[Rhodes22-list] Chain/Rope Rode

[Ronald Lipton]

Bill,

  Did you look at:
http://www.johnsboatstuff.com/Articles/anchor.htm
He calculates the tension needed to lift the end of the anchor 
line off the ground as a function of the weight of the line, and 
includes a spreadsheet which uses an iterative calculation to 
estimate this tension for an arbitrary combination of chain and 
line.  This, in combination with what I think is a reasonable 
estimate of the relative lifting force as a function of angle 
on the Fortress web site, makes a pretty strong arguement 
for a lenght of chain at the end of an anchor line.  

Ron
----- Original Message ----- 
From: "Bill Effros" <bill at effros.com>
To: "The Rhodes 22 mail list" <rhodes22-list at rhodes22.org>
Sent: Friday, January 13, 2006 1:14 AM
Subject: [Rhodes22-list] Chain/Rope Rode


> Slim,
> 
> The formula is totally arbitrary.  You are right, it makes no sense.  
> Reducing all the chain/rope rode answers to English, everyone seems to 
> agree that the "helper metal" theory is rubbish.  No one wants to defend 
> that theory.  Which leaves the catenary curve theory.  The chain is 
> going to pull the anchor in a perfectly horizontal direction by lying on 
> the bottom while the rope forms a catenary curve pulling on the chain.  
> It may take another half day, but the physics majors aren't going to 
> defend that proposition for very long, either.
> 
> So someone will trot out the "protecting the rope from the rocks on the 
> bottom" theory.  But why should a 10 foot boat require only 10 feet of 
> protected rode and a 20 foot boat need 20 feet of protected rode if the 
> chain is pulling all the rode to the bottom?
> 
> Attaching chain doesn't make the rope any stronger.  In fact, it makes 
> it weaker.
> 
> Really going to bed now.  Can't work musicians hours like I used to,
> 
> Bill Effros
> 
> salm at mn.rr.com wrote:
> 
>>Who came up with the formula that says one foot of chain for one foot of
>>boat length?  Shouldn't it be calculated by 
>>weight?  Rik's Flicka, for example, is three feet shorter but (I'm
>>guessing) 2000 lbs. heavier.    Surely his ground 
>>tackle needs to be more robust than that of an R22.
>>
>>Slim
>>
>>Original Message:
>>-----------------
>>From: Michel Meltzer mjm at michaelmeltzer.com
>>Date: Thu, 12 Jan 2006 22:05:16 -0500
>>To: rhodes22-list at rhodes22.org
>>Subject: RE: [Rhodes22-list] Anchoring
>>
>>
>>
>>
>>Ok. Looks like I miss all the Fun today. To save some of the heartache,
>>lets try to organize the issues a bit.
>>
>>We are in a applied engineering domain and practical user experience,
>>the engineers please simplify and use good examples, for the "sailors"
>>please understand there are time proven Numerical methods and you might
>>have to simply accept them, there is a reasonable question if the
>>"model" being used is right, but It only pisses off the engineers with
>>"unproven nonsense", junk arguments, etc....
>>
>>First off how much anchor?
>>1)for the most part it is a function of wind speed and somewhat wind and
>>tide.
>>a)at zero wind a there is no force, so a brick on kite string will work
>>b)at an F5 tornado you can kiss your ask good by
>>c) lets pick a speed that we can agree on for this, I like (1) 42 knots,
>>a very good thunderstorm, (2) 63 knots (the edge of the hurricane and
>>perhaps a once in a lifetime event, but I got nailed their). 
>>d)I could not find the tables for windload from the last time, can
>>someone calculated look/up the load in lb for a rhode22 type of
>>sailboat, IIRC I estimated about 900lb's at the top number, but I might
>>be high.
>>
>>
>>2) Connecting to boat, load forces
>>a)that has never been much of an issue on the rhodes, best statement is
>>connecting to the bow eye lessens the scope
>>b)but if some one wants to agurge forces on the cleats go ahead
>>
>>
>>3)deck chocks
>>a)type
>>b)location
>>c)how installed
>>d)the need for chaffe grards
>>
>>4)scope lengths
>>1)5:1
>>2)7:1
>>3)10:1
>>4)impact crowding?
>>
>>5)rode type and size
>>a)3/8 3 strand new gland
>>b)nylon does not float?
>>c) tripping people up/run over the rope with a floating rode?
>>d) 7/16 and 1/2 do not streght right on a whodes22?
>>e)storage, flacking
>>other?
>>
>>6)Chian
>>a) size (1/4 inch)
>>b)length
>>c)effects on the anchor
>>d)The effects of chaff of the shaft holding the rope on the bottom
>>without it
>>
>>7)setting
>>a)stopped
>>b)moveing
>>c)in a all out emerangys
>>d)in the storm and it dragging
>>
>>7)the effect or wind and tide
>>a)boat chance direction, will the anch break out
>>b)will the anchor reset on its own when the boat moves(which it will)
>>
>>8)anchors types and bottoms
>>(this just gooes on)
>>but..
>>short scope 
>>long scope
>>
>>
>>
>>
>>9)special comments:
>>a)how some danforst set only on their points and one point
>>b)how some danforths when they reset, draw a "line" on the bottom and
>>will not reset
>>c)how some danforst that are mad of AL, will "sail" in slow moveing
>>water and never reach the bottom
>>
>>   
>>
>>This should get it started
>> 
>>
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>>  
>>
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