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Thread: Anchor Reality Check

  1. #1
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    Default Anchor Reality Check

    Does anyone have a Herreshoff reference that would provide HMCo's recommendations for anchor size vs. boat size? Specifically, what size *HMCo* anchor (not just any fisherman, but specifically HMCo's fisherman-style) would they have recommended for my 19' / 3000# sloop? I suspect it's in "The Common Sense Of Yacht Design", but I don't have a copy of that on my shelf, decent used copies look rather pricey, and my I.L.L. request will likely take a while to come through.

    I currently use a 35# ABI fisherman as Bucephalus's bower. I like it and trust it. However, it's rather a brute to deploy, so I'm in the process of patterning up a new, smaller fisherman to have aboard as a kedge. In the process of researching best design practices for a fisherman anchor --and one could hardly get better than HMCo's version-- I have learned A LOT about anchor geometry and proportions, courtesy both of those here on WBF and from J. L. Giblin's excellent synopsis on our host site: http://www.woodenboat.com/herreshoff...e-stock-anchor.

    One of the principles that has become very clear --yes, this is my "DUH!" moment-- is that judging an anchor's appropriateness by its weight alone is pretty ridiculous. An anchor's holding ability is determined by how well its geometry interacts (or doesn't interact!) with any given bottom; the weight of an anchor is merely how much metal is needed to create that geometry in a form and of a scale that won't bend or break under a given amount of strain. If it were only about weight, we could all just carry around big slugs of lead shaped like fishing weights and stop arguing about fisherman vs. Danforth vs. Rockna vs. Bruce vs. ...whatever.

    What I'm hoping to do, with the answer to my initial question, is reverse-engineer the recommended HMCo anchor from its weight. HMCo's formula for determining the dimensions of its anchors was brilliant and consistant --I was able to build an Excel spreadsheet in short order, working from Giblin's article-- so determining its geometry shouldn't be especially difficult.

    But I need that starting point: How big an anchor would HMCo have recommended for my sloop?

    Or, to make the question far more complex and accurate, how much fluke area, at what distance from the crown, and on what length of shank, would HMCo have deemed appropriate for a 19', 3000# sloop? All of which would have taken a certain amount of metal, that would have weighed... what?

    Interestingly (for me, anyway), while the ABI fisherman I use is plainly patterned on the same ideas as the HMCo anchor (it's almost identical to the 3-piece Luke), and is quite close to the HMCo formula in some regards, it is considerably different in others. It holds quite well though, so there's obviously considerable leeway. But while I could just scale down the ABI to my needs, I'd like that HMCo recommendation as well.

    Any help on that HMCo anchor weight would be appreciated --but if you just want to smack me in the head for not previously contemplating all of this in detail, save yourself the trouble, I've already been doing a lot of that.

    Alex

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    Default Re: Anchor Reality Check

    This gives the recommendation for the Luke, which looks like a Herrechoff knockoff. In what way is yours and the Luke different to the HMCo anchor?
    http://www.defender.com/product.jsp?...112&id=3962005
    As you are aware, it is fluke area and angles that are critical. As long as there is enough weight to set the fluke, weight is less important.
    It really is quite difficult to build an ugly wooden boat.

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  3. #3
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    Default Re: Anchor Reality Check

    There's a nice 25 lb. Luke anchor on Ebay right now, $220.

    http://www.ebay.com/itm/like/322601825736?ul_noapp=true

  4. #4
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    Default Re: Anchor Reality Check

    In what way is yours and the Luke different to the HMCo anchor?
    Much shorter shank length: depending on how you wiggle the spreadsheet, ABI/Luke(?) used between 3/4 and 4/5 of what the HMCo would have used.

    The angles are all the same --specifically the angle between the shank and a line from the attachment point at the top of the shank to the tip of the fluke (25), the angle of the palm relative to the shank (45), and, thus, the penetration angle of the palm relative to the bottom (70). I think the shortening of the shank results from changing the radius of the crown: making the radius larger results in a flatter crown and a shorter shank. (Draw a line perpedicular to the shank at the tips of the flukes; the greater the crown radius, the flatter the curve from base of fluke to base of fluke, and the shorter the length of shank from that line to where the circumference of that arc intersects the shank.) The ABI and the Luke (judging from the photos) have a considerably flatter crown than the HMCo anchors.

    HMCo was quite specific about that radius, too. I think because a change in that radius results in a different insertion angle of the *fluke*, if not the palm, into the mud (for instance). Larger radius, flatter crown, arm of fluke is more perpendicular to shank. I could see how this *could* make it more difficult for the palm, the greatest source of holding power, to sink to its optimum depth. As you say, there needs to be enough weight to set the fluke properly, so this less optimum (?) angle *might* have been compensated for by adding weight at the flukes.

    Just guessing.

    Also, from what I can tell, the edges of the flukes on the ABI (perhaps the Luke, too?) aren't as sharp as HMCo makes a point of recommending, which could be detrimental to its performance. Espcially re: compensating for that larger crown radius. I haven't yet had a problem, but I may take a grinder to those edges anyway. May heaven protect my deck and my toes...

    The HMCo anchors are quite long for their weight: by their formula, a basic 9.6# anchor would have a shank length over 28". That's about the same shank length as my 35# ABI. There are A LOT of other differences in there, too --it's a formula that effects every dimension, not a simple weight/shank length correlation-- but comparing only shank lengths, it's an interesting contrast.

    On that same note, a 36# HMCo anchor would have a shank length of 37" (these numbers, from my spreadsheet, are rounded). That's a pretty awkward anchor to be swinging around on a small boat. If I had to guess, ABI, perhaps Luke, made a trade: they added weight in exchange for a shorter anchor that was easier to maneuver around a boat.

    There's a nice 25 lb. Luke anchor on Ebay right now, $220.
    Thank you, Jim. I'll go have a look at it.

    Alex
    Last edited by Pitsligo; 08-09-2017 at 05:21 PM.

  5. #5
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    Default Re: Anchor Reality Check

    As a side note: I looked at the recommendations for anchor size vs. boat length, for Luke anchors, on the Defender website. Ye gods! If a 40# fisherman doesn't hold a 12' boat, nothing will.

    To put it in context, we used to use 50# mushrooms as permanent mooring anchors for our catboats, 12' and 14'. I know they are wildly different anchors, but still...

    Alex

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    Default Re: Anchor Reality Check

    Quote Originally Posted by Pitsligo View Post
    Much shorter shank length: depending on how you wiggle the spreadsheet, ABI/Luke(?) used between 3/4 and 4/5 of what the HMCo would have used.

    The angles are all the same --specifically the angle between the shank and a line from the attachment point at the top of the shank to the tip of the fluke (25), the angle of the palm relative to the shank (45), and, thus, the penetration angle of the palm relative to the bottom (70).
    Yes, that is the key. Think of the fluke in the sand in the same way as a kite on a string. It is all in the angle of attack.
    I think the shortening of the shank results from changing the radius of the crown: making the radius larger results in a flatter crown and a shorter shank. (Draw a line perpedicular to the shank at the tips of the flukes; the greater the crown radius, the flatter the curve from base of fluke to base of fluke, and the shorter the length of shank from that line to where the circumference of that arc intersects the shank.) The ABI and the Luke (judging from the photos) have a considerably flatter crown than the HMCo anchors.

    HMCo was quite specific about that radius, too. I think because a change in that radius results in a different insertion angle of the *fluke*, if not the palm, into the mud (for instance). Larger radius, flatter crown, arm of fluke is more perpendicular to shank. I could see how this *could* make it more difficult for the palm, the greatest source of holding power, to sink to its optimum depth.
    Just so
    As you say, there needs to be enough weight to set the fluke properly, so this less optimum (?) angle *might* have been compensated for by adding weight at the flukes.

    Just guessing.

    Also, from what I can tell, the edges of the flukes on the ABI (perhaps the Luke, too?) aren't as sharp as HMCo makes a point of recommending, which could be detrimental to its performance. Espcially re: compensating for that larger crown radius. I haven't yet had a problem, but I may take a grinder to those edges anyway. May heaven protect my deck and my toes...

    The HMCo anchors are quite long for their weight: by their formula, a basic 9.6# anchor would have a shank length over 28". That's about the same shank length as my 35# ABI. There are A LOT of other differences in there, too --it's a formula that effects every dimension, not a simple weight/shank length correlation-- but comparing only shank lengths, it's an interesting contrast.

    On that same note, a 36# HMCo anchor would have a shank length of 37" (these numbers, from my spreadsheet, are rounded). That's a pretty awkward anchor to be swinging around on a small boat. If I had to guess, ABI, perhaps Luke, made a trade: they added weight in exchange for a shorter anchor that was easier to maneuver around a boat.

    Alex
    Yes, sharpen the (back) of the flukes, so that they will slice into the bottom.
    Whatever the geometry of the arms and flukes, the shank and stock must be the same length (or the stock longer than the shank) so that the anchor will trip and embed the fluke.
    If you want a smaller anchor, increase the fluke area, and ensure that there is enough meat in the crown to resist the drag and shock loads that are trying to open out the angle and straighten the curve of the arms.
    It really is quite difficult to build an ugly wooden boat.

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  7. #7
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    Default Re: Anchor Reality Check

    It is all in the angle of attack.
    70 seems to be the magic number.

    Giblin's article references a mention by of a longer-shanked model "sand anchor" that would have had a flatter angle of attack:

    In “Common Sense of Yacht Design”, (Vol. II pg. 107) L. Francis Herreshoff speaks highly of an additional style of the larger size anchors which he states were of the same design but fitted with a longer shank and stated his father (NGH) some times called them “sand anchors”.
    I'm guessing 70 was chosen as a good all-around penetrator, for general purpose use, and that the flatter angle would have been better in soft bottoms (as it was intended) but would have skated on harder bottoms.

    If you want a smaller anchor, increase the fluke area, and ensure that there is enough meat in the crown to resist the drag and shock loads that are trying to open out the angle and straighten the curve of the arms.
    That's exactly what I currently have sketched. I'm starting with the general principles of the HMCo formula, then following the same (assumed) premise of ABI/Luke --as well as their general proportions-- by shortening the shank to about 75% of HMCo dimensions. The stock ends up being a bit longer than the shank for just the reasons you describe. I'm also reducing the bill angle and shifting more of the weight into the flukes/crown to (ideally) assist penetration.

    But I'm really hoping someone will have something by LFH or NGH that gives a hint what size anchor they would recommend for a 19' boat. It'd be silly for me to aim for the general holding power of a 30# HMCo anchor if they would never have bothered with anything over 20#, even in hurricane season. I'd really like that starting point.

    Alex

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    Default Re: Anchor Reality Check

    Alex, it's not a fisherman, or even close, but have you looked at the Mantus anchor? I'm a neophyte but they look pretty good.

    Jeff

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    Default Re: Anchor Reality Check

    Have you considered a Rocna or their Vulcan design? They seem to be highly regarded and after viewing a number of comparison tests and videos on another thread, they do appear to be the best. EDIT: Except when Rocna is the worst. http://www.boatingmag.com/top-anchors-tested#page-13 But the Mantus is also the best in other tests. The test variables, including the local bottom changing every 5 feet...
    http://forum.woodenboat.com/showthre...nchor-adequate
    Most of the traditional anchors were surprisingly ineffective.
    It looks like you need a 9 kg, 20 lb Vulcan for about $270.
    http://rocna.cmpgroup.net/anchor-sizing-guide
    http://www.marinechandlery.com/vulcan-anchor
    Last edited by MN Dave; 08-10-2017 at 12:25 PM.
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    Default Re: Anchor Reality Check

    This drawing was originally posted by a much valued forumite named Paladin .... IIRC.

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    Default Re: Anchor Reality Check

    Alex, could you post photos of your anchor pattern ?
    '' You ain't gonna learn what you don't want to know. ''
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    Default Re: Anchor Reality Check

    Quote Originally Posted by Pitsligo View Post
    70 seems to be the magic number.

    Giblin's article references a mention by of a longer-shanked model "sand anchor" that would have had a flatter angle of attack:



    I'm guessing 70 was chosen as a good all-around penetrator, for general purpose use, and that the flatter angle would have been better in soft bottoms (as it was intended) but would have skated on harder bottoms.



    That's exactly what I currently have sketched. I'm starting with the general principles of the HMCo formula, then following the same (assumed) premise of ABI/Luke --as well as their general proportions-- by shortening the shank to about 75% of HMCo dimensions. The stock ends up being a bit longer than the shank for just the reasons you describe. I'm also reducing the bill angle and shifting more of the weight into the flukes/crown to (ideally) assist penetration.

    But I'm really hoping someone will have something by LFH or NGH that gives a hint what size anchor they would recommend for a 19' boat. It'd be silly for me to aim for the general holding power of a 30# HMCo anchor if they would never have bothered with anything over 20#, even in hurricane season. I'd really like that starting point.

    Alex
    It is a compromise. Too wide an angle and the anchor will not set in a hard bottom, if it sets in a hard bottom it develops less power in a soft bottom.


    Put the strength in the crown, not the flukes.
    The method for proof testing an anchor is as follows:

    The test load is applied where the drag force is centred on the fluke.
    Page 176 of this tells you what are the required test loads https://www.cdlive.lr.org/information/documents%5CRules%5CMATERIALS%5C2014%20MATERIALS%5 CNotices/14%20materials%20notice%201.pdf
    It will give you a starting point for the loads you are designing for.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Anchor Reality Check

    To reply to various points:

    Yes, I have considered other anchor patterns, but have found none with the combination of proven holding ability on a wide range of bottom types and reasonable stowage as the HMCo fisherman. My sloop has no bow roller, and I have no interest in adding one, so stowage is a real concern (as is the nuisance of a chain leader for modern designs). Most of all, though, I've never had a problem with a good fisherman. I don't have an HMCo, but the ABI is a very good evolution of the HMCo. Has it dragged or not set? Of course; no anchor sets perfectly 100% of the time, and --like going aground-- if you sail for long enough, you'll drag your anchor. But in 40+ years of sailing, I can count those times on one hand, when anchoring with a fisherman.

    All of that said, "fisherman" covers an enormous range of designs based on a basic configuration of geometry. And some of those designs stink, frankly; they'd make a picturesque mailbox stand, if set in concrete beside your driveway, but they ought never go to sea. By contrast, the HMCo design is the gold standard for "fisherman" anchors and is still often used as the benchmark for tests of modern designs. And the tests *I've* seen shows that it still compares well, especially when tested on a variety of different bottoms. For instance, it'll never out-perform a Danforth in sand, but it will set and hold reasonably well, while a Danforth is pretty much useless on rocky bottom.

    Mantus, Rocna, Danforth, Bruce, whatever; all are (arguably) good anchors in their own right, but as Nick says, any anchor is a compromise --on more than just fluke angle-- and for my needs and preferences the compromises those anchors make are not acceptable. The compromises a fisherman anchor makes *are* acceptable to me.

    That's why I'm *really* hoping someone can give me some information about what size HMCo would have recommended for my sloop: the purpose of my OP.

    Peter: thank you for the image post. I had already harrassed Nick into sending me a copy (I found a thread here where he had posted it previously, so PM'ed him), but having it on this thread, for discussion, is worthwhile. The 30 shank-to-fluke angle, as contrasted to the 45 of the HMCo/ABI/Luke anchors, would seem to mark it as specifically for sand or soft mud bottom. The 50 angle of attack (180 - 130 = 50), compared to the HMCo, etc., 70 angle of attack, also speaks of an anchor for soft bottoms. Perhaps someone else with more experience than I would comment on that?

    Here are those multipliers, for those wanting to scale Paladin's anchor:

    T = X
    A = 4.6X
    B = 12.4X
    F = 3.2X (min.)
    S = 18X
    W = 1.68X

    Yes, I will post photos of the pattern when I get it built. Until then, this is the 5.6# dinghy anchor I patterned years ago, based on the ABI:





    It holds quite well, considering how small it is. I designed it for my sister, for her 14' Sid Skiff, and traded the pattern to Port Townsend Foundry in exchange for one of the anchors. They now advertize it on their website. (I patterned their 35# plow, too --a fun challenge!) As I said, it has the ABI proportions, differring from HMCo predominantly in its shank being only about 75% as long as that of an HMCo anchor. Details I added were the tapered shank, to get the weight down near the crown; a "middle finger" in the center of the palm (okay, fine: technically a bill), to aid penetration; a "saddle" cast into the center of the crown for the stock to nest in when it's stowed (I've had my fingers pinched by a stock too many times); and a hole cast through the crown, not just to seize down the folded stock, but for a tripline.

    The ~20# anchor I'm drafting now will probably be along the same lines, but with some refinements from the new information I have about the HMCo anchors: better palm angle, an elliptical shank for better ease in penetration, slightly longer shank, etc. But I really want to know what HMCo would have recommended for my boat, so I have some starting point for sizing it other than "approx. 20#", which is effectively a wild-assed guess based on the 35# ABI I now use.

    Put the strength in the crown, not the flukes.
    Doh! Yes, of course. Typo by me. Though by "flukes" I meant more the arms between crown and palms, where the strain will go.

    The method for proof testing an anchor is as follows:
    I cannot see what you posted there. If it's a YouTube video, for some reason my computer can't see those when embedded in the forum posts. Would you mind posting a URL?

    Page 176 of this tells you what are the required test loads... It will give you a starting point for the loads you are designing for.
    Wow. That's good information to have, not just because it explains the tests, but by showing how the tests are set up --"The proof load is to be applied on the arm or on the palm at a spot which, measured from the extremity of the bill, is one third of the distance between it and the centre of the crown"-- it implies how the forces will be exerted "in the wild."

    Thank you all for the information. And again, if anyone has access to HMCo information that says what HMCo anchor they would have recommended for a heavy 19' sloop, *please* post it here.

    Alex

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    Default Re: Anchor Reality Check

    Here you go.
    https://www.youtube.com/watch?v=6Q1twDVUgKY

    I would sharpen the cutting edges of those flukes, so that they slice into the ground. Grinding off the back surface.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Anchor Reality Check

    Heavens to Mergatroid. That's quite something to watch. Thank you for posting the URL.

    Yes, since those photos were taken I have sharpened the flukes as you describe. I still need to do that for the big ABI, but it's on my list.

    Alex

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    Default Re: Anchor Reality Check

    Easiest thing to do might be to check in directly with Kurt Hasslbalch the curator of the Hart Nautical Museum at MIT. That is where the plans and building records reside.
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    Default Re: Anchor Reality Check

    What alloy would you have it cast in Alex ? Aluminium bronze ?
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    Default Re: Anchor Reality Check

    Easiest thing to do might be to check in directly with Kurt Hasslbalch the curator of the Hart Nautical Museum at MIT.
    I'm guessing you may be right --and thank you very much for the name of a contact. I have requested "Common Sense of Yacht Design" through an inter-library loan, so I'll probably wait and see if that has the information I need, but I expect MIT would be my next stop if CSYD doesn't have what I need.

    What alloy would you have it cast in Alex ? Aluminium bronze ?
    AlBz would be nice, but probably overkill, and more expensive than basic manganese bronze. The dinghy anchor is MnBz, and reading Giblin's article this past week, it details that the smaller (7.5#-16#) HMCo anchors were all cast out of MnBz. So I'd probably stick with MnBz for this latest attempt.

    Alex

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    Default Re: Anchor Reality Check

    The right size anchor is the one that holds under the circumstances you anchor in.
    There are so many variables.
    Especially scope which YOU control and is most often insufficient.

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    Default Re: Anchor Reality Check

    The right size anchor is the one that holds under the circumstances you anchor in.
    There are so many variables.
    Truth. But given that HMCo had a specific anchor for the 12-1/2, I expect they had recommendations for matching one of their anchors to a given boat (assuming competance on the part of the boat's skipper).

    Especially scope which YOU control and is most often insufficient.
    Amen, sadly. Anything less than 5:1 makes me unhappy, and I don't smile much while the anchor's down unless I'm using 7:1. I don't know what modern anchors are like, but seeing how little scope some boats use curls my toes. And watching them drop anchor and dump all their chain rode on a heap on top of their anchor doesn't seem to me like a good way to set the hook, but maybe I'm just old-fashioned...

    Still waiting for my inter-library loan to come through for CSYD. I'll post if I find anything relevant, just as a follow-up.

    Alex

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    Default Re: Anchor Reality Check

    And length of rode will vary depending on how much chain you have at the anchor. The line needs to be as close to horizontal as possible at the shackle, so less chain means much more rope.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Anchor Reality Check

    Quote Originally Posted by Pitsligo View Post
    Truth. But given that HMCo had a specific anchor for the 12-1/2, I expect they had recommendations for matching one of their anchors to a given boat (assuming competance on the part of the boat's skipper).



    Amen, sadly. Anything less than 5:1 makes me unhappy, and I don't smile much while the anchor's down unless I'm using 7:1. I don't know what modern anchors are like, but seeing how little scope some boats use curls my toes. And watching them drop anchor and dump all their chain rode on a heap on top of their anchor doesn't seem to me like a good way to set the hook, but maybe I'm just old-fashioned...

    Still waiting for my inter-library loan to come through for CSYD. I'll post if I find anything relevant, just as a follow-up.

    Alex
    Just don't anchor down wind of them !
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    Default Re: Anchor Reality Check

    Im quietly chuckling here. Reality check. This is a 19' 3000# boat we are talking about. Going way out on a limb here but probably mostly day sailing in reasonably sheltered coastal waters. Just get the heaviest anchor you are comfortable hauling up by hand. As much chain as you are comfortable with and call it good.

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    Default Re: Anchor Reality Check

    Where is the fun in that?
    Steve

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    Default Re: Anchor Reality Check

    Quote Originally Posted by Phil Y View Post
    Im quietly chuckling here. Reality check. This is a 19' 3000# boat we are talking about. Going way out on a limb here but probably mostly day sailing in reasonably sheltered coastal waters. Just get the heaviest anchor you are comfortable hauling up by hand. As much chain as you are comfortable with and call it good.
    My thoughts too Phil, if the OP wants a salty period bronze anchor good for him but any modern anchor will work perfectly, hell even a stone with a hole in it would cover 80% of his needs. It's laughable how the justifications for a HMC anchor as the ultimate pick for multiple bottoms are coming thick and fast. Im sure its a fine anchor but it simply doesnt compare to a modern design for the most part, possibly rock/weed bottoms excepted.
    whatever rocks your boat

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    Default Re: Anchor Reality Check

    Just don't anchor down wind of them !
    No joke!

    Im quietly chuckling here. Reality check. This is a 19' 3000# boat we are talking about. Going way out on a limb here but probably mostly day sailing in reasonably sheltered coastal waters. Just get the heaviest anchor you are comfortable hauling up by hand. As much chain as you are comfortable with and call it good.
    Yes, mostly daysailing for the last dozen years, but before that cruising the coast from Boston, Mass., to Southwest Harbor, Maine, regularly. Since the on-land situation has recently changed, hopefully I'll be able to spend more of my time cruising again. That means I now have from Olympia to the Aleutians, potentially. And really, whether you're six hours or six months from your home port, it only takes one night with the wrong anchor to ruin your fun.

    All that said, there's a lot to recommend the "brute strength and ignorance" approach you suggest. A big anchor and rode is hard to beat, especially if you don't want to bother with the fuss and anxiety of tuning your system of ground tackle. If that's what you choose for your cruising, I can't condemn you.

    I am reminded of the advice I was once given for choosing ground tackle for a trimaran: Go buy the biggest anchor in the store and the most chain your truck can carry without breaking its springs. Now go back and buy the second biggest anchor and the same amount of chain. Now do it again, with the third biggest anchor. Now you're ready to anchor a trimaran --but make sure you anchor up-wind of a mudbank, just in case she still drags...

    Where is the fun in that?
    Bingo!

    Im sure its a fine anchor but it simply doesnt compare to a modern design for the most part, possibly rock/weed bottoms excepted.
    You make my argument for me. Any modern anchor will hold phenomenally --in the specific type of bottom it was designed for. An HMCo anchor will hold well --perfectly adequately, as my experience proves-- in *any* type of bottom. Since I prefer an all-around anchor, not a specialty anchor, it is only logical that I seek out an HMCo-type fisherman. For what I want, for the waters I cruise, I would be foolish to do otherwise.

    Yes, I could buy (for instance) a 16# Mantus (their recommended for my boat) and 10# of chain leader (weight of chain is a wild-assed guess on my part) --but why on Earth wouldn't I do better to just find a 25# fisherman and continue to use my rope rode, which 40+ years has shown me is a perfectly good system in *any* bottom, rather just in sand/mud/gravel? it would be a false economy of weight for less security.

    That I now seek information (refer please to the first paragraph of Post #1) on the recommendations by HMCo for size of anchor re: boat size is for the purpose of moderating the amount of overkill on the size of my ground tackle. Which I expect is exactly what anyone here would be interested in doing on *whatever* style anchor they have decided to trust.

    Alex

  27. #27
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    Default Re: Anchor Reality Check

    Danforth for a light boat
    whatever rocks your boat

  28. #28
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    Default Re: Anchor Reality Check

    Danforth for a light boat
    As I have said repeatedly, I have a great deal of respect for Danforths --in the right place. But in my experience they don't reliably set or hold in rocky ground. I've seen Danforths hold magnificently in sand, but I've seen them drag like a dented tea tray in rocks. I'd guess that you have enough experience anchoring that you have probably seen similar performance. In that light, for a given weight of anchor + the weight of chain leader, a fisherman is (arguably)(in my experience and my opinion) a better *all-around* anchor. Not as good in sand; much better in rocks.

    Any anchor is a compromise. Each one of us finds the compromises we can accept and refines our anchoring system to mitigate those compromises. I have no interest in nor basis for convincing you to swap to a fisherman anchor. Likewise, I would find any certainty that I should swap to a Danforth (or whatever) laughably arrogant. Neither of us knows the other's boat, cruising ground, skill set, the way the boat rides, how much stowage she has available... Anything, on any intimate level.

    But most of all, neither one of us has chosen to learn and adapt to the compromises of the other's preferred anchor --which makes any assurance of our chosen anchor's merits being superior to the other's chosen anchor *entirely* a matter of opinion.

    So let's stick to the OP: I'm looking for information on the HMCo's recommendation for anchor size vis-a-vis boat size specifically in regards to their fisherman-style anchor.

    Alex

  29. #29
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    Default Re: Anchor Reality Check

    Sorry it took me so long. From LFH Common Sense of Yacht Design: He shows two tables, this and Size and Length of Cable:

    Anchor weights, for Herreshoff anchors only, according to the tonnage of the yacht
    Tonnage of Yacht/First Bower/Second Bower
    2/ 15/ --
    5/ 35/ 20
    10/ 55/ 45
    15/ 75/ 60
    20/ 90/ 70
    25/ 110/ 85
    30/ 120/ 90
    35/ 130/ 100
    40/ 140/ 115
    45/ 155/ 120
    50/ 165/ 130
    60/ 180/ 145
    70/ 200/ 160
    80/ 220/ 170
    90/ 240/ 190
    100/ 255/ 200
    I hope this is readable. Weights in Lbs.
    Last edited by Thad; 08-14-2017 at 06:49 AM.

  30. #30
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    Default Re: Anchor Reality Check

    Quote Originally Posted by Thad View Post
    Sorry it took me so long. From LFH Common Sense of Yacht Design: He shows two tables, this and Size and Length of Cable:

    Anchor weights, for Herreshoff anchors only, according to the tonnage of the yacht
    Tonnage of Yacht First Bower Second Bower
    2 15 --
    5 35 20
    10 55 45
    15 75 60
    20 90 70
    25 110 85
    30 120 90
    35 130 100
    40 140 115
    45 155 120
    50 165 130
    60 180 145
    70 200 160
    80 220 170
    90 240 190
    100 255 200
    I hope this is readable. Weights in Lbs.
    I don't think that tonnage will be displacement or weight in this case, but a measure of the usable volume calculated by some common yacht tonnage rule.
    It really is quite difficult to build an ugly wooden boat.

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  31. #31
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    Default Re: Anchor Reality Check

    Below the table is LFH's note: "The tonnage of the yacht used in this table is the total weight or displacement of the yacht expressed in tons of 2,000 pounds weight."

  32. #32
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    Default Re: Anchor Reality Check

    Quote Originally Posted by Thad View Post
    Below the table is LFH's note: "The tonnage of the yacht used in this table is the total weight or displacement of the yacht expressed in tons of 2,000 pounds weight."
    Good, an important clarification.
    It really is quite difficult to build an ugly wooden boat.

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  33. #33
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    Default Re: Anchor Reality Check

    Why did you think otherwise?

  34. #34
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    Default Re: Anchor Reality Check

    I have enjoyed following along greatly.

    I cannot wait to see the anchor you come up with looks like. The other is lovely.

    Peace,
    Robert

  35. #35
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    Default Re: Anchor Reality Check

    Quote Originally Posted by Thad View Post
    Why did you think otherwise?
    The word "Tonnage" refers to the usable volume of a vessel on which harbour dues are based.
    The terms Ton in yacht parlance is similar, and does not relate to displacement.
    Thames measurement (or tonnage)
    Thames Tonnage formula simplified


    When an owner talks about his ‘five tonner’ he refers to a peculiar type of tonnage which has nothing to do with weight. More than a hundred years ago the Royal Thames Yacht Club adopted a formula for estimating the tonnage of yachts, and we still can’t break free of it. The formula takes no account of weight, but relates entirely to length and beam. The measurements are taken in feet. Because beam acts twice as a multiplier, fat boats have disproportionately large tonnages.
    It really is quite difficult to build an ugly wooden boat.

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