[Rhodes22-list] anchoring

[Bill Effros]

Rik,

The point is, when you are anchoring, neither end is free.  Whenever the 
anchor is working, the line is taut. 

BE



Rik Sandberg wrote:
> Bill,
>
>   
>> Plow type anchors work differently -- but the chain works the same -- 
>> and it can't pull an anchor in any direction without maintaining an 
>> essentially straight line to the vessel. 
>>
>> Imagine the boat is directly above the anchor, with chain on the 
>> bottom.  Does pulling in the rode move the anchor?  Horizontally?
>>   
>>     
> We don't try to set our anchors from directly above them .... unless we 
> are completely clueless.
>
> Lets do another little test. You can do this on the way to the tree we 
> were talking about earlier. while you are walking out there, let ten 
> feet or so of that chain drag along behind you. As you walk along, does 
> the chain pull out into a straight line before the free end begins to 
> follow you? I'm pretty sure you will find the answer is no. Half, or so, 
> of that chain will be flat on the ground following along behind you and 
> the rest will curve on up to your hand in an arc. Where the chain leaves 
> the ground will be no where near the trailing end, but nearer the 
> middle. When trying to begin to move and set an anchor there will be 
> somewhat less of a curve in the chain, but it will still begin to move 
> the anchor long before it is straight unless the anchor is very heavy 
> (not likely with a danforth) or the chain is unrealistically light.
>
> Rik
>
> Ayn Rand was a prophet - - it isn't my fault
>
>
>
> Bill Effros wrote:
>   
>> John,
>>
>> If the chain is lying on the bottom where does the horizontal movement 
>> of the anchor come from?
>>
>> Do you think you can pull one end of the chain at a 45 degree angle from 
>> the bottom, and move the other end of the chain parallel to the bottom?
>>
>> I don't think so.
>>
>> I think you keep pulling that chain off the bottom at a 45 degree angle 
>> until it moves the flukes of the anchor into perfect position to dig 
>> into the bottom.
>>
>> The flukes swing on the shank so that the anchor almost always lands in 
>> position to dig in.  The shank is angled at 45 degrees when setting.  
>> The chain lying on the bottom defeats the ability to set the anchor -- 
>> you must pull it off the bottom before the anchor can set. 
>>
>> This requires you to buy an anchor heavier than your chain, or you can 
>> never set your Danforth style anchor properly.
>>
>> Plow type anchors work differently -- but the chain works the same -- 
>> and it can't pull an anchor in any direction without maintaining an 
>> essentially straight line to the vessel. 
>>
>> Imagine the boat is directly above the anchor, with chain on the 
>> bottom.  Does pulling in the rode move the anchor?  Horizontally?
>>
>> Bill Effros
>>
>>
>>
>> John Lock wrote:
>>   
>>     
>>> At 11:52 PM 9/16/2008 -0400, Bill Effros wrote:
>>>   
>>>     
>>>       
>>>> The point is that the anchor most of us use is designed to set by being
>>>> pulled at a 45 degree angle from the bottom.  If you pull it parallel to
>>>> the bottom it just stubs its flukes along and never sets properly.  And
>>>> if you have too much chain, you can never pull it at a 45 degree angle,
>>>> so it will never set at all.
>>>>     
>>>>       
>>>>         
>>> Let me jump in and say I have to disagree with Bill here.  As I 
>>> understand the physics of the Danforth-style anchors, they actually 
>>> depend on a certain amount of horizontal (or parallell) movement to 
>>> get the points of the flukes to dig in.  Here's why...
>>>
>>> With the flukes hinged at the back of the anchor and free to rotate 
>>> about that axis, their mass, pulled downward by gravity, will have a 
>>> natural tendency to rest directly on the points.  Consequently, an 
>>> initial horizontal movement will naturally force the points downward 
>>> and into the mud.  Pulling up on the rode at a 45-degree angle will, 
>>> in fact, help defeat the design by not allowing the mass of the 
>>> flukes to perform their downward deflection.
>>>
>>> The main reason a few feet of chain helps an anchor set is that the 
>>> extra weight helps keep the initial movement of the anchor more 
>>> horizontal, because the rode will begin to rise before the chain 
>>> does.  This helps the flukes get their initial "traction".  Once the 
>>> points dig in and force continues to be applied the rode and chain 
>>> can rise and increase to the 45 degree angle that is ideal to finish 
>>> and maintain the set.  It's those first few inches of movement that 
>>> are critical to the set of the anchor.
>>>
>>> Cheers!
>>>
>>> John Lock
>>> ~~~~~~~~~~~~~~~~~~
>>> s/v Pandion - '79 Rhodes 22
>>> Lake Sinclair, GA
>>> ~~~~~~~~~~~~~~~~~~
>>>
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>>>     
>>>       
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>>     
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