Mic wrote:
The Bulwagga has three flukes mounted in an equilateral arrangement. This
means there is no right way up

Which would mean that is a good thing?

Yes, of course.

This would tend to support the statement that there is no one anchor
for all conditions.

Well, how many anchors do you want to carry onboard. Our ideal is a general
purpose anchor that addresses the failings of the old traditional plows and
claws, provides excellent performance in everything from very soft mud to
very hard sand (all extremes), cuts through weed and grass, is strong enough
to deal with being fouled or used with rock or coral, and so on.

The argument of carrying a claw, plow, Danforth, and fisherman's, each to
address the problems of the others, is nonsense nowadays, because it is
possible to consolidate the weight into perhaps two anchors that will more
reliably and safely meet all requirements. More may be carried as required,
but are not needed to compensate for the poor aspects of the others.

We know from experience that a Rocna will be happy in ALL conditions (except
rock, for which this is no ideal anchor - use a grapnel and be prepared to
lose it). But we are biased and you may choose not to believe us

A kellet ought not be a substitute for scope but under certain
conditions and reasons an anchors performance can be enhanced.

So what? Of course it can, no-one is debating the fact that weight can
provide a bit of shock-absorption and also decrease the rode angle - but not
by enough to make it worthwhile.
http://alain.fraysse.free.fr/sail/rode/dynam/dynam.htm and study the whole
page, particularly sections 2 and 6.

Gord May who you are aware of and is probably one of the most helpful
and respected persons in the internet sailing community:
http://www.cruisersforum.com/forums/...read.php?t=276
"In heavy weather, I always deploy 15 Lb "Sentinal" (Kedge) weights,
suspended a few feet above bottom."
Gord May
GordATBoatpro.zznDOTcom ~ (Requires Decription)

I have read much of Gord May's ideas about anchoring, and much of it is very
misleading and some of it just plain wrong. He is absolutely not an authority
on this topic.

http://www.anchorbuddy.co.nz/
"They...
So the claim that Anchor Buddy makes "They almost double the holding
power of the anchor and reduce the working load of the anchor by up to
50%." is false?

It's an exaggeration.

The ultimate holding power of the anchor cannot be increased by the use of a
kellet, UNLESS it is really big enough in relation to the rest of the system.
You have to understand you are talking about absolutes; i.e. fixed weights
and scale.

For example a 10Kg Rocna, well set, may hold up to a tonne of force. This is
realistic. Assume you have appropriate rode. The anchor will cope with this,
assuming the pull angle is reasonably low. Now the appropriate Anchor Buddy
would be their 8Kg model. Do you honestly think that 8Kg is going to make the
slightest bit of difference to said pull angle, when there is a 1000Kg strain
on the rode?

As you say it will make a bit of difference when the storm has passed, and
there's only 100Kg strain on the rode. So what, you're not worried about
dragging anymore. Hence, a kellet makes next to no difference to ultimate
holding power.

Now consider how much extra holding power an 18Kg anchor would provide,
compared to the 10Kg. Or, if you have the area, add 8Kg more chain to the
system, so increasing the scope.

This faq reasonably addresses the issue of using a larger anchor and
the practical aspects of a kellet. Thats not to say that a bigger
anchor is not better, and how big is big enough isnt always a
consenus. And I have read time and again that its not the weight of
the anchor but its geometric design, but this too is often
contradicted.

It's both, and the focus depends on the anchor. Really weight is, or should
be, less of an issue, hence why the newer designs such as ours put more
emphasis on fluke area and dynamic performance. Consider how 10Kg weight-
force (a little less underwater anyway) compares with 1000Kg rode-force, as
in my example above, and you will see what I mean.

And certainly there is no consenus on what the best anchor is,
probably because there is no one best anchor for all conditions. So
for the ultimate holding power the anchor has to match the bottom
conditions.

Consensus should not be the basis for any kind of scientific decision,
especially not in a field where there are so many misconceptions and almost
dogmatic beliefs. Get to the bottom of the theory, do your own research, get
some experience, and make your own decisions.

--
Craig Smith
Rocna Anchors
www.rocna.com

Message posted via BoatKB.com
http://www.boatkb.com/Uwe/Forums.aspx/cruising/200605/1

On Tue, 30 May 2006 03:52:55 GMT, "craigsmith via BoatKB.com"
u22396@uwe wrote:

Mic wrote:
The Bulwagga has three flukes mounted in an equilateral arrangement. This
means there is no right way up

Which would mean that is a good thing?

Yes, of course.

This would tend to support the statement that there is no one anchor
for all conditions.

Well, how many anchors do you want to carry onboard. Our ideal is a general
purpose anchor that addresses the failings of the old traditional plows and
claws, provides excellent performance in everything from very soft mud to
very hard sand (all extremes), cuts through weed and grass, is strong enough
to deal with being fouled or used with rock or coral, and so on.

The argument of carrying a claw, plow, Danforth, and fisherman's, each to
address the problems of the others, is nonsense nowadays, because it is
possible to consolidate the weight into perhaps two anchors that will more
reliably and safely meet all requirements. More may be carried as required,
but are not needed to compensate for the poor aspects of the others.

We know from experience that a Rocna will be happy in ALL conditions (except
rock, for which this is no ideal anchor - use a grapnel and be prepared to
lose it). But we are biased and you may choose not to believe us

A kellet ought not be a substitute for scope but under certain
conditions and reasons an anchors performance can be enhanced.

So what? Of course it can, no-one is debating the fact that weight can
provide a bit of shock-absorption and also decrease the rode angle - but not
by enough to make it worthwhile.
http://alain.fraysse.free.fr/sail/rode/dynam/dynam.htm and study the whole
page, particularly sections 2 and 6.

Gord May who you are aware of and is probably one of the most helpful
and respected persons in the internet sailing community:
http://www.cruisersforum.com/forums/...read.php?t=276
"In heavy weather, I always deploy 15 Lb "Sentinal" (Kedge) weights,
suspended a few feet above bottom."
Gord May
GordATBoatpro.zznDOTcom ~ (Requires Decription)

I have read much of Gord May's ideas about anchoring, and much of it is very
misleading and some of it just plain wrong. He is absolutely not an authority
on this topic.

http://www.anchorbuddy.co.nz/
"They...
So the claim that Anchor Buddy makes "They almost double the holding
power of the anchor and reduce the working load of the anchor by up to
50%." is false?

It's an exaggeration.

The ultimate holding power of the anchor cannot be increased by the use of a
kellet, UNLESS it is really big enough in relation to the rest of the system.
You have to understand you are talking about absolutes; i.e. fixed weights
and scale.

For example a 10Kg Rocna, well set, may hold up to a tonne of force. This is
realistic. Assume you have appropriate rode. The anchor will cope with this,
assuming the pull angle is reasonably low. Now the appropriate Anchor Buddy
would be their 8Kg model. Do you honestly think that 8Kg is going to make the
slightest bit of difference to said pull angle, when there is a 1000Kg strain
on the rode?

As you say it will make a bit of difference when the storm has passed, and
there's only 100Kg strain on the rode. So what, you're not worried about
dragging anymore. Hence, a kellet makes next to no difference to ultimate
holding power.

Now consider how much extra holding power an 18Kg anchor would provide,
compared to the 10Kg. Or, if you have the area, add 8Kg more chain to the
system, so increasing the scope.

This faq reasonably addresses the issue of using a larger anchor and
the practical aspects of a kellet. Thats not to say that a bigger
anchor is not better, and how big is big enough isnt always a
consenus. And I have read time and again that its not the weight of
the anchor but its geometric design, but this too is often
contradicted.

It's both, and the focus depends on the anchor. Really weight is, or should
be, less of an issue, hence why the newer designs such as ours put more
emphasis on fluke area and dynamic performance. Consider how 10Kg weight-
force (a little less underwater anyway) compares with 1000Kg rode-force, as
in my example above, and you will see what I mean.

And certainly there is no consenus on what the best anchor is,
probably because there is no one best anchor for all conditions. So
for the ultimate holding power the anchor has to match the bottom
conditions.

Consensus should not be the basis for any kind of scientific decision,
especially not in a field where there are so many misconceptions and almost
dogmatic beliefs. Get to the bottom of the theory, do your own research, get
some experience, and make your own decisions.

I appreciate the fact that you have participated in this discussion as
the representative of an anchor company. And I have read many of your
items in different forums. I think it was a good business decision to
give one of your anchors to Dashew for his new boat to keep (he was
using a Spade?) and thus evaluate. I expect his review will be
unbias.

Mic sailing since '67

--
Craig Smith
Rocna Anchors
www.rocna.com

Message posted via BoatKB.com
http://www.boatkb.com/Uwe/Forums.aspx/cruising/200605/1

I appreciate the fact that you have participated in this discussion as
the representative of an anchor company. And I have read many of your
items in different forums. I think it was a good business decision to
give one of your anchors to Dashew for his new boat to keep (he was
using a Spade?) and thus evaluate. I expect his review will be
unbias.

Thanks.

We didn't give Dashew a Rocna, he bought it. No for Wind Horse he originally
had a Bruce knock-off made by a local NZ company that produce copies of just
about anything, but we talked him into a Rocna.

So far so good although he hasn't yet published a full review. He originally
said he wanted a good amount of time and experience on different seabeds etc
before commenting. He has always been a big proponent of Bruces, so any
change in his position will be significant.

--
Craig Smith
Rocna Anchors
www.rocna.com

Message posted via http://www.boatkb.com

"craigsmith via BoatKB.com" u22396@uwe wrote

For example a 10Kg Rocna, well set, may hold up to a tonne of force. This
is
realistic. Assume you have appropriate rode. The anchor will cope with
this,
assuming the pull angle is reasonably low.

Just wondered what type of rode would handle this force? On your site, you
recommend the 10Kg anchor for cruising boats up to about 30'. What would
teh corresponding chain/rode dimensions be to match teh anchor strength?

The Rocna anchor looks quite interesting and seems to be a good idea, at
least for some anchoring conditions.

A few comments:

1. Testing by pulling with a truck with little or no scope angle does not
really prove anything ( but is easier to film!)

- Would it not be better to do a comparison of the anchors with a larger
scope angle and typical rode/chain combinations. This may take a lot of
testing using a boat, a diver, undewater cameras etc, but as you said "Get
to the bottom of the theory, do your own research, get some experience, and
make your own decisions". Seems to me that pulling an anchor along a beach
with a truck is not the best way to make a scientific conclusion.

- What happens if the bottom is soft mud or weed as we often see in the
Great Lakes - Will the roll bar still work, or will it just sink in and not
roll? I would like to have seen some comparisons of anchors setting in less
ideal conditions.

- The part showing the difficulty of getting the anchor unstuck is not too
encouraging for those of us with bad backs

2. The web site does not give the size of the attachment slot for the
shackle. Can you fit a shackle that will take a 1 tonne working load through
the slot?

In our area, most boats seem to have a Bruce or knockoff - But, more
recently we see Delta or knockoffs. Nothing really works well in weed and
soft mud but weight helps. The knockoff Bruces are a cheap way of getting
weight, so I suspect that might be the driving force. In fact, I have just
added a 15Kg Bruce type because my 10Kg Delta just does not work that well
(10M, 5T cruising sail).

GBM

The angle of attack of the pulling force aside:

Isn't it funny how the other anchors start out in hard sand? You can
see large parts falling off while the anchors are high speed dragged;
that sand looks hard enough to drive on.
The rocna starts out in a muddy pool of 'quicksand' that is so soft
that even the pieces of mud/sand that the rocna piles up melt back into
the surface immediately. Watch the left foot of the guy who tries to
work it free after the test sink in. And the rocna gets a nice slow
motion pull.

All that doesn't necessarily make it a bad anchor, but this video shows
a seriously bad test. The test proves two things we already knew: The
most important factor in anchoring is the substrate, and good marketing
requires artful lying. This was too blunt, mate, try again!

On Tue, 30 May 2006 09:16:42 -0400, "Lakesailor"
wrote:

For example a 10Kg Rocna, well set, may hold up to a tonne of force. This
is
realistic. Assume you have appropriate rode. The anchor will cope with
this,
assuming the pull angle is reasonably low.

Just wondered what type of rode would handle this force? On your site, you
recommend the 10Kg anchor for cruising boats up to about 30'. What would
teh corresponding chain/rode dimensions be to match teh anchor strength?

1/2 inch (12mm) 3 strand nylon has a breaking strength of about 7,000
lbs and a Safe Working Load approximately 1/3 of that. Typical anchor
rode for a 30 foot boat would be about 200 ft of 1/2 inch 3 strand,
shackled to 15 or 20 feet of either 1/4 or 5/16 inch chain. That is
enough rode to safely anchor in 30 ft of water.

For a storm anchor I'd use 5/8 inch 3 strand nylon with 5/16 HT chain.

Shackles rated for 2,200 lbs are easy to find.

Lakesailor wrote:
Just wondered what type of rode would handle this force? On your site, you
recommend the 10Kg anchor for cruising boats up to about 30'. What would
teh corresponding chain/rode dimensions be to match teh anchor strength?

Up to 33', at light displacement. Our sizing is conservative; in practice,
even a boat of that size will need up around 70 knots of wind to generate
something like a tonne of force. Wave action etc adds to the equation but if
you restrict the model to considering only wind, you can see how we are
talking about "extremes"; most boats, especially of that size, are not set up
to handle those conditions. Accordingly you can't really expect the rode to
be strong enough - and what about whatever the rode's attached to?

Anyway, you would normally use 6mm chain with a Rocna 10, 8mm if you wanted.

G40:
6mm - SWL: 350Kg, break 1000Kg
8mm - SWL: 800Kg, break 3200Kg

so you would use the 8mm, or a high tensile grade of the 6mm, if you needed
the strength. Rope matched to chain is usually stronger, so that's not an
issue.

2. The web site does not give the size of the attachment slot for the
shackle. Can you fit a shackle that will take a 1 tonne working load through
the slot?

Shackles: use the largest size the pin of which will fit through the last
link of chain. So the chain dictates the size used, and the slot on the
Rocna's shank is ample. A quality tested 8mm shackle for 6mm chain or 9/10mm
for 8mm should not introduce a weak-point.

The Rocna anchor looks quite interesting and seems to be a good idea, at
least for some anchoring conditions.

For all anchoring conditions, that's the point

1. Testing by pulling with a truck with little or no scope angle does not
really prove anything ( but is easier to film!)

It levels the playing field as I said above. The guy going on about shanks
etc and scope affecting setting behavior is wrong and also missing the point.

If you set your anchor using the relatively weak power of a sailboat's engine
and prop, if you're using decent rode then the actual angle of pull you're
placing on the anchor during setting is not the same as the scope; i.e. if
you have out 5:1, the angle is not dictated by that trigonometry, but rather
the catenary of the chain, which will make the pull surprisingly flat - it
may even be horizontal, with part of the chain remaining on the bottom.

Does not apply to powerboats with 1,000 HP using two meters of chain and a
bit of string.

- Would it not be better to do a comparison of the anchors with a larger
scope angle and typical rode/chain combinations. This may take a lot of
testing using a boat, a diver, undewater cameras etc, but as you said "Get
to the bottom of the theory, do your own research, get some experience, and
make your own decisions". Seems to me that pulling an anchor along a beach
with a truck is not the best way to make a scientific conclusion.

Yes, it would be better, but our video is supposed to be a simple
demonstration of why the traditional plows and claws are bad, and simply why
we've bothered coming up with the Rocna.

A "proper" video would be an hour long and would still be hurt by the fact
that we are not independent, so the validity of such a production would
always be vunerable. So, we're not really the people to do it - although I
would like to at least re-do our existing one at some point, to address some
of its problems.

- What happens if the bottom is soft mud or weed as we often see in the
Great Lakes - Will the roll bar still work, or will it just sink in and not
roll? I would like to have seen some comparisons of anchors setting in less
ideal conditions.

No it works fine, the roll-bar's radius is quite large for exactly that
reason.

Weed and grass are difficult for any anchor. It's also pointless testing or
doing demonstrations, because every patch of weed is different to the next.
The cynical viewer could claim we just did the test over and over again
before it happened to work.

The important factors are a certain amount of tip-weight, a low profile fluke
with sharp edges, and dynamics that encourage force from the rode's pull to
be transfered to the anchor's tip, so it cuts in. So the Rocna meets this
requirement, and is a further improvement on the WASI or German Buegel, which
is very popular now in the Mediterranean (weed city).

- The part showing the difficulty of getting the anchor unstuck is not too
encouraging for those of us with bad backs

Well that was after over a tonne of force was applied to it - most of the
time you'll never get it that stuck, and if you do, you probably won't mind a
bad back as payment

Although, it's not really a problem. Reduce the scope to 1:1 and leave it for
a few mins, and wave action will work it out. Or if you're in a hurry power
it out backward.


In our area, most boats seem to have a Bruce or knockoff - But, more
recently we see Delta or knockoffs. Nothing really works well in weed and
soft mud but weight helps. The knockoff Bruces are a cheap way of getting
weight, so I suspect that might be the driving force. In fact, I have just
added a 15Kg Bruce type because my 10Kg Delta just does not work that well
(10M, 5T cruising sail).

GBM

Deltas are generally good, except in soft mud. They simply don't have the
fluke area. Peter used to have a 40Kg Delta on his boat, and incidents in
soft stuff were one of the main reasons for designing the Rocna - and he had
already eliminated other types over the course of his lifetime, selecting the
Delta as the then best option.

I am sure that a 15Kg Delta would have offered a similar if not better
upgrade in your case. Understand your point about cheap weight, but you get
what you pay for.

But the simple solution is try a newer type - you don't have to put up with
those problems any more. Bulwagga, WASI, Rocna.

--
Craig Smith
Rocna Anchors
www.rocna.com

Message posted via BoatKB.com
http://www.boatkb.com/Uwe/Forums.aspx/cruising/200605/1