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Mic
 
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Default Demonstration footage of boat anchors

On Thu, 25 May 2006 11:00:39 -0400, "Glenn Ashmore"
wrote:

A few observations:

First I noticed a number of other patterns on the beach including a Spade
but no test results for them.
Second, beach sand reacts very different from ocean bottom. And most
important, the test were done with effectively infinite scope. Zero angle
between the rode and the beach. This works against fixed shank patterns
like the claw and the plow because it holds the shank down keeping it from
righting.


Humm...but wouldnt that apply to the Rocna too?
It would seem to and was one of my first thoughts of this test.
that is probably why an anchor with a mini float attached to it tend
or seems to be effect in keeping it in a good or better setting
position.

Setting on a normal 4 or 5 to 1 scope the rode is angled upward
which lifts the shank and helps right the anchor. When set on a 4:1 scope
the claw type will set easier than almost any other pattern which accounts
for its popularity. It just doesn't have the holding power.


Heres another link, go to the paragraph that starts "So we bought a
15# alloy SPADE which so far has done OK. ..."
"We recently learned that we were improperly setting the anchor, i.e.
we should be setting out only 3:1 scope then leave the anchor to work
down with surge. After it has been deployed for a time we can then
back down on it and/or let out more scope. "
http://goose--bumps.com/goosebumps-main.htm


The Rocna does have good holding power and is relatively inexpensive but the
big hoop just compensates for poor balance.


This seems to be addressed at
http://www.bluemoment.com/newanchors.html
"Some commentators incorrectly assume that a high tip weight is
required to push the tip into the seabed, quoting specifications such
as percentage-weight-on-tip (i.e. what percentage of the total weight
of the anchor rests on the tip when in a setting attitude)."

"However, the reality is that forces in the form of torque applied by
the rode as your boat pulls on it are far more important than the
relatively small amount of weight force present."

" “The SPADE was the best performer for a given weight. It was
roll-stable and held extremely well. It was also the most deeply
buried anchor. The Delta… and Bruce… gave about 60% of the SPADE's
hold.” This was before the Rocna was developed, and the Bügel was not
tested."


http://www.practical-sailor.com/boat.../01anchor.html
"Anchor Reset Tests
When direction is reversed 140°, a third of the anchors never broke
out, another third reset at some length, and two never reset."

"the Bulwagga anchor that challenges the Spade in every category. The
Bulwagga’s only shortcoming: It’s clumsy to handle and difficult to
stow."

I would think that the Bulwagga would be righted on the bottom every
time given it design.
http://www.noteco.com/bulwagga/multi...pdf_Jan_01.pdf

I am not advocating any particular anchor, I thought the footage of
this test maybe of interest.

I do believe that any anchors performance can be enhanced with the use
of a kellet or Anchor Catenary.

Mic67

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com