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Anchor for the Thames


Yeletah

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5 hours ago, Cal Ando said:

Thanks Tim for this.   The text suggests that my 10m of chain and 30m of rope is still too short for Limehouse. (45m chain or 75m rope).   Anyone else carry this much and still float?   Better stick to Brentford then!

I notice from the phone number that the text is really old.   Whilst information such as this is still relevant, hopefully the Thames might have silted up a few metres by now!

 

The PLA's requirement for the Jubilee pageant was 15m chain and 35m of warp, and that is what I have. It's manageable (chain in a bucket). It's unlikely that you would be at Limehouse at HW. The sounding on  my chart is 5m in the middle of the channel, so 12m at high water. The Thames is actively surveyed by the PLA's hydrologists and dredged as needed, so it certainly won't have silted up since the guide was written! 

 

If possible, I would wait until the tide/wind took me out of the main channel before dropping anchor.

 

lime.jpg.9dafd5102a27bbeadb1ccf59fb2637bf.jpg

Edited by Scholar Gypsy
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2 hours ago, Scholar Gypsy said:

The PLA's requirement for the Jubilee pageant was 15m chain and 35m of warp, and that is what I have. It's manageable (chain in a bucket). It's unlikely that you would be at Limehouse at HW. The sounding on  my chart is 5m in the middle of the channel, so 12m at high water. The Thames is actively surveyed by the PLA's hydrologists and dredged as needed, so it certainly won't have silted up since the guide was written! 

 

If possible, I would wait until the tide/wind took me out of the main channel before dropping anchor.

 

lime.jpg.9dafd5102a27bbeadb1ccf59fb2637bf.jpg

 

Just for clarity, as people not used to tidal waters may think that the chart depths shown are 'actuals', they are LAT (Lowest Astronomical Tide) heights

 

These are not the actual depths of the river.

 

If the tide tables show (for example) a Low Water of 0.83 metres and a high water of 6.9 metres, these figures have to be added to the LAT, so 'your' 5.3m channel actual depth becomes :

 

6.13m at Low water

12.2m at High water

 

 

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1 hour ago, Alan de Enfield said:

 

Just for clarity, as people not used to tidal waters may think that the chart depths shown are 'actuals', they are LAT (Lowest Astronomical Tide) heights

 

These are not the actual depths of the river.

 

If the tide tables show (for example) a Low Water of 0.83 metres and a high water of 6.9 metres, these figures have to be added to the LAT, so 'your' 5.3m channel actual depth becomes :

 

6.13m at Low water

12.2m at High water

 

 

Thank you - I should have made that clearer.  And the numbers that are underlined are negative, so the 2 at Nelson Dockyard would be 1.13 above water level at low tide (0.83-2) and a depth of 4.9 metres at high tide (using the same example).  

 

Variances to the projected level of half a metre are commonplace - VTS tell you this every 30 minutes, not that it should matter much to a narrowboat skipper! 

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3 minutes ago, Scholar Gypsy said:

Thank you - I should have made that clearer.  And the numbers that are underlined are negative, so the 2 at Nelson Dockyard would be 1.13 above water level at low tide (0.83-2) and a depth of 4.9 metres at high tide (using the same example).  

 

 

Also referred to as a  "drying height" which explains it very clearly.

 

Howard

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16 hours ago, Scholar Gypsy said:

The PLA's requirement for the Jubilee pageant was 15m chain and 35m of warp, and that is what I have. It's manageable (chain in a bucket). It's unlikely that you would be at Limehouse at HW.

A genuine "well done" for taking the official advice.   So many nowadays think "Oh! that'll do" and 99.99% it will.   That .01% is what gets people into trouble.

 

Whilst I think of it.  if some of the chain gets caught round the pointy bits of your anchor (i.e. it goes down fouled) is it coincidence or just a fluke?

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On 04/08/2020 at 17:05, Cal Ando said:

Like the blind fawn - no eyed-deer.   Almost certainly the water tank but unless its a weird bespoke shape, probably not where I want to put the ring.  (right by the gunnel and right in front of the cabin bulkhead.

BUT I now know the force of my boat being stopped is:  1/2mV*V/d    (1/2 M Vsquared / distance over which force acts)

where m is the mass of the boat, V is its speed and d is the distance taken to stop from its travelling speed to 0 (i,e, snatch distance)

m = 17,000 kg, V = 7 knots = 3.6m/s (YIKES) and d = 4m allowing for anchor movement when biting, rope stretch etc

THUS force = 27,540 Newtons which = 2,808 kg or about 3 tonnes

 

Thus in theory, any chinese steel M12 bolt from Lidl which would be rated at 4 tonnes should be adequate.

 

If my estimate of 4m  stopping distance is inaccurate and it's 2 m, then this is double the force so would need M16 to be safe

What about the force of the "snatch" if the anchor catches in something immovable like the roots of a tree?

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55 minutes ago, Keeping Up said:

What about the force of the "snatch" if the anchor catches in something immovable like the roots of a tree?

The snatch is adsorbed by the long stretchy rope between chain and boat, and also by the heavy chain as it is lifted from the river bed, hence the guess of 4m stopping distance.

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  • 2 weeks later...

Hi - I am about to go out on the Thames from Oxford to Reading and need to get an anchor for a 40ft Springer.

I have read through numerous posts on here and my head is swimming!

 

Please, can someone suggest - very straightforward - what weight of Anchor, Length of Chain and length of Rope I would need for this?

I will also want to go from Bath to Bristol at some point, but am hoping that would be about the same.

 

Also - where is a good place to get it from, and get it delivered to - most likely around Kidlington.

 

It was suggested to me by someone who used to run tugs to NOT have a chain - instead get some weights to run down the rope and hold it horizontal... with a retrieval line connected to the weight and one to the back of the anchor, to make it easier to pull up in stages.   What are peoples thoughts on that?

 

Many thanks in advance

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25 minutes ago, Cinimod said:

Hi - I am about to go out on the Thames from Oxford to Reading and need to get an anchor for a 40ft Springer.

I have read through numerous posts on here and my head is swimming!

 

Please, can someone suggest - very straightforward - what weight of Anchor, Length of Chain and length of Rope I would need for this?

I will also want to go from Bath to Bristol at some point, but am hoping that would be about the same.

 

Also - where is a good place to get it from, and get it delivered to - most likely around Kidlington.

 

It was suggested to me by someone who used to run tugs to NOT have a chain - instead get some weights to run down the rope and hold it horizontal... with a retrieval line connected to the weight and one to the back of the anchor, to make it easier to pull up in stages.   What are peoples thoughts on that?

 

Many thanks in advance

 

I'd recommend different types of anchors and heavier weights, but if you follow this at least you can tell you insurers that you followed guidelines.

 

You can try inland waterways chandlers but you may struggle, suggest you try Coastal Boat Chandleries but be ready for postage / carrier charges of £30-£50 (ish) They ARE HEAVY

 

https://www.force4.co.uk/department/chandlery-above-deck/anchoring-mooring/anchors

 

 

 

 

 

Anchoring Guidance Thames.jpeg

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4 hours ago, Cinimod said:

(snip)

It was suggested to me by someone who used to run tugs to NOT have a chain - instead get some weights to run down the rope and hold it horizontal... with a retrieval line connected to the weight and one to the back of the anchor, to make it easier to pull up in stages.   What are peoples thoughts on that?

(snip)

The most you have to lift on recovery is the weight of the anchor plus a water depth of chain, less the buoyancy. While weights on the chain have their place, I don't think they will make recovery any easier.

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7 hours ago, Iain_S said:

While weights on the chain have their place

Hi Iain - the suggestion was to NOT HAVE A CHAIN - just the anchor and rope... then instead of the chain you have a couple of 10kg weights...

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9 hours ago, Cinimod said:

Hi Iain - the suggestion was to NOT HAVE A CHAIN - just the anchor and rope... then instead of the chain you have a couple of 10kg weights...

 

 

 

Is the proposal to have weights 'tied off' at various distances down the rope ?

 

Why would you not have chain ?

It sounds like a real bodge-job, I wouldn't be rigging that every night, when a simple 100% length of chain is going to give far better performance.

 

In tight anchorages where there is little room but you need to get 'scope' on your chain, there is a trick to help (which is what your tug-driver may have been referring to)

 

Anchor ring | Ultra Marine Anchors

 

 

Think about why and when YOU are going to need an anchor (when you have lost control, engine or gearbox), so, on the Rivers you are going to want to deploy your anchor in an emergency and need to get it 'out' fast and get it to 'set' fast (and first time) you will not have time to play about sliding weights down the rope - by the time you do that you will be over the weir.

Edited by Alan de Enfield
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7 minutes ago, Alan de Enfield said:

 

If the weights have slid down to the anchor, how does the scope on the rope alone work then ?

I know nowt about anchors so this is a genuine question. If the weights are free running on the warp then as you lift the anchor won’t they be left on the bed, so that you’re only lifting the weight of the anchor? Then once the anchor is aboard you can lift the rest of the warp complete with weights?

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1 minute ago, WotEver said:

I know nowt about anchors so this is a genuine question. If the weights are free running on the warp then as you lift the anchor won’t they be left on the bed, so that you’re only lifting the weight of the anchor? Then once the anchor is aboard you can lift the rest of the warp complete with weights?

 

If the weights have slid all the way down to the anchor, then you either have to pull the weights back up on their own bit of 'string' (sliding them 'up' the anchor warp), or you haul the anchor warp up and the weights will come up with the anchor (adding their weight to the anchor weight).

 

The only way the weights could remain on the bed was if they were no attached to the anchor or the anchor warp.

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1 minute ago, Alan de Enfield said:

 

If the weights have slid all the way down to the anchor, then you either have to pull the weights back up on their own bit of 'string' (sliding them 'up' the anchor warp), or you haul the anchor warp up and the weights will come up with the anchor (adding their weight to the anchor weight).

 

The only way the weights could remain on the bed was if they were no attached to the anchor or the anchor warp.

I was imagining them sliding back ‘up’ the warp as the anchor was lifted. Perhaps you’d need to pay out some slack to enable that to happen.... or maybe it’s just a dumb idea :D

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16 minutes ago, Alan de Enfield said:

I wouldn't be rigging that every night

and

16 minutes ago, Alan de Enfield said:

Think about why and when YOU are going to need an anchor (when you have lost control, engine or gearbox), so, on the Rivers you are going to want to deploy your anchor in an emergency and need to get it 'out' fast and get it to 'set' fast (and first time)

 

As an emergency brake one (hopefully!) wouldn't need to set the anchor every night ...

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24 minutes ago, TheBiscuits said:

and

 

 

But possibly the Tug-Driver was (which I was comparing to)

 

I'll repeat - if you need to use an anchor on the Rivers it needs to be immediately deployable, and it needs to function immediately. You will not have time to pay out the anchor, ties some weights onto a line, slide the weights down the warp and tie off both the anchor warp and the 'weight-line'.

 

It must be common sense to use what is going to give you the best and fastest result, and that is a suitable type and size of anchor and 100% (5x depth) of suitable chain.

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34 minutes ago, WotEver said:

I was imagining them sliding back ‘up’ the warp as the anchor was lifted. Perhaps you’d need to pay out some slack to enable that to happen.... or maybe it’s just a dumb idea :D

But you pull up the anchor by pulling-in the warp.

 

UNLESS - you use a trip-line attached to the anchor - nor its getting even more complicated, you now have, the main anchor warp, an anchor trip line and a 'weight-line'.

 

Far simpler to just use a single anchor warp and the correct anchor and chain.

 

Illustration shows 'weight attached to warp', trip line and main warp, compared to 100% chain.

 

Anchoring | Anchors, Anchor Chains and Ropes - Jimmy Green Marine

 

 

 

You do not really need a trip line, all you do is motor forward pulling in the anchor warp, and as you get over the top of the anchor, tie it off  and continue driving forward and the anchor will be pulled out backwards.

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Very many thanks for the replies - all very useful... 
I am considering going with this - https://www.marinescene.co.uk/view/13245/claw-bruce-style-15kg-galvanised-standard-anchor-kit

 

As it is on a narrowboat, I think that I only need enough chain to get the anchor to lie flat on the bed and dig in... then the rope.
This is the arrangement I had - before I had to deploy, then cut it loose on the Trent a few weeks back when the engine cut out on the tidal section just before a bridge!
I was unable to retrieve as it was tied off at the stern and not the bow.

 

I believe it should do the job?   The only river I am planning on being on now is the Thames between Oxford and Reading, and the K&A where it has river stretches, between Reading and Bristol.

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38 minutes ago, Cinimod said:

This is the arrangement I had - before I had to deploy, then cut it loose on the Trent a few weeks back when the engine cut out on the tidal section just before a bridge!
I was unable to retrieve as it was tied off at the stern and not the bow.

 

Very few on here have ever used an anchor 'in anger', would you be prepared to 'tell the story' problems , what you did, how it worked out and what would you do differently next time. ?

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14 hours ago, Cinimod said:

Hi Iain - the suggestion was to NOT HAVE A CHAIN - just the anchor and rope... then instead of the chain you have a couple of 10kg weights...

Yes, understood,  but I was suggesting that using weights and rope rather than chain would not make recovery any easier

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11 hours ago, Cinimod said:

Very many thanks for the replies - all very useful... 
I am considering going with this - https://www.marinescene.co.uk/view/13245/claw-bruce-style-15kg-galvanised-standard-anchor-kit

 

As it is on a narrowboat, I think that I only need enough chain to get the anchor to lie flat on the bed and dig in... then the rope.
This is the arrangement I had - before I had to deploy, then cut it loose on the Trent a few weeks back when the engine cut out on the tidal section just before a bridge!
I was unable to retrieve as it was tied off at the stern and not the bow.

 

I believe it should do the job?   The only river I am planning on being on now is the Thames between Oxford and Reading, and the K&A where it has river stretches, between Reading and Bristol.

I think you are more experienced than most on here at deploying an anchor from a narrowboat in an inland river. I have never had to do it and hope I never do

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On 18/08/2020 at 11:16, Alan de Enfield said:

would you be prepared to 'tell the story' problems , what you did, how it worked out and what would you do differently next time. ?

Very happy to share the story...

 

I went out of Keadby onto the tidal Trent with all going very smoothly... 

It was a warm day and I have an air cooled Lister engine from around 1975 in a 40ft Springer.

 

At the time of leaving the lock, the tide was still on the ebb, so was pushing up river against the outgoing tide.

 

In order to make headway, the engine needed to be going at quite a rate, and as she is a trad layout, the engine is very noisy in the cabin right in front of me, so I had the top of the hatch only partially open...  

 

Long story short, not too long after getting onto the river the engine cut out... just before the M180 bridge (https://goo.gl/maps/zjigUeaQD3tNPew16)

 

My first action - was to try and restart the engine, by turning the key... the starter clicked, but nothing happened... 

As I was heading for the centre column of the bridge, I thought it would not be a good idea to hit it... so deployed the anchor.

I had the anchor sitting next to me at the back of the boat for just such an eventuality, as I am 'skippering' on my own (From York to Bath...) 

 

The anchor deployed, and lodged - at this point the tide was on the turn, so the flow was reasonably neutral to slightly incoming.

 

I spent the next 10 or so minutes, trying to figure out what to do next... I could manually turn the 'wheel thingy' which has the belt to the alternator on, so the engine did not appear to have jammed... I checked the starter battery was OK, turned everything off and on again...  then the engine started up again... 

 

By this time the flow was coming in pretty rapidly and even though the anchor was deployed securely I had still been pushed under the bridge (slowly), fortunately away from the centre column.

 

As I had travelled out with a couple of other boats they were kind enough to be waiting to see if I needed help.

 

The issue I had is that I had tied the anchor to the stern of the boat... and with the flow coming in so quickly there was no way I could back up over the anchor to get it up.

I did try to pull it up and almost ended up getting knocked overboard as the tiller swing in the current - (I did have a life jacket, but would not advise falling overboard on a tidal river in full flow!)

 

One of the other boats came back to try and help me - the plan being to tie up together and pull me back over the anchor so that I could pull it up.

 

However, that did not go entirely to plan... whilst we got a rope on, the other boat overshot and got caught by the current which swung her round behind me, resulting in their prop slicing the rope to the anchor (good job it was not all chain, or it would have got tangled and who knows what would have happened!)

 

I then spent the next few hours (not sure how many, but it was quite a while) taking it very steady to get to Torksey.

 

The following day I was lucky enough to be able to borrow and anchor to complete the journey up the tidal Trent to Cromwell...  

From Cromwell to Nottingham - I just took it slow and steady, with no anchor - had anything gone wrong then, it would have been a matter of trying to get into the bank somehow...  a very anxious few days boating.

 

So - things worked out alright in the end - just need to replace the anchor, which whilst it is a cost, is a lot less substantial than hitting a motorway bridge or sinking the boat.

 

What would I do differently? - Very definitely have the anchor ties on to the front of the boat.   
That way, when you are ready to recover the anchor, all you need to do is to power forward over it and pull it up - assuming you can get going again.

 

So on engine failure or other loss of control - get your anchor our ASAP to stop your movement - then take time to assess what needs doing and call for help if you need to.
 

 

 

 

Edited by magpie patrick
Correction at poster's request
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8 hours ago, Cinimod said:

Very happy to share the story...

 

I went out of Keadby onto the tidal Trent with all going very smoothly... 

It was a warm day and I have an air cooled Lister engine from around 1975 in a 40ft Springer.

 

At the time of leaving the lock, the tide was still on the ebb, so was pushing up river against the outgoing tide.

 

In order to make headway, the engine needed to be going at quite a rate, and as she is a trad layout, the engine is very noisy in the cabin right in front of me, so I had the top of the hatch only partially open...  

 

Long story short, not too long after getting onto the river the engine cut out... just before the M180 bridge (https://goo.gl/maps/zjigUeaQD3tNPew16)

 

My first action - was to try and restart the engine, by turning the key... the starter clicked, but nothing happened... 

As I was heading for the centre column of the bridge, I thought it would not be a good idea to hit it... so deployed the anchor.

I had the anchor sitting next to me at the back of the boat for just such an eventuality, as I am 'skippering' on my own (From York to Bath...) 

 

The anchor deployed, and lodged - at this point the tide was on the turn, so the flow was reasonably neutral to slightly incoming.

 

I spent the next 10 or so minutes, trying to figure out what to do next... I could manually turn the 'wheel thingy' which has the belt to the alternator on, so the engine did not appear to have jammed... I checked the starter battery was OK, turned everything off and on again...  then the engine started up again... 

 

By this time the flow was coming in pretty rapidly and even though the anchor was deployed securely I had still been pushed under the bridge (slowly), fortunately away from the centre column.

 

As I had travelled out with a couple of other boats they were kind enough to be waiting to see if I needed help.

 

The issue I had is that I had tied the anchor to the bow of the boat... and with the flow coming in so quickly there was no way I could back up over the anchor to get it up.

I did try to pull it up and almost ended up getting knocked overboard as the tiller swing in the current - (I did have a life jacket, but would not advise falling overboard on a tidal river in full flow!)

 

One of the other boats came back to try and help me - the plan being to tie up together and pull me back over the anchor so that I could pull it up.

 

However, that did not go entirely to plan... whilst we got a rope on, the other boat overshot and got caught by the current which swung her round behind me, resulting in their prop slicing the rope to the anchor (good job it was not all chain, or it would have got tangled and who knows what would have happened!)

 

I then spent the next few hours (not sure how many, but it was quite a while) taking it very steady to get to Torksey.

 

The following day I was lucky enough to be able to borrow and anchor to complete the journey up the tidal Trent to Cromwell...  

From Cromwell to Nottingham - I just took it slow and steady, with no anchor - had anything gone wrong then, it would have been a matter of trying to get into the bank somehow...  a very anxious few days boating.

 

So - things worked out alright in the end - just need to replace the anchor, which whilst it is a cost, is a lot less substantial than hitting a motorway bridge or sinking the boat.

 

What would I do differently? - Very definitely have the anchor ties on to the front of the boat.   
That way, when you are ready to recover the anchor, all you need to do is to power forward over it and pull it up - assuming you can get going again.

 

So on engine failure or other loss of control - get your anchor our ASAP to stop your movement - then take time to assess what needs doing and call for help if you need to.
 

 

 

 

 

It just shows how easy it is to need an anchor.

Thankyou for that, I think the last 3 lines should be engraved into every boaters brain.

 

 

 

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