Manual versus windlass anchors

[NormanS]

You should not need to 'drag' an anchor until it sets - most modern anchors engage virtually immediately and set (lock up) in their own shank length You can tell if the anchor is 'dragging' and not engaged as if you simply rest your fingers on the chain just forward of the bow roller you can feel the anchor bouncing along the surface of the seabed. An all chain rode transits vibrations exceptionally well - mixed rodes, and snubber/bridle lack the sensitivity. Of course you can also tell if the anchor has not engaged as all the other yachts in the anchorage are moving closer or further way or....

Jonathan

How do you manage to "feel" your chain forward of the bow roller, with your 30m snubbers? ?

 

[noelex]

What I was responding to was the suggestion that a heavy anchor would get a lesser grip than a lighter one, of PRECISELY THE SAME MAKE, in use by the same boat.

It is a pity that there is a reluctance to acknowledge the basic principle that a larger anchor of the same design and material as a smaller anchor, will have a higher ultimate holding ability.

It is argued this extra holding ability is not needed, but the advocates of small anchors seem to spend a great deal of time laying multiple anchors, using very long scopes and swapping between different anchor designs if the wind is much above moderate. This seems a lot of fuss to save a small amount of weight.

Having used oversized anchors for 3,000+ nights at anchor I am hooked . The increased security to cope with the sort of conditions I indicated on post #43 is great, but the versatility created by the higher ultimate holding ability is what I suspect most boat owners will appreciate the most.

This versatility is because ultimate holding ability of a larger anchor will be better than a smaller anchor of the same design and material across all substrates and at all scopes. So a larger anchor opens up anchoring possibilities that would otherwise be untenable, or at least unwise.

The anchor size needs to be able to be comfortably managed by the vessel and the crew. This is a first priority. Some boats need to use small anchors. If you have a lightweight multihull or a smaller monohull with no anchor windlass this will create restrictions on the anchor size that can be comfortably managed.

 

[TJ1982]

On the matter of whether to plump for an electric windlass for a new (to the OP) boat, we were recently faced with the same question. We’ve a 20kg Rocna on 60m of 8mm chain and envisage spending most nights at anchor, when permitted to leave our mooring. For us, operating our SL manual windlass is frustratingly slow.

In February, we obtained quotes for supply & installation from three different firms:


Quote 1 (using existing batteries)
Lofrans Tigres Windlass £1094.52
Circuit Breaker £149.18
Foot Switches (2) £19.00
Carriage £12.60
Battery cable/connectors £280.00
Shipwright Labour £150.00
Shipwright Materials £40.00
Electrical Labour £640
TOTAL - £2385.30 + VAT (£2,862.00)

Quote 2 (using existing batteries)
Lofrans X2 12V windlass £884.34
Circuit breaker £170.85
Foot switch, black s/s £54.23
Foot switch, red s/s £54.23
Battery cable; 2 runs @ 8m £195.36
Crimp ends £6.00
Labour £800.00
Carriage £15.00
TOTAL - £2,180.01 + VAT (£2,616.01)

Quote 3 (additional battery in forecabin)
Lewmar Pro Series 1000 with 8mm gypsy
Foot Switches on Bow
Rocker Switch at Helm
85AH Battery in forecabin
Split Charge Relay
Associated wiring/battery cables
TOTAL - £1,510.67 + VAT (£1,812.80)


Lockdown has stalled progress for the time being, so we’re not yet committed to any of the above.

 

[geem]

It is a pity that there is a reluctance to acknowledge the basic principle that a larger anchor of the same design and material as a smaller anchor, will have a higher ultimate holding ability.

It is argued this extra holding ability is not needed, but the advocates of small anchors seem to spend a great deal of time laying multiple anchors, using very long scopes and swapping between different anchor designs if the wind is much above moderate. This seems a lot of fuss to save a small amount of weight.

Having used oversized anchors for 3,000+ nights at anchor I am hooked . The increased security to cope with the sort of conditions I indicated on post #43 is great, but the versatility created by the higher ultimate holding ability is what I suspect most boat owners will appreciate the most.

This versatility is because ultimate holding ability of a larger anchor will be better than a smaller anchor of the same design and material across all substrates and at all scopes. So a larger anchor opens up anchoring possibilities that would otherwise be untenable, or at least unwise.

The anchor size needs to be able to be comfortably managed by the vessel and the crew. This is a first priority. Some boats need to use small anchors. If you have a lightweight multihull or a smaller monohull with no anchor windlass this will create restrictions on the anchor size that can be comfortably managed.

How many of your 3000 nights at anchor were in winds that were above 40kts? Cant see an argument for a larger anchor if there is no wind or light winds which a fair percentage of your 3000 nights would likely be.
We have never needed a larger anchor in the last six years of living on the hook. Our cruising ground has predominantly been the windy Caribbean. I certainly dont want the weight of something I dont feel I need hanging over the front of the boat where unecessary weight has the most detrimental effect on boat performance and motion. Our three alternate anchors are all aluminium.
How do you work out a bigger anchor provides anchoring possibilities compared to the one the manufacturer says is the correct one for my boat?

 

[srm]

Cant see an argument for a larger anchor if there is no wind or light winds which a fair percentage of your 3000 nights would likely be.

Agreed, however I was very happy to have my slightly overweight Bruce set on the evening when the coastguard's forecast was for light variable and about an hour later the masthead anemometer hit and stayed against the 60kn stop until after dawn. I also used the full 45 fathoms of 3/8 chain. Once we were stable a second anchor was laid with the scope flaked on deck, to act as a backup should we drag. We also had a wind induced current through the anchorage. Gusts must have been well above 60 kn. Perhaps a lighter Bruce would have done the same job, I have no way of knowing.

 

[geem]

Agreed, however I was very happy to have my slightly overweight Bruce set on the evening when the coastguard's forecast was for light variable and about an hour later the masthead anemometer hit and stayed against the 60kn stop until after dawn. I also used the full 45 fathoms of 3/8 chain. Once we were stable a second anchor was laid with the scope flaked on deck, to act as a backup should we drag. We also had a wind induced current through the anchorage. Gusts must have been well above 60 kn. Perhaps a lighter Bruce would have done the same job, I have no way of knowing.

I dont think there is any argument with slightly oversized. Even on manufacturers selection charts you can be between two anchor sizes for your particular boat. Choosing the bigger one is not really an issue when its likely to be 5kg or so. Its those that go up a couple of sizes from that and claim its the only way to go with no supporting evidence but swear it makes a difference that I just dont understand. Especially when your anchor and my anchor clearly work in tough conditions

 

[Rappey]

I think both arguments for and against a oversize anchor are both valid as the reasoning is sound from both sides.
The hybrid anchors like the viking are lightweight due to a high carbon steel plate rather than a weighted bulky fluke and have a much larger surface area than a traditional anchor of the same weight.
I've watched many youtube anchor shootouts and many are well executed using many variables. You can have a ultimate winner but then find another video where it fails completely.
The viking blurb about how they tested them to destruction with commercial craft and tractors and how they immediately dig deep , plus the notch to send a loop of chain to reverse pull out a stuck anchor then add the cheap price is compelling.
I have a bruce copy and a bruce seems one of the least capable anchors today ?
I may be buying a viking eventually. 10 metre boat and 14 tons, seems a 12.5kg is adequate ?

 

[noelex]

How many of your 3000 nights at anchor were in winds that were above 40kts?.

We have had our new boat for just over 2 years and have had 9 named storms at anchor. 40 knots will be experienced more often than the very high wind speeds of named storms, but I don’t keep an accurate record to answer your question. Winters in the Mediterranean (in our previous boat) and in north western Scotland tend to be fairly windy, so we see high winds at anchor probably more than most which is why I place importance on the best anchoring gear.

I certainly dont want the weight of something I dont feel I need hanging over the front of the boat where unecessary weight has the most detrimental effect on boat performance and motion. Our three alternate anchors are all aluminium.

Not all boats can carry oversized or even the recommended size of anchoring gear. As skipper, you are in the best position to make this assessment. The only caution I would add is for most cruising boats most of the weight is in the anchor chain. Oversizing the anchor often only results in a small percentage increase in the total weight of the anchoring gear. Nevertheless this small percentage increase may be too much for some boats. I would encourage you to stay within the range where the anchor can be managed comfortably by the boat and crew.

How do you work out a bigger anchor provides anchoring possibilities compared to the one the manufacturer says is the correct one for my boat?

A larger anchor will have a higher ultimate holding ability than a smaller anchor of the same design and material. This applies to all substrates (with rare exceptions such as rock) and at all scopes.

This higher ultimate holding ability means the anchor will hold reliably in stronger wind. This is commonly thought of as just providing better security in good substrates in extreme conditions, but it also means providing better security in moderate conditions when the anchorage has characteristics such as a less than ideal substrate, poorer protection, or where a shorter scope than may be ideal is required.

When comparing anchors of the same design and material, the ultimate holding ability is roughly proportional to weight. So, for example, an anchor that is 20% heavier will have approximately 20% more ultimate holding ability. The substrate can be such that it offers 20% less grip before you are back to square one. Or the scope can be shorter. For example, most anchor manufacturers agree a change from 5:1 to 3:1 represents around a 20% reduction in holding ability. So in very rough terms a scope of 3:1 with the larger anchor provides a similar ultimate holding ability as 5:1 with the smaller anchor. It is no surprise that the users of small anchors quite sensibly typically insist on large scopes for the conditions.

You do need to exercise some judgement. A relatively large anchor is not a panacea for anchoring everywhere, but it does not just provide extra security for extreme conditions, it also provides a lot of extra versatility. This is achieved for a relatively modest increase in weight.

 

[srm]

I have a bruce copy and a bruce seems one of the least capable anchors today

Agree regarding the copies. Early copies changed the geometry to get around the patent so they only look like a Bruce but do not work as well.
However, genuine Bruces still work as well as they did before. I would not use a copy but am happy to use the two originals that I have kept over from boat to boat.

Just as an amusing aside, way back in the 70's a guy made a fabricated copy of the Bruce and was going to sell it to the oil industry as a cheaper version of the real thing. (The Bruce anchor was originally designed for mooring large offshore structures). It won various awards for inovation. I got involved by chartering my boat for a publicity film to promote this fabricated anchor.

The inventor turned up with a dinky little thing and a lot of rope. My first reaction was "that looks like a copy of a Bruce" only to get a long harange about the angles of penentration being different. I then suggested some chain between anchor and rope - no not needed. Ok, so I removed my genuine 30 kg bruce off the bow and droped the chain into the locker so as not to upset the filming. Took them to a shallowish bay with a nice sandy bottom. A diver was filming the anchor as it was lowered to the sea bed. We gently backed up with me on the helm and the inventor (who claimed to be an experienced sailor) paying out his rope on the bow, around 40 ft away from me.

By the time we had laid rope across the width of the bay and I was nearing the far shore I decided to dig the anchor in. Gave the engine a short burst astern, inventor almost gets pulled through the pulpit as he had not thought to take a turn around the windlass warping drum. He was saved by his anchor, the camera man said it just started to dig in then seemed to jumped out of the seabed and disapeared.

The final episode was the inventor going to prison for contempt of court when Bruce enforced their patent.

 

[geem]

[











When comparing anchors of the same design and material, the ultimate holding ability is roughly proportional to weight. So, for example, an anchor that is 20% heavier will have approximately 20% more ultimate holding ability. The substrate can be such that it offers 20% less grip before you are back to square one. Or the scope can be shorter. For example, most anchor manufacturers agree a change from 5:1 to 3:1 represents around a 20% reduction in holding ability. So in very rough terms a scope of 3:1 with the larger anchor provides a similar ultimate holding ability as 5:1 with the smaller anchor. It is no surprise that the users of small anchors quite sensibly typically insist on large scopes for the conditions.


[/QUOTE]
So for example, if we took two identical Spade anchors of the same dimensions. One in steel and one in aluminium. We then set the anchors on identical scope. Which one has the higher ultimate holding capacity assuming everything is identical, both anchors fully set?

 

[Rappey]

When comparing anchors of the same design and material, the ultimate holding ability is roughly proportional to weight

So here's an interesting one ?
A delta anchor will hold roughly 90x it's own weight.
A rocna will hold 145 times its own weight.
True or not I got that from an article that's about the delta and explaining why they say the rocna is an improvement. It is a rocna website.
It's a fairly interesting read as also gives a small amount of anchor history.
Delta anchor (Rocna Knowledge Base)
Please don't tell me it's not relevant . You know who you are !!! Haha ?.
What I was looking for was surface area to compare how much smaller a hybrid anchor could be .
The idea that an oversize hybrid anchor just won't set properly and keep getting pulled out sounds very plausible ?
The hard part about larger and smaller is proving any of it.

 

[geem]

So here's an interesting one ?
A delta anchor will hold roughly 90x it's own wei
A rocna will hold 145 times its own weight.
True or not I got that from an article that's about the delta and explaining why they say the rocna is an improvement. It is a rocna website.
It's a fairly interesting read as also gives a small amount of anchor history.
Delta anchor (Rocna Knowledge Base)
Please don't tell me it's not relevant . You know who you are !!! Haha ?.
What I was looking for was surface area to compare how much smaller a hybrid anchor could be .
The idea that an oversize hybrid anchor just won't set properly and keep getting pulled out sounds very plausible ?
The hard part about larger and smaller is proving any of it.

I didnt do that very well. Slow internet connection cocked things up a bit. I was quoting Nolex. In the words above where it said QUOTE

 

[Rappey]

I didnt do that very well

That's OK. I will fill in while you have another try ? Haha..

 

[noelex]

So for example, if we took two identical Spade anchors of the same dimensions. One in steel and one in aluminium. We then set the anchors on identical scope. Which one has the higher ultimate holding capacity assuming everything is identical, both anchors fully set?

Steel and aluminium anchors are not of the “same design and material”.

However, to answer your question, the steel Spade is better than the same physical sized aluminium Spade (obviously the weights will be significantly different). I have seen this many times underwater and there are independent magazine tests showing significantly worse results for the aluminium version.

For example, the large 2009 multi magazine anchor study tested identically sized aluminium A80 and steel S80 recorded the following holding figures:

Steel S80 1705 kg Aluminium A80 1052 kg

Still, the steel Spade is an excellent anchor so the aluminium version is OK if weight is a premium.

Spade acknowledge the difference and do not recommend that the aluminium version is used as a primary anchor.

 

[Catalina36]

Let's cut the cr*p. Buy a Maxwell 1500 watt and it'll eat any chain and anchor you're ever likely to set.

 

[corinthmistral]

Quite simply - if you anchor a lot buy an electric windlass. If you anchor rarely, leave it as it is.
Like most external items exposed to salt water, Electric windlasses are best used regularly and well maintained - greased and electrical connections kept dry and/or well blasted with WD40.

 

[Neeves]

How do you manage to "feel" your chain forward of the bow roller, with your 30m snubbers? ?

If you attach the snubber, any snubber, and then power set - some of the power of the engine is being used to stretch the snubber - which frankly seems daft if not totally bizarre It appears to show a complete misunderstanding as to the reasons for using a snubber. . You do not attach a snubber or bridle until the anchor has been set, power set or using the wind. If you want to take the load off the windlass - use a short, less than 1m, dyneema strop attached to a strong point (samson post if you have an older yacht.

Jonathan

 

[Neeves]

Noelex - as you are unable to define the characteristics and attributes of your own anchor I find it difficult to understand how anything you troll about other anchors has any relevance. You are fortunate in using an anchor so big - it has a similar ultimate hold to a Delta of the same weight. It is a pity you have not warned the gullible who followed your advice of the poor hold characteristics, compared to say Rocna, You are fine - don't you have any concern for those you misled?

I'm sure the moderators will consider this - Anchors are a safety device, evidence of misleading data should be aired and corrected. There is a large accumulation of data underling the idea that a Mantus has the same hold as a Delta of the same weight, from Universities, The US Navy etc. Before you consider banning me for upsetting Noelex - ask him to produce hold data on a Mantus, Ask him for a hold comparison of Mantus vs Rocna - as he says a Mantus is better than Rocna. You have a note on FAKE NEWS - use it.

Mods, I am happy to submit to you brief data on Mantus. I'd post but I am subject to confidentiality

Jonathan

 

[Neeves]

Steel and aluminium anchors are not of the “same design and material”.

However, to answer your question, the steel Spade is better than the same physical sized aluminium Spade (obviously the weights will be significantly different). I have seen this many times underwater and there are independent magazine tests showing significantly worse results for the aluminium version.

For example, the large 2009 multi magazine anchor study tested identically sized aluminium A80 and steel S80 recorded the following holding figures:

Steel S80 1705 kg Aluminium A80 1052 kg

Still, the steel Spade is an excellent anchor so the aluminium version is OK if weight is a premium.

Spade acknowledge the difference and do not recommend that the aluminium version is used as a primary anchor.

I have a steel Spade, in fact stainless steel and an aluminium Spade, S80 and A80. I have tested the 2 together countless times in different seabeds, different rodes and different scopes and I cannot tell the difference. I have a 2t load cell and measured the hold. So I have not tested once - but multiple times.

The stainless steel Spade sits, along with other redundant anchors, in my workshop. We carry and use the aluminium Spade regularly. I suspect that Spade do not recommend the aluminium Spade as a primary because the shank is not man enough (we have replaced our aluminium shank with a better, stronger, one (having bent the original).

 

[srm]

Just some personal observations on the argument that bigger / heavier anchors do not set properly.

My boat has a hull length of 35 ft, displaces around 8.5 tons in cruising trim. The Rocna table puts in on the cusp of 15 and 20kg. As we have a platform bowsprit, twin roller furling headsails, lazyjacks, stern gantry and pilot house cabin windage is more than the AWB so the 20kg would be indicated. My rule of thumb is one size larger so I bought the 25kg.

I spent the next five years living on board, mainly at anchor, for five or six months each year. Mainly in Scottish waters and Scandinavia. During this time I anchored on a variety of sea beds.
The Rocna fluke tends to hold bottom sediment so I noted the sample in my sailing guide books. Most anchorages produced a sample, though sand could be seen spilling off the fluke as the anchor was lifted and was usually clean by the time it left the sea. Even after a calm night on the typical black mud/clay of many west coast of Scotland anchorages the deck wash hose usually needed the help of the boat hook to dislodge sediment from the body of the fluke. After a few windy days the anchor was well and truly dug in taking some effort to break out. A few times we hauled the chain tight vertical and waited for ten minutes or so when the anchor would then break out easily.

Maximum wind speeds at anchor during this period was around 50 knots. The 20kg would probably have performed just as well, but I size my main anchor for a sustained mean wind speed of 60 knots plus, along with storm surges raising water levels by two to three meters having past experience of these conditions in my cruising area.

Obviously, this oversized anchor was initially setting well and then burying deeply with increased environmental forces.

Draw your own conclusions.