon during her ten-year odyssey, the more spectacular ones have taken outgoing tides and used a later inflow to haul her up unsuspecting rivers with the flow and against the odds.
I consider the Thames estuary fair game; it frightens most London boaters. Tides? Waves? There be disaster unspecified.
The first visit to Dartford Creek, early in 2015, involved going down from Bow Lock to Crayford Ness, blundering up to a safe haven and staying over.
Much pre-planning and surveying had gone into the months prior to that first arrival. There was no 'CreekData' before Pentargon's arrival. I had to make my own.
Volunteers had excavated an old mooring bollard from beneath forty years of neglect to provide a purchase for Pentargon's lines on her first visit: the first boat in forty years to overnight in the Creek.
Pentargon tied up alongside at 5.30pm on the 26th April 2015, having descended on a wing and a prayer from Bow Lock with a crew which included three intrepid London skippers and arrived under my helm.
Over the years, the IWA took boats up Dartford Creek and down again on a single turn of tide, scurrying back to The River while they still had water under their boats but no evidence that they or anyone had gone up the Crayford Arm. Certainly no admission that anyone had stayed over in the Cray, as Pentargon did on a number of visits during 2015 and 2016.
It is worthy of record that, as a result of the years of neglect, I was not able to make up to Crayford Wharf in 2015 due to a stand of mature alder trees, which the Dartford group contrived to 'dissipate' with the help of some National Rail engineers and tree specialists who happened to be working in the area, thus clearing the Crayford Wharf approaches to their advantage and that of future RiverCreek adventurers.
The "Tuesday Night Club" had visited the Dartford arm, with Steve Haywood hitching a ride but I have yet to nail the full story!
Conrad Broadley took his sloop up to Crayford in 2016 and overnighted too but had to leave, at 4.30am, to catch a very early tide due his deep draught keel.
The Thames barge 'Decima' was next to brave it, leading to the inaugural Dartford Nautical Festival in 2018 involving a whole fleet of narrowboats from St.Pancras Sailing Club. Pentargon missed that auspicious weekend, being fifty five miles upstream resting in Nauticalia's yard at Shepperton.
Pentargon had recently completed the most diverse and extensive British Waterways ring ever achieved solo.
In June 2017, she was logged at Gailey Wharf being modified to comply with "Class D" Inland Waterway Use, a class higher than she would ever use or need.
All the tidal Thames between Teddington and Gravesend is "Class C" and all the Bristol Channel north of Avonmouth is the same! In August 2017, Pentargon would take the tide from Sharpness to Bristol using the "Rivercreek Technique".
(and you are allowed to infer that there was only one person on board)
Reports on the methods used to get the London adventurers to Dartford for the 2018 festival were noted with amusement by this scribe. No-one from that auspicious and intrepid group thought to contact the one sailor who knew the Creeks and the Thames intimately. But they came to no harm. Outside of the Dartford group, no-one else knew that Pentargon had made multiple visits to the Creeks in 2015 and 2016 and had stayed over for weeks at a time while on a C&RT licence.
I did all the tide surveying, depth sounding, observing how the tide interacted with the Darent and it was better than a Master's degree. I moored by Steam Crane Wharf, pitched up on various berms and explored Crayford Creek in all weathers and stages of tide to see what a narrowboat could and could not do in an uncharted River Creek.
FIRST DESCENT TO DARTFORD
The first descent to Dartford was done by exiting Bow Lock at the top of an 8am tide [photo] which flowed Pentargon out to sea without any fuss. Minimal science was used and the method is centuries old.
We got to the mouth of the Darent about 11oc with the Tilbury tide gauge reading 3m and dropping. I turned the boat into the creek once we cleared the Ness and drove the boat aground in the channel.
The bed of the Darent is higher than the surface of the estuary so the tide could ebb away all it wanted and enter its next cycle.
Pentargon would be going nowhere for the next four hours simply because it had been grounded. This trick works only with 'flat-bottomed' boats or one with twin keels.
Once the water returned, about 3oc, we floated. As the tide continued to rise, the flow up the creek pushed us upriver and, bit by bit, we proceeded upstream, with repeated groundings as time and tide lofted us higher and further inland.
About 4.30pm came our last grounding. Just below Bob Dunn bridge is a massive shoal of Kentish mud. Once by that, the boat began to move forward with less and less stops until we were in sight of the lock and the quay and the welcome party, the members of whom could not understand what was taking us so long.
Here another massive mudbank caused by the lock itself and forty years of neglect stopped us awhile. We got in to the quay about 5pm but could not breast the cill.
So we tied up in the lock and were warmly welcomed by the Friends of Dartford and Crayford Creek. The boat crew had had a long day, so they took off for the railway station, oystering back to London for tea.
I waited another hour and slipped over the cill as soon as my 24" draft allowed.
Pentargon was "home and dry" as it were [photo]. During the night I played with the lines as the night tide flowed and ebbed.
"CANAL BOAT"
Martin Ludgate, in an article on the potential development of Dartford Creek, in 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 story is worth sharing with you.
Dartford volunteers had excavated an old mooring bollard [photo] from beneath forty years of neglect to provide purchase for Pentargon's lines on that first visit: the first boat in forty years to overnight in Dartford Creek. Pentargon tied up alongside at 5.30pm on the 26th April 2015, having descended on a wing and a prayer from Bow with the skipper and three intrepid London boaters on board.
TAKE IT AS GIVEN ...
that the bed of a tributary is going to be,
by definition, higher than the main river.
that any boat can go up any tributary
on a rising tide without any power
so long as she is "under command"
The Hufflers did it thus and the vice is versa
Punching is for boxers and leather workers
Hufflers or sailors do not punch tides.
They go with the flow
Each tributary has its own flow dependent on its size, how much rain has recently fallen [or not] in its basin and how much water is being nicked [or not] upstream .
The height of tide appropriate to Dartford is measured from the nearest tide gauge, at Tilbury, five miles downstream from the mouth of the Darent or eight 'water' miles away if you are at the cill by the lock.
Water flows over the cill when the Tilbury gauge reads 5meters. It took weeks of comparing tidal predictions with real-life measurements monitored off London VTS Ch69 to establish this in 2015. There was no published data to fall back on.
All the Hufflers were dead, the last lock-keeper was frail and, even though I got to meet him, the knowledge was gone. New 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.
A RISING TIDES LIFT ALL SHIPS
Pentargon needed more than 4m on the Tilbury gauge to enter the creek without grounding to enjoy a continuous run upstream where 5.6m gauged at Tilbury would let her to scrape over the cill.
Fine tuning showed that cill tide happens about 20mins after Tilbury. Coming and going showed that it took Pentargon about half an hour from barrier to lock.
Back in the day when all the greaseproof paper used in England was made here and Dartford was a thriving town bloated by paper making and pharmaceuticals, steam cranes lifted the raw material from lighters and finished paper went out on lighters. Hufflers brought lighters up and down with light poles and very little muscle power.
TILBURY GAUGED
Tilbury 6.3m was another crucial measure for Pentargon. It allowed her to slip on and off various berms which dried out when the tide receded (photo). Tilbury 6.9m was the highest tide recorded at any time during my stays and in practice anything over 6.3 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 nearly prevented her from leaving the Creek late in October which could have been a disastrophe.
Another variable for users of any of the main Thames tributaries is the Thames Barrier. The Environment Agency monitors weather and tides in the estuary and acts on it. Once a month they test the system by closing the barrier and drop the Barking and Dartford gates for the day. Of course, when or if there's a flood threat to London, the order will go out to do it for real.
THE RIVER CREEK TECHNIQUE
The method for getting into Dartford is to approach from seaward on a rising tide. If you've come down from London, moor or delay somewhere downriver. Greenhithe is good. You can listen to London VTS on Ch69. You can use the buoys there but they are chargeable. I usually drop an anchor on the land side of the buoys.
Staying afloat, tells you what the tide is doing. Once Tilbury has passed 3.5m rising, you can let go and drift gently up the Kent bank under the QE2 bridge and past Littlebrook Chimney. There is absolutely no reason to cross over.
In fact, I would not recommend it. You are a narrowboat fogodsake. Your draft is a metre or less. You are a "pleasure craft" and, if you are under 42', you don't even need a radio although this scribe likes to keep the PLA sweet, so I do carry VHF.
Let the tide gently drift you up and you will approach Crayford Ness about 3/4hr after weighing anchor with the tide near enough to 4m at Tilbury and running well in its third hour. You DO know your Rule of Twelfths, don't you? Since you're well inshore and in shallow water, you needn't worry about the flow or river traffic. The Dartford Channel will be very obvious when you get to it from the Kent side, whereas it is very difficult to get it 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.
By the time you reach the lock, Tilbury will be well past 5m with the flow increasing [rapidly] over the next 30mins as you drift along. My own experience of water speeds is that you may get 2kts between the barrier and the Crayford turn off and then 1kt through Bob Dunn.
You will reach the lock after Tilbury has passed 5m and the rule for getting over the cill is to add your draft to 5m. Pentargon draws 0.6m so can cross 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 5.4m and the rising tide will ease me over in its own time. This trick was very useful for getting over the cill at Barking!
SERIOUS STUFF NOW
Pentargon used a variation of the Dartford Technique to get up the River Avon to Bristol after overnighting on a 12m tide, in "Portishead Hole".
The artist Hillary Kington captured "The Hole" as I found it, but I did not get to see much wildlife as I slept right through the night and slipped away in the morning as soon as The Hole began to flood.
The Avon Technique introduced an extra dimension developed overnight by studying what charts and maps and tidal predictions were on board added to my observations coming in.
The Avon is a big river whose outflow was easy to feel coming down on the Saturday.
Inside King Road, the outgoing tide grabbed the river and poured it down inshore and I ended up east of the pier, travelling west to fetch up in the fairway channel close by but not in the hole. Using the Dartford Technique I just drove her onto the mud and went to bed.
About 8pm, the night tide began to flood, I brought Pentargon off the marina fairway and again ploughed her in, but cast the Danforth. Since I could see the mudbanks which would later be covered and I had grounded her, I knew it would be safe underneath. AND. I was able to observe the shape of the hole when the fairway dried out! I knew I'd be safe all night.
My tide tables and last night's observations confirmed that I'd be able to float off at 8am and there would be an inshore tidal flow towards Avonmouth harbour wall in its second hour. (Recall, if you will, the Rule of Twelfths) I already knew the Avon would be flowing strongly out to sea.
Here my knowledge and experience of tide fighting river and land became critical. By moving the boat off a little and pointing it directly at Avonmouth Harbour wall, I knew the tide would take me towards the wall and I would lose the river under the tide for long enough to gather my wits.
Don't ask me why rivers do this. In theory, fresh water is less dense than saline water.
In reality the sea tends to flow over the river at a confluence. Ok! So the Amazon is an exception and stays fresh on top of the salt water for over 200 miles out into the southern Atlantic .
But this is the Avon. So I fetched up by the harbour wall just as the first of the tide was bouncing off it to go upstream.
All I had to do was stay close to the wall, watching for the boundary between the river coming down and the sea bullying its way up. I found the boundary quite easily and was able to manoeuvre Pentargon along staying well in the saline.
It is not a good idea to mess with this boundary. The slightest intrusion of the bow into the outgoing river could turn the boat on sixpence, pulling her into the outgoing river and sending her down towards the sea in a thrice.
With the building tide however, and the Bristol Channel tide is an aggressive tide, the boundary began to fade and the tide took charge before Pentargon had gone half a mile upstream.
It upstaged the river completely and the rushing tide shot myself and my boat up the gorge at such a speed that I covered the six miles to the holding point in less than an hour.
The rest is at 38and 39 Gossip List 2 in BLOG LISTS PENTARGON
The boat used was a 1973, 36' Springer with a 1968 Lister SR2, running at 1100rpm, delivering 6HP to the prop, translating to 2kts over still water.
The method was developed on the Thames from previous experience as a volunteer engineer/navigator on a sail training ship based on the Thames
... the method was used to access Barking Creek without using the 'municipal' lock, to enter and explore Dartford/Crayford Creek over two Summers ... and Bow Creek with its access to Bow Locks ... and in 2017 to navigate solo from Sharpness via Portishead to Bristol
Background to Pentargon's skipper ... "Born in Ireland by a tidal estuary ... grew up by another tidal estuary ... where I sailed dinghies from childhood ... reared family by the Shannon estuary ... learning the ways and wiles of tides and estuaries, crossed the Shannon Estuary in 1990 using tides to descend the Ratty River, proceeding to the further shore and returning on a rising tide, using a leaky blow-up inflatable!
In 1999, I came to live by the Thames Estuary and expanded my estuary lore, befriending old rivermen, lightermen, ferry skippers and, indeed, anyone who would talk with me. They all seemed to recognise 'one of their own' or at least someone who spoke the same language as them. I found them easy to listen to and easy to learn from. I amassed an enormous amount of river lore from assorted old codgers on many trips in the Estuary, especially as a volunteer on the sail-trainer Kenya Jacaranda.
Later as a 'stoker' with the London Unit of the Maritime Volunteer Service I learned the urban Thames from Tower Bridge to Teddington, and the seaward reaches to Southend, including why the Barrier will not save London and what depth the water will be on Mile-End Road when it does fail.
The old men showed me tricks played by Old Father Thames which have yet to appear on the web or even in books. Getting my own boat in 2012, I realised its potential as an Estuary Explorer.
Pentargon is an unusual build as narrow-boats go and a detailed investigation brought to light that she was constructed using ship-building techniques ... and so, having became a boater to explore the ditches of England, I could also go down to the seas I'd come from again.
And I did! Pentargon was and is registered as a 'small ship' (SSR 161019) and her unique features have been exploited to the full in various ascents and descents of the Thames from Teddington or Brentford to Limehouse or Bow, using tides to carry the boat hither and thither upstream initially before venturing the other way! Then in 2017, during the longest solo ring ever completed on Britain's Inland Waters, the estuary experience was put to the ultimate test on the Bristol Channel.
"Rivercreek" was inspired by Martin Ludgate's article "Up the Creek" (Canal Boat, August 2018), where he credited Pentargon for kick-starting the use of Dartford Creek as 'a leisure destination for 'intrepid canal boat skippers'.
Among many adventures undertaken by Pentargon during her ten-year odyssey, the more spectacular ones have taken outgoing tides and used a later inflow to haul her up unsuspecting rivers with the flow and against the odds.
I consider the Thames estuary fair game; it frightens most London boaters. Tides? Waves? There be disaster unspecified.
The first visit to Dartford Creek, early in 2015, involved going down from Bow Lock to Crayford Ness, blundering up to a safe haven and staying over.
Much pre-planning and surveying had gone into the months prior to that first arrival. There was no 'CreekData' before Pentargon's arrival. I had to make my own.
Volunteers had excavated an old mooring bollard from beneath forty years of neglect to provide a purchase for Pentargon's lines on her first visit: the first boat in forty years to overnight in the Creek.
Pentargon tied up alongside at 5.30pm on the 26th April 2015, having descended on a wing and a prayer from Bow Lock with a crew which included three intrepid London skippers and arrived under my helm.
Over the years, the IWA took boats up Dartford Creek and down again on a single turn of tide, scurrying back to The River while they still had water under their boats but no evidence that they or anyone had gone up the Crayford Arm. Certainly no admission that anyone had stayed over in the Cray, as Pentargon did on a number of visits during 2015 and 2016.
It is worthy of record that, as a result of the years of neglect, I was not able to make up to Crayford Wharf in 2015 due to a stand of mature alder trees, which the Dartford group contrived to 'dissipate' with the help of some National Rail engineers and tree specialists who happened to be working in the area, thus clearing the Crayford Wharf approaches to their advantage and that of future RiverCreek adventurers.
The "Tuesday Night Club" had visited the Dartford arm, with Steve Haywood hitching a ride but I have yet to nail the full story!
Conrad Broadley took his sloop up to Crayford in 2016 and overnighted too but had to leave, at 4.30am, to catch a very early tide due his deep draught keel.
The Thames barge 'Decima' was next to brave it, leading to the inaugural Dartford Nautical Festival in 2018 involving a whole fleet of narrowboats from St.Pancras Sailing Club. Pentargon missed that auspicious weekend, being fifty five miles upstream resting in Nauticalia's yard at Shepperton.
Pentargon had recently completed the most diverse and extensive British Waterways ring ever achieved solo.
In June 2017, she was logged at Gailey Wharf being modified to comply with "Class D" Inland Waterway Use, a class higher than she would ever use or need.
All the tidal Thames between Teddington and Gravesend is "Class C" and all the Bristol Channel north of Avonmouth is the same! In August 2017, Pentargon would take the tide from Sharpness to Bristol using the "Rivercreek Technique".
(and you are allowed to infer that there was only one person on board)
Reports on the methods used to get the London adventurers to Dartford for the 2018 festival were noted with amusement by this scribe. No-one from that auspicious and intrepid group thought to contact the one sailor who knew the Creeks and the Thames intimately. But they came to no harm. Outside of the Dartford group, no-one else knew that Pentargon had made multiple visits to the Creeks in 2015 and 2016 and had stayed over for weeks at a time while on a C&RT licence.
I did all the tide surveying, depth sounding, observing how the tide interacted with the Darent and it was better than a Master's degree. I moored by Steam Crane Wharf, pitched up on various berms and explored Crayford Creek in all weathers and stages of tide to see what a narrowboat could and could not do in an uncharted River Creek.
FIRST DESCENT TO DARTFORD
The first descent to Dartford was done by exiting Bow Lock at the top of an 8am tide [photo] which flowed Pentargon out to sea without any fuss. Minimal science was used and the method is centuries old.
We got to the mouth of the Darent about 11oc with the Tilbury tide gauge reading 3m and dropping. I turned the boat into the creek once we cleared the Ness and drove the boat aground in the channel.
The bed of the Darent is higher than the surface of the estuary so the tide could ebb away all it wanted and enter its next cycle.
Pentargon would be going nowhere for the next four hours simply because it had been grounded. This trick works only with 'flat-bottomed' boats or one with twin keels.
Once the water returned, about 3oc, we floated. As the tide continued to rise, the flow up the creek pushed us upriver and, bit by bit, we proceeded upstream, with repeated groundings as time and tide lofted us higher and further inland.
About 4.30pm came our last grounding. Just below Bob Dunn bridge is a massive shoal of Kentish mud. Once by that, the boat began to move forward with less and less stops until we were in sight of the lock and the quay and the welcome party, the members of whom could not understand what was taking us so long.
Here another massive mudbank caused by the lock itself and forty years of neglect stopped us awhile. We got in to the quay about 5pm but could not breast the cill.
So we tied up in the lock and were warmly welcomed by the Friends of Dartford and Crayford Creek. The boat crew had had a long day, so they took off for the railway station, oystering back to London for tea.
I waited another hour and slipped over the cill as soon as my 24" draft allowed.
Pentargon was "home and dry" as it were [photo]. During the night I played with the lines as the night tide flowed and ebbed.
"CANAL BOAT"
Martin Ludgate, in an article on the potential development of Dartford Creek, in 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 story is worth sharing with you.
Dartford volunteers had excavated an old mooring bollard [photo] from beneath forty years of neglect to provide purchase for Pentargon's lines on that first visit: the first boat in forty years to overnight in Dartford Creek. Pentargon tied up alongside at 5.30pm on the 26th April 2015, having descended on a wing and a prayer from Bow with the skipper and three intrepid London boaters on board.
TAKE IT AS GIVEN ...
that the bed of a tributary is going to be,
by definition, higher than the main river.
that any boat can go up any tributary
on a rising tide without any power
so long as she is "under command"
The Hufflers did it thus and the vice is versa
Punching is for boxers and leather workers
Hufflers or sailors do not punch tides.
They go with the flow
Each tributary has its own flow dependent on its size, how much rain has recently fallen [or not] in its basin and how much water is being nicked [or not] upstream .
The height of tide appropriate to Dartford is measured from the nearest tide gauge, at Tilbury, five miles downstream from the mouth of the Darent or eight 'water' miles away if you are at the cill by the lock.
Water flows over the cill when the Tilbury gauge reads 5meters. It took weeks of comparing tidal predictions with real-life measurements monitored off London VTS Ch69 to establish this in 2015. There was no published data to fall back on.
All the Hufflers were dead, the last lock-keeper was frail and, even though I got to meet him, the knowledge was gone. New 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.
A RISING TIDES LIFT ALL SHIPS
Pentargon needed more than 4m on the Tilbury gauge to enter the creek without grounding to enjoy a continuous run upstream where 5.6m gauged at Tilbury would let her to scrape over the cill.
Fine tuning showed that cill tide happens about 20mins after Tilbury. Coming and going showed that it took Pentargon about half an hour from barrier to lock.
Back in the day when all the greaseproof paper used in England was made here and Dartford was a thriving town bloated by paper making and pharmaceuticals, steam cranes lifted the raw material from lighters and finished paper went out on lighters. Hufflers brought lighters up and down with light poles and very little muscle power.
TILBURY GAUGED
Tilbury 6.3m was another crucial measure for Pentargon. It allowed her to slip on and off various berms which dried out when the tide receded (photo). Tilbury 6.9m was the highest tide recorded at any time during my stays and in practice anything over 6.3 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 nearly prevented her from leaving the Creek late in October which could have been a disastrophe.
Another variable for users of any of the main Thames tributaries is the Thames Barrier. The Environment Agency monitors weather and tides in the estuary and acts on it. Once a month they test the system by closing the barrier and drop the Barking and Dartford gates for the day. Of course, when or if there's a flood threat to London, the order will go out to do it for real.
THE RIVER CREEK TECHNIQUE
The method for getting into Dartford is to approach from seaward on a rising tide. If you've come down from London, moor or delay somewhere downriver. Greenhithe is good. You can listen to London VTS on Ch69. You can use the buoys there but they are chargeable. I usually drop an anchor on the land side of the buoys.
Staying afloat, tells you what the tide is doing. Once Tilbury has passed 3.5m rising, you can let go and drift gently up the Kent bank under the QE2 bridge and past Littlebrook Chimney. There is absolutely no reason to cross over.
In fact, I would not recommend it. You are a narrowboat fogodsake. Your draft is a metre or less. You are a "pleasure craft" and, if you are under 42', you don't even need a radio although this scribe likes to keep the PLA sweet, so I do carry VHF.
Let the tide gently drift you up and you will approach Crayford Ness about 3/4hr after weighing anchor with the tide near enough to 4m at Tilbury and running well in its third hour. You DO know your Rule of Twelfths, don't you? Since you're well inshore and in shallow water, you needn't worry about the flow or river traffic. The Dartford Channel will be very obvious when you get to it from the Kent side, whereas it is very difficult to get it 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.
By the time you reach the lock, Tilbury will be well past 5m with the flow increasing [rapidly] over the next 30mins as you drift along. My own experience of water speeds is that you may get 2kts between the barrier and the Crayford turn off and then 1kt through Bob Dunn.
You will reach the lock after Tilbury has passed 5m and the rule for getting over the cill is to add your draft to 5m. Pentargon draws 0.6m so can cross 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 5.4m and the rising tide will ease me over in its own time. This trick was very useful for getting over the cill at Barking!
SERIOUS STUFF NOW
Pentargon used a variation of the Dartford Technique to get up the River Avon to Bristol after overnighting on a 12m tide, in "Portishead Hole".
The artist Hillary Kington captured "The Hole" as I found it, but I did not get to see much wildlife as I slept right through the night and slipped away in the morning as soon as The Hole began to flood.
The Avon Technique introduced an extra dimension developed overnight by studying what charts and maps and tidal predictions were on board added to my observations coming in.
The Avon is a big river whose outflow was easy to feel coming down on the Saturday.
Inside King Road, the outgoing tide grabbed the river and poured it down inshore and I ended up east of the pier, travelling west to fetch up in the fairway channel close by but not in the hole. Using the Dartford Technique I just drove her onto the mud and went to bed.
About 8pm, the night tide began to flood, I brought Pentargon off the marina fairway and again ploughed her in, but cast the Danforth. Since I could see the mudbanks which would later be covered and I had grounded her, I knew it would be safe underneath. AND. I was able to observe the shape of the hole when the fairway dried out! I knew I'd be safe all night.
My tide tables and last night's observations confirmed that I'd be able to float off at 8am and there would be an inshore tidal flow towards Avonmouth harbour wall in its second hour. (Recall, if you will, the Rule of Twelfths) I already knew the Avon would be flowing strongly out to sea.
Here my knowledge and experience of tide fighting river and land became critical. By moving the boat off a little and pointing it directly at Avonmouth Harbour wall, I knew the tide would take me towards the wall and I would lose the river under the tide for long enough to gather my wits.
Don't ask me why rivers do this. In theory, fresh water is less dense than saline water.
In reality the sea tends to flow over the river at a confluence. Ok! So the Amazon is an exception and stays fresh on top of the salt water for over 200 miles out into the southern Atlantic .
But this is the Avon. So I fetched up by the harbour wall just as the first of the tide was bouncing off it to go upstream.
All I had to do was stay close to the wall, watching for the boundary between the river coming down and the sea bullying its way up. I found the boundary quite easily and was able to manoeuvre Pentargon along staying well in the saline.
It is not a good idea to mess with this boundary. The slightest intrusion of the bow into the outgoing river could turn the boat on sixpence, pulling her into the outgoing river and sending her down towards the sea in a thrice.
With the building tide however, and the Bristol Channel tide is an aggressive tide, the boundary began to fade and the tide took charge before Pentargon had gone half a mile upstream.
It upstaged the river completely and the rushing tide shot myself and my boat up the gorge at such a speed that I covered the six miles to the holding point in less than an hour.
The rest is at 38and 39 Gossip List 2 in BLOG LISTS PENTARGON
