AU594800B2 - Improved anchor - Google Patents

Description

594800 COMMONWEALTH OF AUSTRALIA FORM C 0 M P L E T PATENTS ACT 1952 E SPEC I FICATION FOR OFFICE USE: Class Int.Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: 94 Priority: 4 I. 9 Related Art: 9 *9 4 Tnis document contains the iamendments made under Section 49 and is correct for prhiting.

'Name of Applicant: SAddress of Applicant: r a 4 DULMISON MARINE PTY. LTD.

8 Bay Street GREENWICH N.S.W. 2065

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,Actual Inventor: PHILIP WELLESLEY DULHUNTY Address for Service: SHELSTON WATERS, 55 Clarence Street, Sydney 4 Complete Specification for the Invention entitled: "IMPROVED ANCHOR"" The following statement is a full description of this invention, including the best method of performing it known to me/us:- 1 Complete of PH08676 PH7237 Dated this 24-10-86 31-7-86 1/ 10 ~R *R Ii

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This invention relates to anchors particularly to that are able to "ifly" or glide away from a sea going vessel and secure themselves on the seabed.

The usual method uf anchoring a vessel is to drop anchor upstream of the desired position and then pay out the anchor cable as the vessel drifts downstream a sufficient distance to enable the anchor to catch on the bottom and hold with a suitably high horizontal component of resistance.

This often requires several attempts before the vessel comes to rest in the desired position. It is particularly awkward when anchoring pleasure craft in a closely spaced group.

Designers have actively sought ways of overcoming this archaic method of dropping anchor. For example US Patents, numbers 3,611,974, 3,946,695 and 3,295,153 disclose an anchor that can glide away from a vessel; however these examples of the prior art are unfortunately not able to engage the sea bottom with the same load bearing capacity as is provided by the conventional Danforth anchor.

Even the Danforth anchor fails to engage the sea bottom when the current is running in the opposite direction to the wind. In this case the blade of the Danforth anchor tends to override the centre position and hence present itself like a kite so that it simply floats at th6'end of its rode, and the pressure of the water prevents the blade from burying into the sea bottom.

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i~K It is an object of the present invention and its preferred embodiments to ameliorate the above discussed disadvantages by providing an anchor which will move away from a vessel in a horizontal direction and also provide adequate securing means for the vessel.

According to one aspect of the invention there is provided an anchor comprising a central elongate shank having a weighted forward end and means at its rear end for attaching an anchor line, a blade having a longitudinal axis and a pair of bottom engaging upswept wings extending outwardly on either side of said axis, said blade being hingedly mounted to said shank by a 9 linkage arrangement including a front link and a 0corresponding, longer rear link for rotation with respect 0 to said shank about an axis transverse to said shank and said longitudinal axis, means to positively limit the maximum extent of rotation of said blade away from said shank, said blade being rotatable with respect to said shank from a first position in which said shank can rest on said blade with said longitudinal axis substantially parallel with said shank, to a second position defined by said maximum extent of rotation, the arrangement permitting said shank to rest on said blade in said first position and move forwardly on said wings away from a Svessel as the anchor sinks to the sea bottom, whereupon on reaching the sea bottom a rearward force applied to the anchor line causes said blade to assume said second position and securely engage the sea bottom.

The advantages of this type of anchor, are that 3 L I-LIAr---. T 7 r firstly by "flying" the anchor in the upstream direction it will "fly" into the seabed upstream of the vessel thereby allowing the vessel to remain approximately above its desired position. Secondly if the anchor is let go downstream the velocity of the current will carry the anchor on until the end of its rode whereupon the anchor opens out like a pantograph and the blade sinks into the seabed holding the vessel fast.

The blade of this anchor has been designed firstly to prevent the anchor from rolling on its back and secondly to direct flow so that the pressure of the water exerts a downward force driving it into the seabed.

In one embodiment, the limiting means for positively 0o 0 limiting the maximum extent of relative rotation may o 0 So. comprise the base of a slot extending along the longitudinal blade axis from a point near the axis of rotation. The slot is open at its rearward end to permit the rear link to move through the slot on relative ,rotation until it abuts the blade at the base 20 of the slot.

For preference the forward end of the anchor is weighted and has hydrodynamically designed so that a 4 4 downward pressure is exerted on the shank during forward i. \motion thereof, thus preventing the anchor from opening out. Accordingly while the anchor is in the closed position the underside of the weighted forward end i extends below the level of the blade so that as the anchor hits the seabed it opens to beyond the overcentre 4 :i' Pr- 10 94 .9 94 9 4 94 4 4 949 44 4 44 9 4 4,9.

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9*4 position thereby enabling the blade to sin% well into the seabed as the strain in the anchor line is taken up.

Experiments have shown that when the anchor Is fully open the blade penetrates the seabed at a angle to the shank 0 of approximately Preferably the hinge is so arranged that an upward or rearward pull on the shackle end of the shank will open the anchor out. However it is preferable that when the anchor is in the closed position the shank and the hinge lie within the dyhedral angle of the wings thereby providing a low centre of gravity resulting in the greater stability as the anchor moves away from the vessel.

Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 is a plan view of a first embodiment anchor according to the invention.

Figure 2 is a side elevation of the anchor shown in Figure 1.

Figure 3 is a front elevation of the anchor of Figure 1.

Figure 4 is an underside view of the anchor of Figure 1.

Figure 5 is a rear elevation of the anchor of Figure Figure!,6 is an enlarged fragmentary section showing the hinging of the blade with respect to the shank. The 4.

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4 3 i;ti- *r~nac; blade is shown in its fully open position, as also shown in Figure 7.

Figure 7 is a perspective view of the anchor showing the blade in its fully open, bottom engaging position.

Figure 8 is a schematic side elevation of a second embodiment anchor according to the invention.

Figure 9 shows the blade of the second anchor of Figure 8 in a partly hinged configuration.

Figure 10 shows the blade in its fully open position.

Figure 11 is a plan view of the second anchor.

Figure 12 is a plan view of a third embodiment anchor.

Figure 13 is a plan view of a fourth embodiment anchor.

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a Referring initially to figures 1 to 7 of the drawings, the first embodiment anchor includes a central elongat shank 1 having a weighted forward end 2 and a hole 3 at its rear end 4 for attaching an anchor line S(not shown). A Llade 5 is hingedly connected to the shank 1 by means of a. pair of attachment flanges 6 which support a hinge bolt 7 defining a transverse axis of rotation 8.

The blade also includes a forwardly opening slot 9 extending parallel to the longitudinal blade axis 10, as best shown in Figure 4. The bottom or rearward end 11 of the slot 9 is located adjacent the hinge axis and acts as an 'Abutment to limit the extent of relative rotation of the blade beneath the shank, as best shown in Figures 6 6a, 9* 99 9 9 9 99 99 99# 99 9 99 9~ 99 9 9 9.99 9, .9 99# and 7.

The open slot prevents build-up of sand which would otherwise clog the mechanism and prevent the blade from hinging, thereby preventing the anchor from secirely engaging the sea bottom. This is particularly important in sandy bottom conditions.

The blade 5 includes a pair of upswept wings 12 which extend symmetrically outwardly and rearwardly on either side of the longitudinal blade axis 10. The blade also includes rearwardly directed flukes 13 and 14 for engaging the sea bottom. Preferably, the central fluke 14 is inclined slightly downwardly, as shown in Figure 2, to assist in engaging the bottom.

In operation, an anchor line is attached to the rear end 4 of the shank and the anchor is dropped into the water with the shank resting on the blade in its first position as best shown in Figure 2. The blade then supports the shank and propels the anchor forward through the water in a gliding motion as the anchor sinks.

The weight of the blade rearward of the hinge axis 8 would ordinarily hinge it automatically into its fully open second position. However, its gliding g-haracteristics under water keep it in a generally horizontal position while the anchor is moving through the water.

The wings bring the anchor to rest on the sea bottom a substantial distance away from its point of entry to the water, depending upon the water depth and glide 99 9 999 .99 99 9 99 .9 9.

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angle. Tests have produhced glide angles of the order of~ :1 Once the anchor has reached the sea bottom, the blade tends to hinge away from the shank under its own weight. Rearward tension applied to the anchor line moves the blade into its position of maximum rotation in which it firmly engages Lhe shank as shown in Figures 6 and 7 and securely engages the sea bottom.

To assist opening of the anchor on reaching the sea 10 bottom the forward 2 of the shank 1 preferably extends It 61 It below the level of the blade 5 such that upon contact of the forward end with the sea bottom the shank tends to I pivot about the forward end resulting in the blade moving to its open position.

The anchor may be constructed of any suitable heavy material or combination of materials whicn will provide t t' the necessary strength.

The second embodiment of the anchor is shown in figures 8 to 10. For ease of description, corresponding features have been given corresponding re~ierence numbers and need not be further described. In this second 4 embodiment, however, the blade is hingedly connected to the shank by a linkage arrangement including an identical A pair of front links 20 and a corresponding pair of longer rear links 21.

All the links are rotatably mounted at their ends and the unequal lengths of the front and rear links is such that the blade can hinge between the first position -8- L' 3C. i ii I shown in figure 8, through the intermediate position of figure 9 to the second position of maximum rotation with respect to the shank, as showr. in figure 10. An abutting toe portion 22 on one or both of the rear links 21 engages the blade to limit the extent of rotation. This ±s preferably of the order of 27 to 33 degrees.

The extent of rotation of the blade may also be limited by extending the toe portion of the rear link through a slot provided in the blade such that as the blade rotates the toe portion bears against the end of the slot or a stop positioned therein to limit further rotation thereof. This arrangement has a further «i advantage in that the slot acts to limit sideways to movement of the link so that nuts or retaining pins are not required to hold the link in position.

wt It will be appreciated that while the blade rotates with respect to the shank as in the first embodiment, the axis of rotation in the second embodiment is not fixed with respect to the shank and the forward end 23 of the blade ends up spaced downwardly away from the shank in I the position of maximum rotation, as shown in figure The position of maximum rotation is arranged to Or maintain the forward end 23 spaced downwardly from the 41 shank as this has been found to improve the engagement of the blade. That is, contact between the blade and shank 7 is prevented and in this way the load applied to the anchor is transferred primarily through the shank and rear links and not to the leading edge of the blade. If 9- 2W r the load is applied to the front of the blade the anchor tends to rotate about the fiukes and not dig into the seabed.

It has been found that the second embodiment provides stronger bottom engagement than the first embodiment since rearward tension on the second embodiment shank drives the rear end of the blade more securely into engagement with the bottom with less total angular rotation.

The blades of the anchor of figures 8, 9 and 10 are planar but it will be appreciated that in other embodiments those blades may have their side wings 9. 4 upswept similarly to the blades of the Figure 1 embodiment.

According to still other embodiments of the invention the blade is hinged at or near its front edge to the shank and the extent to which it may move away from the shank into its second position is limited by a link similar to the link 21 of the Figure 8 embodiment but slotted longitudinally to permit the blade to lie against the shank as the anchor descends to the bottom.

Alternatively, but less preferably, such a link may be replaced by a length of chain or other collapsible tensile member.

In a further embodiment, it is preferable to arrange 11 the attachment points of the links of the second embodiment so that the pantograph linkage formed thereby goes overcentre when the anchor is in a closed position 10 i 7 L r pp.- LI i i s @0 0 0 0 0 0 e 0 so as to restrict the pantograph from opening when the anchor is being launched or in flight.

The second embodiment is preferred for use with a forward propelling wing arrangement as described above but may also be applied to conventional anchors with a rotatable blade but with no forward movement characteristics.

Other forward propelling blades that may be used with the second embodiment are shown in figures 12 and 13. With the superior ground engagement characteristics of the second embodiment, the rear of the blade does not require special rearwardly extending ground engaging formations like the flukes 13, although these are Preferred for added security. The embodiment shown in Figure 12 is provided with two swallow tail points or flukes 24 which restrain the blade from rolling to one side as it may do with a central fluke and permits easier penetration into cohesive soils.

The linkage may also be provided with means to lock the pantograph in its open position when not required to be "flown" away from the vesel, for example, when it is lowered over the side of the vessel in the normal manner.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

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Claims (14)

1. An anchor comprising a central elongate shank having a weighted forward end and means at its rear end for attaching an anchor line, a blade having a longitudinal axis and a pair of bottom engaging upswept wings extending outwardly on either side of~ said axis, said blade being hingedly mounted to said shank by a linkage arrangement including a front link and a corresponding, longer rear link for rotation with respect to said shank about an axis transverse to said shank and said longitudinal axis, means to positively limit the maximum extent of rotation of said blade away from said shank, said blade being rotatable with respect to said shank from a first position in which saidi shank can rest on said blade with said longitudinal axis substantially parallel with said shank, to a second position defined by said maximum extent of rotation, the arrangement permitting said shank to rest on said-blade in said first position and move forwardly on said wings away from a vessel as the anchor sinks to the sea bottom, whereupon 20 on reaching the sea bottom a rearward force applied to the anchor line causes said blade to assiine said second position and securely engage the sea bottom.

2. An anchor according to claim 1 wherein said limiting means comprises the base of a slot extending along the longitudinal blade axis from a point near said axis of rotation, said slot being open at its rearward end to permit said rear link to move through said slot on I. *0 *4 00 00 I 00.: ~I 1 K 12 relative rotation until said rear link abuts said blade at the base of said slot.

3. An anchor according to claim 1 or claim 2 wherein said weighted forward end has a shape whereby fluid flowing over its top uurface exerts a downward force thereby maintaining said blade in said first position during said forward movement of said anchor.

4. An anchor according to claim 1, 2 or 3 wherein said pair of upswept wings extend symmetrically outwardly and rearwardly on either side of said longitudinal axis of said blade.

An anchor according to any one of claims 1 to 4 wherein the bottom of said weighted forward end extends, in use, below the level of said blade, when said blade is 6f in said first position, such that upon contact of said forward end with the sea bottom the shank tends to pivot about said forward end resulting in said blade rotating to said second position.

6. An anchor according to anyone of the preceding claims wherein said front and rear link each comprise an I €t identical pair of links.

7. An anchor according to claim 6 wherein said links are rotatably mounted at their ends and said lengths of Isaid front and rear links are such that said blade can hinge between said first position to said second position of maximum rotation with respect to said shank, said i blade being held spaced from said shank when in said second position. 13 I. F. 1.

8. An anchor according to claim 1 wherein said limiting means comprises an abutting toe portion on one or both of said rear links engaging said blade to limit the extent of said rotation to between 27 and 33 degrees.

9. An according to claim 7 wherein the pantograph linkage formed by said front and rear links moves to an overcentre position when said blade rotates to said first position.

An anchor according to any one of the preceding claims including means to lock said blade in said second position.

11. An anchor according to any one of the preceding claims wherein said blade includes rearwardly directed flukes for engaging the sea bottom.

12. An anchor according to claim 11 wherein the tips of said wings form one set of said flukes and further pair of flukes are located on a rear portion of said blade and extend symmetrically on either side of said shank. sof

13. An anchor substantially as hereinbefore described with reference to Vigures 8 to 10 of the accompanying drawings. DATED this 21st day of December, 1989 S1 DULMISON MARINE PTY. LTD. SAttorney: PETER HEATHCOTE y/ Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS ®.C1

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