The World's Best
Anchors Explained
Anchor Classification
Although there are many different types of anchor most can be classified
depending onto its characteristics and how well they meet the 7 factors that
make a good anchor.
1.
The
anchor must dig in fast every time.
2.
The
anchor must bury deep.
3.
The
anchor must give the maximum holding power without dragging.
4.
The
anchor must offer a constant resistance to movement – even is it moves under
extreme load.
5.
The
anchor must hold despite wind or current shifts.
6.
The
anchor rode must not be able to snag the anchor.
7.
The
anchor must be strong enough to withstand very high loads.
Please note that the ratings given above are
relative to the physical size of the anchor and not the weight. An
anchor with no ballast such as a Sword or Manson Supreme can give a
higher holding power for a given weight than a SPADE for example, due to
a larger surface area but the lack of ballast will give poorer weight
distribution and penetration in difficult seabeds.
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1.
The anchor must dig in fast every time.
In order to bury fast an anchor
needs to have the right angle for penetration every time, this can be
achieved by two methods. Anchors such as a plough anchor only land at the
right angle about 50% of the time and therefore fail in this area.
a) The SPADE is the only anchor to
adopt the right angle naturally every single time by using the weight
distribution and an angled ballast chamber. This also positions 50% of its
weight over the tip ensuring penetration even in difficult seabeds such as
kelp.
b)
Other anchors such as the Rocna, Supreme and Sword use
a combination of a righting device and the pull on the rode to ensure rapid
penetration. This is extremely effective in all but the most slippery
seabeds. The righting device can be a roll bar or as with the Sword
and Océane, a combination of shank and blade curves. A roll bar
takes weight away from the tip, relying more on the force pulling on the
rode to achieve effective penetration.
2.
The anchor must bury deep.
The deeper an anchor buries, the greater the
mass of seabed above the anchor and therefore the greater the holding
power. Concave anchors can be made to bury further than convex anchors
which tend to plough just below the surface. (Flat anchors fall between the
two).
3.
The anchor must give the maximum holding power without dragging.
Holding power is achieved as a result of
surface area, blade profile and the depth the anchor has buried. Some
anchors with large surface areas will bury well in sand but fail to
penetrate deep enough in more difficult seabeds. Concave offers better
holding than flat which in turn is better than convex.
4. The anchor must offer
a constant resistance to movement – even is it moves under extreme load.
A convex anchor, once set, will offer a high
initial resistance but once the force is sufficient enough, it will pull
free. Concave anchors move earlier but bury deeper rather than pull free.
Eventually they will reach a point where they cannot bury further so they
offer a constant resistance to movement.
5. The anchor must hold
despite wind or current shifts.
Concave anchors with a fixed shank are
generally roll stable and will not break out. Convex anchors have a greater
chance of breaking out due to the fact that they do not bury as deeply and a
sudden wind-shift can cause break out. Flat (Danforth) style anchors have
two penetrating tips, which invariably makes the anchor roll out during wind
shifts.
6. The anchor rode must
not be able to snag the anchor.
Anchors that
do not turn instantly can become fouled by their own anchor rode, causing
them to fail. This is not a problem associated with new generation
anchors.
7. The anchor
must be strong enough to withstand very high loads.
This is particularly important
with new generation anchors that offer greater holding power. Chain can
carry high shock waves from the surface when tight and an anchor that does
not move can reflect these waves back up the chain. It is theoretically
possible for a reflected wave to combine with a new shock wave coming down
the chain to create a mega shock wave. This can produce enormous loads at
the anchor. Anchor shanks should be strong enough to take the large loads.
SPADE
anchor shanks (except the 2
smallest sizes) are made of a hollow triangular box section to create a
super-strong shank without compromising weight distribution.
Anchor
Classification
Class 1 – New Generation anchors with passive
penetration and grip-ability
·
It always positions itself
correctly - if it falls upside down, it automatically turns over under
natural conditions.
·
It turns with the wind and
tide without pulling free.
·
It offers good holding power
and will not pull out.
·
Force applied at tip even
without force on anchor rode.
·
Good weight distribution
·
Natural angle of attack.
·
Will grip on coral or rocks
Examples:- SPADE
Class 2 – New
Generation anchors with requiring active penetration with Grip-ability.
·
It always positions itself
correctly - if it falls upside down, it automatically turns over under
natural conditions.
·
It turns with the wind and
tide without pulling free.
·
It offers good holding power
and will not pull out.
·
Requires force to be applied to rode to adopt
penetrating angle and force to be applied at penetrating tip.
·
Will grip on coral or rocks
Examples:- Océane,
Sword, Rocna, Manson Supreme, Bugel, Wasi, SARCA
Class 3 – Roll stable
anchors that always adopt correct position with grip-ability
·
It always positions itself
correctly - if it falls upside down, it automatically turns over under
natural conditions.
·
It turns with the wind and
tide without pulling free.
·
May not have significant surface area and
therefore poorer holding power.
·
Normally relies more on weight than surface
area.
·
Will grip on coral or rocks
Examples:- Fisherman’s
Class 4 – Roll Stable
Anchors offering high holding power with poor grip-ability
·
Does not normally roll out on turning of tide.
(Anchors that are not concave will pull out at some point and this is more
likely to occur when the tide turns).
·
May not right itself if it lands on its side.
·
Offers Significant holding power and minimal
risk once set.
·
Unlikely to give reliable grip on coral or rocks.
Examples:- Brake,
Stealth
Class 5 – Roll Stable
Anchors offering reasonable penetrating ability and grip ability but poor
holding power
·
Does not normally roll out on turning of tide.
·
May not right itself if it lands on its side.
·
Offers reasonable holding power but will pull
free under high loads dur to low surface area in direction of pull.
·
Reset possible after break-out,
but unlikely in weed.
Examples:- Bruce, Claw
etc.
Class 6 – Roll Stable
Anchors offering reasonable holding power
·
Does not normally roll out on turning of tide.
(Anchors that are not concave or without adequate surface area will pull out
at some point and this is more likely to occur when the tide turns).
·
May not right itself if it lands on its side.
·
Offers reasonable holding power but will pull
free under high loads.
·
Reset possible after break-out
·
Unlikely to give reliable grip on coral or rocks.
Examples:- Delta,
Bruce, Kobra, Shark, FOB Rock,
Class 7 – Non roll stable anchors
offering reasonable or significant holding power
·
High holding power once set.
·
High risk of rolling out on wind or tide shifts
·
Possibility of break out under extreme loads.
·
After break out may adopt position where anchor
can not reset.
Examples:- CQR, Danforth,
Fortress, Brittany, FOB, FOB Lite etc.
Class 8 – Anchors that offer poor
penetrating and holding properties but reasonable grip on rocks coral etc.
·
Poor penetrating
·
Poor Holding
·
Poor Roll stability.
·
Weight reliant
·
Barbs etc. to grip
Examples:- Grapnel etc.
Class 9 – Anchors that offer poor
penetrating and holding properties and no ability to grip on rocks coral
etc.
·
Poor penetrating
·
Poor Holding
·
Poor Roll stability.
·
Weight reliant
THIS CLASSIFICATION IS WORK IN PROGRESS AND
COMMENTS ARE WELCOME. |