Note: Descriptions are shown in the official language in which they were submitted.
Background of the Invention
This invention relates to an additional improvement of an anchor as
described in the Netherlands' patent specification 151 034 and in the
corresponding U.S. patent specification 3 90~ 446. The main features of this
type of anchor, which is called STEVIN anchor, are that it has a two-handed
fluke with the anchor shank pivotally mounted in a slot between the two fluke
hands on a hinge in a hinge box formed at about the geometric centre of the
fluke surEace area by side plates on the inner edges oi the fluke hands and
head plates connecting the side plates and delimiting the pivoting angle of
the shank, and the fluke hands converging from a substantial depth at their
inner edges towards each other to form sharp outer edges, and that it has
- ~ rear stabilizers on the outer edges of the fluke hands.
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e fluke hands of the anchor type in the aforesaid patent specifications
each terminate forwardly in a flat tip. It appeared in practice that in hard
ground the thus far described anchox keeps on sliding along the ground on
the shank and will not penetrate further.
; Summary of the Invention
The present invention has as its object to overcome the aforesaid dis-
advantage of the prior anchor type and is characterized in that each fluke
hand has a pair of outwardly curved finger tips on which flange plates with
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upstanding tips are arranged forming front stabilizers. This
novel feature improves the cutting penetration action in hard
ground due to the fact that the stability of the anchor dùring
its penetration is enhanced.
~ An additional aspect is that the hinge bo~ and the
--~ rear stabilizers are diverging rearwardly, considered in plan
view, i.e. that the openings therebetween are widened rearwardly ;
so that the penetrating soil will not cause obstructions which
would impede the action of the stabilizers.
Further provided is a pre-cutter to facilitate the
penetration of the shank. ~-
` ~ The new anchor is further characterized by an opening
for an anchor shackle in the rear end of the fluke, and the
anchor shackle and the hinge pin~ are integrally cast on the
shank.
The invention is described more in detail in the
following specification with reference to the drawings, in
which examples of the invention are shown.
Brief Description of the Drawings
Figure 1 is a plan view of the new anchor;
Figure 2 is a view in elevation, and partly in section,
of the anchor which is lying on the water bed as illustrated,
but when considering the view turned upside down the anchor ~
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is seen in this figure lying with the shank shown in dotted
lines on a deck;
Figures 3 through 5 (sheet 1) are respective sectional
-views according to the lines III-III, IV-IV and V-V in figure l;
Figure 6 (sheet 1) is a semi-front view of the anchor;
Figure 7 (sheet 1) is a semi-rear view of the anchor;
Figure 8 (sheet 1) is a top view of the part of the
shank with the hinge pin and the
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new anchor shackle; and
figures 9 through 11 show a shank which is provided with a rack guide, in
top and bottom view, respectively, and a number of sectional views at the
locations indicated with a through f.
Description of the Preferred Embodiments
The anchor 1 as shown in the figures is provided with a pair of flukes or
fluke hands 2,2 which are rearwardly integrally joined by a hinge box 3.
The shank is pivotally connected to the flukes 2 by a pivot pin 5 which is
journaled in the hinge box 3. In front of the box 3 are a pair of fluke
angle delimiters 6 above and below the shank 4, which are divergingly
rearwardly directed, with a thus rearwardly widened opening therebetween in
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order to prevent clod formation when penetrating into the ground. Also the
rear stabilizers 7,7 are arranged so that they diverge rearwardly to prevent
clod formation to occur due to which their stabilizing action would be
impeded.
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Particularly in figure 1 the new front stabilizers are illustrated. Each
fluke 2 has a pair of outwardly curved tip~ 8 for penetration in hard ground.
For the stabilization during penetration serves a vertical fluke 9 on the
outer and eventually on the inner fluke tips 8, which is inwardly directed
while forming diverging peaks 10.
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; ~ In the rear of the hinge box 3 which connects the two flukes 2, there is an
opening 11 for an anchor shackle 12 which can be used for tandem arranged
anchors. The anchor shackle 12 and the hinge pin 5 are integrally cast on the
shank 4.
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As is particularly illustrated in figure 2 the anchor 1 is provided with a
pre-cutter 13 so that the shank 4 can easily penetrate. In this figure the
anchor is shown in its position on the water bed, but when the drawing is
turned upside down, the anchor is seen with the shank 4 in dotted lines
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lying on a deck 14, and in dotted lines at 15 also the height of a man is
indicated on a scale corresponding with a 15 tons anchor. The anchor 1 has a
negative penetration position when it lies on the deck 14, to prevent it
from damaging the deck.
Generally stated the main factors for the holding power of an anchor are
- penetration, strength and stability.
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Penetration is achieved by sharp fluke tips and an anchor which is
streamlined as much as possible.
The latter is achieved by arranging the fluke angle delimiters 6 so that a ~
maximum fluke angle is obtained. The fluke angle delimiters consist as -
illustrated in figure 1 of rearwardly converging plates which leave a
rearwardly widened opening therebetween considered in a cross-sectional
plane parallel to the anchor ground.
The anchor is designed so that eventually penetrating soil at that location
will not caùse obstructions in the hinge box 3 which serves to rigidIy
connect the two flukes 2. The shank 4 can be passed through the box from the ; -
rear and the hinge pin 5 can be secured by means of two little locks.
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The anchors which are thus far used offshore have the disadvantage that the
attachment of a tandem arranged anchor renders the anchor unstable. Generally
the pennant-wires are fastened to the flukes. In the present anchor the
anchor sha~kle 12 is secured to the pivoted shank 4. Pulling is now in line
with the main chain or wire and the anchor remains stable. Moreover this is
production saving as it is now not necessary to provide a separately welded-
on shackle. The pivot pin 4 is also cast integrally on the shank 4.
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To prevent clod ~ormation, i.e. obstruction of the passing sand, the depth
of the fluke 2 within the fluke angle delimiters 7 is reduced. In other
anchors this would always lead to clod formation and the anchor would break
out earlier. In the present pivotal anchor this is prevented.
As is already mentioned in the foregoing it appeared in practice that
generally in hard ground pivotal anchors keep on sliding along the ground on
the shank and will not penetrate further. The portion of the fluke which is
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in the hard ground should provide that on the one hand the shank is still
somewhat forced therein and on the other hand that the quantity of shifted
soil is as large as possible. A square fluke tip would counteract penetration,
a round and/or sharp tip would limit again the width of the fluke at the rear
side, and accordingly, the surface area. By providing two pairs of fluke tips
8 a better cutting penetration action in hard ground is achieved. Moreover
during
this enhances the stability/penetration. The outwardly directed fluke tips
facilitate breaking-in when the anchor would unexpectedly be pulled along the
ground on the fluke side.
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For breaking-in and stabilisation a vertical plate is to be arranged at the
front of a fluke tip, which is outwardly directed with the front side 10.
The object thereoE is that when the anchor slides along on the side, the
vertical plate at the front side penetrates into the ground. whereupon the
anchor will pull itself again in the normal manner into the ground.
on the other hand these plates have the property that when the anchor after
penetration is askew the fluke tip which is most deeply penetrated is
automatically pulled out by the plate 9 by greater pressure and the anchor
thus stabilizes.
Stabilisation stocks, prisms or plates are often used in anchors. Stocks
have the disadvantage that in hard ground the stocks would counteract the
penetration. Frameworks as in the Eel-anchor have the disadvantage that they
extend parallel to the flukes and thus have a bad stabilizing action. In
that case they only serve to effect the correct penetration position.
The combination of the wings of the Stevin-anchor and the frame of the Eel-
anchor as used in the Flipper Delta-anchor, has the disadvantage that when
breaking out along the whole width of that framework a wall of sand is
created, as due to the diverging plates the sand in the framework is
compressed. .
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Prisms have the disadvantage that when penetrating into hard ground too
much resistance is offered and the anchor will break out earlier than is ~ :
necessary. :
In order to obtain a good penetration the two fluke plates rearwardly at ;
. the sides are outwardly curved and at the outer sides they are provided : --
:~ with a vertical converging plate 16 which is favourable for the stabilizing . .
action of the anchor.
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An enhanced stabilizing action is achieved by a converging bent plate 17.
In this case to be arranged on the top and bottom of the two flukes along
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about one third of the fluke width, so not along the whole width as in the :
Flipper anchor and not parallel as in the Eel-anchor.
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.. Besides the simple manufacture of this stabilizer it has the advantage that
the top 18 serves f~r the correct penetration position and the sides for a
:~ correct stabilisation. The anchor will nevertheless keep a correct
'. penetrating action because this stabilizer, due to the converging shape,
. will not.retain the ground, but will pass it easily. . :.
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~ ~ The fluke angle.delimiters 6 which are equipped with claws 6' for
.. ~ .penetration in hard ground, and the stabilizers are formed so that the anchor .:.
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~- will be directed upwardly with the fluke tips and thus will not darnage the .
deck of the anchor handling vessels with the sharp tips 6' and 10.
`. Accordingly, when the anchor is hauled in on the pennant-wire the anchor will . `.:
.. automatically.rest on three points 20. If the anchor is pulled forward again . ; :
. to enter the water, a.releasable wire or rod 21 can temporarily.be placed ~
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between fluke and shank as is indicated in the drawing.
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. On the bottom of the:.sea the fluke will automatically.be canted downwardly . .
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.. with the tips due to.the high pressure on the fluke delimiters. In soft ground
the top and bottom side of the stabilizers will take over the function of
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adjusting the penetration angle.
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As is already mentioned in the foregoing the shank has in hard ground the
tendency to slide along the bottom. By using a pre-cutter as indicated at 13
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a groove is first cut in the hard ground, which will facilitate the
penetration of the shank.
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Figures 9-11 show a rack guide 22 to get the anchor into the rack in the
right manner. It is indaed a fact that the sharp shank gives difficulties
because when the anchor is pulled into the rack, due to the chamfer of the
shank, the anchor will come in askew and the bolster or the rack will enter
between the two flukes. A pyramid-shaped boss on the sides of the shank at
the front as indicated in cross-section in figure 11 gives the possibility
for the anchor to turn in the right direction, and to tip over the fluke
to be neatly positioned under the rack.
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