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Old 12-10-2018, 01:26 PM   #21
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What you are experiencing is your vessels natural tendency to heave to when forward speed goes to zero. At anchor in light winds and no current boat’s are pretty much free to float forwards backwards and sideways whenever drag force induced by the vessels wind age is less than the forward pulling forces of the anchor rode. Rigging a riding sail aft with it’s clew forward might give enough reward force but hey in light wind who cares.
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Old 12-17-2018, 01:53 PM   #22
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Anchor

Same problem with my single engine trawler. I replaced my nylon anchor line and anchor. I use all chain and anchor both oversized for my boat. I was able to reduce my rode and diminish my swings. I place a snubber from the chain to my Sampson post to reduce stress on my windlass. I carry two anchors for different bottoms. A danforth and a plough. On the biter end of my chain where it attaches to boat in anchor well I use nylon line. This I can cut the chain and anchor loose in an emergency. The end of the chain is attached to a large float and line for anchor retrevial. I know some will comment this is wrong but it works and anchor never dislodges when current or wind direction changes. I have weathered 60mph winds at anchor safely. It does add forward weight but in my boat this is a plus.
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Old 12-17-2018, 02:51 PM   #23
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Our 41 foot full keel boat will swing at anchor (so it's not just a matter of a full/partial keel unless you happen to be in a current that keeps your pointy end upstream). Attaching a bridle to the chain and secured to the boat's side cleats (about five feet abaft the anchor platform) helps a lot in reducing the swing, but she still swings!
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Old 12-17-2018, 04:05 PM   #24
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Originally Posted by Giggitoni View Post
I’ll try your solution next time!

I’ve never tried it, but I’ve read that one can tie a line near the stern and tie a hitch on the bitter end of the line to your anchor rode. Tighten the line enough to pull the stern a few degrees to the side. Supposedly this will remove a lot of the “fish tailing”. I can also imagine that by doing this could create a recipe to increase fish tailing. I’ll go back to sleep now...
A great way to reduce the "fish tailing" is to shorten -by about a foot- one of the two snubber lines.
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Old 12-17-2018, 04:53 PM   #25
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A great way to reduce the "fish tailing" is to shorten -by about a foot- one of the two snubber lines.
I utilize two snubber lines. I’ll try shortening one next time. Thanks!
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Old 12-17-2018, 06:05 PM   #26
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The sides of your boat are curved, right?...like the surfaces of an airplane wing. In a perfect world after you anchor, the wind, even a tiny wind, should stay dead ahead and your boat should not swing. But that if perfect wind shifts even 5 degrees and now your curved sided boat is an airplane wing generating lift (call it suction) on one side and disrupted air flow on the other. The boat now swings or pulled to the side generating the lift. If it swings too far the anchor line going tight jerks it back the bow may go through the eye of the wing and the roles will be reversed, lift or suction will be generated on the opposite side and disrupted air flow on the other. This process repeats itself all night.

In additions to shifting winds the wake of a passing boat or a shifting swell can also upset the equilibrium in that perfect world.

The worst boats for this are like one of my boats, a fin-keel racing sloop. The only fix is to anchor stern to and lay in you bunk and listen to the slap, slap, slap of the waves under the transom.

My other boat is a large power cat that anchors with a bridle so no problem. If your boat has a wide beam pretty far forward you might try rigging a bridle fixed a little way aft of the bow. Boats with full length extended keels avoid most of this.


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Old 12-17-2018, 09:05 PM   #27
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I’am on the upper Mississippi and anchor out fairly often. I’ve found that turning the wheel one way or the other cuts way down on swinging at anchor, stopping it completely at times.
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Old 12-18-2018, 04:10 AM   #28
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We have always found that attaching your anchor Snub line to the front cleat near the anchor winch and the other end of the snub line on one of the cleats half or one third the way down the same side, works best. This will ensure that there is a positive drag down one side and the wind and current flow will create enough flow that will greatly minimize the swinging. This we found works the best.
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Old 12-18-2018, 06:00 AM   #29
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Our last boat would swing quite a bit at anchor when the wind would pick up over about 15-18 kts. I've measured the swing angle as pushing 180 degrees.


I tried a bunch of tricks suggested here in a previous thread, and by others, including:


1) Use a two line snubber rather than a single line


2) Use an asymmetric snubber


3) Tie through the hawse pipe on only one side so the boat presents at an angle (extreme version of the symmetric snubber)


4) Hanging fenders off one side of the boat (yup, someone suggested that)


None of it made any difference.


I then found an article that seemed credible that explained what was happening. The basic dynamic is that the boat's natural center of rotation (the point around with it rotates if you pull sideways on one end) is BEHIND the center of force for wind hitting the boat. The result is unstable, like an arrow with feathers in the front rather than the back. Now this is all about the wind effect and doesn't take current into consideration. In my experience, current will almost always dominate wind.


So when a boat swings, here's what happens:


- As soon as the boat is anything other than perfectly into the wind, the point the wind force is acting on is forward of the boat's rotation center, so it wants to spin the boat around, and it does.


- But, as the boat rotates, more and more of it's side profile presents to the wind, and the center of windage shifts aft. The more house structure you have aft, the faster the center of windage will shift aft.


- As soon as the center of windage moves aft of the rotation center, it now wants to straighten the boat out, which it does. The anchor rode is also pulling from the bow, and that further encourages the boat to straighten out.


- As the boat straightens, momentum causes it to overshoot and the whole process repeats itself in the other direction.


The solutions offered were two fold, and you can find elements of them in all the remedies and tricks that people have suggested.


Remedy 1: Shift windage aft. This is why a small sail rigged aft helps, as does hanging fenders off the side (see, the person who suggested it wasn't crazy). Canvas "curtains" on aft railing, or enclosed aft decks could all help too. On some boats it might be possible to reduce forward windage, but I suspect that would be rare. Our last boat, with a high bow and forward pilot house, has lots of forward windage, so it makes sense that it would swing a lot.


Remedy 2: Move the anchor rode attachment point further forward. This has the effect of moving the boat's rotation point forward, and moving the relative location of windage aft. Unfortunately, this is impractical on most boats unless you want to make some permanent modification. At least I couldn't think of any practical way to rig a spar to move the anchor attachment point forward.



Hopefully this give everyone the basis for evaluating remedies. It helped me quite a bit, and was a significant factor is switching from a forward pilot house, to an aft pilot house boat.
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Old 12-18-2018, 07:13 AM   #30
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a guess, put out a stern anchor to discourage movement.
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Old 12-19-2018, 02:50 PM   #31
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I found that a bucket tied to a 5 to 6 foot line on a stern cleat slowed the swing down to not really notice it much. You will never stop it, just make it livable for you and your crew.


It is easy to do as long as you remember to pull it up before getting underway again. No need to get the line wrapped on the shaft or around a rudder.
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Old 12-20-2018, 07:52 AM   #32
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Most trawlers have highest windage up front, but even more important: the deepest part of the keel far aft. Hence the bow is picking up wind and moves easily while the stern is planted more firmly. On our Selene we rig the stabilizing sail to dampen this skating. Another solution is a line tied to the middle or rear cleat on a snubber on the chain creating a V shape that keeps one side of the boat in the wind. Disadvantage is higher (wind)strain on your anchor. Third solution when you have a second anchor on the bow, is dropping the second anchor straight down just touching the ground. This anchor will dampen the speed in which the bow overtakes the stern quite a bit.
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Old 12-20-2018, 08:16 AM   #33
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Mine swims pretty badly in some anchoring conditions. I've messed with various solutions, none worked very well and were generally a PITA. So now I just ignore it. Boat swims. Have a beer and go to bed.
That was our final solution on our last sailboat. We tried a riding sail, a bucket off the stern, and the bow, a kellet, offset bridal, extra anchor off the bow, and stern, every possible rudder position, but nothing worked.

We finally just said to hell with it and learned to live with it!
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Old 12-20-2018, 11:09 AM   #34
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If there is any current running under the boat whatsoever, first and easiest thing is to use some rudder. This almost always works for us, as we rarely anchor in still waters.
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Old 12-20-2018, 01:55 PM   #35
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That was our final solution on our last sailboat. We tried a riding sail, a bucket off the stern, and the bow, a kellet, offset bridal, extra anchor off the bow, and stern, every possible rudder position, but nothing worked.

We finally just said to hell with it and learned to live with it!



Same here.
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Old 08-05-2019, 07:29 PM   #36
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I'd love to say live with it, and mostly its quite alright. I was anchored a couple weeks ago in strong winds, and my boat does the full 180' swing. so in the middle of the night 3-5 foot wind waves are hitting the boat on the beam. severe rolling, poor dog sliding from one end to the other, sliding door opening and closing with force, had to lock that to stop it.


So for all the treads about anchoring in 80 knot winds, this I haven't seen addressed. Many suggestions seem they might help in moderate conditions to reduce the swing, but if you absolutely need to keep the bow to the waves, will a drogue do that job?
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Old 08-05-2019, 08:39 PM   #37
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So for all the treads about anchoring in 80 knot winds, this I haven't seen addressed. Many suggestions seem they might help in moderate conditions to reduce the swing, but if you absolutely need to keep the bow to the waves, will a drogue do that job?
A few years back, I was in Ft Lauderdale, weather was terrible. The port was closed, ships were anchor out, bow into the wind, 2 bow anchors out and throttles at 1/2. According to the conversation on the ships and port authority, even with anchors out, throttles open 1/2, the ships were losing ground. That had to be exciting on the ships.
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Old 08-05-2019, 08:58 PM   #38
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A drogue will help staying pointed into the waves only if there is a strong current in the same direction of the swell.

There are times that the wind, current & swell are all coming from different angles, and changing every time you get something set up do deal with the issue. It can get frustrating.
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Old 08-06-2019, 05:02 AM   #39
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I am not a fan of chain ,( unless anchoring in coral) but an all heavy chain anchor setup might slow down the constant veering ?
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Old 08-06-2019, 10:28 AM   #40
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Tks ff, it already has heavy chain. It really is the windage, with a forward pilot house and high bow.. Only care for extreme cases when swells get involved. Should be rare, but when in that situation some solution besides motoring on would be good to have .
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