[Rhodes22-list] Anchoring -- Phuzzy Physics

[Arthur H. Czerwonky]

Dave,
Like you, I have been sitting back and witnessed to the grinding of teeth.  Your summary hits the mark - the anchor will become set, and stay set based on the ability to keep the anchor shank horizontal, the chain rode weight will help the process.  I'm surprised that no comment was made on the greatest function of the rode - namely that on a rough or rocky bottom, a rope will eventually be cut to shreads and break, unlike the chain.  Much of my muddy-bottom sailing will require one or two mushroom anchors, but I'll always use heavy chain rode on the coast.
Art

-----Original Message-----
>From: DCLewis1 at aol.com
>Sent: Jan 12, 2006 2:23 PM
>To: rhodes22-list at rhodes22.org
>Subject: Re: [Rhodes22-list] Anchoring -- Phuzzy Physics
>
>
>Bill,
> 
>I?d prepared a long winded discourse regarding the forces on anchors, etc,  
>but when I signed on I saw you were being assailed on all sides, so let me back 
> off and just state what I think are the core issues.  
> 
>The whole, point of a metal chain anchor rode is not to help the anchor  sink. 
> The whole point of a metal chain anchor rode is to help set the  anchor, it 
>may also help keep the anchor set.  
> 
>It seems to me that what?s going on at the boat end of your rode is of no  
>consequence for anchoring.  I think all the forces and angles of interest  for 
>freeing and setting an anchor are at the anchor shank.  The flukes,  etc, will 
>adapt, but to set the anchor you need to get the shank within it?s  operating 
>range, and in my limited experience that?s always more horizontal than  
>vertical.
> 
>Everything else being equal, the additional weight of chain rode adjacent  to 
>the anchor shank will offset vertical forces coming down from the anchor line 
> and allow the anchor shank to be more horizontal.  In many quiescent cases,  
>the weight of the metal chain will actually eliminate any vertical force on 
>the  anchor shank entirely, all the forces to the anchor will be horizontal so 
>the  shank can be horizontal - that's optimal. Again, more horizontal is good 
>when it  comes to setting and holding.
> 
>Bottom line - anything which helps keep the anchor shank horizontal or more  
>horizontal is a good thing.  A metal chain rode attached to the shank does  
>that.
> 
>Now, you CAN achieve much the same effect by letting out a lot of scope -  
>but it?s not uncommon to be constrained so that you can?t let out a lot of 
>scope  - but in no case will having a chain rode hurt you in terms of setting and  
>holding.  So use chain rode, and carry enough anchor line, the two may get  
>you through.
> 
>Like you, I?ve anchored without chain rode, but I?ve also had problems on  
>occasion.  I think it was because the anchor shank was too high,  I  think 
>chain rode would have helped.
> 
>I?ll be very interested to see the results of the anchor tests.
> 
>Dave
>
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