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Old 06-07-2016, 12:52 PM   #81
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Bill,
Hurrycane in Chesepeke Bay?
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Old 06-07-2016, 01:18 PM   #82
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I obtained a copy of an old book called the complete book of anchoring and mooring by a guy named Hinz

The Complete Book of Anchoring and Mooring: Earl R. Hinz, Richard R. Rhodes: 9780870334528: Amazon.com: Books

Excellent book for calculating loads due to wind, shear, surge, etc. In it he recommends half the anchor weight in chain, which generally works out to about a boat length, perhaps slightly less.

However, back to the question about Danforths and Fortresses, I've heard something along the lines that the shank needs to be lifted in order for it to set properly, so they do not recommend full chain.
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Old 06-07-2016, 04:16 PM   #83
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PMako,
I think that's the book Marin kept talking about trying to drum up support for all chain. So Hinz recomends not much chain just like Chapman.
The problem w most here is that they have no flexibility. They have one rode rigged up ready to deploy and the spare a PITA to get out and deploy. Some have two anchors and rodes ready to go on the bow pulpit. So most trawler guys need an anchor and rode good enough for a 50 knot blow.
If I had a bigger boat w a single rode and anchor I'd likely have a big to very big anchor and 25% of rode in chain. And a quickly attachable nylon section to extend the whole thing out to 6 or 700'.



Does Hinz say anything about rigging and operating (winch wise) a combination rode other than the usual combination gypsy?

So the experts are'nt talking all chain ... sure is popular here.

Articulated shank (Danforth and Fortress) need to lift their shank to .... Never heard that before. I think Steve (Panope) used all chain and don't recall there being a setting problem. Don't see how that would aid setting much less be necessary to bring it about. Dono
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Old 06-07-2016, 04:59 PM   #84
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If you can estimate the loads from wind, waves, swell, currents etc. including dynamics resulting from gusts ... And if you can assure that the anchor will take those under the given conditions at the ground - the rest is simple math solving the differential equation of the catenary.
Will try to post a small excel sheet end of the week when back from business (sh..., still have to work to finance my boating life)



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Old 06-07-2016, 05:44 PM   #85
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Quote:
Originally Posted by Capt.Bill11 View Post
As I recall this book does one of the best jobs I've seen explaining the forces that act on an anchor and rode that I've seen.

https://www.amazon.com/Complete-Anch.../dp/0071475087
You are right about that. And frankly book learning seems to be superior to the experience learning for most on this thread, to which my reaction in general is

To the point I almost wonder if several of these posters have ever anchored overnight, let alone multiple nights..
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Old 06-07-2016, 07:11 PM   #86
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George,
Book learning and experience are both very important.
The way you talked about it makes everybody think they've been attacked.
Lots of experience anchoring in nice weather dosn't teach much and anybody can pop off a book of opinions w just a little bit more trouble than posting on TF.
Criticizing everybody isn't of much value either.
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Old 06-07-2016, 07:26 PM   #87
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Wadden,
My experience reading about wind forces produces results all over the map.

I've thought of tethering a boat in a steady wind w an accurate tension meter or scale.

Measuring frontal area is useless because there are so many little things that increase drag. How much drag is that cleat or windshield wiper. Sounds silly but there are hundreds or possibly thousands of little things that cause drag. Some things just can't be made into numbers. And approximations could be 75% (or worse) off of reality. And then there's the bottom. The sea floor. The biggest variable. By far.
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Old 06-07-2016, 07:52 PM   #88
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I haven't seen any mention of Forfjord Safety anchors. My dad was a big fan of these and used them often on his salmon trollers. There is one boat on my dock in LaConner that has one on the bow. I looked at them on the Kolstrand site and they are very expensive. I think they are more often encountered on commercial boats.
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Old 06-07-2016, 09:09 PM   #89
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Steve (Panope) tested his own Forfjord and it did poorly I belive.

I've always thought of them as a cross between a Danforth and a Navy anchor. And I think at times they probably only burry one fluke and pretend they are a Kedge. I bought one, tried to set it .. it would'nt so I deployed my trusty 13lb Danforth and it set right away.

Yes the fishermen in Alaska almost worship the Forfjord. The #2 anchor choice among the fishermen is the Claw and the 3rd is the Dreadnought. I personally think the Claw is better than the other two but this post is rather subjective. Now and then one can find a Forfjord supporter but not often.

78,
There was a thread on the Forfjord in the recent past. Don't remember the essence of what was said. Check it out.
Looked it up. It's on page 2 toward the top and titled "Forfjord" .. went 4 pages.
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Old 06-07-2016, 09:31 PM   #90
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I probably posted that in the wrong thread, just sort of popped into my head while reading this one! I think dad like it for varied bottom conditions and of course weight is not such a concern on a fish boat so he could go heavy.
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Old 06-08-2016, 05:06 PM   #91
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Quote:
Originally Posted by Nomad Willy View Post
Wadden,
My experience reading about wind forces produces results all over the map.

I've thought of tethering a boat in a steady wind w an accurate tension meter or scale.

Measuring frontal area is useless because there are so many little things that increase drag. How much drag is that cleat or windshield wiper. Sounds silly but there are hundreds or possibly thousands of little things that cause drag. Some things just can't be made into numbers. And approximations could be 75% (or worse) off of reality. And then there's the bottom. The sea floor. The biggest variable. By far.

Eric,
agree, all text books will give us only rough estimates on the loads, the interaction of anchor and ground etc.. We shall not take those theoretical and empirical figures as absolute numbers. These are more or less "house numbers", giving us only an order of magnitude of that what we have to expect out there.
And I also agree with the posts above claiming that all those nice theories are not valid to replace masters experience. If it comes to decisions out there I also trust on my gut and act according to experiences made in the past. My own experiences or those heard from other reliable experienced boaters.
But these theories might give us guidance and indication if we are designing a new anchor equipment for our baby. Or if we are in the planning phase for a trip to new to us destinations asking ourselves "are we well equipped?" Then theory might give us a second opinion to base our decision not only on recommendations.

And last not least: I'm tired to see anchor neighbors dragging their ground tackle in a windy night throughout the bay and telling me "don't know, I applied exactly 5:1 as I was instructed during captains course, so what went wrong?" ...


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Old 06-09-2016, 08:04 AM   #92
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Sorry if anyone takes it personal, that's the interweb for you. I get concerned that impressionable newbies (and I certainly was one once) might actually buy into some of this stuff. If someone's posts make it seem apparent to me that they have little if any practical experience (or they've just been lucky doing the wrong thing), and that my own extensive experience couple with that of experienced cruisers that I know personally counters that, I feel obliged to counter. Much of this "experience" is based on making a lot of mistakes, be they through ignorance, misinformation, inattention, impatience or just basic ineptitude.

I don't consider myself any sort of master mariner, but just a regular guy and his regular wife who ultimately learned to be pretty OK at boating, though far from perfect.

There are a lot of topics here I don't have much if any experience with, and thus never weigh in on. But I do feel obliged to " pay it forward" for all the help I got along the way myself. If you want to throw some theoretical trial balloons out there, don't get insulted if some people endeavor to pop them.
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Old 06-09-2016, 10:53 AM   #93
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waddenkruiser,
That's a good point. Many people aren't familiar enough w boats to notice while looking at a boat "that's about right for a boat of that size" and many want specifics dripping w specififications ("X" disp, "X" frontal area one needs an "X" weight anchor for such and such wind). Many will walk the dock and observe most 30' boats have anchors that are about 20lbs or whatever. Few will have the experience to say the've anchored 100 times in this or that wind on various bottoms and not dragged. Many on this forum have that experience but almost all head for the harbor and a stout dock when the wind is expected to blow. And w modern weather forecasts we almost always know.

Many will consider one that eyeballs the situation reckless or at best uninformed and the eyeballer will consider the by the book guys to be insecure. Some think for themselves w little knowledge or experience to guide their thinking. And others are not comfortable unless widely accepted standards are adhered to. These folks would be likely to say "according to hoyle" ...

Ideally though IMO all these sources of guidance will be used to help one make decisions that are important. It's hard to go far wrong using a lot of all the information availible, observations and personal experience plus recomendations by people and anything else we think is credible or some may even throw in "that anchor looks cool".
But re the chain question even widely accepted expert sources of information are at opposite ends of the range of possibilities. And then some say (like me) that all chain is best for anchoring performance but use and recomend short chain lengths. Chapman says "a few feet of chain" and other credible sources say all chain is best. What to do? Hence this thread.
The obvious response is to notice even the experts disagree so one is inclined to error on the safe side ... bigger anchor and more chain. And that (I think) guides most of the thinking here on TF. Also very few want to be viewed as reckless, uninformed or not very bright so the bigger (or more) is better philosophy rules the most common and accepted numbers and practices of the trawler community and TF.
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Old 06-09-2016, 11:40 AM   #94
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I think the main issue is some think that one anchor or another, or anchoring one way or another, or one type rode or another is better.... even in the smallest way....yet there's no proof in most cases.

Some thing that generically adding bits or pieces or subtracting them from ground tackle are weak points or hindrences.....well....no one can actually prove it and others with experience dispute it.

It's just a discussion with many possible facts or errors....not science only, not art only....

But those that use the collective wisdom of many and practice within their equipment's and experience capabilities have the best handle on how they should probably operate.

For every anchoring success story, someone can probably dispute it.
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Old 06-09-2016, 12:26 PM   #95
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I'm from the school of use enough chain to anchor the boat,and then a good all around anchor to anchor the chain. While danforths/ fortresses have great setting and holding power when things like little rocks, bags, reversing tides or currents don't happen, these things do happen often enough where we go, to relegate them to number two status. Im not sure how this looped video is going to work but it shows a 60' boat anchored in 50' of water in 30 knots of wind and building seas. Catenary force is probably around 1800 pounds while the wind force is considerably less leaving much of the chain laying flat on the seabed. Having dove lots of anchors throughout my life and having seen in real time how anchor rode's behave in extreme conditions, as well as having done all the math with regards to catenary forces, wind forces, rigging angles and leverage calculations, we seem to be able to get it right about 99 percent of the time...as long as you hold your mouth right.Name:  ImageUploadedByTrawler Forum1465489448.179464.jpg
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Old 06-09-2016, 05:58 PM   #96
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cafesport wrote;
"Danforths as #2 status"
Number two is rather high but there's no doubt about their holding power and their faults. Since most bottoms are mud or mud/sand a strong case could be made for a Dan (or Fortress style Danforth) as primary and a Claw as secondary. I've never had a Danforth pick up anything but seaweed but the fluke gap is an obvious problem.

What on earth is "catenary force"?
I keep hearing about chain anchoring boats and pass on to isle #2.

psneeld,
How does one "generically add pieces"?
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Old 06-09-2016, 06:07 PM   #97
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Post 53....

[QUOTE=Nomad Willy;449022

..............

You don't seem to get it Scott.
Of course chain and shackles are pulled below the surface in/on a soft bottom. It's a matter of degrees. More is better so rode that slices more easily down in the bottom substrate has an advantage. Better is better. That's all. Like dual exhaust is better than one. Just a little better but better.[/QUOTE]

Sorry...I don't get it.....
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Old 06-11-2016, 01:32 PM   #98
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Tried to post a small spreadsheet calculating the catenary (all chain and chain + rope) but failed unfortunately. XLS files are not supported as attachment.
I used it together with some text book data as a sizing tool for our equipment, refer to #91. It is definitely not intended to be used out there to decide whether it is safe or unsafe to anchor or to calculate rode length to be applied under actual conditions or whatever ...
Please PM if you are interested, would send it via e mail.



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Old 06-11-2016, 02:31 PM   #99
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wadden,
I don't need to calculate anything.
Just wondering what catenary force is.
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Old 06-11-2016, 03:00 PM   #100
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Catenary Engineering Solutions

http://home2.fvcc.edu/~dhicketh/Diff...oreysDifEQ.pdf
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