The Offshore Voyaging Reference Site

Two More Anchor Selection Criteria

One of the many great things about the comments we get here at AAC is that they often remind me of important things that I forgot to put in the original article.

So here are two of those from my recent article on anchor selection:

Setting Distance

In that article I did add two selection criteria to the ones Steve over at SV Panope used (correct rode attachment and roll bars, or rather the lack of roll bars), but I should have added a third: how short the distance is from the point the anchor lands to a full set after really leaning on it with the engine in reverse.

Why this matters in order of priority:

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Terence Thatcher

I use a steel Spade 44 lb. on chain for my primary anchor on my Morgan 382–18,000 design displacement, surely more loaded for cruising. I like to have a second anchor on the second roller for emergencies, such as if my windlass dies and I need to switch to a rope rode. You have said elsewhere that you would not use an aluminum Spade as a best bower. Why? I am contemplating replacing my old Delta 44 (the second anchor) with a Spade aluminum 20, which is lighter but, I believe, has the same dimensions as the steel model. Or perhaps an aluminum 44 lb, which would be bigger in dimensions but not add weight on the bow. I have no separate “storm anchor.” So, what is the concern with aluminum? Bending? Thanks, as usual for your help.

Richard Simons

Terence, I am having the same thought but thinking about the sarca excel in aluminum, that looks easier to stow than the steel version, albeit more costly.

Matt Marsh

From a “respect the marine environment” standpoint, setting distance is extremely important.

An anchor that bites right away on the first try, and holds on short scope, is vastly less destructive to seabed life than one that plows a furrow for 50 feet and then needs a 7:1 mass of chain dragging around to stay set in case of wind.

Arne Mogstad

That is a VERY good point! Especially in more vulnerable areas! But then again, the marine environment is vulnerable everywhere….

Martin Minshall

Very good point Matt.

Marc Dacey

I actually thought of this a couple of days ago when we saw a local boat in the cove beneath our rental unit drag a cement mooring from the boat ramp over the seabed to its appointed place. The thing must weigh 650 kilos and given that there are shellfish, lobsters and mackeral in here, I imagine it was very hard on the bottom.
I actually thought of this a couple of days ago when we saw a local boat in the cove beneath our rental unit drag a cement mooring from the boat ramp over the seabed to its appointed place. The thing must weigh 650 kilos and given that there are shellfish, lobsters and mackerel in here, I imagine it was very hard on the bottom.

Ross Golding

I am having a Oyster565 built and scheduled to do the 2022-2023 Oyster World Rally.The bow sprit is set up for a CQR which I did not want. The other option available to fit the bow stem is an Ultra which I chose to go with.I am aware of all the discussion regarding swivels, stainless rode etc and feel I have set up reasonable solutions. The boat comes with a kedge anchor(Spade S100 20Kg) stored in the sail locker.
My question is would you recommend an additional anchor ,which would need to be stored in a lazarette? If so which anchor would you recommend? BTW: Oyster does not recommend or discourage a 2nd anchor.

Thanks for all you bring to the sailing community.

Charles Starke MD

Hi Ross
You might look at the specifications for a galvanized Spade since the shape is very similar to an ultra. It probably will fit.
I carry a 99 lb galvanized Spade as primary and a larger 66 lb aluminum Spade as a secondary in stern storage for a 47’ 40,000 lb displacement boat.
Beat wishes,
Charles L Starke MD FACP
s/v Dawnpiper

Martin Minshall

One aspect of anchoring that isn’t covered very often is chain weight or what a very experienced Australian Cruiser described to me as “the jiggle factor”. He had a midsized yacht but had elected to use 13 mm (1/2 inch) chain. He contended that having significant chain weight lying on the bottom for a couple of boat lengths ensured a low angle of pull and insulated the anchor from swell or wind shifts that could “jiggle” the anchor out. My boat at only 11M (37 feet) can’t carry that much weight in the bow. Nevertheless I have 60M of 10mm chain backed up by 60M of 16mm eight braid which is lighter than all chain (admittedly the way to go on bigger boats). I have dove on my anchor hundreds of times in clear tropical waters and many times I have seen a wind shift has only partially moved the heavy chain. Some blogs recommend going to high test chain in a smaller size – I think this is a mistake!

Dick Stevenson

Hi Martin,
I believe that this question was just addressed in a recent AAC stream in which I gave an URL to an article I wrote on the subject.
I suspect you sleep very well. 60M of 10mm chain (on an 11M boat followed by rope) means, I would guess, that you are anchored on all chain the vast majority of your anchoring and rarely use the braid. That the chain is large (in my estimation) for your size boat also contributes to sleeping well. (And I like this rope/chain combination for many boats, especially coastal cruisers.)
I would argue that, unless one goes to grotesque levels of chain size, the chain will be lifted off the seabed at some point in foul weather: often when a gust joins with swell/wave action to throw the boat back. Whether this occurs at Full Gale vs Near Gale matters a little, but not a lot: because it will happen.
The goal then is to dampen the shock load on the anchor. Certainly, chain contributes, but a good snubber is essential in this ground tackle system as well. Then the shock loads never reach the level necessary to snatch the anchor free.
I would suggest that ground tackle be looked at as a system. You have a certain amount of weight you wish to dedicate on your boat and that weight that needs to be able to address your anticipated anchoring needs. I would suggest that weight put into a well-designed anchor (Spade, perhaps Excel, but definitely not old generation such as a CQR) is far more effective than weight put into the chain. Choose chain by your evaluation of the rode strength needed and put your weight into an anchor that makes the wags on shore chuckle. And then buy extra chain length, because, when you have the room, little beats scope for keeping the anchor in place.
As to what you refer to as a “jiggle factor”: I have never heard talk of this phenomenon nor have I ever experienced it. Those who might suffer in this way, I would suspect, never had their anchor well set in the first place (perhaps using an old generation anchor). In my way of thinking about anchoring, if the anchor is well set in the first place, the “tweaks” of a little jiggling are more likely to compact the seabed around the anchor and, perhaps, dig it in deeper, but do not cause a problem.
My best, Dick Stevenson, s/v Alchemy

Martin Minshall

Thanks for your comments Dick and John for your link. You are correct in saying we are on chain 95% of the time. And yes… is all about your total anchoring System. I left Vancouver Canada in 2011 with a 44 lb Delta as my primary anchor. Delta did well on a number of anchoring tests back in the 90’s. I changed to a 55 lb Rocna when I got to NZ because I had had trouble setting the Delta a couple of times in soft mud. Rocnas are probably the most popular anchor on Kiwi boats – I may have chosen differently given John’s subsequent articles about Spades etc but to us the new style anchors are vastly superior to any of the anchors we grew up with. We have a very good snubber System and our procedure on anchoring is much as John describes. My whole system has been thoroughly tested……we were holed up at Minerva reef (a very open anchorage 6 days north of NZ) once where it was blowing 40+ for 2 1/2 days. The water depth was 45 feet and we had all the chain + all the rode out (= 120 M / 390 FT) which is a scope of nearly 9. This and many more extreme anchoring experiences teach you to have confidence in your total anchor / rode / snubber / setting technique and to sleep soundly at night. There is one other reason I favour a proportional (relative to the size of the boat) heavy anchor + heavy chain; many times in the SW Pacific we had to search for a patch of sand amongst the bommies (coral heads). After the initial set I would shorten scope to the point our rode was not going to wrap around any bommies. At this point I get the mask and snorkel on and check in a circle to make sure our rode was not going to swing into one of these. Being safe on relatively short scope in these circumstances is a plus!

Martin Minshall

A final word……number of times when ultimate holding power with a bar tight rode was the main concern = twice in 11 years of Bluewater cruising. Number of times we had to use less than textbook scope because of the proximity of coral heads, other boats, etc = hundreds of times! Hence my preference for an anchor and chain system that is oversized for the boat!

Eric Klem

Hi Martin,

My experience dealing with coral is mostly limited to the Bahamas and Carribean so I am not an expert there but I did want to comment on chain weight versus anchor weight at short scope which is a little different than the discussion at longer scopes. If we want to compare on an equal weight basis, then comparing a typical 40′ cruising boat with a 50 lb anchor and 300′ of “heavy” 3/8″ chain, you would be comparing to a setup with 300′ of “light” 5/16″ chain and a 167lb anchor. Even if they only carried 200′ of chain, that would still be correlated with a 128lb vs 50lb anchor. I am not totally sold on a weight for weight comparison but I do think it is a useful way to think about it but I really can’t imagine having a 167lb anchor on that size boat, maybe 100.

The first issue of course is setting and it is unclear to me which one will set better, it may depend on depth and seabed. Heavier chain improves the angle of pull on the anchor which is good provided it is not already horizontal whereas a heavier anchor will set better than a light anchor. The most efficient thing weight-wise may simply be a kellet (~50lbs?) attached to the chain a few feet in front of the anchor if your goal is simply to get the rode pull horizontal and you truly can’t let out more scope even momentarily. I don’t like this and don’t recommend it though, I think that the situations where it makes the difference are pretty fringe and it adds several problems while only helping with setting. In practice, we chose an anchor that was supposed to have excellent short scope setting capability and indeed, it has been very impressive, out of curiosity we have tried setting at 2:1 in 15′ of water and a harder bottom and found it was still able to set. As Panope’s videos show, most of the good anchors will set at relatively short scopes like 3.5:1 in softer bottoms although he is using relatively heavy chain and it is a medium depth.

But when it comes to holding, I think the heavier anchor scenario is always going to win. I actually ran some numbers on this a few years ago and I remember it being quite clear that the angle of pull difference on the anchor was pretty small compared to the improvement from the larger anchor regardless of depth. Holding power scales roughly linearly to weight so the heavy anchor scenario has roughly 3.3X the holding at the same angle of pull. If we compare published numbers for reduction in holding power from say 5:1 to 3:1 scope which is overly conservative for the chain weight change, you generally see a reduction around 40%. If we apply this to the heavy anchor, we find that the light chain heavy anchor setup still has an overall holding power advantage of around 2X which is quite significant. My memory is that in truth the difference is even bigger, trying to change the angle of pull with weight just isn’t efficient.

Of course, in an ideal world we would all be storing chain in a locker by the keel where the weight was not a big penalty and we could just have both big anchors and heavy chains. In the absence of that, I think you can get a decent set on surprisingly short scope with the right anchor and light chain and your overall holding power goes up dramatically by shifting weight to the anchor.


Drew Frye

I won’t comment re. self-fouling. It has never happened to me and John covered it.

Setting distance is important. Also important, and not mentioned, is the ability of an anchor to “lock up” and not creep at all. John implied this, but I thought I would repeated it. A common flaw in anchor testing is to use a steady pull method, because it is faster. In fact, you need to pull, and then pause the winches, and see how well tension is maintained for a few to 20 minutes. If tension drops steadily, the anchor is actually dragging. If it drops a small amount and then holds, that is acceptable. A relatively non-stretch rode is required, unless motion of the anchor can be accurately measured by some other means. Personally, I prefer tension and an ultra low stretch rode, because even a fraction of an inch per minute, is quite a lot taken over 24 hours.

Fast setting matters because one of the most common reasons for failure in my soft mud testing was for the rode to lifted by a rotten stick or other debrise, preventing the anchor from going deep. It doesn’t take much, probably only a few pounds of lift at the wrong place, just as chain only provides a small amount of down force. The sooner the anchor stops moving, the better the odds. In a dirty bottom, there is no such thing as “stable dragging.” Sooner or latter, the anchor with trip on something, if only a soft spot.

Locking up is also important. Anchors that set shallow, being in softer material, have more of a tendency to creep. This can lead to tripping. But it can also lead to loss of tension, which matters in Med moors and shore ties. Knox emphasized this is his testing, and construction and oil rig anchor companies focus on it, but few recreational anchor tests measure static hold.

John Scaramuzzo

Would it make sense to add these two criteria and re-run the ratings spreadsheet? It might not change the outcome, but it would add more clarity to the factors behind the ranking order and it might flip one.

Kerri McHale

Just this morning, we had a self-fouling incident with our Sarca Excel, and I recalled reading your latest article on this no more than a month ago. This seems like a remote possibility to me before now. So here’s one data point that it can self foul.

We had anchored in an area with strong tidal currents that switched overnight. When we weighed anchor in the morning, we kept running into serious issues of the chain jumping off the gypsy due to twist (also an issue we’d never had before this incident), and when we finally got the anchor up (after dumping the chain twice), this is how it came up. Looks like just what you imagined the potential to be: getting caught on the fluke.

Kerri McHale

Yes, we tried it first without the swivel, as we totally agree that it is just one more point of failure. But this anchor loves to come up rotated 180º practically every time, and the swivel makes it much easier to right before stowing.

Kerri McHale

Yes, thanks for the things to consider. We actually replaced the gypsy (horizontal windlass) just two years ago, and it definitely fits the chain (we replaced the chain a year later, and regret that we did not do them both at the same time, because now we’re stuck with BBB longer! 😆). The only time the chain really jumps is when there’s twist in it (like in the fouled anchor incident). It just seems to me to be the way the anchor likes to hang, compounded by a bobstay that is too close and it leans against when coming up. We’ve been really happy with how the Sarca Excel performs when anchored, but it’s honestly just not a good fit for the size/design of our old-fashioned pulpit/roller (it fit well when we just tested stowage on a dry run, but has quite a few issues coming up and down that we didn’t have with the old CQR).

Robert Chabot

I had the same self-fouling incident with my Spade (S100) on a mud bed in St-Nicolas bay (St-Lawrence golf). I anchored as my usual way except that I pile up my chain on the anchor dropping point before backing the boat. May be it’s was the problem because usually, I unwind progressively my chain while baking the boat. I was stunning!

David Somers

New member today and while looking forward to a plethora (I know what it means) of great research, I confess my sign up purposes are to explore hoop-less replacements for my Rocna 33kg. Watched all of Steve’s great YouTube’s (before aware / subscribing to your site) and all your articles with words SPADE, SARCA, Vulcan in them as I do my best before merely asking for answers. Plus many others in your “anchoring” field. ALL this driven my the goal of getting that Asym2 tack out on a pole and clear of railing. I no longer feel dirty going hoop-less… But, each time I’m about to pull the trigger: to a Vulcan, SPADE, then to an EXCEL, that last ten percent of research always reveals a shocking downer. I’m in the Chesapeake bay until I fully retire so my aperture is wider than Chesbay but soft mud remains a big part of the calculus (A 30k lb displacement 46 footer that ends up “thunderstormed” on the beach before/during retirement has a way of severely narrowing ones aperture).
VULCAN: This quickly became least favorite despite local love because holding in harder stuff down the road can’t seem to match the other two and, primarily, it fits in the platform so poorly. Even if the anchor retaining pin did allow that giant french curve of a shank to rise enough to allow that elbow to get to the roller, it still seems like a giant pendulum under the platform just waiting for the bow to plunge. Not terribly secure.
SARCA: despite Steves valid concerns of “what’s going on inside that hollow shank” and lead, and price, and rust….seems SPADE is super everywhere but where I am…soft mud / muc where it turns into a great field tiller near the mud surface. Read accounts of LONG overnight drags in Ches and US southeast “plough mud”.
SARCA EXCEL: Yes…The holy grail (for my situation)! Maybe it doesn’t set quite as fast but possibly because it keeps deep diving until I’m not trying to hold in soft mud. Steve tests even demonstrably rates it the highest for the soft stuff. The SCARAB power boat look of the laser cut-outs be damned! But wait, ACC newby here reads August ‘21 update….chain wrap! Aughh. Sure, maybe I’m suffering a little paralysis through analysis but I prefer to accept the risk of a very low probability of occurrence when the consequences are not so catastrophic. I find my landward piece of mind corrupted by “could that chain have possibly found the back of the anchor in the last tide / wind swap?” Did the last reset hide that cozy little chain catcher beneath they surface like my engine set probably did?
Your thoughts My Liege? (Preferably not to include give up the bowsprit or the Ches Bay)