Anchoring overnight (peacefully)

[GHA]

No. It is the belief that catenary is not enough in water <30-40 feet with short scope that has been thrown out. I've done snubber testing for a magazine article (I use on 35' long) and I like high grade chain.

However, it is also easy to prove (calcultation or observation) that in 40 feet with 5:1 scope the chain will stay very near the bottom and that there is some curve to absorb shock. The point at which it is not enough depends on wind strength, depth, chain grade (weight), scope, exposure to waves, and how much shock is acceptable, with no single simple solution. Of course, since most of us anchor in <20 feet, the point is moot. I generally anchor in <7 feet, so I use a long snubber.

yes, and to add to the mix remember with dynamic loads that it doesn't take much horizontal movement even in quite deep water to go from a bit of chain on the bottom to bar tight when relying purely on catenary to act as a shock absorber, the force goes up exponentially as opposed to a snubber where its more linear.

 

[NormanS]

yes, and to add to the mix remember with dynamic loads that it doesn't take much horizontal movement even in quite deep water to go from a bit of chain on the bottom to bar tight when relying purely on catenary to act as a shock absorber, the force goes up exponentially as opposed to a snubber where its more linear.

Please enlighten me, where are you getting all these dynamic loads from? Are you anchoring out in the open sea? The anchorages that I use are all sheltered from the sea, but obviously not from the wind. If I find the wind gusty and troublesome, I use an anchor sail, to keep the boat's head up to the wind.

 

[GHA]

Please enlighten me, where are you getting all these dynamic loads from? Are you anchoring out in the open sea? The anchorages that I use are all sheltered from the sea, but obviously not from the wind. If I find the wind gusty and troublesome, I use an anchor sail, to keep the boat's head up to the wind.

Can happen anchored in a bay with gusts coming down from the mountains in every direction. Worst I had was in La Gomera with gusts from every direction (school boat on the pier saw 60kt peak) , the boat shooting across the anchorage as the next one came in. Stressful night.
Bearing in mind we're talking about worst case here ( I think ) I live mostly on the hook and can't remember the last time I set a snubber.

 

[jdc]

Please enlighten me, where are you getting all these dynamic loads from? Are you anchoring out in the open sea? The anchorages that I use are all sheltered from the sea, but obviously not from the wind. If I find the wind gusty and troublesome, I use an anchor sail, to keep the boat's head up to the wind.

Although GHA, to whom you addreses the question answered it perfectly, let me add a '+1': gusts are inevitable if your anchorage is sheltered by high(ish) ground and there is a strong wind blowing. And in many parts of the world this is pretty much every day.

Let's take an example of a F8 gusting 9 in open sea but anchored in a bay. Most of the time the wind is less than 20knots and sometimes falls to near zero, even with with a slight back-wind. But every couple of minutes bang comes a gust whose direction may differ by 90 degrees from the last such blast and 180 degrees from that a minute ago, and whose speed may exceed the wind speed in open water: certainly we experience 45 knots often enough. The effect of this is for the boat to start moving - even if you've a riding sail since the direction it comes from has changed - until you bring up against the rode. How much snatch you get depends on the boat, the depth, the scope, the weight of rode and the stretchiness of rode, but it's surely not a constant force on the rode.

 

[geem]

Can happen anchored in a bay with gusts coming down from the mountains in every direction. Worst I had was in La Gomera with gusts from every direction (school boat on the pier saw 60kt peak) , the boat shooting across the anchorage as the next one came in. Stressful night.
Bearing in mind we're talking about worst case here ( I think ) I live mostly on the hook and can't remember the last time I set a snubber.

I cant think of the last time I didnt set a snubber. We live on the hook for 7 months of the year

 

[Neeves]

>Take your head out of the sand and get a good snubber setup, far more effective at reducing forces on the anchor when the wind pipes up

A snubber works to a small extent but a riding sail attached to the backstay, or in our case the mizzen topping lift, works significantly better. It the reduces the the snatch load cuttng the swinging angle, that can reach 90 degrees, to 35 to 40 degrees. We bought one from Sailrite but I never saw another one on the 800+ boats I saw at anchor and always wondered why they didn't use one. http://www.sailrite.com/Anchor-Riding-Sail-Kit-12-5-Sq-Feet No doubt the majority will disagree with this post as usual.

I do disagree that a snubber works to a small extent. You can have a snubber that is as elastic and as long as you want, or as inelastic and long as you want. It can work at 30 knots or at 60 knots - you just need to choose the snubber size.

I do agree a riding sail would be very advantageous, they are seldom seen and very difficult to rig on a catamaran - in fact cannot think how to do it. We have no convenient back stay.

Jonathan

 

[NormanS]

Although GHA, to whom you addreses the question answered it perfectly, let me add a '+1': gusts are inevitable if your anchorage is sheltered by high(ish) ground and there is a strong wind blowing. And in many parts of the world this is pretty much every day.

Let's take an example of a F8 gusting 9 in open sea but anchored in a bay. Most of the time the wind is less than 20knots and sometimes falls to near zero, even with with a slight back-wind. But every couple of minutes bang comes a gust whose direction may differ by 90 degrees from the last such blast and 180 degrees from that a minute ago, and whose speed may exceed the wind speed in open water: certainly we experience 45 knots often enough. The effect of this is for the boat to start moving - even if you've a riding sail since the direction it comes from has changed - until you bring up against the rode. How much snatch you get depends on the boat, the depth, the scope, the weight of rode and the stretchiness of rode, but it's surely not a constant force on the rode.

I am well aware of all that. I sail on the West Coast of Scotland, and always anchor.
Do you use an anchor sail?

 

[GHA]

Please enlighten me, where are you getting all these dynamic loads from? .

I am well aware of all that.

So you knew the answer before asking...

 

[Neeves]

I also concur with the posts suggesting that well sheltered anchorages are prone to gusts and bullets coming from all and every direction. Our solution is to tie to shore lines, but then we can get in close and we have sufficient line.

As thinwater suggests a shallow large anchor lightly set, because its both a harder bottom and the anchor is big will be prone to tripping every time a bullet impacts the yacht at greater than 90 degree to the previously set direction. I would not suggest a more deeply set smaller anchor is any more reliable (or not) but thinking small, well sheltered anchorages are 'safer' is not necessarily correct. Before we learnt the error of our ways we bent a swivel in such a location, the small anchor did not move but the swivel bent (attached directly to the shank). We have not used a swivel since.

Jonathan

 

[Neeves]

Best wishes for 2017.

May you all have a healthy, happy and successful 2017.

May our future debates on anchors and anchoring be without rancour and of a constructive nature - despite our differences.

Best wishes,

Jonathan

 

[GHA]

Best wishes for 2017.

May you all have a healthy, happy and successful 2017.

May our future debates on anchors and anchoring be without rancour and of a constructive nature - despite our differences.

Best wishes,

Jonathan

:encouragement::encouragement:

 

[noelex]

It does not matter how big your anchor is - if the windage of your yacht develops a rode tension of XXXkg then that is the hold the anchor will develop, big or small (unless its too small). If you think the big anchor develops more hold - you can make a fortune as you are developing energy from nothing. Though some of the tension is needed to bury more chain of the smaller anchor and the bigger anchor enjoys more direct attention.

That debate should be - do you want a big anchor shallower set with less buried chain at XXXkg or a smaller anchor more deeply set with more buried chain at XXXkg.

You are ignoring the obvious difference that the larger anchor has a higher maximum holding power than the smaller version (assuming both anchors are the same design and material).

There are exceptions to the above rule, such as when anchoring in solid rock, but these situations rare.

 

[Neeves]

You are ignoring the obvious difference that the larger anchor has a higher maximum holding power than the smaller version (assuming both anchors are the same design and material).

There are exceptions to the above rule, such as when anchoring in solid rock, but these situations rare.

I am actually not ignoring the fact the larger anchor has a larger POTENTIAL hold. As long as the small anchor is large enough then you will never ever reach its maximum POTENTIAL. A number of holding capacity tests show that a 15kg anchor has a POTENTIAL hold of 2,000kg - no yacht for which that size of anchor is recommended will ever reach that hold (the bow roller will pull off first). Too many members of this forum use the recommended sized anchor, or smaller, and do not drag suggesting the use of oversize anchors is unnecessary - you would be better with anchors better suited to the condition you might encounter than rely on one very big anchor that might be defeated.

In marginal or difficult seabeds, say mud, or the other extreme, say hard, seabeds you would be better using an anchor known to offer technical excellence. As an example - a Fortress will perform well in mud but will possibly be defeated in medium to thick weed. A Spade may (and I stress the may) penetrate the weed but will not perform well in mud. The Fortress will be factorially better in mud (than virtually any other anchor) and the Spade, because it has a weighted toe and no 'obstructions' may be one of the best solutions in weed (though a Luke or fishermans would possibly be a better answer - if you happen to carry one).

Jonathan

Edit: As Thinwater suggested a large anchor not deeply set, because it is too large to be set with the limited engine capacity of a yacht, is more likely to trip than a smaller anchor deeply set and with buried chain. If you examine set anchors with the chain exposed you will find that as the chain 'tweaks' the anchor shank also tweaks, side to side and up and down. This movement reduces hold. Buried chain offers some protection as the tweaking is cushioned by the seabed in which it is buried.

This is not an issue with a slightly larger anchor - but is with an anchor whose increase in size is sufficient to offer 'real' additional capacity.

close edit

 

[prv]

As an example - a Fortress will perform well in mud but will possibly be defeated in medium to thick weed. A Spade may (and I stress the may) penetrate the weed but will not perform well in mud.

I'm surprised by that. Sure, I can imagine an equivalent-weight Fortress would do better due to the enormous fluke area, but I've never heard or experienced the idea that a Spade is poor in mud. That combination probably constitutes the majority of my (entirely drag-free) anchoring in the last few years.

Pete

 

[Neeves]

Sorry Pete, should have said THIN MUD.

We were anchored in SW Tasmania and we tried a Spade, an Excel and then the Fortress and a nearby yacht tried a CQR. The only anchor to offer success was the Fortress. The mud had the consistency of used engine oil. The other yacht tied to trees, Swan 42 from memory.

In thick mud - many anchors will offer success.

But, many anchors rely on a hard substrate to self right, think of roll bar anchors - in mud that substrate does not exist and I have seen anchors drag upside down for many yards, because they, roll bar and shank, sink into the mud (same happens in very soft sand). A Spade depends on the weighed toe to self right - so the characteristic is not the same issue

Jonathan

 

[Poignard]

Having snorkeled on many anchors over the years, I have yet to see a CQR buried and not half buried on its side. I always wondered how they did not drag like that......... But then the wind would come and.........

That's interesting. If I anchor in mud, my genuine 35lb CQR usually comes up with mud on both sides. Suggesting it has either been buried completely or has flipped over at some point.

 

[noelex]

We were anchored in SW Tasmania and we tried a Spade, an Excel and then the Fortress and a nearby yacht tried a CQR. The only anchor to offer success was the Fortress. The mud had the consistency of used engine oil. The other yacht tied to trees, Swan 42 from memory.

You have reported this incident before with no mention of using a Spade, only the Excel, which is a little confusing. See the link for the full story.

http://www.mysailing.com.au/cruising/dipping-an-anchor-toe-into-muddy-waters

"We were using our steel 15kg Excel and it would not hold our cat under engine power in reverse. It might have set securely with time but we were not willing to wait and see. Pottinger is quite sheltered but a Storm was forecast and we were not taking any chances nor were we wiling to 'wait and see'. Our Excel would be considered by some to be undersized, but I do not think that is the issue - it's just the wrong anchor! Loki, I think the original yacht (a Swan?) alongside us had the same issues, they were using a genuine CQR which they tried to set 5 times, they eventually tied to a tree as well as deploying the anchor. A superficial analysis of the foregoing would be to suggest that convex anchors do not work in thin mud, this is true, but importantly - neither do concave anchors (Rocna and Supreme are disappointing disasters). Additionally to have either a concave or convex anchor offer reliable performance in thin mud all the evidence points to having an anchor at least 2 times the 'normal' recommended weight - and this is simply unrealistic, when a Fortress, or Danforth (with Danforth's) serious weight implications), will achieve the same result."

 

[Neeves]

You have reported this incident before with no mention of using a Spade, only the Excel, which is a little confusing. See the link for the full story.

http://www.mysailing.com.au/cruising/dipping-an-anchor-toe-into-muddy-waters

"We were using our steel 15kg Excel and it would not hold our cat under engine power in reverse. It might have set securely with time but we were not willing to wait and see. Pottinger is quite sheltered but a Storm was forecast and we were not taking any chances nor were we wiling to 'wait and see'. Our Excel would be considered by some to be undersized, but I do not think that is the issue - it's just the wrong anchor! Loki, I think the original yacht (a Swan?) alongside us had the same issues, they were using a genuine CQR which they tried to set 5 times, they eventually tied to a tree as well as deploying the anchor. A superficial analysis of the foregoing would be to suggest that convex anchors do not work in thin mud, this is true, but importantly - neither do concave anchors (Rocna and Supreme are disappointing disasters). Additionally to have either a concave or convex anchor offer reliable performance in thin mud all the evidence points to having an anchor at least 2 times the 'normal' recommended weight - and this is simply unrealistic, when a Fortress, or Danforth (with Danforth's) serious weight implications), will achieve the same result."

And your point is?

I also did not mention we tried different scopes and different locations (in the same area), that we had dinner on Loki, that the forecast wind never actually eventuated.

 

[vyv_cox]

That's interesting. If I anchor in mud, my genuine 35lb CQR usually comes up with mud on both sides. Suggesting it has either been buried completely or has flipped over at some point.

Similarly to Chris, I have dived on dozens of CQR anchors and have yet to see one fully buried in the design manner. This one was taken in winds gusting to 30 knots, after about F4-5 in the opposite direction. The marks of the chain before the anchor rotated can be seen to the left. The anchor is holding but its attitude would not fill me with confidence.

 

[prv]

That's interesting. If I anchor in mud, my genuine 35lb CQR usually comes up with mud on both sides. Suggesting it has either been buried completely or has flipped over at some point.

Maybe it's a mud vs sand thing? I can't think of many times I've been snorkelling over a muddy bottom. It's generally a Mediterranean charter activity which mostly means sand, or in the UK it's something about anchoring off a (sandy) beach that puts me in mind of swimming. And if I did snorkel over a muddy bottom, it's likely that the visibility won't be good enough to see it anyway.

The CQR is reputed to be better in mud than other bottoms.

Pete