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Thames Ring


GeoffS

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And you don't "need" to have it at the stern. Anchors should always be attached to the bow, and never more so than on a narrow-boat, which has little freeboard at the stern, and often plenty of places for water to come aboard and get below.

In which case, see my last post, and explain why I should not be concerned that the boat would need to do a full turn in the river as part of the process of becoming (hopefully!) anchored.

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Alan, whilst I understand your concerns, it's a question of balancing two risks. In my view, as a regular Thames tideway user, and with many years of sailing experience, I would think the risk of being hit by somebody while you turn is much less than the risk of being swamped if your stern is held down by an anchor cable, and a boat comes by making a lot of wash.

 

I have a lot of freeboard at the stern of my boat, but I still wouldn't dream of anchoring from the stern. Furthermore, raising a stern-deployed anchor would be a nightmare.

 

I might add that whilst I often go single-handed above Wandsworth Bridge, I always prefer to have somebody with me below Wandsworth. That person's most important responsibility is to drop the anchor if necessary, while I stay on the wheel.

 

I think I might start an anchor-renting business.

Edited by sebrof
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While I agree with sebrof about anchoring from the bow on the tideway, I do worry about the well deck scuppers at the bow of my boat which are much closer to the waterline than the engine room vents at the stern. If the bow doors are closed (which the should be), then I supposerelatively little water would get into the cabin before the bow's buoyancy brought it up again and the water flowed out through the scuppers. I think I would only use a stern anchor in the immediate vicinity of a bridge or where I couldn't turn the boat.

Edited by blackrose
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While I agree with sebrof about anchoring from the bow on the tideway, I do worry about the well deck scuppers at the bow of my boat which are much closer to the waterline than the engine room vents at the stern. If the bow doors are closed (which the should be), then I supposerelatively little water would get into the cabin before the bow's buoyancy brought it up again and the water flowed out again through the scuppers. I think I would only use a stern anchor in the immediate vicinity of a bridge or where I couldn't turn the boat.

 

If I were very close to a bridge, then my strategy would be to drift through the bridge, and anchor beyond. This assumes I still have some steerage way. If I haven't, then it means I didn't act fast enough. The decision to drop anchor needs to be taken, and acted upon, very quickly.

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And someone with the necessary VHF licence and equipment of couse, (assuming Geoff doesn't have it himself ....)

 

Or you can take part in one of St Pancras Crusing Club's regular organised convoys, in which case you don't need your own VHF.

 

David

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Alan, whilst I understand your concerns, it's a question of balancing two risks. In my view, as a regular Thames tideway user, and with many years of sailing experience,

 

But with respect, how applicable is that sailing experience to the particular circumstances of a narrowboat?

 

I would think the risk of being hit by somebody while you turn is much less than the risk of being swamped if your stern is held down by an anchor cable, and a boat comes by making a lot of wash.

 

I have a lot of freeboard at the stern of my boat, but I still wouldn't dream of anchoring from the stern.

 

But why would a narrowboat stern be held down more by an anchor than a narrowboat bow? The underwater shape of most narrowboats is pretty much the same at both ends, so I would expect the effect to be similar.

 

And unlike many other types of boat, most modern narrowboats have low scuppers at the bows which could allow water to enter if the bow is held down, whereas they have no such openings at the stern (some older boats with air cooled engines excepted).

 

And if the anchor is to be deployed quickly in an emergency, then it is best placed within reach of the steerer. Even if you have an anchorman poised at the bows he/she is unlikely to be as alert to possible dangers all the time as the steerer. And then there is the problem of communication between bow and stern...

 

Furthermore, raising a stern-deployed anchor would be a nightmare.

 

Why is raising any more difficult from the stern than the bow? And anyway, if circumstances are such that you have to deploy the anchor, then the issue of how to raise it is surely very much a secondary consideration.

 

On balance I can see considerable merit in having the anchor at the stern, especially when travelling downstream/with the tide.

 

David

 

David

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Interesting, David.....

 

Much more in line with how I saw it, although I admit that was more by thinking about it, than by any published guidelines.

 

It seems, so far, that there is no good consensus about where the anchor should be carried, then, particularly if the net "flow" is in the direction you are travelling.

 

What do you do on Fulbourne ? I'm not sure trying to deploy it off the front would be any safer than off the back ! Does anyone normally sit on those bows if you are on the tideway ?

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But with respect, how applicable is that sailing experience to the particular circumstances of a narrowboat?

 

Because sailors do a lot of anchoring, in all sorts of different conditions, and tend to be much better informed on the subject than people who often don't have anchors at all, and, if they do, have often never used them.

 

But why would a narrowboat stern be held down more by an anchor than a narrowboat bow? The underwater shape of most narrowboats is pretty much the same at both ends, so I would expect the effect to be similar.

 

You've obviously never seen a narrow-boat out of the water. There is more buoyancy at the bow, and the bow is usually higher out of the water. Don't forget the swim.

 

And unlike many other types of boat, most modern narrowboats have low scuppers at the bows which could allow water to enter if the bow is held down, whereas they have no such openings at the stern (some older boats with air cooled engines excepted).

 

That is certainly a point to consider.

 

And if the anchor is to be deployed quickly in an emergency, then it is best placed within reach of the steerer. Even if you have an anchorman poised at the bows he/she is unlikely to be as alert to possible dangers all the time as the steerer. And then there is the problem of communication between bow and stern...

 

No. The steerer should steer. The crew should deploy the anchor.

 

Why is raising any more difficult from the stern than the bow?

 

Because it is much easier to motor up to the anchor going forwards than it is going astern. ETA: And you are less likely to get the anchor rope round the prop if the anchor is at the bow.

 

And anyway, if circumstances are such that you have to deploy the anchor, then the issue of how to raise it is surely very much a secondary consideration.

 

Any decent boatman is going to try to resolve problems himself, rather than call on others to do so. In many cases, it will be possible both to identify and rectify the cause of power loss while at anchor. Then, it is necessary to get under way again with as little drama as possible.

 

On balance I can see considerable merit in having the anchor at the stern, especially when travelling downstream/with the tide.

 

Go and practice what you preach, then come back and tell us what happened. If you are alive to do so....

Edited by sebrof
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It seems, so far, that there is no good consensus about where the anchor should be carried, ...

 

No consensus on the part of narrow-boaters because they have no experience.

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No consensus on the part of narrow-boaters because they have no experience.

 

You've obviously never seen a narrow-boat out of the water. There is more buoyancy at the bow, and the bow is usually higher out of the water. Don't forget the swim.

 

I'm not sure you strengthen your arguments by treating people in quite such a patronising way !

 

How totally ridiculous to suggest to someone like David that he has no idea of the underwater shape of his narrow boat.

 

I actually think the issues with deploying an anchor at the front of a boat over 70 feet long, which then has to swing around through a full 180 degrees can not be easily dismissed.

 

The boat is going to need, probably at least 100 feet or river width to swing around in, probably with no predictability about which way round it will go. It will be completely broadside to the flow for part of that time, so is going to get dragged along very rapidly indeed whilst in that situation. The steerer on the back of the boat will presumably have travelled onwards (maybe) another 200 feet, at which point the whole lot needs to end up held in place. No mean feat to get away with safely, I'd say!

 

OK, much of the Thames is a big wide river, but there are many places where needing that much water will me a major issue. I'd not fancy broadsiding some bridge piers, which seems to me not a possibility one can easily dismiss.

 

Just because I have never so far has to drop an anchor doesn't mean I shouldn't question the way of doing it that has the greatest chances of success for the boat in question.

 

It doesn't sound to me that too many people have actually had to do it with a narrow boat, whatever may be their experience of other types of boat. I'd say a narrow boat is a very different beast in many sorts of ways, and the considerations are potentially quite different.

 

Oh, and if you look at plans of narrow boats, you will find the hull shape remarkably similar at each end, for the underwater part. It's for this reason it has been not uncommon to take the back end of a butty, (which broadly shares it's underwater profile with a motor), and turn it into the front of a different boat. If you look at two boats side by side, where the front of each actually started life as opposite ends of the same boat, then the profiles are actually very similar. Something a narrow boat owner will tend to know, but others seem to find surprising.

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There is much more buoyancy in the front of a modern narrowboat - the bow flares out and is relatively tall. The stern, under the water, is cut away and narrow and it is also the lowest part of the boat.

 

The hull openings at the front of my very ordinary narrowboat are the gas locker and bow deck drains. They have no direct connection with the main floating part of the boat. In contrast, the openings at the rear are air vents directly into the engine bay and the main body of the boat.

 

Every boat is different but these observations can be applied to most modern cruiser and semi-trad boats.

 

 

I am not sure that I like the idea of anchoring in a strong stream from the rear of the boat. Firstly, you will have to secure from a dolly that is not on the centre-line of the boat. Then you will have to contend with the rudder wrapping itself to one side. This will put a lot of twist and extra drag on the boat - possibly contributing the anchor failing. Secured front the centre stud at the front, the boat presents the least resistive profile to the flow, and the rudder can be used to position the boat too.

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Every boat is different but these observations can be applied to most modern cruiser and semi-trad boats.

Actually, no they can't.

 

Although the air vents cut in the side of the hull at the stern are a standard Liverpool Boats feature, and some other boats do have them, (MJG's being an example, I remember), they are not at all common in these days of skin tank cooled engines. I'd say the vast majority of modern build narrow boats have no such feature.

 

For older boats with air cooled Listers, yes, of course there were generally hull apertures, but it really is not that commonplace on newer builds, (LB boats apart).

 

Many modern boats will be watertight at the back end if held down to nearly the level of the stern deck.

 

However, on a boat like ours, if you start to flood the bow deck through the drain holes there, (and they really are fairly low down), then you have only about 2" of front step to fill up, before you start to flood the cabin.

 

Other than water up the exhaust pipe, (which will not sink you), on Chalice, I'm far more concerned about potential water ingress at the front, than at the back.

 

Generally the hull depth at the front of a modern narrow boat is no greater than at the rear. The main reason they generally sit higher at the front, (and not all do), is down to the weight of the engine, and the fact that an equivalent amount of "ballast", (which may include water in a front tank), has not been introduced to bring the boat level, (probably because in many cases it would result in flooding the gas locker, the fore deck, and ultimately filling the boat with water!).

 

Have you not noticed that in those relatively rare cases where a new build shell, with no engine is put into water, they almost invariably sit near level ? There really is generally not a lot more buoyancy at the front of most modern builds - simply there is usually just more weight at the back!

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Let me try this one again - because the bow of the boat flares both out from the sides and forwards (ie: gets significantly wider as you move up), then the more you press it into the water the more it resists - the deeper you push it into water the more strongly it rises back up. The back of the boat is straight and offers no special resistance to being pulled under.

 

Perhaps an anchor at both ends is the answer - which is what I have! I just regard the rear one as a total last resort device.

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Let me try this one again - because the bow of the boat flares both out from the sides and forwards (ie: gets significantly wider as you move up), then the more you press it into the water the more it resists - the deeper you push it into water the more strongly it rises back up. The back of the boat is straight and offers no special resistance to being pulled under.

Except......

 

The back of most boats has an uxter plate and a counter above that, more or less immediately above the normal level it sits in the water.

 

The extra water that would be displaced by pulling that several inches further downwards will be significantly more, not less, than if you pull the bow down by an equivalent amount.

 

Also as soon as it starts to be pulled under, it has effectively increased the backward "floating" length of the boat by a couple of feet.

 

The stern of most typical counter-sterned narrow boats will offer far more buoyancy per extra inch it is pulled down, than will the front.

 

These are not me guessing - the simple applied maths /physics says that must be so.

 

The only possible reason you might get away with pulling a bow down into the water more than the stern, is if it is sitting further out of it in the first place.

 

But with many boats the bow deck drain holes are not that far above waterline. Once under, most boats will not have much capacity to collect that water before it starts to enter around the front cabin doors.

 

I'm not trying to be argumentative, but I genuinely believe your argument is wrong for the vast majority of relatively newly built leisure narrow boats.

 

Of course holes deliberately cut in the stern, as your boat will have, change the dynamics considerably, but that is a comparatively unusual situation.

 

Anyway, my final word, as I don't think I'm going to convince you, am I.

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At the beginning of all this I did say it was a question of balancing two risks. I obviously don't know your particular boat, Alan, and it may be that there are features of your boat that swing the argument the other way. Length, for example. I would agree that a longer boat will create more of a hazard when turning than a shorter one. However, the Thames is a wide river in the busy parts, and longer boats than yours are turning all the time.

 

I disagree that the turning circle would be much more than the length of the boat. Why should it be?

 

Furthermore, I am aware that there are SOME narrow-boats that are not significantly more buoyant at the bow than at the stern. In general, however, narrow-boats ARE more buoyant at the bow, as you point out yourself: "The main reason they generally sit higher at the front, (and not all do), is down to the weight of the engine...". [My emphasis]. To which I would add also that the hull is cut away at the stern in the region of the prop.

 

I'm sorry if you thought I was being patronising, but frankly, narrow-boaters know little of anchoring unless they have other boating experience, so even if there were a consensus, it wouldn't necessarily be right!

 

ETA: Another point against anchoring from the stern is greater resistance to the flow of the river, making it more likely that the anchor will drag.

Edited by sebrof
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When we did the tideway on Dads NB from Limehouse last yr , we had an anchor front & rear , I have always used an anchor on the cruiser off the bow so would have dropped that first in an emergency situation as thats what I am used to, how the boat would have behaved & whether the anchors we carried would have been sufficient I'm not sure (Although the Limehouse lockies were ok with them) I think my Danforth on the cruiser would hopefully be ok in that situation , although some of the anchors I have seen on NB's would have difficulty stopping a canadian canoe!

 

I wonder how many canal NB owners have ever dropped an anchor in any situation let alone an emergency one , so far our usage has been for pleasure use , in an emergency things can be very different - Once again I have been astounded at pics in other posts of folks on the tideway without any life preservers worn.

 

But Rights or wrongs I guess the last few posts will have put off the OP from cruising the Limehouse to Brentford Section anyhow.

 

Maybe a Government funded research project could advise us on the correct anchors to be used ? At least it would end speculation & only add a few quid to the licence fee.... :rolleyes:

 

Grabs coat (We should have a Smiley for this!)

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I disagree that the turning circle would be much more than the length of the boat. Why should it be?

OK, I know I said "my final word, but you asked a question.

 

I assume when anchored you have considerably more rope out than the depth of the river - i.e, that the rope will come up to the boat at a rising angle from the river bed.

 

As the boat swings around, the bow will describe an arc, with the anchor at its centre. If the bow say swings around an arc with a radius of 30 feet, (quite possible I'd say, if you are dragging the chain around to a new position as well), then for a 70 foot boat like David's the stern could easily describe as much as a 100 foot arc as it swings.

 

I'm more concerned that an entire side of a 70 foot boat will at one point of the process be completely broadside on to the flow. It's obviously going to be propelled around with some force, and potentially have a lot of momentum that you are hoping that anchor will finally stop. I'd have thought the less opportunity the boat has to "take off" from the position where you tried to deploy the anchor, the more chance it might actually work.

 

People seem convinced that the stern of a narrow boat will somehow present far greater resistance to flowing water than the bows. Personally I'm not persuaded the differences will be that great, although the argument about the rudder swinging and presenting some extra resistance is a valid one, I accept.

 

Also several of you don't seem concerned that on many boats if the front well drain holes are held under, the whole boat could fairly soon start to fill. It worries me!

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OK, I know I said "my final word, but you asked a question.

 

I assume when anchored you have considerably more rope out than the depth of the river - i.e, that the rope will come up to the boat at a rising angle from the river bed.

 

As the boat swings around, the bow will describe an arc, with the anchor at its centre. If the bow say swings around an arc with a radius of 30 feet, (quite possible I'd say, if you are dragging the chain around to a new position as well), then for a 70 foot boat like David's the stern could easily describe as much as a 100 foot arc as it swings.

 

I'm more concerned that an entire side of a 70 foot boat will at one point of the process be completely broadside on to the flow. It's obviously going to be propelled around with some force, and potentially have a lot of momentum that you are hoping that anchor will finally stop. I'd have thought the less opportunity the boat has to "take off" from the position where you tried to deploy the anchor, the more chance it might actually work.

 

People seem convinced that the stern of a narrow boat will somehow present far greater resistance to flowing water than the bows. Personally I'm not persuaded the differences will be that great, although the argument about the rudder swinging and presenting some extra resistance is a valid one, I accept.

 

Also several of you don't seem concerned that on many boats if the front well drain holes are held under, the whole boat could fairly soon start to fill. It worries me!

 

Whilst I am sure that the bow will describe an arc, I am not convinced it will be a very big one. I see no reason why, when the boat is broadside-on, the anchor will not be on a line at a right-angle to the centre of the boat.

 

Two things worry me. First, it is unusual, when anchoring, to be moving rapidly. If the anchor were to bite hard, the strains on the anchor itself, the rode, and the hull fitting, would be huge. At least, with the anchor affixed to the bow, the momentum would not be fully arrested until the boat had turned fully. Affixed to the stern, the potential for catastrophe would be huge. I think it is very likely that something would give way if the boat were moving rapidly.

 

Second, (assuming a bow-fixed anchor), as the bow swung round there would be a considerable toppling force on the hull, and the higher the point at which the rode was fixed, the greater the turning moment.

 

The more I think about this whole thing, the more it worries ME (on your behalf). :(

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  • 7 years later...

My wife and I plan to take our narrowboat down the Grand Union and sail the Paddington Arm returning along the Thames to rejoin the Grand union...I think about 3 hours on the Thames. I have read about the suggestion of doing this anti-clockwise but wondered about the tide effects. Would I try to plan this around high tide so if tasking the anti-clockwise direction we would not be swept past the Limehouse entrance? How would I coordinate this with avoiding the tour ships which I hear create a great wash that would not be good for us. I would love to actually talk to someone who has done this and my email is nickbomayne@tiscali.co.uk (I have no problem revealing this) if someone would be kind enough to 'chat' other than on this blog. Another simplistic question is how far from the bank does one sail ie. a compromise between getting stuck and avoiding faster boats? Are there marker buoys? The anchor discussion is interesting but it would be hard to have it on the cramped back of our trad boat but would safety considerations mean no-one should pass inside the cabin....so my wife would have to be out the front manipulating the extremely heavy anchor?

Thanks, Nick

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  • 5 weeks later...
On 02/04/2019 at 10:16, Nick Mayne said:

My wife and I plan to take our narrowboat down the Grand Union and sail the Paddington Arm returning along the Thames to rejoin the Grand union...I think about 3 hours on the Thames. I have read about the suggestion of doing this anti-clockwise but wondered about the tide effects. Would I try to plan this around high tide so if tasking the anti-clockwise direction we would not be swept past the Limehouse entrance? How would I coordinate this with avoiding the tour ships which I hear create a great wash that would not be good for us. I would love to actually talk to someone who has done this and my email is nickbomayne@tiscali.co.uk (I have no problem revealing this) if someone would be kind enough to 'chat' other than on this blog. Another simplistic question is how far from the bank does one sail ie. a compromise between getting stuck and avoiding faster boats? Are there marker buoys? The anchor discussion is interesting but it would be hard to have it on the cramped back of our trad boat but would safety considerations mean no-one should pass inside the cabin....so my wife would have to be out the front manipulating the extremely heavy anchor?

Thanks, Nick

Come on you Thames experts

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If you want to do the tidal Thames through London but you're at all concerned about how to do it then it's a lot easier going upstream from Limehouse to Brentford. I've done it several times in both directions and I prefer the downstream journey but that entrance to Limehouse can be tricky. 

 

Whichever way you do it you should have either the upstream or downstream edition of this guide which you can Google and download.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.waterways.org.uk/waterways/canals_rivers/river_thames_tidal/thames_tideway_guide_upstream&ved=2ahUKEwjv2OXllPrhAhUo0aYKHYy0AlUQFjAAegQIAhAB&usg=AOvVaw1pRPzK0bfNyV4B2PuIwzcI

 

By the way, think if your boat is over 45' long then you'll need someone on board with a VHF radio and license.

 

Obviously as well as the anchor and enough chain & rope, you need to be sure your boat is capable of going on tidal waters. Engine power/not going to overheat, fuel tank not full of sediment, engine vents not too close to the waterline, etc.

 

You can go inside the cabin if you need to go to the toilet or to access the bow, but it's a good idea to keep your bow doors shut. Just make sure everyone's wearing life jackets and out on deck for the journey unless they need to go inside for a short time. Don't go inside if the boat is in trouble.

Edited by blackrose
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On ‎05‎/‎07‎/‎2011 at 14:47, GeoffS said:

First, even though I may have the offer of some crew for the the tidal Thames, I am planning that I will be single handed. What is your honest advice about the possibility and sensibility of being able to complete this single handed?

I have done the Thames from Reading to Oxford and back single-handed, without any problem.  Also done Brentford to Teddington on a somewhat overloaded narrowboat.  If a boat is putting up a big bow wave, turn into it, so it doesn't swamp you.  I learnt that while punting.  Keep your bilge pump running - just in case.  Go for it.

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I am interested in this topic because I have been thinking about taking Dotterel on this trip. I have had a look at her hull and the lowest downflooding point is the front door sill via the front deck drains. The most threatening are probably the engine bay side vents. They are 30cms above the water line with the boat level and no crew on board. 

 

Coincidentally a nearly identical boat from Alevechurch moored opposite us last week and the vents have been covered. See pic.

 

Should I think about doing something similar and sealing the front door for the tidal bit? Also if seal the side vents should I ventilate the engine bay  through the deck?

 

Cheers Graham

 

 

IMG_20190501_164124.jpg

  • Greenie 1
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Probably a good idea - but make sure (if an air cooled engine) that there is sufficient air cooling from 'other sources' ...  to keep the engine running. Similarly for the front holes, though they're much smaller in area (?)

If you're worried it's sensible to avoid navigating during the hours that the trip boats run. After (say) Battersea Bridge there's less fast moving traffic with horrendous wash, thus reducing the risk of huge waves.

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