So the question is: Should you use one anchor or two, and if two, in what circumstances?
One Anchor or Two?
by John Harries
Reading Time: 6 minutes
Next: Two Anchors Done Right
Previous: 15 Steps To Getting Securely Anchored
- Introduction
- 4 Vital Anchor Selection Criteria and a Review of SPADE
- SARCA Excel Anchor—A Real World Test
- SPADE, SARCA Excel, or Some Other Anchor?
- Rocna Resetting Failures and evaluation of Vulcan and Mantus
- Some Thoughts On The Ultra Anchor, Roll Bars and Swivels
- Specifying Primary Anchor Size
- Kedge (Secondary Anchor)—Recommended Type and Size
- Third Anchors, Storm Anchors and Spare Anchors
- Anchor Tests—The Good, The Bad, and The Downright Silly
- Making Anchor Tests More Meaningful
- We Love The Way Our Anchor Drags
- Things to Know About Anchor Chain
- Selecting a Chain Grade
- Anchor Chain Catenary, When it Matters and When it Doesn’t
- Anchoring—Snubbers
- Anchor Rode Questions and Answers
- Q&A: Hybrid Rope And Chain Anchor Rodes
- Anchor Swivels, Just Say No
- A Windlass That Makes The Grade
- The Perfect Anchor Roller
- Install A Wash-down Pump—And Save Money!
- Anchoring—Kellets
- Anchoring—Chain: Stoppers, Termination and Marking
- 20 Tips To Get Anchored and Stay Anchored
- Choosing an Anchorage
- Choosing a Spot
- 15 Steps To Getting Securely Anchored
- One Anchor or Two?
- Two Anchors Done Right
- It’s Often Better to Anchor Than Pick Up a Mooring
- Yawing at Anchor, The Theory and The Solution
- Yawing at The Anchor, an Alternative Cure
- How To Use An Anchor Trip Line
- ShoreFasts—Part 1, When to Use Them
- ShoreFasts—Part 2, Example Setups Plus Tips and Tricks
- ShoreFasts—Part 3, The Gear
- Gale And Storm Preparation, At Anchor Or On A Mooring
- Storm Preparation, All Chain On Deck
I agree with everything you’ve written John,
John,
Glad to see the fall didn’t affect your mind.
In years (far) past we have used Bahamian and tandem arrangements. The Bahamian nearly cost us the boat, and the tandem saved it in Hurricane Fredrick ’79. In each case we would have liked a single anchor solution. We have moved to an oversized Spade this season. Only time will tell if this was wise.
Hi John:
I need to set up a shorefast on my boat. How have you sized your shorefast, what material is it made of and how long is it.
Thanks
Stan
Hi Stan,
I have a piece on our shore fast system coming some time this winter.
Until then, you can get a lot of information by entering “shore fast” into the search box next to the menu.
Hi John,
Our first season, after a few weekends of anchoring, my wife agreed she preferred being on the hook. Once I received that green light, a 10kg Rocna (w/chain) went on the bow of our 3200 lb. boat, as I knew the first time dragging would likely be our last time anchoring. We usually manage a pretty restful sleep.
“Bow and stern…. How much more are the loads?…. I would hazard a guess that they are at least three times greater if the wind is blowing from the beam.”
Sounds a bit low…. let’s check. Knowing Morgans Cloud‘s dimensions, I’d peg her projected area as about 3.75 times greater when viewed from abeam as when viewed from ahead.
From the photos you’ve shared with us, I’d guess her drag coefficients beam-on are about 2-3x larger (above waterline) and ~5x larger (below waterline) than their head-on counterparts.
So, as a very rough first guess using a metric boatload of crude approximations, you might be looking at (3.75 * ~4) = 15 times the forces if she is held beam-on, versus being held bow-on.
I think I’ll reserve that stern anchor for kedging off, thank you very much….
Hi Matt,
Wow, 15 times! I knew the problem was bad, but I had no idea how bad. Then when you consider that wind pressure goes up with the square of speed the whole thing gets very scary.
Your calculation really makes you think about using shore fasts too.
Thanks so much. I will change the post to reflect this new ( to me) information.
I hadn’t thought of it either, John, until you brought it up.
That a boat beam-on presents 3-4x more area to the wind and waves is, to most people, obvious.
That her drag coefficients are so much larger beam-on than bow-on should not be surprising- from the bow, she’s a streamlined body; from the side, she’s nearly a flat plate.
Combine the two, and you get some scary numbers. For shorefasts, I suspect it’s not as bad, because you (a) know the prevailing wind/wave direction, and (b) often leave enough slack that she can re-align herself by 30-45 degrees if she needs to.
Hi Matt,
Actually, in most cases where shorefasts are used they are kept really tight to stop the boat surging about and then coming up hard. Also, shorefasts are usually used in small coves where the wind gusts from a multitude of different directions. So I think the problem of high loads is at least as bad. On the bright side, if the small cove selected is tree surrounded the wind and gusting is dramatically reduced. This may be why shorefasts are much loved and used by those who cruise in Patagonia, but not so much by those of us who confine our cruises to the north where there are no trees.
The calculation of drag-coefficient and area resulting in an overall increase of approximately 15 x seems a bit over the top to me (especially the drag-coefficient part).
However, an other engineering aspect will also play its role. It is the working components (vectors) of the forces in the two lines. The working components shall equal the forces exerted by beam-wind and beam-current where these vectors are only (very) small relative to the line tensions. This is the case when the lines are tight. The working vectors become more effective when the lines are less tight and allow for better angles to act against the wind and tide.
Having said all this I would agree with both of you that the increase in line tension is unexpectedly big and that such positioning could end in unexpected failures where breaking of the fore rode is probably the worst.
Cd for a streamlined body with a blunt stern, like a sailboat hull end-on, is in the range 0.04 to 0.1 by projected area.
Cd for a beam-on hull is hard to figure exactly but, approximating from primitive geometric forms, should be confined to the range 0.3 to 0.8 by projected area.
Cd for the superstructure is on the order of 0.7 in either direction, but wind load on a trunk cabin and dodger is tiny compared to the forces of the water, waves and wind on the hull itself.
Projected area beam-on is, for a monohull, at least 3 times more than projected area head-on.
I didn’t believe it at first either, until I checked the Cd figures against several different tables. If you hold a boat like John’s at bow and stern so that it’s beam-on to everything, you’ll get about 15x the force as if you let it swing bow-on. That’s just the total force on the boat- not the tension on the rodes, which as Martin points out will depend on the exact vectors involved.
Good stuff. This matches advice from the likes of Steve and Linda Daschew, but of course it’s superbly written and backed by your experience, John. Other advocates of the one-big-anchor school are Nick and Josie of s/v Jedi, a Sundeer 64, which rode out Hurricane Ivan (Cat 5) on Grenada, hanging on their big Bruce and 3/8″ G70 chain and chain stopper (the snubbers melted and parted).
Query:
The recommendation is for an anchor one or even two sizes too big, for our 38′ x 6t cat we’ed then need a 25kg instead of the ‘modern’ 15kg Anchor Right Excel we carry (not that in the grand scheme of things 10kg is very much). But what else to carry, Mr Murphy is out there and he has an insatiable appetite for anchors, so we have need of another 25kg anchor which will sit grumpily in the anchor locker (that is if Mr Murphy is already saitiated by someone less fortunate). We prefer the shore line (which might be afixed to a well buried anchor) and or 2 bow anchors, in your definition – underweight (in our case at 90 degrees and of equal size to the 15kg Excel – alloy makes a good fall back (Fortress or Spade). But depends on the anchorage, any fall back anchorage, and what the winds is lilely to do.
Beyond 25kg I would certainly prefer humping 2 smaller anchors than one big one and as long as the primary is strong enough (a big unknown) then the secondaries as alloy ensures remedial spine work is unnecessary.
I like the approach you describe. On my Valiant 42, I have a 66# Spade on the bow with an all chain rode. I have a backup Spade #44 (disassembled) in the bilge with a mixed line and chain rode in the bow anchor locker.
I hope I never have a reason to use the backup anchor, but it wouldn’t take too long to get it out and bring it to the bow.
I also have a Fortress anchor on the stern, but the only use I have had for that is when bow in at a bulkhead.
You had suggested stirring things up
It might have been in an earlier thread but why this fascination with Rocna and Spade? The same pairing appears in (an)other thread(s). What is wrong with Spade and Supreme or Boss or Excel or SARCA or Fortress. All (named brands) have holding capacity beyond anything most people will need (if sized correctly). 2 concave anchors looks like overkill, roll bars are very 1970’s, two galvanised anchors (spine threatening – depends on yacht size and strength of partners). Just seems parochial and ‘restrictive(?)’ but – its your website 🙂
But I was never considered as a mover and shaker.
Hi Jonathan,
Note that I say “new generation anchors LIKE the SPADE and Rocna” which clearly implies that there are other options.
Having said that, here at AAC, we only recommend products that we have extensive first hand experience with, or verified second hand experience from multiple sources who we know personally and trust.
Our readers come to AAC for experienced based facts, not speculation. They can get enough of the latter on the forums.
Incidentally, if you look under anchors in the menu, you will find our thoughts on the Luke and Fortress.
Thanks John, it’s why I trust this site.
I always slept well with my 35# CQR (bottom permitting) on a 30′ boat. My next boat will have at least twice the recommended size.
John,
Very nicely stated and the least controversy I have ever seen generated from an anchor article.
With respect to tandem anchor set ups, I used tandem (19# hi tensile Danforth on a 60# CQR) to good effect when on the US east coast in hurricane country, especially in the really soft stuff of the Chesapeake. This was before we moved to using a 66# Spade 4-5 years ago now (on our Valiant 42) and although we have been whacked by a few storms, on this side of the pond there is less occasion to do the kind of storm preparation that hurricane’s generate.
I have kept tandem anchors in mind though.
I am not sure I agree with the second anchor “lying on its side not set”. It is hard to know what is going on down there on the bottom and I suspect with careful deployment both anchors could be laid down ready to set. The issue (unlike my old CQR) might be that the Spade would set quickly not giving the second anchor an immediate chance to set itself. That might remedy itself when the storm hits.
I suspect you may be correct in observing that a wind shift may have you lying on one anchor. One could argue the second was just backup in this case.
Your third point is the kicker for me as I am loathe to set up anchors where the ability to get underway is compromised. To that end I set up the tandem with a short rode (less than depth of water) and a pennant to grab so as to easily secure the “hanging” second anchor. With the anchor roller far from the hull, the Valiant is well set up to motor a bit with the second anchor dangling but unlikely to hit the hull in a fire drill. We could not go to sea like that, but we could roam the anchorage looking for another spot if need be.
I agree about that this generation of anchors and getting “over” sized has changed the anchoring techniques that many of us were weaned on. With a down side so minimal, I will likely keep tandem anchoring in my possibility repertoire. It still makes sense to me, although I am aware that going to the trouble of setting up tandem anchors may be doing more for my anxiety level than to actually hold the boat in place.
One scenario where multiple anchors still have a place, I believe, is where the storm/hurricane forecast is such that you choose to anchor the boat and go ashore for safety. Hurricane Bob was one such for us. Ginger looked at me with our 3 children and said we were going ashore and that the worst consequences were what insurance was for. We used multiple anchors. Other storms we stayed aboard and then we were prepared to work the boat in ways such as you described and felt ok with less ground tackle deployed.
Good discussion and all good anchoring points. Thanks, Dick Stevenson, s/v Alchemy
Jonathan, Not “parochial and ‘restrictive” from my point of view, but rather predicated on lots of 1st hand experience and reports from skippers and boats who range widely in the most marginal of conditions and pay a lot of attention to what works. Spades and Rocnas have met the test so far. Others may follow and surpass.
Dick Stevenson, s/v Alchemy
John,
your paper is spot on. Though we until now haven’t done any high latitudes sailing, we have a 42kg/92 pound Bugel anchor on our 48′ aluminum boat and with a decent bow roller and anchor windlass it is very manageable.
The main problem is often to convince the designer/builder of the boat to accept that the future owner wants a “ridiculously large” anchor. In their mind it seems that their customer is not capable to set the anchor properly. It takes some self-conciousness to stop the discussion and say “I want it done like that, period”.
The second problem is to find shackles, swivels, chain hooks, and stoppers that are up to the job considering the high holding power of a large anchor of the new generation.
Thanks again for the post, even if it didn’t stir so much controversy with this audience ….
dietmar
Hi Dietmar,
Thanks for the support.
I would agree with Dick on shackles and swivels. Here are our thoughts:
http://www.morganscloud.com/2007/09/01/which-anchor-shackles/
http://www.morganscloud.com/2010/09/12/anchor-swivels/
Dietmar,
I do not use swivels or chain hooks, but for shackles, the only match for G4 chain that I have come across are made by Crosby. For 5/16 inch g4 chain I use 1017450 = 3/8″ G-209A shackle doubled with either 1017472 = 7/16″ G-209A shackle, or the 1017494 = 1/2″ G-209A shackle to the anchor. They are an alloy and preclude the shackles being the “weak” link and last as well or better than the galvanized shackles one finds everywhere.
Dick Stevenson, s/v Alchemy
John and Dick have here alerted me to the Crosby catalogue of anchor shackles. I notice that they catalogue some round pin shackles (with split pin securing) as anchor shackles, as well as screw pin shackles.
I find screw pin shackes with a large flange for screwing, are awkward in an anchoring system: the flange can foul on the bow roller, and if used as joining shackles in the middle of a chain can also foul on the winch gypsy.
I would be interested to know what you think of round pin shackles with split pin to secure the pin, in an anchoring system?
Hi Simon,
I’m not sure I would want to use split pin secured shackles since I would worry about the pin being damaged on a rock and failing. We have used normal shackles for years (wired of course) without problems. Maybe our anchor roller is wider than yours?
Also, we don’t recommend joining chain at all since we have never yet seen an elegant way to do that which is both as strong as the chain and will go over the windlass wildcat.
Hey John!
I sail like you with a 25kg Spade and a 60 kg Spade. It is a good solution. The Spade is the best anchor I ever had. But there are types of bottom that the Spade can not handle: Tall grass and very hard clay. Tall grass I find east of Denmark and west of Sweden. The solution on tall grass is that on deeper bottom close by, there is always soft clay. You have to move a little. On very hard clay I use tandem anchor. Two old traditional ship anchors and lots of chain will do it. Then it is the steel weight that holds the ship, not the grip of the anchor.
The vikings used often shorefast (or landrope as they called it) and a light anchor on a short line. This is a good metode on the west coat of Norway. Many places you will find steel poles ashore marked with a bulls eye for landrope purpose. Even if this pole could look very private, you have as a sailor the legal right to use the pole. I always bring fittings to fasten the landrope. Moutain climbers have developed many good products here. When close to a glacier, a landrope is often the only safe anchor metode because of very strong fall winds.
I hope your leg is getting better and I never understood why people put boats ashore and stop sailing in winter time, it is too much risk taking.
Best regards Svein
Hi Svein,
All good information, thank you. You must have really hard clay in Scandinavia! I have yet to find a bottom of clay too hard to get our SPADE to set in.
And yes, we have used the “fortoyningesbolta” in small anchorages in Norway many times, they are just great and amazingly common.
You are right, the land is way too dangerous! Still on a walker, which is making me crazy, but slowly getting better.
Strangely Spades are not available, unless you order individually at rather high freight rates, in Australia. (This I might add is Australia’s loss – its a good anchor. But its expensive in Europe and with freight, wallet crunching here). I have seen 3 in 15 years (including ours), in Australia. Equally oddly we enjoy the same taxing weather as most other marine areas. Actually because we overlap Capricorn we also enjoy Cyclones (that you might call Hurricanes, and our distant neighbours Typhoons), because we are geographically large we also overlap The Roaring Forties and we also have yachtsmen who have suffered from the effects of Tsunami when visiting our very close neighbours. Despite the diversity of these natural phenomena (and the absence of Spade) we seem to cope quite well. As far as I am aware Australian’s are as intrepid as anyone else, on the water, but possibly reticent (?) :). There are other experiences and anchors that you might consider and these experiences might be to the benefit of many.
If, in your book, there are only 2 anchors – and we only have easy access to one (whose history has been, to say the least, chequered) then you are not to engender much response if you will summarily dismiss our practice and experiance as not meeting your standards (because we do not use the anchors you consider of merit).
Maybe there is a Luddite in us all:)
Jonathan
Jonathan,
You don’t have to agree with me, but please stop putting words in my mouth.
One more time:
Note that I say “new generation anchors LIKE the SPADE and Rocna” which clearly implies that there are other options.
Having said that, here at AAC, we only recommend products that we have extensive first hand experience with, or verified second hand experience from multiple sources who we know personally and trust.
Our readers come to AAC for experienced based facts, not speculation. They can get enough of the latter on the forums.
Incidentally, if you look under anchors in the menu, you will find our thoughts on the Luke and Fortress.
informative and interesting article…i have intuitively always shied away from using more than one anchor…now i understand better why this is a good approach normally…i have a 55lb delta as the bower for my new dufour 425 and it always performs well…do you consider this among the new generation anchors ? do you like deltas ?
richard s. in tampa bay
s/v lakota
Hi Richard,
I have no first hand experience with the Delta, but based on reliable second hand reports I would say that it is one of the better of old generation plow types.
However none of these older plow types hold a candle to the new generation anchors. If it were me, I would replace it with a SPADE or a Rocna.
We have a Delta and agree that it’s one of the better “old generation” types. A Rocna, Spade, or Manson is on our list of potential acquisitions.
On our 30 footer we had a 22 lb Delta and it did perform very well. We have since replaced it with a 25 lb Manson Supreme and it is far superior. The Manson sets almost instantly.
I could always break the Delta free the next day by hand. Sometimes it would take a good bit of effort but I could do it. The Manson laughs at me. Once set it does not budge and we have to use the engine and power over it to get it to break free.
Going to the Manson and 8 plait line was one of the best upgrades we made to our boat.
Our 80lb Manson Supreme aboard our Outbound 44 seems to fit your specification well – we certainly feel secure with it and have not been tempted into a 2 anchor lay. I agree that I might be tempted into it – just to satisfy the need to “do something proactive.” I like the idea of prepraing a second rode ready for deployment – maybe that will satisfy my do something needs!
My back-up anchor is probably a bit weak in your opinion – a Fortress 23 – but it stows nicely! I guess we could replace that with a 25kg Spade but I’m not sure if my money might be better spent on something else…
John, it seems to me your anchoring is well thought out, well practiced, and now well said. And , the comments that have followed have been stimulating. However, I have to ask, if the Spades set and hold so well why do they need to be “oversized”? Is it for the overall strength of the anchor? Is it to assist the initial set of the anchor which you test so rigorously? Or, possibly to assist the reset of the anchor if it rolls over in a wind shift? Thanks.
Steve
Hi Steve,
We recommend that all anchors for voyaging boats be at least one size larger than that recommended by the manufacture, not just SPADE anchors.
And no, it’s not about setting, resetting, or tensile strength.
The reason is that we would guess that most anchor designers will produce a size table based on general use. We also assume that different anchor designers are making different assumptions about what general use is. Bottom line, there are a lot of assumptions going into the process of calculating a sizing table, and many of those assumptions are pretty arbitrary.
On the other hand, a voyaging boat will, sooner or later, be faced with an anchoring situation that is extreme, not general use, maybe a hurricane, or a really nasty fall storm, and in this case the ultimate holding of a larger anchor may save the boat.
The Mt. Murphy of whom you and Jonathan Neeves speak was my grandfather. I’ve developed a corollary to his law: “If anything can go wrong, it already has: you just don’t know about it yet.”
I do agree with your statements. We converted to a Rocna from Delta.
Here are in short the advantages we noticed:
1. Set much faster. Instant I would say.
2. Cut thru kelp much better. Tested in Norway.
I´m sure Manson, Ultra anchor are more or less as good.
When would I consider 2 anchors? I´m not sure. If I was in a hurricane hole waiting for the big one, I would hesitate as I have to little experience with 2 anchors. It would not be the right moment to gather experience.
Another good reason for not having two anchors on your bow is that somebody might steal one…the best one, of course, and not feel too guilty because they still left you with one.
That’s what happened to me in the marina in Peniche.
Maybe they were making a statement that I only need one anchor!!! (just joking about this last part)
I’m in total agreement with you.
Agree 100%. In Hurricane Marty in the Sea of Cortez, there were some boats in the same hurricane hole at Puerto Escondido as us, who decided to use two anchors or an anchor and a mooring in various configurations.
All but a few had problems with fouling and dragging (I did a questionnaire and article for CW on the anchors used and results). Their big problem was that they could not retrieve the tangled anchors in the middle of the storm, while those dragging with just one anchor out could do so and reset.
We only had one anchor out and didn’t drag, but watching boats get swept past us as they vainly tried to get things under control convinced us to never try any sort of a tandem anchor arrangement!
Hi Carolyn,
Great real world experience, the very best kind of information. Thank you.
I also wonder of your reasoning for choosing an anchor 2 times the size. Most modern anchors would be considered to have 2 times the holding capacity of the earlier designs yet most suppliers of modern anchors recommend the same size of their more efficient models as the less efficient older designs. So most modern anchors would have twice the holding capacity of the earlier models – yet you still want to go oversize. Possibly you are being cautious given that the hard won experience of you and your correspondents is based on the original specifications of your preferred roll bar model and you are taking into account the underspecified models (of which there are still 100’s sitting on bow rollers) and the fact that the new production has a shank that is ‘claimed’ adequate, but undefined. (Adequate for lunch or adequate for a hurricane?)
Interestingly if you ask Spade they will tell you the materials from which their shanks are made. Manson advertise the quality of steel in their shank. Anchor Right actually quote the brand name of the steel in the shank of their Excel. If you ask Fortress they will tell you the alloy they use and would point out that their shank is twice the thickness of an equivalently sized gal anchor. You obviously have questions of your prefered roll bar model or you might not be quite so cautious.
If the anchor is engineered and designed correctly then 2 sizes too big is simply extra weight, extra investment, might need a new windlass (given the mud these concave anchors can lift). 100’s of us anchor with the recommended sized Spade, Supreme, Excel, Fortress etc we anchor (at times) under arduous conditions. I do not think any of us would consider buying another anchor, with the same efficiency as our already adequate anchor, 2 sizes too big.
Hi Jonathan,
I guess we will have to agree to disagree on that one.
See my answer to Steve above and do keep in mind that I have two SPADE’s, one the recommended size and our bower that is two sizes bigger. We have had both for 15 years and some 60,000 miles, anchoring from the Bahamas to Greenland. In other words our recommendations are based on practical experience, not theory.
Look around any anchorage frequented by cruisers and you will find that anchor size scales pretty accurately to miles cruised. Example: Steve and Linda Dashew, who have over a quarter of a million miles under their belts, size there anchors at twice the size I do!
Thanks John, I knew there was a reason for two oversized anchors on our bow. 8>)
Another reason, if one were needed, for not setting two anchors 45 degrees off the bow is fear of the boats ahead dragging back into your trap. Certainly their dragging anchor will catch upon one of your rodes and either dislodging the anchor or dragging them into your boat. Having been in this situation in Scotland we set up fenders and lines to attempt to catch a dragging boat before it caught our anchor. Miraculously the dragging boat’s anchor caught hold just before they arrived for midnight tea. That was our last dual anchor/dual rode set.
Hi Steve,
A really good point. Kind of like setting a spider web for your fellow cruisers!
John:
I absolutely agree with yours assertion: one modern design, over-sized anchor. Over the years I’ve tried many combinations of multiple anchors all with the same result: fouled anchors and foul language from the fore deck. The one thing I have not tried, but makes eminent sense to me, is adding weight (chunk(s) of lead) to the chain to increase the catenary effect and decrease the shock loads on the hook.
Anyone have experience with this approach to increase the holding power of a single anchor?
John
S/V Sargo
Hi John,
This whole catenary, shock damping issue comes up over and over again, and for good reason, since it sounds so compelling.
However, several good engineering studies have shown conclusively that heavy chain and kellets don’t help at all in holding power or shock damping. In fact heavy chain may make the shocks worse since the boat will be pulled further in toward the anchor in the lulls and have further to go back again in the gusts.
The key thing that these studies have all shown is that at about gale force (34 knots) the chain is pulled out bar straight, no matter how heavy (within what a boat can carry). So at the very moment you need the shock absorption and better angle to the anchor, it goes away.
We can also confirm this from observation: At about gale force “Morgan’s Cloud” pulls our entire 340-feet of 7/16 G4 chain out bar taut.
John,
I agree with the article other than the omission of one situation where the second anchor can add greatly to comfort. On the Pacific coast of Mexico we have some anchorages that can be quite rolly and it’s common practice to set out a stern anchor simply to keep the bow into the swell. This is solely for comfort, not safety. Of course it could be argued the better rested crew is safer. On Exit Strategy we simply row the stern anchor out rather than dropping it prior to setting the bow anchor.
My suggestion is to use a fairly light anchor because it should not require much holding power to simply hold the bow to the swell. In fact, I’d rather see the stern anchor break loose readily in the event of a surprise like what happened to us one day in Matanchen Bay near San Blas. The forecast showed nothing unusual so we were anchored towards the middle of the bay, well out of the reach of the bugs that populate the shoreline around dusk.
In the middle of the night, the wind picked up and the direction of the seas changed almost 90 degrees putting us beam to the 2-3 foot waves. I elected to extend the rode of the stern anchor and make it a second bower anchor. This actually worked quite well and we enjoyed a peaceful night after that.
When we head back south, (hopefully with a new Rocna, Spade, or Manson), I’ll add a lighter anchor to add to the inventory for these rolly anchorages. In hindsight, I could have simply buoyed the stern anchor and set it loose completely for later retrieval.
Hi Dave,
Now there’s a good point. Have done the same in the Eastern Caribbean.
Jonathan,
I think of larger anchors as a gaining a great deal while loosing little. For my 40 foot boat, 35 lbs might be recommended, I am heavy so go to 45. I do have 66 lbs. For that 20 or 30 pounds difference I consider myself safer by a considerable margin, way more than twice. For everyday piece of mind it is worth every pound of weight and dollar I spent, let alone for storms. For ex.,I am better able to leave the boat for long hikes without worry. I sleep like a rock and rarely do “anchor watches” after a quick check, even in quite potent winds. Further I spend considerably less time attempting to get the anchor set; generally I stick it and its done. Far less re-anchoring/futzing etc than was the case with smaller or less competent anchors. So the weight on the bow is not a big deal for me. Nor is the money when thought of over the life of the anchor or when one spends significant numbers of nights every year at anchor.
Dick Stevenson, s/v Alchemy
Hi Dick,
Now there’s a lot of good sense packed into a small space. I could not agree more.
I have often wondered.
I predicate the question with the idea we are using modern highly efficient anchors.
If you take the recommended sized anchor and set it properly then, for the sake of argument, it sits with the top of its shank at seabed level. If you have a 2 sizes bigger anchor it will not set so deeply, your engines in reverse will not rev higher. You could drive the boat backwards using momentum but that will develop a snatch/dynamic load.
So we have one anchor set fully and the other set ‘less fully’. A storm cell passes through and winds switch suddenly through 90 degrees. Will these 2 anchors have the same holding capacity at 90 degrees or will the well set, lighter one, be better or worse.
To put another way is a well set smaller anchor better then a less well set larger anchor. And if weight comes into the answer – would one be better with a well set gal Spade or a 2 sizes bigger less well set alloy Spade?
My scenario is based on sudden wind changes, really strong gusts and assumes the anchors were as originally set.
It seems that a “bigger badder anchor” would require a “bigger badder windlass”, no?
I wonder what would be the 120lb Spade analog for the Adventure 40? 100lbs? More?
Do you envision for the A-40 a windlass system that could recover the anchor manually? It seems like a manual-only option would save a great deal on costs; in any case, if we are talking about anchor sizes that are virtually impossible to recover by hand, it seems like a manual-power option would be prudent.
What is your contingency plan on Morgan’s Cloud for anchor recovery if your windlass motor (or engine power) fails?
As always thanks for the informative posts and discussion – hope you are feeling well.
(And yes, I did go back and read your post on windlasses before commenting)
Hi C. Dan,
Yes, certainly bigger anchors require bigger windlasses, although, having said that, my reasoning for advising the installation of oversized windlasses is more to do with the loads imposed on anchor retrieval in high winds.
The Adventure 40 will certainly have an anchor at least one size bigger that the anchor manufacture’s recommendation chart, in keeping with our basic thinking on that point. So, with a SPADE or Rocna that would equate to around 45 pounds. Keep in mind that “Morgan’s Cloud” is over twice the size of the Adventure 40.
As to a windlass for the Adventure 40, I really have not done any research on the options. Manual is certainly one way to go.
As to backup on MC, our Ideal Windlass has a manual backup. We also carry a spare motor for it, although we have never had to use it.
Excellent article!!
Diffidently diffidently disagree on one thing, based on my experience with my last boat. A modern lightweight 30′ LOD cutter she sailed horribly on single anchor in intense wind.
When I put out a 2nd anchor, a vee of 2 anchors off the bow, she merely wiggled on the same spot. Which makes sense. This cuts down enormously on forces working on the anchor from different angles & on chafe.
So for those boats that sail at anchor in high winds, I would think a vee of 2 anchors is a good solution.
My current boat, a 39 LOD Colin Archer type has no such trouble – 1 anchor off the bow in F10 is no problem – she barely shuffles a few degrees off the wind.
A 2nd rode is insurance in more than 1 way – a rode might part due to chafe, or the anchor in play might drag til the 2nd anchor comes into play.
If retrieval is inconvenient just buoy the secondary anchor for later pickup.
Regarding comments on weight on the bow. I’m 200 pounds & my boat couldn’t care less if I’m standing with a pal on the pulpit under sail. So it is fine to have a ‘huge’ anchor!!! Have to totally ignore the racer’s maxim for minimum weight!!
Regarding comment on boats dragging into a trap of a vee of two anchors. If on board & on watch, just let out one rode til slack & well sunken. You can wait til,the last minute to choose which rode to let out to dodge a boat dragging down onto you.
Hi Nick,
All interesting points. (For those who don’t know him, Nick has a lot of experience including some pretty impressive high latitude voyages.)
A few thoughts on your points:
Back when we used to anchor on two anchors from the bow, I never found that it made a great deal of difference to the boat’s tendency to sail. Having said that, different boats have different characteristics. Be that as it may, the key issue to me is that even if the two anchors have a positive affect on sailing, that will only be so as long as the two rodes are equally loaded. As soon as the front (common in most storms) comes through with its attendant wind shift, that benefit will go away. I think a much better solution for boats that sail at the anchor a lot is a small riding sail set aft. These work amazingly well, as shown by some friends that kept their boat on a mooring in a windswept harbour on the north coast of Norway though the winters. Before setting a riding sail, they thought they would lose her in the frequent hurricane force storms, due to the violent sailing she did. With the sail, the problem was solved and she lay quite head to wind with much less load on the mooring.
As far as a second rode as insurance against chafe,, I think that is a very good point if you are anchored on rope, and particularly if you believe that there are sharp obstructions on the bottom.
I still think that dropping a shorefast is easier and safer than buoying an anchor, particularly if it is blowing really hard and you in a hurry. Also, much less subject to error, say fouling the life lines or pulpit. (I have done both in storm force conditions.)
I don’t think that slacking a rode will help you much in the real world of boats dragging in very strong winds, that Carolyn wrote about. First off, with the blowing spray and in the dark you won’t even see the boat about to drag on to you. Second that boat will still be dragging her anchor(s) along the bottom, where they are likely to snag your rode, even if slacked. Third, slacking rodes and pulling them in again in the type of conditions that Carolyn is referring to is a pretty dangerous activity.
Hi John, think I should clarify this.
My last boat was a lightweight coastal sailor & a total disaster on one anchor in high winds. Vicious sailing to & fro, 180 degrees to either side of the anchor, severe heeling as she raced from tack to tack, with extreme forces on the anchor as it whipped the bow around to start the other tack. Ghastly.
On two anchors she was gentle as a kitten. Yes there was shuffling sideways but essentially the bow stayed on the same spot. The rode opposite the tack she was on pulled her around before there was any momentum. Back & forth. A totally different behavior. The alternation of force from one rode to the other did not matter. It was highly effective.
I suspect that many modern sailboats, being lightweight, with minimal keel, and a lot of windage up forward, handle like my old boat did at anchor. And that many of their owners, like me, never got around to getting a riding sail. On my part that was due to laziness, not ignorance.
Owners of such boats, if without riding sails, are likely to have several anchors onboard, and they do need to know about the possibility that deploying 2 anchors will really help.
Of course a riding sail is far far better, and for many reasons.
Hi Gents,
good article, thks, mostly agree on all,
we, on hopperdredgers (here 20.000t deadweight, 142m long), are always on a kind of bahamian moor to hold our ships in position when pumping sand ashore on reclaimation sites, through the floating line connected on the bow, meaning one bow anchor and one (big) floating line connected to the shoreline, no other choice unless you a powerfull Dynamic positioning system …
this works well on most occasions as we pump out in less then one tide or tide change, but we usually have to reset the whole thing if/when the tide is changing, especially on high current rivers like the Thames, Schelde or Singapore strait … if we don’t wanna crash on the river sides …
We also use aft anchors, combined with the bahamian as above to limit the side movments, but i comfirm that this always become very messy when things go wrong, or if you don’t reset BEFORE any tidal change ! we avoid as much as we can, and prefer keeping the stern free,
Another thing we discovered on the forums lately is a new anchor design for tandem anchoring.
interesting idea, like any new ones ! but … not really KISS, again,
as i definitely like the (non-commercial) tech talks one can find on Peter Smith’s site on anchoring and others (e.g. :
http://www.petersmith.net.nz/boat-anchors/tandem-anchoring.php
i took the liberty to ask him his toughts abt it,
i guess he would agree for me to share those on aac, here is the answer :
Bonjour Bruno, Thanks for your feed back.
I have looked at the design you refer to. I can see no merit. It is playing on inexperienced sailors perceptions and fears. It is just an attempt to make the deployment and recovery of a tandem system more user friendly and find a market niche.
The design still uses the Delta/ fixed shank plough principle which is further compromised hence the inclusion of the roll bar.
The principles and negative aspects of Tandem anchoring as discussed in the article on my web site are still relevant and have not been addressed. To set both anchors one anchor must be dragged to set the other. Deltas tend to require a substantial drag distance before they set.
In strong winds any deviation from a straight in line pull will dislodge the first anchor which then just becomes a ‘kellet’. The second anchor must then be dragged before the first can reset.
The extra complexity adds extra, possibly dangerous complications on the foredeck at a time when they are not needed. .
Why not just take the combined weight of the system and install a bigger or properly sized anchor.
EG. If the two anchores in the tandem system weighed 20 and 15 KG. plus chain and shackles, say 5kg = 40kg combined weight with the high chance only one anchor is ever set.
In the case of Rocna, the recommended all condition anchor would be a #20kg. If a #33 was installed the vessel would be anchoring on a Hurricane proof anchor at all times with no added complexity or compromises in the system and you would still have less weight on the foredeck.
The most experienced High Latitude Professional Charter skippers I know such as Jerome Poncet, Dion Poncet, Wolf Kloss, Steve Dashew et al all anchor on single adequately sized big modern achors (Rocna’s) .
Regards, Peter.
Conclusion, i just got myself a Rocna
Hi Bruno,
Interesting about how you handle the anchoring the dredger. I’m always fascinated by how you commercial mariners do the extremely tricky things you do in confined waters.
And yes, I agree with you and Peter on the TANDEM ANCHOR EXTRA—talk about a solution looking for a problem, and way too complicated. Peter’s last point is the killer: “Why not just take the combined weight of the system and install a bigger or properly sized anchor.”
Differences in setting large or small anchors and then enjoying a 90 degree wind shift:
Anchor shanks are ‘L’ shaped (excepting a Fortress). There are thus 2 lever actions possible, one vertical and one horizontal. A bigger anchor will have greater lever actions than a small one, longer shank – therefore longer levers.
If both anchors are set to the same ‘capacity’ – and I cannot see why a bigger one will set to a higher capacity than a smaller one (if the same yacht) then the longer lever actions of the larger anchor will pull out the larger anchor more easily than the smaller one. This lever action will be greater for the large anchor because the seabed will offer less support to the larger shank – because it is set less deeply. Consequently the larger anchor has more chance of pulling out under a dynamic load than the smaller one. Considering the care with which the anchor is first set the thought that a larger one might more easily pull out seems to contradict the idea of using a larger anchor. This is especially so with roll bar anchors that in weed can choke – and never re-set
You wanted contrary views?
Jonathan
I wouldn’t worry too much about all the theories: that lovely little comment about “anchor size scales pretty accurately to miles cruised” tells you all you need to know. The ancient 25lb CQR on my 3500 kg Nicholson Half-Tonner is now officially designated as garden ornament, to be replaced by a 35lb ‘something new-generation’. I’ve already got a 35lb CQR lashed down in my midships oilskin locker, with its own rope-chain set ready to go, so I guess I can’t carry any food…..
Hi Nick,
Our CQR is a garden ornament in Arctic Norway. I wonder how many there are in such use world wide?
Thanks for the support.
As a designer of Wemar Tandem Anchor System I feel the need to explain some of the priciples implemented. It is not just about the holding power as anticipated in the forum, it actually brings many other useful features:
1. The system allows to use only one anchor for daily stops, so no more heavy loads on the windlass when unnecessary.
2. The system allows to use much heavier combined weight of the anchors as the windlass only handles one anchor at a time.
3. There is much less swing of the boat, especially when main anchor is set closer to the boat.
4. It provides a choice of options, both anchors can be set at any distance desired.
5. For the first time, it introduces redundancy and therefore additional safety while staying at anchor. Would you jump out of the plane with single parachute?
Hi Peter,
Yours is a difficult comment for me to answer because you have obviously invested a lot of effort to engineer your tandem anchoring system.
But, on the other hand, since a lot of people rely on this site for information about offshore voyaging, I do feel compelled to answer.
I’m sorry, but I just can’t see any benefit in your system over a single new generation anchor of the same weight. Worse still, I see a lot of disadvantages, of which most are fundamental to tandem anchoring that I have already detailed in the post above. In addition to those points, your system uses plow type anchors and both multiple tests and experience have shown new generation concave fluke anchors to be superior to plows. Also, testing and experience have show that anchor effectiveness seems to increase at a more than linear rate with size. In other words, one big anchor sets and holds substantially more than doubly better than an an anchor of half its weight.
Further, I really can’t agree with any of your points above:
Windlass load is, in my opinion, simply not relevant since I feel very strongly that windlasses should be powerful for other reasons. I’m also confused as to how your system decreases the swing of the boat. In fact, the swing circle will be exactly the same as a single anchor as long as your nearer anchor holds, and substantially more when that anchor is dragged into line with the farther anchor.
As for the parachute metaphor, I think that’s flawed too: With your system, the user is still hanging on a single rode and you have upped the complexity over a single anchor substantially. Further to that, a skydiver carries a spare parachute because he or she has no way to know if the primary parachute will function properly until it is too late to fix it. That is not the case in anchoring since we can back down with the engine and set it, thereby knowing that it is functioning properly. And, as I have said many times, in 14 years of using a new generation anchor I have never had it drag once set.
CQR’s and Bruth’s and Danforths are girl anchors. Spade, Rocna and Buguls are boy anchor. One BIG anchor is spot on.
However we did drag in Easter Island. Scoured bottom, at night of course, big blow, scarey.
S.
on the difficulties to have an openminded but mediated forum, compromises, courtesy and tolerance are essentials and well respected at AAC, i feel, even if i don’t always agree !
if i don’t, i just keep reading looking for convincing arguments, and if not, i just leave others to their minds and experiences,
anyhow,
anchors, scopes and anchoring is definitely a sensible and rageous subject around the planet, where everyone will make his essential life choice before going asleep in any anchorage,
when i rediscovered sailing, i kept surprised that most cruisers don’t run watches when at anchor …we, on big ships, never leave the bridge alone …
PS : my new Rocna is smaller then my old Danforth (which will stay o/b …), own personnal compromises !
enjoy sailing and anchoring !
Rgds
An interesting and well-written article, thank you.
I generally rely on a single anchor, but my focus is as much on using heavy chain as it is on the weight of the anchor itself, as well as using a lot of scope.
My feeling is that the combined weight of the ground tackle is significant in ensuring holding in strong wind, but that scope is critical to the prevention of ‘snubbing’ that can overload the anchor.
Having had accurate information on the wind direction for a hurricane’s arrival at Bermuda, I was able to ride it out safely anchored ‘open hawse’ (about 60 degrees), with scope of almost 20:1 in the water. Despite 85 knots of wind, we were ‘snug’.
This was in a heavyweight and old fashioned yacht, so we have a good windlass for handling the cables.
I’m guessing most already know this, but for the case in which the boat is not aligned with the swell, there is an alternative to a stern anchor or shore fast. You can use a spring line, attached to the anchor rode forward of the bow with a hitch, led to the stern quarter. Tension the spring to yaw the bow towards the swell. The downside is that it requires adjustment as the wind and current shift around. And it’s for benign conditions. Let the spring go slack if the wind really picks up.
Colin,
The method you describe is well suited for a short duration stay. As you mention, changes in wind or current will necessitate an adjustment, which in our cruising grounds would translate to getting up in the middle of the night. To be effective it should be tied far enough down the rode (away from boat) to provide some leverage.
Hi C-Dan
The Simpson Laurence 555 two speed manual windlass (no longer available) used to be the standard for serious cruisers. Never had a burned out motor! I can testify that it will retrieve 360′ of 3/8 BBB plus a 45# CQR and 100# of kelp. And you won’t have to take along a set of barbells to keep in shape!
Seriously, the downside to a manual windless comes when you need to retrieve the anchor rapidly and get underweigh for safety. This is a serious consideration, and for me sufficient reason to choose a power windlass (but one with good manual back-up capability.
Hi Richard,
Thanks for the information and thoughts. I think you are right that we will need to go electric, both for the reason you state, and because, although I have not researched it, I’m not sure that any really good manual windlasses are being made today. Does anyone out there know of one?
Hi John,
I know of two manual windlasses being made today, the Goiot 308 and the Royal Windlass by Lofrans. I have no experience with either, but found out about them while researching kit for my 22-footer which is under construction.
In the end I decided to pull in a 10kg Rocna bower by pure musclepower assisted by a chainstopping pawl, but am leaving space for a manual windlass just in case I’m not as strong as I fancy myself to be :-).
Hi Sverre,
Thanks for the information. One of the very cool things about small cruising boats is the option of going really simple like you have.
One final note before this contentious topic blows away—(LOL).
Give me a choice between a 30 year old reconditioned SL 555 manual and any size Lewmar V series and I’ll take the SL in a minute. Of course there is a story, but suffice to say that any piece of equipment that requires thousands of pounds of pull from a masthead high tech halyard to disassemble has no place on my boat.
For that matter, no vertical capstan windlass meets the minimum criteria of having an adequate manual back up capability. And if you cruise for very long you will need it at some time. (Ideal and Lighthouse may be the exceptions that prove the rule, but they are horizontal capstan designs and have good manual modes as well)
No way I’d put up with a manual windlass on a 40 footer. If the windlass is of good quality, properly installed, and properly maintained it will give many years of service. To have to deal with a manual windlass for years of anchoring based on the fear of an electric windlass malfunctioning is not my idea of a good time. It’s a lot easier to make the decision to re-anchor when you have a powered windlass. I’ll leave the old SL 555’s to the purists.
Hi Dave,
The specific Lewmar windlass I was referring to is a V2 series, the largest one available and installed on a two year old $2m plus custom sailboat. Undersized Delta anchor, 3/8 chain. It failed with stripped drive gears when we were anchored on an open ocean reef off Honduras. After five hours of struggle to disassemble it I finally resorted to a halyard, spinnaker pole spreader and a power winch to separate the components so it could be removed from the boat. Incredibly poorly designed piece of gear that deserves to be thrown overboard.
And yes, I too would prefer to have a good quality horizontal windlass with manual back up over the old SL 555.
You didn’t mention the use of a kellet/sentinal on the rode. I let out all my chain (125′) until it still is just on the gypsy, or less if that length is not required.grab the chain forward of the bow roller, shackle a 10lb mushroom anchor on and set the total nylon/chain rode to the appropriate length. Advantages:pull when setting the anchor is directly along the bottom, acts as a shock absorber, providing a cushion that reduces peak loads on the anchor. The chain never gets taut.
Hi George,
I did not mention kellets because I’m not a fan of them. While I think that they may have some marginal benefit in getting an old style anchor like a CQR to set on a rope rode, other than that they, in my opinion, do nothing to increase ultimate holding or damp shock loads. In fact I think they may even make shock loads worse in a blow since they will pull the boat forward toward the anchor in a lull, leaving her more distance to go back, building speed all the way, in a gust.
I’m not the only one that thinks this way either, in that there is solid engineering analysis that shows that a rode weighted by a kellet, or its own weight (chain), will be pulled out straight in gale force winds and above, so that at the very moment you need the better angle to the anchor or the shock absorption, it goes away.
On “Morgan’s Cloud” we have verified by observation that our entire 340-feet (100 meters) of 7/16 chain is pulled bar taut in gale force (34 knot) winds and above. We can also pull the chain bar taut with just 1800 RPM in reverse (our normal setting practice) on our Perkins 87 HP engine.
So in summary, our position is that kellets and/or extra heavy chain are at best an unnecessary complication. Worse still, if a anchor will only stay set with a kellet attached, that indicates to us that it is not in fact properly set at all and will drag if and when the wind comes up past 30 knots.
I am not saying I disagree, but how can you tell what the middle of the chain is doing from looking at the end?
Hi Ed,
Interesting question. Well, I can see the angle of the chain for at least 20-30 feet when it is pulled out hard, which is, I think a pretty good indicator of what the rest is doing. Also, when we back down to set with our full 340-feet of chain out, the boat moves backward slowly until the engine RPM reaches 1800. At that point increased RPM has no effect, which would seem to indicate that we have pulled the chain straight.
Finally, I have seen credible engineering studies that have calculated that the weight and length of chain rode that a cruising sailboat can carry is pulled near-straight when about gale force is reached. And since on our boat 340-feet of 7/16 chain is pulled out straight, which weighs a great deal more than any kellet, I’m satisfied that this logic extends to that device.
Peter Smith, designer of the Rocna, and an engineer, has some good information on this here.
I’m convinced. I was actually interested in your approach to the problem and I think the engine rpm/movement relationship tells us all one needs to know.
I don’t use a kellet for holding power but they do have other uses. There is an article about them on my website should anyone be interested. (liveaboard.sv-moonshadow.com)
Ed
Hi John,
very happy with my original (very old) manual windlass from Goiot, very KISS indeed,
Last summer, i lifted unadvertidly the concrete block of 70x70x70cm of a fix mooring as my acnchor jammed in her chain …
Hi Bruno,
Thanks for the information. I love these real-world first hand reports. Even if we end up, as I expect we will, with a high quality electric windlass on the Adventure 40, information like yours is still great.