Actual use of anchors in emergencies on UK canal/river network

[howardang]

19 minutes ago, IanD said:

Either way it was inappropriate scaremongering pure and simple -- "beware of going on a river, this might happen to you".

 

The fact that it wasn't to do with an anchor is my memory failure, but the scaremongering principle is the same -- "don't even think about going out on a river without an anchor, it's unsafe and stupid".

 

P.S. I wasn't the one who kept calling them dolphins, I'd never heard of the term -- but I assumed people using the term know what they were talking about since they were speaking from a position as "experts"... 😉

The booms across weirs are not called dolphin. I have moored to many dolphins over the years and if you need confirmation google mooring dolphins. Dolphins are structures to which a ship can  moors, often to be found at each end of a pier or jetty. 
 

Howard

[Guest]

6 minutes ago, howardang said:

The booms across weirs are not called dolphin. I have moored to many dolphins over the years and if you need confirmation google mooring dolphins. Dolphins are structures to which a ship can  moors, often to be found at each end of a pier or jetty. 
 

Howard

 

Most of us actually knew this, but it was just another petty dig by Ian.

[howardang]

6 minutes ago, M_JG said:

 

Most of us actually knew this, but it was just another petty dig by Ian.

An object lesson to some on this forum to be aware of self appointed (and opinionated) so called “experts”🤭

This forum seems to attract them.

 

Howard

[Alan de Enfield]

Well C&RT certainly call (called|) them Dolphins. A few years ago when the 'dolphins' across the top of the weir at Cromwell broke away and they had no spares they announced that "the river was closed to leisure traffic until they could source new component parts from the Netherlands to repair the weir dolphins."

[GUMPY]

8 hours ago, Alan de Enfield said:

C&RT certainly call (called|) them Dolphins.

How many times are cart right about anything🤔

 

 

About every time there is a blue moon

[IanD]

12 hours ago, Goliath said:

And that’s why I tell anyone who travels with me on a river that I have an anchor, it makes them feel safe.

 

Absolutely, and that's because many (most?) people don't understand the difference between actual risk and perceived risk, and worry more about occasional headline-grabbing disasters instead of much more common everyday ones which nevertheless kill far more people.

 

Examples include worrying about nuclear power (much lower risk than "safe green" hydroelectric power, and far *far* lower than fossil fuels), airplane crashes (you're much more likely to die in a car crash going to the airport), "stranger danger" from paedophiles (the culprit is much more likely to be Uncle Jim) -- or a narrowboat ending up "under the dolphins (TM)**" after its engine fails (much lower risk than sinking in a lock due to cilling or hangup or tied rope).

 

It's human nature, but the flames of fear are often inexcusably fanned by the likes of the Daily Wail (motto: "Be afraid! Be *very* afraid!"), bloggers putting out clickbait ("HOW MY BOAT NEARLY SANK!!!") -- and people who post scary and inappropriate disaster photos in response to an innocent question... 😞

 

Me, I get on a plane, and if we run into CAT*** triggering shrieks of horror onboard, I just look out of the window and watch the wings flapping up and down, secure in the knowledge that thanks to engineers they have to bend *way* further than that to break (go and look at wing stress testing videos, they're unbelievable...) and that IIRC**** there are no cases of an airliner ever being brought down by this.

 

That's the difference between actual risk and perceived risk... 😉

 

** TM=Trade Mark    ***CAT=Clear Air Turbulence   ****IIRC=If I Remember Correctly  😉

Edited November 29, 2022 by IanD

[Mike Todd]

19 hours ago, IanD said:

 

Danforths and similar anchors have been used for many years and have undoubtedly saved many lives at sea. That doesn't mean that they're the best choice nowadays, either from the POV of safety or even cost-effectiveness, because they are known to not be especially effective either at reliable setting or holding under stress, as has been shown multiple times in tests, and also by multiple accounts of them failing to set or hold in real life.

 

Which is what I said -- a cheap anchor that works (for example) 75% of the time (which means it fails 25% of the time) is not as good a bet as a more expensive anchor that works (for example) 95% of the time (which means it fails 5% of the time). All numbers are picked to illustrate the point, I'm not claiming they're accurate...

 

Danforths are not used because they're particularly good, they're used because they're cheap, easy to stow, available everywhere, are the widely used "go-to" solution when you just need to tick the "is an anchor fitted?" box, and work most of the time -- but also *don't* work rather more of the time than some others... 😞

 

If you actually want an anchor as an effective safety precaution, there are much better ones available nowadays, some for not much more money -- though none are as easy to stow.

 

 

I hope I don't have to explain "TWC"... 😉

 

Aha, so now *you're* looking for validation of *your* choice of anchor... 🙂

TWC into Wiki yields at least 25 options, none of which seem relevant!

[enigmatic]

17 hours ago, Goliath said:

Must admit, I’m one of the foolish, I have no anchor or life jacket.

I rarely use a river, and then only when the river is slow and benign.

 

Having said that, I was on the Thames and the Kennet a few years ago when both were a bit racy.

Good fun and thinking back an anchor probably wouldn’t have been much help stopping my boat at speed, a life jacket would have been sensible though. 

The anchor is more for when your boat has no speed whatsoever, and the river decides you want to start heading downstream not upstream, and definitely not towards a bank, like me last week (I have another knackered drive plate for my collection!)

 

On the Kennet a boat pole would probably be more use.

 

 

14 minutes ago, Mike Todd said:

TWC into Wiki yields at least 25 options, none of which seem relevant!

It's a reference to a Canalworld user who dwells in the Politics forum...

 

[peterboat]

16 hours ago, howardang said:

The booms across weirs are not called dolphin. I have moored to many dolphins over the years and if you need confirmation google mooring dolphins. Dolphins are structures to which a ship can  moors, often to be found at each end of a pier or jetty. 
 

Howard

They have them on the house up to goole

[GUMPY]

17 hours ago, howardang said:

The booms across weirs are not called dolphin. I have moored to many dolphins over the years and if you need confirmation google mooring dolphins. Dolphins are structures to which a ship can  moors, often to be found at each end of a pier or jetty. 
 

Howard

My suspicion is that some weirs have posts preventing access rather than a boom and the name has migrated in some quarters to mean the boom. Doesn't make it right though. 

Edited November 29, 2022 by Loddon

[Wanderer Vagabond]

3 hours ago, enigmatic said:

The anchor is more for when your boat has no speed whatsoever, and the river decides you want to start heading downstream not upstream, and definitely not towards a bank, like me last week (I have another knackered drive plate for my collection!)

 

On the Kennet a boat pole would probably be more use.

 

 

 

That was my thought as well with the mention of the Kennet. Given the usual width of that river,there are many scenarios there where the unwise deployment of an anchor would make a bad situation a whole lot worse. Imagine you've come out of Midgham Lock, heading towards Woolhampton bridge, with the current, and a tyre wraps itself around the prop. With a pole you might fend off from the bridge, (or not hit it too hard), lob an anchor over the bow and you are going to be sideways across the river, and jammed.

[Guest]

ISTR there are 'Dolphins' on a stretch of the Soar to allow boats to moor that are caught on a rapidly rising/flooding river.

 

 

Edit 

Found 'em. 

 

https://www.geograph.org.uk/photo/6181841

Edited November 29, 2022 by M_JG

[howardang]

1 hour ago, M_JG said:

ISTR there are 'Dolphins' on a stretch of the Soar to allow boats to moor that are caught on a rapidly rising/flooding river.

 

 

Edit 

Found 'em. 

 

https://www.geograph.org.uk/photo/6181841

.....and here is a boom on the Trent

 

Howard

[Guest]

6 minutes ago, howardang said:

.....and here is a boom on the Trent

 

Howard

 

If only he'd deployed an anchor, eh?

[Mike Todd]

2 hours ago, M_JG said:

ISTR there are 'Dolphins' on a stretch of the Soar to allow boats to moor that are caught on a rapidly rising/flooding river.

 

 

Edit 

Found 'em. 

 

https://www.geograph.org.uk/photo/6181841

and on the Trent IIRC.

[Momac]

An anchor would have been no help in this case . Oddly there are much safer places to leave a boat within a mile upstream and only a little further downstream of this location.

The photograph demonstrates how much difference a little rain can make  to a river . For the  avoidance of doubt this is no-tidal.

I am pleased to see most people wear life jackets when under way on the river.

[Alan de Enfield]

1 minute ago, MartynG said:

An anchor would have been no help in this case . Oddly there are much safer places to leave a boat within a mile upstream and only a little further downstream of this location.

The photograph demonstrates how much difference a little rain can make  to a river . For the  avoidance of doubt this is no-tidal.

I am pleased to see most people wear life jackets when under way on the river.

 

It shows the dangers of 'wild mooring' on rivers.

[Alan de Enfield]

On 28/11/2022 at 18:34, howardang said:

Good to see that you have a fulfilling hobby. However, if you look on danforthanchors.com it says something different.

 

Following more research I can find nothing else to support either the 1939 dates, or the much later patent dates. One assumes that the Danforth company would know their own history so I'll add that bit of knowledge to my records and will use that information in future.

 

Thank you for the correction and providing the link.

 

(The day you stop learning is the day you die.)

 

 

What is of interest is the performance figures quoted by the Danforth company and the recommended boat sizes for each weight of anchor.

 

It does tend to reinforce the comments regarding the poor holding power of the design against later designs.

 

The 26lb Danforth (slighter lighter than the alternative anchors tests below) gives a holding power of 1500lbs

 

The Wasi / Breugel (design early 80s & Patent 1986) weighing 32lbs gives a holding power of 4000lbs

 

More recent designs such as the Fortress (22lb anchor) and the Manson (35lb anchor) both achieved a holding power of over 5000lbs (the test equipment only went to 5000lbs)

 

So not only is the speed of 'setting' much poorer, the holding performance is a fraction of a more modern (not necessairly a very expensive) anchor.

 

The Danforth manufacturers data shows that for a 55ft-60ft boat a 100lb anchor is recommended giving a holding power of 3500 lbs.

 

A 15kg (33lb) Wasi (2nd hand cost £60) outperforms a 46kg (100lb) Danforth. The only place I can find a 100lb Danforth for sale is Canada and the price is $635.

The downside (for narrowvboaters is that the Wasi does not disassemble - However the Kobra (discussed earlier) does dissasemble.

 

For someone who has difficulty lifting 'a heavy anchor' consideration could be given to later designs where much lighter weights give far better performance.

 

 

 

 

 

 

 

 

 

Edited November 30, 2022 by Alan de Enfield

[IanD]

33 minutes ago, Alan de Enfield said:

 

Following more research I can find nothing else to support either the 1939 dates, or the much later patent dates. One assumes that the Danforth company would know their own history so I'll add that bit of knowledge to my records and will use that information in future.

 

Thank you for the correction and providing the link.

 

(The day you stop learning is the day you die.)

 

 

What is of interest is the performance figures quoted by the Danforth company and the recommended boat sizes for each weight of anchor.

 

It does tend to reinforce the comments regarding the poor holding power of the design against later designs.

 

The 26lb Danforth (slighter lighter than the alternative anchors tests below) gives a holding power of 1500lbs

 

The Wasi / Breugel (design early 80s & Patent 1986) weighing 32lbs gives a holding power of 4000lbs

 

More recent designs such as the Fortress (22lb anchor) and the Manson (35lb anchor) both achieved a holding power of over 5000lbs (the test equipment only went to 5000lbs)

 

So not only is the speed of 'setting' much poorer, the holding performance is a fraction of a more modern (not necessairly a very expensive) anchor.

 

The Danforth manufacturers data shows that for a 55ft-60ft boat a 100lb anchor is recommended giving a holding power of 3500 lbs.

 

A 15kg (33lb) Wasi (2nd hand cost £60) outperforms a 46kg (100lb) Danforth. The only place I can find a 100lb Danforth for sale is Canada and the price is $635.

The downside (for narrowvboaters is that the Wasi does not disassemble - However the Kobra (discussed earlier) does dissasemble.

 

For someone who has difficulty lifting 'a heavy anchor' consideration could be given to later designs where much lighter weights give far better performance.

 

 

 

 

 

 

 

 

 

 

I don't think there's the slightest doubt that thought the Danforth may have been been good in it's day (i.e. better than an Admiralty pattern anchor!) there are far better anchors around today, the Kobra being a good example.

 

The question of how big an anchor you need (for a narrowboat on a river) is another interesting one; all the usually quoted sizes (e.g. X lbs for a Y foot boat) are for seagoing vessels, and are intended to give safe mooring under poor conditions e.g high winds (see the YW article, table below). Here an 18m boat (which is often taken as the figure to be used for a narrowboat) shows 900kg force in a 30 knot wind -- but the footnote also points out that "strictly speaking it's the beam that matters not the length". So based on this a narrowboater might select (for example) a 16kg Kobra 2 with >1000kg holding power.

 

However this would really only apply to a wideboat which has similar beam to the type of boat referred to, you might expect a narrowboat with half the beam to need a rather smaller anchor than this, maybe only half the size?

 

Another way to look at this is to ask what the anchor is being asked to do here; not holding a seagoing boat offshore against a very strong wind, but stopping a boat and holding it in place against the flow of water on a river. If you imaging a boat going upstream and suffering an engine failure, it can't possibly take more than the available engine thrust to keep it in place (since this was enough to drive it upstream) -- and for 20hp, at 100hp/ton bollard pull this is only about 200kg.

 

(actually it would be even less than that since the boat won't be stationary under full power, since drag force varies with the square of current it would probably only be half that again, maybe 100kg -- but then again you need more force to stop a boat than hold it in place, and there are shock loads to consider when the rode tightens...)

 

All of which explains why Danforths seem to work OK in many cases, a 20kg Danforth will stop an engineless narrowboat most of the time -- but not *all* the time if it fails to set or drags, which they're prone to.

 

A modern anchor like the Kobra is better, but in this case mostly because it's more reliable at setting and not dragging rather than being able to withstand double the pull, which isn't needed under these conditions

 

But it sounds reasonable that even a 10kg Kobra would be fine for a typical narrowboat, more reliable setting than a 20kg Danforth, similar or higher holding force, and half the weight so *much* easier to stow and deploy.

 

Thoughts?

 

(no accusations please, I'm not saying what I will or won't do or who is right or wrong, just looking at the facts...)

 

Edited November 30, 2022 by IanD

[Alan de Enfield]

Yes - anchoring a NB (or NB/WB) is very different to 'a storm at sea' and there are dozens of charts and tables showing loads applied by various sized boats,

In the table you used it does say that 'shock loads (even in wind gusts) can exceed 'static loads' by a factor of 3x

 

Another table, where an 'overnight' (working) anchor requires 4x the holding power to a 'quick stop for lunch' hook.

 

 

 

But non of these situations relate to a 20 (?) tonne boat being bought to a 'handbrake' stop, they are all planned events where the anchor is slowly lowered and the boat reversed under power until the anchor is felt to set.

 

Another table using boat weight and length shows different figures :

 

 

 

Then throw in the variable of 'scope' (noting that a scope of 3:1 reduces the holding power of an anchor by ~50% and a scope of 2:1 reduces the holding power by 65%) and it is easy to see that consideration needs to be given to not only the type and weight of anchor, but the whole anchoring system.

 

 

 

 

 

There is so much 'science' and so many variables that I'd suggest the best advice is to buy the best anchor you can afford (what is the potential loss of your boat or family worth) and get the heaviest in that make / model that you can physically lower overboard - if you can retrieve it after you get 'going again' then treat it as a bonus.

 

Look for 2nd hand ones where folks may have traded up from a 'very good anchor' to an 'exceptional anchor' there are bargains to be had. Use a length of 10mm (or better still 12mm) chain at least the length of the boat and a good length of 19-22mm Nylon rope (ideally Octoplait, but 3-strand is far cheaper) to give a good 'elastic' scope which can help minimise the shock loading.

 

 

 

 

Edited November 30, 2022 by Alan de Enfield

[IanD]

Thanks Alan, there's a lot of information there, none of which I would argue with -- at least, in the situations it refers to 🙂

 

Most of this does indeed refer to seagoing boats, as can be seen by the length/beam ratios in the first table you gave. There are other factors which apply to seagoing anchors but not the "emergency narrowboat" one, for example the need to stay secure if the pull changes direction (like in the YW review where the some come out quite badly) -- this matters not a jot for the "stop me going over the weir" case.

 

Another one is shock loading, which is not just intended to deal with what happens when the anchor is dropped but what happens when a boat bobs up and down in a rough sea and pulls the chain tight and slack -- you don't want this to make the anchor gradually drag each time the boat rises. Again this doesn't matter for the case in question, if the shock load is bigger than the anchor can hold it will drag and slow the boat down until it does hold, assuming it sets and stays that way after dragging (so maybe not a Danforth then...)

 

If you take what was said in the YW article about it being beam that matters -- which will be true for both wind and water loads -- and we then look at the tables you just posted, these quote a 20kg/44lb anchor (without specifying type...) for a 16m boat, and that this might have 14'-16' beam with a 1600lb load for a "working anchor" -- which is about 700kg. This would be about right for a widebeam canal boat, but much bigger than needed for a narrowboat. Note that Danforth quote 1600lb holding power for their 25lb anchor, which seems *extremely* optimistic going by test results...

 

And you're perfectly right that the whole anchoring system needs taking into account including the scope 🙂

 

Completely agree with you that one of the new-age anchors (e.g. Kobra -- not even that expensive...) is a much better choice than a Danforth, especially because of reliability of setting and holding. How big to use is the question -- having one that's easy to stow/unstow and deploy is a big advantage, because if it's a PITA to get out and get ready you're less likely to do it, human nature and complacency being what it is ("the river/weather looks fine, I won't bother getting the anchor out this time") -- and having a big heavy anchor that some of the crew might have difficulty lifting and dropping over the size doesn't help either.

 

The other point of view is that loads and loads of boaters use 20kg Danforths, and even a 10kg Kobra is better then this on test from *all* points of view -- reliability, holding power, maybe even cost. From the Kobra website:

 

"Tests carried by French magazines Voile Magazine and
Moteur Boat Magazine gave clear evidence that ”a 6 kg Kobra anchor held
a 600 kg traction load, in a mixed sand-mud seabed”, which corresponds
approx. to the traction exerted by a 42-knot wind on a 9 m boat, where
a 12 kg anchor is traditionally recommended." -- so a 10kg Kobra would replace a 20kg Danforth.

 

In the end it'll come down to how heavy an anchor you think everyone can easily lift, and possibly how much space you've got to stow it -- for example if it's going into a bow locker (mine will), it has to go through the hatch. My suspicion is that -- for the purpose under discussion, emergency use on a river for a narrowboat -- a 10kg or bigger Kobra will be absolutely fine, and 20kg is definitely overkill and will be no safer but much more of a PITA to use... 😉

[Alan de Enfield]

16 minutes ago, IanD said:

In the end it'll come down to how heavy an anchor you think everyone can easily lift, and possibly how much space you've got to stow it -- for example if it's going into a bow locker (mine will), it has to go through the hatch. My suspicion is that -- for the purpose under discussion, emergency use on a river for a narrowboat -- a 10kg or bigger Kobra will be absolutely fine, and 20kg is definitely overkill and will be no safer but much more of a PITA to use... 😉

 

 

Very much so.

 

When on the river (in our NB) the anchor would sit on the roof, or in a tub at the stern, with the rode running along the roof and attached to the strong point in the bow.

When we were on canals it was all put away into the bow-side locker (under the seat) along with the bags of 'coal'. (We had a deep well deck with the water tank forward of the well deck)

[GUMPY]

What's needed is someone to do tests and calculations specifically  for narrowboats so we can then use a table to work out our anchor size/type.

 

[Mike Todd]

Midland Chandlers seem only to stock Danforth . . . 

[ditchcrawler]

1 hour ago, Mike Todd said:

Midland Chandlers seem only to stock Danforth . . . 

That is because that is what "most" narrowboaters ask for