Anchoring

[noelex]

Thanks. I asked the question in genuine innocence, only to feel terribly guilty shortly afterwards in case it was an euphemism for the ‘B’ word that dare not speak its name in these parts.

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This was tropical storm Brett. We have been through 13 named storms at anchor and I think we held an anchor watch for at least part of each storm, on the other hand I cannot remember any other anchor watches.

Brett turned out to be a very mild named storm (nothing worse than a typical winter’s day on the west coast of Ireland ), but the boat directly in front of us ended up dragging and when these things happen you need to keep an eye on the situation.

 

[noelex]

With a significant change in the direction of force on an anchor it will normally "shuffle" and remain buried under the seabed as it rotates around to a new direction. There is no need to reset the anchor, as it does not typically break out.

The photo below shows this "shuffle". The semicircular arc of sand in the bottom of the photo has been caused by the anchor shank of my Matus M1 anchor rotating under the sand (in this case over about 120°), as the wind has significantly changed direction.



This "shuffle" happens only when there is reasonable force on the anchor. Generally tide alone is not sufficient to change an anchor’s orientation, nor is a change in direction when the wind is light or even moderate. The photo below shows the typical underwater appearance in these conditions. This was a Rocna anchor on a large catamaran. The anchor remains unchanged even though the boat and chain will move around to other side of the swing circle.

 

[lustyd]

With a significant change in the direction of force on an anchor it will normally "shuffle" and remain buried under the seabed

Your post seems to be based on good holding in sand in good conditions with very little tide. Anchors break out all the time for various reasons, and a good 4kt tide will certainly do more than shuffle an anchor gently in a circle

 

[RupertW]

It sounds like you bought the wrong size new anchor to me. Modern anchors absolutely don’t need reversing to dig in, that’s the whole point as they reset when the tide turns.
Suggest you take a long hard look at whether your new one is too large for the boat.

You don’t reverse to set the anchor you reverse to test the seabed and that’s just as necessary with a new as an old anchor.

 

[FairweatherDave]

You don’t reverse to set the anchor you reverse to test the seabed and that’s just as necessary with a new as an old anchor.

Apologies but slightly curious about definitions here. To me an anchor is "set " when it has dug in and is holding the boat against the opposing forces of whatever wind and tide there is. It might reset if the direction of those forces changes with the tide or a wind shift. To me "reversing " tests the degree to which an anchor is set, which will be a test of the sea bed too. (And I appreciate different sea beds have different holding). In my case when I dragged I would suggest I hadn't technically dragged as I hadn't "set" the anchor (I hadn't reversed it in with significant force).

 

[Baggywrinkle]

My cruising ground is the Adriatic (no tide to speak of), and I don’t like marinas or ports – we anchor most of the time and it can get a bit interesting when anchoring overnight. I can always find shelter from a prevailing wind due to the number of islands, so it’s the localised thunderstorms that cause the most problems – and I’ve experienced my fair share of those.

The best solution to problems in strong prevailing winds is to find an anchorage in the lee of the prevailing wind … it’s not the wind strength per se that’s the problem, it’s the waves. Ensuring the fetch in the prevailing wind direction is as small as possible is always the first priority for me, so I watch the weather forecast and pressure charts all the time and organise myself accordingly, moving if necessary to keep land between me and the prevailing wind – hammering to windward to get to an anchorage is preferable to being battered by waves at night on a lee shore IMO.

As others have already said, setting the anchor well with the right scope is essential for the proper functioning of the anchor. I personally don’t use rode except on my second anchor which sees very little if any use – if you have two anchors down, it can make bugging out quite fraught as they may well end up tangled round each other, and I have left the rode/chain anchor behind before and recovered it later - better to lose the anchor than the boat. If the weather is really foul, with very strong prevailing winds then I will head into a marina or harbour. A few euros on a marina berth is well worth the money if it is really hairy.

I like to keep as much space between me and other boats as possible, leaving plenty of room to swing. I put out 5-7 times the depth in chain dependent on expected wind strength, and let the boat settle in the prevailing conditions to lie to anchor. When it has settled, I engage reverse (at tickover) while watching a realtively close fixed point – it will move relative to the background until the anchor buries itself and the relative movement stops … I then gradually increase the power until in full reverse - the points will move a bit more, but soon stop, at this point, the anchor chain is taught going straight-out from the bow, I hold it for a bit and then I slowly reduce power and switch the engine off when it gets back to idle, then I get out a beer and watch everything for about 20 mins until I’m happy that we are not moving relative to anyone else. If during this process the chain goes suddenly slack, then the anchor has pulled out and skipped - if I have enough space, I’ll stop the boat and start the process of pulling with the engine again … if it’s tight for space, I pull it all up and re-anchor. After this, not only do you know the ground is good, but the anchor is also set well for the prevailing conditions at the time.

Once settled the boat should be good to leave .. and I’ll happily go ashore for dinner or drinks, coming back late in the evening. I leave a tablet on board with Navionics recording the track so when I return to the boat I can see where it’s been and know how big to set the anchor alarm radius. I set the anchor alarm based on boat position, not anchor position because I want to be awake if the area the boat is swinging in changes, for example if the wind does a 180 in the night - which it often does in the build-up to a thunderstorm and IMO it's better to get an alarm when the prevailing wind shifts than when the anchor starts to drag – by which time you could have another boat wrapped round your pulpit.

Top tip number one, when going ashore, leave an easily identifiable light on your boat – a nice coloured LED lit cockpit is good – makes it much easier to find the boat again in an anchorage full of similar boats.

When going to bed I set my anchor alarm based on my recorded track and go to sleep. I’m a light sleeper and often wake up if the sound of the wind or waves changes … I’ll check the navionics track and either go back to sleep or pop my head out to have a look around.

If the alarm goes off, I check my recorder track, check the anchor has re-set properly by going on deck and observing for a bit, also check that no other muppet has broken out and is drifting towards me. Once happy that all is OK I’ll go back to bed with a new alarm set but I won’t sleep very well – just accept it’s going to be one of those nights.

Top-tip number two, try and anchor upwind of charter boats, I’ve been forced to move at night to avoid getting collected by wayward charter boats on a number of occasions. I've also had to leave anchorages a number of times due to localised storms, sometimes starting an impromptu overnight passage to a better anchorage or a marina, then spend the next day catching up on sleep.

These are my experiences after a good few decades of overnighting at anchor, it's not as scary as it at first seems and becomes very enjoyable as time passes and confidence builds, just another opportunity to be self-reliant rather than paying for berthing or mooring.

 

[14K478]

I started sailing my own boats in 1969. I've done so ever since. I have used Fisherman, Danforth and CQR anchors. When I started sailing we didn't agonise about anchoring; we just anchored, and if we wanted to go ashore, we went ashore, setting a riding light if it was going to get dark.

Despite my obvious incompetence and my hopelessly out of date adherence to the CQR, I have dragged an anchor twice in the past fifty-four years Once was off a glacial moraine in a fjord and once was dragging into the hole at Stone Point in Walton Backwaters - in both cases I was asking the CQR to do the impossible as the bottom was clay and getting rapidly deeper...

I suppose I have tempted Poseidon now...

 

[Poignard]

I

I started sailing my own boats in 1969. I've done so ever since. I have used Fisherman, Danforth and CQR anchors. When I started sailing we didn't agonise about anchioring; we just anchored, and if we wanted to go ashore, went ashore, setting a riding light if it was going to get dark.

Despite my obvious incompetence and my hopelessly out of date adherence to the CQR, I have dragged an anchor twice in the past fifty-four years Once was off a glacial moraine in fjord and once was dragging into the hole at Stone Point in Waltin Backwaters - in both cases I was asking the CQR to do the impossible as the bottom was clay and getting rapidly deeper.

I suppose I have tempted Poseidon now...

I know what you mean.

It used to be so easy before they invented online forums.

 

[RupertW]

Apologies but slightly curious about definitions here. To me an anchor is "set " when it has dug in and is holding the boat against the opposing forces of whatever wind and tide there is. It might reset if the direction of those forces changes with the tide or a wind shift. To me "reversing " tests the degree to which an anchor is set, which will be a test of the sea bed too. (And I appreciate different sea beds have different holding). In my case when I dragged I would suggest I hadn't technically dragged as I hadn't "set" the anchor (I hadn't reversed it in with significant force).

My post was responding to the post which seemed to suggest that new gen anchors didn’t need a hard set using reverse. My point is that I know my anchor works because I used it successfully hundreds of times before but I don‘t know whether that particular bit of sea bottom will hold my boat if the conditions get worse.

Anchors get set by being pulled whether by tide or wind or engine or all three and almost by definition will set themselves by the wind and tide present at the time. Stronger conditions should set them deeper and better or if the sea bed is not good enough will drag (E.g. heavy weed holding on only by strong roots, inch deep sand over a hard plateau, a loose but heavy rock).

I suppose my way of looking at it is that you never need to use the motor to set the anchor for the current conditions but it’s a good short cut to mimicking much worse conditions and sleeping well because you have proved it will probably hold, or moving to another spot because you’ve found out it probably won’t.

 

[benjenbav]

Unfortunately what you were taught wasn’t based on science. We know better now so it’s good to update your understanding.

I’m hoping Neeves is ok, thought he’d be here by now!

Bit of a time difference ‘tween UK and Oz. Even Jonathan needs some kip.

 

[14K478]

Bit of a time difference ‘tween UK and Oz. Even Jonathan needs some kip.

I think its the World Cup...

 

[benjenbav]

I think its the World Cup...

That was a good performance by Australia in the final. And I don’t think Travis Head could justifiably have been accused of dropping anchor…

 

[FairweatherDave]

My post was responding to the post which seemed to suggest that new gen anchors didn’t need a hard set using reverse. My point is that I know my anchor works because I used it successfully hundreds of times before but I don‘t know whether that particular bit of sea bottom will hold my boat if the conditions get worse.

Anchors get set by being pulled whether by tide or wind or engine or all three and almost by definition will set themselves by the wind and tide present at the time. Stronger conditions should set them deeper and better or if the sea bed is not good enough will drag (E.g. heavy weed holding on only by strong roots, inch deep sand over a hard plateau, a loose but heavy rock).

I suppose my way of looking at it is that you never need to use the motor to set the anchor for the current conditions but it’s a good short cut to mimicking much worse conditions and sleeping well because you have proved it will probably hold, or moving to another spot because you’ve found out it probably won’t.

Cheers Rupert. Completely agree.

 

[Tranona]

3...2...1 ... we have a standard issue anchor thread!

No idea who Peter Smith is but Eric Hiscock was quite relaxed about dumping the CQR over followed shortly by a pile of chain and leaving the boat to sort it out. As he pointed out back in 1950 in "Cruising Under Sail", the business about not dropping the chain on top of the anchor dates back to stocked anchors and related to not getting a turn of rode round the stock - the original "fouled anchor".

Pete Smith designed and made (in the early days) the Rocna anchor.

You may find this and his other thoughts on anchoring use and design helpful
petersmith.net.nz/boat-anchors/catenary.php

 

[doug748]

"I am looking for advice and good practice... "



Never anchor downwind of any boat equipped with one of these:



.

 

[srm]

"I am looking for advice and good practice... "



Never anchor downwind of any boat equipped with one of these:

View attachment 167961

.

Unless they have the blue "Silent Wind" blades. They bring the sound down to a civilised level. Or at least they do on my boat.

 

[NormanS]

I have been anchoring for many decades now, mostly, but not only in Scottish waters. When I started sailing, anchoring was what you did. There was no other realistic alternative. Engines were termed "auxiliary", and were not dependable. We anchored under sail.
It's noticeable that the received wisdom now seems to be that anchors must be "set" using an engine. Strangely, my anchor doesn't know whether it is being pulled in by the engine, or by the wind, current, or the boat's momentum.

When the wind really gets up in the 60 to 70 knot region, the pull on the anchor is much more than that provided by any initial setting by engine. In such conditions, the initial "set" means very little. It is then that the choices of adequate equipment, and suitable locations are paramount.

 

[srm]

It's noticeable that the received wisdom now seems to be that anchors must be "set" using an engine. Strangely, my anchor doesn't know whether it is being pulled in by the engine, or by the wind, current, or the boat's momentum.

Likewise, I have had many a comfortable night's sleep after laying the anchor and chain under sail. In the 80's I ran skippered charters and RYA practical courses in Scottish and Norwegian waters. We did as much as possible under sail, including on and off piers as well as into and out of anchorages. Technique was varied depending on wind and locality. Crews got a greater satisfaction from making a passage without turning the engine on.

 

[noelex]

Your post seems to be based on good holding in sand in good conditions with very little tide. Anchors break out all the time for various reasons, and a good 4kt tide will certainly do more than shuffle an anchor gently in a circle

It has to reasonable holding. All bets are off in, for example, rock substrate.
People overestimate the force on the anchor from current. This article gives a good analysis:

Forces
A quote from this article :
"We can see a 6 kt current - which is unlikely in most anchoring situations - has about the same effect as a 20 kt wind." (This is for a yacht with a 10m waterline).

The force on the anchor system from a 4kt current is only about 30 daN (about 31 kilogram-force).

 

[Roberto]

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