[Rhodes22-list] Anchoring -- Phuzzy Physics

[Michel Meltzer]

Bill I been subject to "helper metal" and "A kite and a brick", in both
cases olfaction it seems to avoid any real discussion, I view an anchor
as a tool that you understand and use like any tool. But you are getting
me nervous here because, it seems that you are having a fixation here, I
mean we are talking about an anchor, not your mother, out faith or
politics. An anchor zealot? It like you can not here anything against
the "anchor", you will lay down your life for the anchor, the anchor can
do no wrong, only you know the right anchor and everyone else is wrong
about an anchor. Have you named the anchors? Anchors 12 program?

Now the nervous part(and I not sure I kidding now), are you upset with
me for talking about the anchors? Like you find it funny and tongue
check like written or are you upset? Reread some of you posts, saying
you are a little "committed" to your view is somewhat of an
understatement.

I play it straight, lets talk about anchors, chains and the FX-7, could
we say on subject please.

First off we are in a "dynamic model", the pieces do interact.

http://www.johnsboatstuff.com/Articles/anchor.htm 

The is an very good article, what is saying is by adding Centenary
effect the shaft (pull) on the anchor says more horizontal to the
ground. I think your reply is "So what, The line is going to go straight
after 178 pounds(22 feet 1/4 and 150 of 3/8, 14 feet water), it has no
effect", That not quite the end of the story. It the "dynamic model",
what it also doing is delaying the full shock load from reaching the
anchor and the boat connections for 178 pounds, think of it like floor
padding, you jump from a 10 feet onto a concrete floor, broken ankle,
same jump onto 4 inches of padding walk away. Same impact speed, same
weight so the same impact force, How did the padding work?(well it
soft....but what is soft in this case), the padding changed the impact
time curve, think in term of graphs, instead of a straight vertical up
line(i.e going from falling to full weight on the concrete floor), you
now see a curve form on the graft with your weight growing onto the
padding over a longer period of time, the "give" delay and spread out
the shock load so the instance impact force never reached the bone
breaking point. The Centenary effect does the same thing for both the
anchor and boat cleats.

But now I hear you say, But the rope will do that!!! it has a different
"curve" than lifting the chain, it take longer to stretch the rope, also
once you go above about 10% of the working limit of the rope the fibber
start breaking, the chain could care less. In padding term think of it
as a soft pad over a firmer pad. The work as a team with both cruves
working together, you been on a boat in 20 knots, it not a steely load
it going from 0-full load, osculating, wave, winds, boat sailing at
anchor, etc............... 

Now the "helper metal" crap, you missed the whole point in one respect, 
Chafe!!!!!!!!!!!!! You are not diving on the anchor, you have no idea in
that rode/anchor is on a rock, old rebar, a 1934 broken BUD bottle, what
ever... after about 6 feet chain at 6:1 scope the rope is about 1 foot
of the floor, so hopefully it is above/not forced to rub against
anything that will cut it. Now here the badnew these anchors burry them
self, lets say power it down OH 1.5 feet, that means 10 feet or so of
line under sand/mud/rock and what else has built their in the last 300
years, and the line is shifting around a 30 square foot circle of the
"mixture" as the boat swinges, rubbing against it, plowing thought,
going taught...  


helper metal path 2, sorry but this one you are wrong, lets start off
with a 4 pounds AL anchor, in water it loss 35% of it weight in water
(specific gravity 2.8 vs 7.8 for steel or 12%, BTW is a bigger loss in
saltwater but not in the mood to correct the math), so it is only 2.6
pounds, water is 20 times for dense air and the FX-7 is designed to show
a 32 degree angle of attack with broad blades, bottom line it "fly" in
pretty slow water, and we are talking about sailboat speeds, the augment
about other anchor or brick or cinderblocks was nonsense, speed is not
approaching infininity, none of the anchor type (none danfors, like
Bruce, luke, QCR, delta, etc..) are know for it or have a shape likely
to do it. The steel ones do it less.

I think you are convinced that either stop the boat or you get to play
out the rope fast enough that it will be just like stopping the boat.
Well I simple do not agree he, Even with everything ready to run, still
had issue get line out, My taste but if I am using the anchor for safty
I want it to work right not.

Next issue, setting a daforth, they simple do not set every time, That
is the "standard" complaint, show up in every last test, every sail who
uses them  has their own stories, I bet you to have a few to, I pick up
this theme again on reset.

When set the do hold nice, but that not the end of the story.

Boats more around, wind change, tides, etc... The reset problem, the
frount come thought, 180 degree wind shift, boat swings around, assuming
150 feet of rode the boat has built up some speed over that 300 feet and
pulls the anchor out. Now that the boat is moving backwards and the
anchor is on it own to reset, all the fancy trick to set it are not
aviable, you not their or sleeping. It can be bad news, Then you pick up
and another problem they have, because the boat is moving at a somewhat
constant speed when they do breakout their Point kind of "scribe" a line
on the bottom instead dig back in, they seem to get in a "steadstate"
around it(BTW argue with PS about it not me) BTW I know you could set
two or even 3 but what about the swing of the people around you.

They do great in mud, sand/clay/hard stuff they like dig in sideways on
one point and would not dig in(again take it up with PS).

BTW I ran some quick calculation, the 8hp nision should be getting about
130-150 lb of dig in power, up to 190 if you switched to a sailboat
prop.
But you are way below the number from the fortress website for their
"powerdigging" and it looks like ABYC wants 400 lb for a working anchor,
http://www.epcomarineproducts.com/pdfs/H-40.pdf

So what other anchor type do we want to talk about? I was shocked the
bruce did so well in PS, they got luckly, BTW I know their problems
also.

-MJM
PS
   

> -----Original Message-----
> From: rhodes22-list-bounces at rhodes22.org [mailto:rhodes22-list-
> bounces at rhodes22.org] On Behalf Of Rik Sandberg
> Sent: Friday, January 13, 2006 9:57 PM
> To: The Rhodes 22 mail list
> Subject: Re: [Rhodes22-list] Anchoring -- Phuzzy Physics
> 
> Bill,
> 
> What you seem to be having trouble getting a handle on in this reply
is
> that lifting the weight of all that chain requires energy. Much more
> energy than just lifting a nylon rode. That energy is taken from the
> motion of the boat as it tightens the rode, ie it slows. Therefore it
is
> moving slower when it snubs up against the end of the rode and is less
> likely to jerk the anchor out of it's set.
> 
> Rik
> 
> Bill Effros wrote:
> 
> > Herb,
> >
> > It is true that a catenary curve develops between a tug and its tow,
> > but it only happens because both are moving.  As you noted, when the
> > tow is stationary, and the tug is moving, the line becomes
completely
> > straight before the tow starts to move.  Once both are moving at the
> > same speed, the weight of the tow line creates a catenary curve.
This
> > can become dangerous if the tow starts to travel faster than the
tug.
> >
> > If you look at Ron's example of wind force on a properly sized and
set
> > anchor, a chain rode would be completely straight--just as it would
be
> > if you attached one end of a piece of chain to your pickup truck,
and
> > the other to an eye bolt embedded in a boulder.  Your truck would
not
> > be able to budge the rock, but the chain, which initially was lying
on
> > the ground, would form a straight line to your truck.  There
wouldn't
> > be a catenary curve except for a brief moment as the truck took up
the
> > slack.
> >
> > Bill Effros
> >
> > Herb Parsons wrote:
> >
> >> "When your boat pulls your anchor into the bottom, the anchor rode
> >> becomes taut.  The angle of the rode is exactly the same whether or
> >> not you have any chain between the anchor and the point on your
boat
> >> where the rode is tied off."
> >>
> >> That's not true Bill. I've never been underwater and watched a
boat,
> >> but I HAVE towed a few boats. We were taught in the class I took (I
> >> forget the term though) about the thickness of the rope used to
two.
> >> If you use a thicker rope, it not only adds strength, but weight.
> >> When you pull the other boat, it pulls taught, then goes to a
> >> semi-slack mode. I forget the terminology, but they showed
pictures.
> >> A tug pulling a boat with a lighter line had less of a curve, and
the
> >> angle of the pull was steeper. The instructor even mentioned in the
> >> class that this was similar to the effect of using a heavier rode
on
> >> an anchor.
> >>
> >>
> >> Herb Parsons
> >>
> >> S/V O'Jure
> >> 1976 O'Day 25
> >> Lake Grapevine, N TX
> >>
> >> S/V Reve de Papa
> >> 1971 Coronado 35
> >> Lake Pontchartrain, Louisiana Coast
> >>
> >>
> >>
> >>
> >>>>> bill at effros.com 1/12/2006 10:43:39 am >>>
> >>>>>
> >>>>
> >> Dave,
> >>
> >> I, too, have read the "horizontal pulling force" theory of anchor
> >> rode chain.  As soon as you think about your mechanics and physics,
> >> you will know that it's rubbish.
> >>
> >> When your boat pulls your anchor into the bottom, the anchor rode
> >> becomes taut.  The angle of the rode is exactly the same whether or
> >> not you have any chain between the anchor and the point on your
boat
> >> where the rode is tied off.
> >>
> >> The anchors we use dig in properly at an amazingly wide range of
> >> angles.  Horizontal is not one of them.  Vertical is also not one.
> >> That's what the whole notion of "scope" is about--putting the rode
at
> >> the proper angle to cause the flukes to dig in.
> >> These anchors set properly despite the fact that people put chain
in
> >> their rode, not because of it.
> >>
> >> Bill Effros
> >>
> >>
> >> DCLewis1 at aol.com wrote:
> >>
> >>
> >>
> >>> Bill,
> >>>
> >>> There's no way I'm an expert at anchoring, but I do know a bit
> >>> about  mechanics and physics. You're certainly right about an
> >>> anchor's generally  sinking, but the chain rode issue may be about
> >>> how the anchor engages the  bottom, and stays engaged with the
> >>> bottom -  not about sinking the  anchor.  Consider an anchor on
the
> >>> bottom with sufficient chain rode, if  there is a pull from the
> >>> anchor line with any vertical component, the weight of  the rode
can
> >>> counteract the effect of the vertical pull and ensure  that forces
> >>> on the anchor are horizontal (i.e. notionally  parallel with the
> >>> bottom).  I believe anchors are really made to deal with
horizontal
> >>> forces; the anchoring effect is achieved primarily by  flukes,
> >>> plows, or other appurtenances optimally engaging the bottom, and
> >>> that requires horizontal forces.  Without the rode, any
substantial
> >>> pull on  the anchor line that has a vertical component may cause
the
> >>> anchor to lift  vertically, in which case it may not engage
> >>> properly, or at all, with the  bottom.
> >>>
> >>> Dave
> >>> __________________________________________________
> >>> Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
> >>>
> >>>
> >>>
> >>
> >> __________________________________________________
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