anchor scope

[webcraft]

Re: arrant nonsense

[ QUOTE ]
Doesn't this sound like a case of those of limited knowledge trying to cry down those of greater knowledge?

[/ QUOTE ]
First, let me say that my anchoring expriences have been mostly good . . . since I learned to put out a decent scope and make sure the hook was set properly.

I am not a commercial skipper (although I have a commercial endorsement) but have a fair amount of experience in a variety of waters on a variety of yachts. That however is not the point. Every bit of literature on the subject agrees that 3-1 is the MINIMUM scope on an ALL CHAIN RODE.

If conditions warrant it (eg F4 or above or a bit of a swell) then EVERY authority I have ever read (with the exception of you and Mirelle) recommends increasing this to 4-1, 5-1 or more.

AND - all authorities agree that that with a mixed rode 3-1 is ALWAYS inadequate.

Here's a few:

J.D. Sleightholme:
"The scope of line paid out is popularly quoted as being a requirement of depth of water x 3 for a chain cable and depth x 5 for rope, but this is an absolute minimum for normal weather only - unless a much heavier anchor is used. . . .There must be sufficient length of cable aboard to provide a scope of up to x 10 in really bad conditions . . .
(from 'This Is Sailboat Cruising')
------------------------------------------------------------------------
Nigel Calder:
"I insist on a minimum scope of 4:1, and prefer to lie to 6:1"
(Article, Yachting Monthly)
------------------------------------------------------------------------
Simon Jinks
"Over the last 15 years the recommended chain scope has risen from three times the depth to five times the depth . . . this is . . . related to the increased windage of beamy, high-freeboard modern boats . . ."
(Yachting Monthly, ' Playing Hooky', August 2000)
------------------------------------------------------------------------
Ralph Bagnall-Wild
"The three times the depth with chain five times with rope guide is shown to have no basis in mechanics and to lead to dangerously short scopes in shallow water. Three times the depth pus ten metres is generally a better guide . . .
(Article, PBO, March 1998)
------------------------------------------------------------------------
Prof. John H. Knox
"As I've argued before, a scope of five should be regarded as the minimum for safe anchoring"
('Will My Anchor Hold?" - PBO August 2002)
------------------------------------------------------------------------

And I could find more, but I think I've made my point . . .

So - I repeat - your arrogant assertion that you are right, that 3-1 is always adequate scope and that the rest of us are just c**p at anchoring is dangerous nonsense that may mislead some poor soul who has just bought an AWB with mixed rode.

I shall view any other posts by you with suspicion now, Ships_Cat. After all, how much sailing experience can you have if you are only 7?

- Nick

 

[PeterStone]

Maybe he should have defined his terms

Interesting that he added that bit - assuming that he did and that it wasn't the work of an editor - a bit like in Adlard Coles's 'Heavy Weather Sailing'.

It makes you wonder though what he meant by 'a sea running'. Possibly the sort of seastate you might find at an open anchorage - like St Helena - not typical of what we encounter off our relatively sheltered shores.

 

[Guest]

Re: Disagree. Completely.

[ QUOTE ]
Whereas on the other hand you have a number of posters who apparantly have bad or lacking in confidence anchoring experiences and who seemingly can only relate judgements from the knowledge of others.

Furthermore, as far as I am aware, those having good anchoring experiences and relating judgements developed from their own knowledge actually work at a professional level in the marine industry. Whereas, as far as I know, those relating judgements quoting from the knowledge of others do not - perhaps they could clarify if this is so or not.

Doesn't this sound like a case of those of limited knowledge trying to cry down those of greater knowledge?

[/ QUOTE ]

My experiences at anchor have been excellent, I love anchoring.

While I know that there are many on the forum who have far greater knowledge of sailing than I do, and I respect Mirelle's experience, when on board I do spend a great proportion of my time at anchor. Last summer for example I anchored overnight on approx 50 nights, in a different anchorage on each occasion.

Happily I had no bad experiences (dragging, or coming too near other boats) during that time. I did drag once four years ago - on a 3x scope. My boat's anchor is used as much as the mooring warps. I am sure that there are people who anchor more than that, but I anchor more than enough to start drawing some conclusions for myself.

 

[Guest]

Re: You have Eric Hiscock on your side....

No, I have every respect in the world for his view, but as MacHurley22 pointed out, he amended it. The revised wording is remarkably close to the wording in the Mirabella V report I quoted.

What is more, both he and Mirabella V are talking about an all-chain rode. Your typical coastal boat, especially those under command of someone sufficiently inexperienced to be looking for guidance here, will most likely have a combination of rope and chain. The 3:1 recommendation is barely adequate in that case.

Personally, even with all chain, I would put down 4:1 for a good night's sleep, unless the anchorage is a tight one for whatever reason. Describing that as "bad seamanship" is I think nonsense. If bad seamanship goes against common sense, then I am in favour of bad seamanship. As I mentioned elsewhere, in a typical anchorage it has little effect of swinging room anyway, and one is more likely to foul other boats by dragging.

 

[scarlett]

Boats A and B

In my opinion boat A should move. They cannot necessarily reset their dragging anchor my merely letting more out. I think one has a duty to anchor properly every time or take the consequences. Boat B does not know that boat A crew have not anchored properly.

I would welcome a constructive critique of my method in crowded Med anchorages. [ Some that just look like a mass of boats when you arrive. Boats within fender use closeness. ] I find a boat of similar characturistics and motor up to her stern. Drop the anchor as near as polite to her transom and drop back scope 5 if there is room. Maybe my bow is sometimes a bit close to their stern but when we swing there is always room between us and if not they can let out some if they are unhappy --- or I can take a little in. It needs a bit of common sense ith regard to other boats nearby but whist I have ended up near other boats, never had a problem with it.

 

[Guest]

Re: Downright bad seamanship and irresponsibility!

If A has been dragging, the chances are that their anchor has weed wrapped round it, and they should pull it up, clean it and reset it properly. Just letting out a bit more scope is inadequate. Scope is not enough in itself - it has to be combined with a well-set anchor.

So A should re-anchor purely for pragmatic reasons. The fact that B may have been rude by anchoring too close is irrelevant, purely of historical interest.

 

[snowleopard]

Re: Downright bad seamanship and irresponsibility!

who should move is academic. as you can see from round here, re-anchoring would involve an implicit admission of fault and that just ain't going to happen!!!

in reality, once you're dragging the chances are you won't be able to remedy the situation just by letting out more scope, you'll most likely have to re-anchor which makes it up to you to give the other boat room.

 

[trouville]

Re: Downright bad seamanship and irresponsibility!

In the med perhaps the waves are shorter and faster than the UK.?
I always plan to anchor in 8 meters minimum 5 and maximum 12meters and so far always managed,

Except in Capria there the best was 15 meters and gulf St Tropez, out side the port 20 meters!! on the otherside by St Maxim its 8 Meters

I always put out 3:1 as with a manual winch and by hand, more takes to much effort to get it in again.

I have a 12 ton Hillyard and use a 35 LBS Danforth,i have as well a 35LBS and 25LBS CQR and have 45 meters on one and 35 on the other and two chain pipes and two chain lockers. I have as well 60 meters of 18mm line.

I start with 3:1 but if the wind changes or picks up i either leave or put out more chain, only once in Cassis in 6meters did i have to put out a full 70 meters 8mm chain

The worst thing that night was the sound of a large MOBO grinding away on the beach and the waves pounding it.

I dont think the anchor weight within certain limits is the importent factor but the chain that lifts off the sea bed with the swell, The anchor must be heavy enough to dig in and hold, but then the chain must do the work,if not you snub and can soon break any chain or fitting!

I use the 35LBS becouse its the biggest i can reasonalby handel getting the thing back on deck,in good or rough conditions, and been able to change my anchor spot several times,not wanting to do that in the middel of the night when a fat boat that drops its hook up wind with small anchor drags on to me,

On my 2 ton Folkboat i will try a 25LBS danforth with 30meters 8mm chain and 40 meters 16mm line,and will have a 35LBS just in case

 

[PeterStone]

Re: You have Eric Hiscock on your side....

Naturally the 3:1 scope referred to by Hiscock and others is sensibly only relevant when applied to all chain rode. Nowhere have I argued in favour of it being applied when there is a combination of rope and chain - that would be folly. In any case, as I said earlier, I personally deploy more chain when the wind pipes up. However, the fact that someone like Hiscock and other experienced sailors who post here believe that 3:1 scope is adequate, should open the debate about what is safe practice. I must admit to being surprised at how deeply entrenched are people's views on this.

Whether Hiscock amended the text because he changed his mind (unlikely, because he already had vast experience when he wrote his book first time around) or whether to clarify his views on anchoring in extreme conditions we will never know. Remember that many of his anchorages will have been pretty exposed and heavy winds and big seas would have imposed unusually heavy strains on his ground tackle. However - even with the text amended - he still says 3:1 unless there are strong winds and a big sea running.

What we do know is that he sailed 110,000 miles, presumably anchoring with a 3:1 scope, and came to no harm. The fact that he carried only 180ft of 5/16" chain on his main anchor indicate that he probably practised what he preached - he was very opposed to using a combination of rope and chain. You might think he was wrong in his thinking - as clearly many do - but you can't think he was just lucky to have got away with it surely?

A few years ago I anchored in Walton Backwaters on a 3:1 scope (all chain). Perfectly adequate for a sheltered anchorage. Another boat arrived and anchored downstream of me on a much longer scope. When the tide turned and we both swung round he was impossibly close to me. I ended up having to pay out more chain which then caused us to be closer to him when we swung back the other way at the next turn of tide. Surely in a tight anchorage which is sheltered we have a duty to fellow sailors to be considerate when calculating what scope to lie to.

I have never dragged overnight using my bower anchor - and I have anchored frequently. I have dragged a couple of times though, using the kedge for a lunch stop. Maybe I've been lucky in 32 years of sailing but I think that correct choice of ground tackle is the first step to a good night's sleep.

 

[Guest]

Re: You have Eric Hiscock on your side....

I wouldn't at all argue with Hiscock or say that Hiscock was wrong: I find his chapters on anchoring the most useful I have come across (that's why I referred to him as an excellent resource on the subject in the original debate on the MoBo forum). But although he does not state it explicitly (and I therefore cannot prove it), I read his words as setting out rather the minimum acceptable for good practice. Don't forget that Hiscock did not suffer from 'modern conditions', so there would be no reason on earth why he should not veer considerably more much of the time, except for the effort of winding it back in.

Also, bear in mind the bit that Webcraft dug out quoting I think it was Simon Jinks, that perceptions as to what is an acceptable scope have changed in the last 15 years. The other sources quoted referring to even 10x scope or more include some pretty authoritative sources, and should not be dismissed any more than Hiscock's view - much as I admire Hiscock, there is nothing holy about his words, they have to be read with a liberal dash of common sense. Obviously you yourself apply common sense to his statement, because in difficult conditions you veer more than Hiscock states in your edition of his book.

I would not argue with your contention either - in an anchorage that is becoming crowded, it is often only decent to use 3x. But I would keep a careful eye on my boat at high tide in those circs if there was a decent wind about.

Interesting that all the anchor dragging/tangling incidents seem to happen at Stone Point, the East Coast's answer to Newton Creek. Personally I much preferred anchoring round the corner behind Honey Island, down Hamford Water /forums/images/graemlins/wink.gif

 

[PeterStone]

Re: You have Eric Hiscock on your side....

<Personally I much preferred anchoring round the corner behind Honey Island, down Hamford Water>

Ah - well we used to sail with our 3 daughters when they were very young and they liked to go ashore on the sand and collect shells, which would end up being deposited somewhere on the boat and getting forgotten till we cleared out the boat when laying up.

You can still lie to anchor in many places on the East Coast and have the place pretty much to yourself. My last 2 anchorages before sailing to France in June 2003 were The Roach close to The Crouch and Stangate Creek on The Medway, both of which were pretty deserted.

 

[Guest]

Re: You have Eric Hiscock on your side....

I'm sure there's an easier way to post a pic here, but hopefully this should work: a pic of my boat anchored at Stone Point (on a 4x scope! /forums/images/graemlins/smile.gif)

http://www.croftsphoto.com/StonePoint.jpg

Yes, I used to anchor in the Roach too, up a small creek whose name I forget just upstream from that boatyard place. Was lovely - at low tide a perfect pool cut off from the river and surrounded by waders at close quarters /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

 

[PeterStone]

Re: You have Eric Hiscock on your side....

You're probably thinking of Shuttlewoods at Paglesham. Yes - a wonderful river for a peaceful overnight stop.

Great picture of your boat at Stone Point proving it's not just mud on the East Coast - well ok - maybe about 90%.

Incidentally, I agree that the other authoritative sources quoted that recommend greater scope are equally valid. I think you need to weigh up the conditions/your ground tackle/the composition of the sea bed and come to a decision based on all these factors and if in doubt increase the scope - I don't see that it can do any harm in any case unless you are constrained by swinging room.

 

[Superstrath]

What Sport!

There is nothing so much fun as arguing about something ephemeral.
For what it's worth, we never ran out less than a quarter mile of cable when sidling up to an oil platform....

 

[Guest]

Re: You have Eric Hiscock on your side....

Yes, that's right, I think it was called Pagglesham Creek. Lovely! /forums/images/graemlins/smile.gif

In a way, it can be looked at this way: the choice is between whether you consider 4:1 to be 'normal' and shorten it to 3:1 if circs dictate, or whether you regard 3:1 as 'normal' and lengthen it to 4:1 if circs permit.

ie.: is the cup half empty or is it half full!

 

[machurley22]

RYA

Surprised no-one has mentioned the RYA yet (perhaps we're all too experienced on here!) but the standard scope is 4:1 for chain and 6:1 for warp as recommended on yer Yotmeister course with provisos about swinging room and the way different types of boats lie.

Dave

 

[Mirelle]

Crikey! What have I done!

Spend the day with scraper and brush (amused to note that the first fine Saturday of Spring brings almost every owner of a boat in the yard out!) and come back to find a "voluminous correspondence".

I must admit straight away that I had in mind an all chain anchor rode.

I am surprised to learn that AWB's need to veer more than older types. I don't mean that I doubt this - I've never anchored in one for more than lunch - but I mean that in my opinion that suggests that their ground tackle and rode is perhaps inadequate for their windage, etc.

The yottimags used to be full of acerbic comments about folks who anchored with rope and swung all over the place. If most people now use rope that comment has become out of date.

It is perfectly sensible to veer more chain - or weight the chain - in expectation of strong weather, but I don't think it is sensible to do so routinely.

 

[Ships_Cat]

Re: Disagree. Completely.

and I respect Mirelle's experience

If that is so why do you (and others) not demonstrate it. Mirelle (and myself, with some sympathy of view from a couple of others) made some claims regarding scope. The whole thrust arising out of that by some has been to prove him (and those who are interested in his view or who support it) wrong.

It has been a foolish and amateur like scramble to find contrary published opinions from others and/or make shallow statements to the contrary. If you were sensible, and did indeed respect the view of an experienced person your (and some others) thrust would have been "Now, this guy is experienced and knows what he is talking about. I wonder what he means, I would be very interested in his expanding on what he says so that I can better understand where he is coming from."

Let me take one just one example of a loose and extravagant claim not directly related to anchoring (to avoid inflaming that matter) used by yourself to support your attack. You said words to the effect that an insurer would "certainly" be of unhappy view should you drag to an accident with only 3:1 scope. Does that mean that you have asked a sample of insurers what their view is on the matter or have worked frequently with them to know that they "certainly", as you claim, would be of that view. I would suspect that Mirelle has vastly more experience than yourself with marine insurers and from my own standpoint, where I have frequently been engaged by insurers to provide technical advice, I find your claim of "certainly" to be nonsense.

There is a lot more to what is being said to you than you appear to be able to comprehend and I find yours (and some others) determination to prove it wrong from your amateur standpoint, rather than try to understand what is being said very strange and a discredit to you.

Perhaps to help you see where I am coming from, if I, who snaps off a few photos occasionally, took a disagreement to one of your technical views on photography and just set out to rebutt and prove you wrong rather than explore your views with you, then you would likely think me a fool. Webcraft, just taking the liberty of using him as another example, would likely think me a fool if I did the same in respect to web design.

Some of the things that come to my mind when I hear you and others talk of scope in anchoring is that I frequently see cruise ships at "anchor" in very tight quarters for hours at a time with no scope or anchor at all because that is the safest option (they are not on moorings in case that thought introduces confusion), and I have worked with class to allow what some on here would say were very "undersized" anchoring systems (they would not hold the vessel under most circumstances). If you do not see where that is leading think of matters such as the proper operation of vessels, where they should be with respect to their capabilities, etc.

But no doubt I am talking into a black hole with no effect possible so I will not persist any further as it is basically just too tiresome to do so - similar to trying to cover points with a "knowledgeable" teenager. Enjoy your discussion which you have protected to your own parochial and not very knowledgable viewpoint by locking out some, whose views I suspect would otherwise have much to offer, by making it tiresome for them to respond.

John

 

[Guest]

Re: Disagree. Completely.

I'm not sure what provoked the tirade.

Just to correct a few things: I have plenty of experience with insurance companies, having advised quite a few of them over the years - even helped to set one or two up.

Certainly I respect Mirelle. I also respect many of the other authorities that have been quoted. In the end I come to my own conclusions based on my own experience. The extent of my experience with sailing is something that you are unaware of, and are therefore unable to comment on. It does not stop you from commenting though - presumably commenting on subjects you know nothing about is a speciality.

You imply that you are a 'professional'. But I would not trust the word of someone who holds himself out as so experienced as you imply you are - someone who is truly experienced at sea would have learned a little more humility. If you want to contribute to the discussion, I would suggest doing so in a way that is a helpful contribution to the discussion rather than merely a diatribe with no content.

 

[Ships_Cat]

Re: Disagree. Completely.

If you want to contribute to the discussion, I would suggest doing so in a way that is a helpful contribution to the discussion

I suggest that you read my posts early in the thread - it seems that I did contribute if you revert to them, but it quickly became apparent that there was no mileage in my talking about anchoring soon after them however.

John