Patent Publication Number: US-5829379-A

Title: Plate anchor

Description:
This application is a PCT continuation application of PCT/EP95/02871, filed Jul. 20, 1995. 
     FIELD OF THE INVENTION 
     The present invention relates to a plate anchor, such as for anchoring a boat, ship or other vessel. More specifically, the present invention relates to a plate anchor having two spaced anchor plates which are disposed in a plane, with a central gap between them that extends in the longitudinal direction of the anchor, and having an anchor shaft which is swingably mounted on a pivot means disposed in the end region of the anchor plates directed generally away from the anchored vessel, whereby the shaft can be swung into and through the gap. 
     DESCRIPTION OF THE PRIOR ART 
     Known plate anchors are not equally effective in hard and soft anchoring media, for example, bottoms and soils, and when subjected to stress derived from drift, current or swinging of the anchored object, such anchors are readily dislodged from the anchoring medium. 
     SUMMARY OF THE INVENTION 
     The underlying problem addressed by the present invention is to devise a plate anchor which is effective and has high holding force in anchoring media of all types, in particular when subjected to appreciable horizontal tensile stress. 
     This problem is solved by a plate anchor of the general type described by incorporating into each anchor plate at least one forwardly disposed pointed claw element and at least one lagging pointed claw element, with all of the claw elements having lateral edges which are backswept in the direction generally away from the anchored vessel. 
     The basic advantage of the plate anchor of the present invention is that it has at least four flukes having edges which are backswept in the direction generally away from the ship or anchored vessel, wherewith the flukes can engage the anchoring medium simultaneously. The anchor is thus effective in a wide variety of anchoring media. In a hard anchoring medium, the forwardmost pointed claw element of each anchor plate engages the anchoring medium first, and then the lagging pointed claw element of each anchor plate is brought into engagement with the anchoring medium. The high resistance of the anchor is provided by the simultaneous engagement of the four pointed claw elements with backswept edges and by the fact that the resistance area increases as the engagement becomes deeper. 
     Advantageously, the plate anchor of this invention is caused to open under the influence of the inclined tension with a horizontal component exerted by the anchor chain fixed to the drifting, tending, and bobbing vessel sought to be anchored. Under such circumstances, the anchor develops a high and persistent holding resistance, because the laterally disposed pointed claw elements bear progressively increasing loads. Further, the anchor resists spinning out of engagement, because it has a wide surface of engagement between the outermost pointed claw elements. If the anchor does suffer a breaking of its hold, it rapidly re-engages, because at least one of the pointed claw elements will engage the anchoring medium regardless of the anchor attitude, i.e., the angle between the anchor plates and the underlying anchoring medium. 
     The anchor plates in accordance with the present invention also advantageously do not require a crossrod to achieve engagement, because the outer flukes ensure reliable engagement is regardless of the orientation conditions encountered during dragging of the anchor. Even without a crossrod, the anchor plates of the present anchor will reliably engage the anchoring medium in an even fashion, and the anchor will not tend to spin out of engagement under the influence of generally horizontal tension. In a preferred embodiment, a device having tooth-like claw members is provided in the region of the end of the anchor directed generally away from the anchored vessel which digs into the anchoring medium in a manner to augment the torque that urges the flukes of the anchor plates into engagement whereby they dig into the medium. In a further preferred refinement, a detent device is provided which delimits the angle by which the anchor shaft can swing away from the plane of the anchor plates, and a mechanism is provided to adjust that angle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in more detail hereinbelow with reference to the accompanying drawings: 
     FIG. 1 is a plan view of a plate anchor in accordance with the present invention; 
     FIG. 2 is a lateral view of the plate anchor shown in FIG. 1; and 
     FIG. 3 is a view of a detail of a variant embodiment of a plate anchor in accordance with the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the embodiment illustrated in FIGS. 1 and 2, the plate anchor is essentially comprised of a divided anchor plate, or two anchor plates 2, 3 and an anchor shaft 1. The shaft 1 has an eye 11 or the like for fixing an anchor chain, at the end of the shaft 1 directed generally toward the ship or other vessel to be anchored. The two anchor plates 2, 3 are disposed in a single plane, and have between them a gap 12 which extends in the longitudinal direction. The shaft 1 is swingably mounted with respect to a pivot axle means 6 disposed at the end of the anchor directed generally away from the ship, whereby shaft 1 can be swung into and through the gap 12. 
     It is a particular feature of the present invention that each of the anchor plates 2, 3 has a fluke member having a forwardmost pointed claw element 21, 31 and at least one fluke member having a lagging pointed claw element 22, 32, and wherein the sides of said claw elements are generally backswept away from the ship. The forwardmost pointed claw elements 21, 31 are preferably disposed next to the shaft 2, and are mutually generally symmetrically disposed with respect to the vertical midplane of the anchor. The lagging pointed claw elements 22, 32 are disposed rearwardly of the forwardmost pointed claw elements 21, 31, where the rear end of the plate anchor is defined as the end directed generally away from the ship. The lagging elements 22, 32 are also disposed laterally outward of the forwardmost elements 21, 31 away from the longitudinal center line of the anchor. The two lagging elements 22, 32 are also mutually generally symmetrically disposed with respect to the vertical midplane of the anchor. 
     Preferably, the lagging pointed claw elements 22, 32 of the anchor plates 2, 3 are configured such that lateral edges 23, 33 of the respective anchor plates 2, 3 extend from the apex of the respective forwardmost claw elements, at 21, 31, at an angle such that the edges 23, 33 progress laterally outward with the progression rearwardly in the direction toward the end of the anchor which is directed generally away from the ship. At points 24, 34, each angularly backswept edge 23, 33 undergoes a transition to a lateral edge 25, 35 which progresses forwardly in the direction toward the end of the anchor which is directed generally toward the ship. The lateral edges 25, 35 terminate at the apex of the lagging pointed claw elements, at 22, 32; at which point another lateral edge 26, 36 extends to the rear end face of the anchor plates 2, 3, which rear end face is directed generally away from the ship. Preferably, the lateral edges 26, 36 are disposed at an angle such that they progress inwardly with progression rearward in the direction toward the end of the anchor which is directed generally away from the ship. 
     Thus, the two anchor plates 2, 3 when viewed in combination have a crown-like appearance. Known plate anchors, in contrast, reach their maximum width at the rearwardmost end. The advantage of the plate configuration of the present invention is that, once approximately half of the anchor plates 2, 3 have engaged the anchoring medium, the resistance against further engagement does not increase. 
     Preferably, a detent device 5 is provided which defines the range of angles within which the anchor plates 2, 3 are swingable with respect to the anchor shaft 1. Preferably, device 5 is comprised of detent plates 51, 52 mounted to the opposite sides of the anchor plates 2, 3, wherein the detent plates define an angle which is oriented symmetrically with respect to the longitudinal axis of said anchor plates 2, 3. The V-shape of the angle opens in the direction toward the end of the anchor directed generally toward the ship. The detent plates 51, 52 extend transversely in the lateral direction. When the anchor shaft 1 is swung outwardly, the shaft comes to abut one or the other of the detent plates 51, 52 in the region of the gap 12. Preferably, the angle between each detent plate 51, 52 and the longitudinal axis of the anchor plates 2, 3 does not exceed about 45 degrees. Also, preferably, each detent plate 51, 52 is welded to the anchor plates 2, 3 via triangular web members 28 disposed at equal distances in the lateral direction from the longitudinal axis of the anchor. Thus, the detent plates 51, 52 serve also to hold the anchor plates 2, 3 aligned in a single plane (see FIG. 2). 
     FIG. 3 shows a variant embodiment of the present invention wherein adjusting devices, preferably set screws 55, which extend through the detent plates, are provided to adjust the angle (or range of possible angles) between the detent plates 51, 52 and the anchor plates 2, 3. 
     Preferably, as shown, the detent plates 51, 52 also extend in the direction generally away from the anchored vessel. The projecting members constituting these extensions are designated with reference numerals 27 and 37, respectively. This provides a convenient means for standing the anchor vertically on a deck or the like, with the extensions 27, 37 serving as legs resting on the deck. The geometric form represented by the detent plates 51, 52 with their extensions 27, 37 is preferably that of rectangular plates which intersect at an angle. Appropriate gaps are provided in the extensions 27, 37 which gaps correspond to the gap 12. 
     The detent plates 51, 52 preferably extend in the lateral direction (transversely) over essentially the entire width of the anchor plates 2, 3. Thus, the detent plates hold the anchor plates together. 
     As seen from the drawings, the free edges of the detent plates 51, 52 are preferably beveled, and preferably have tooth-like claw members 53, 54 which dig into the anchoring medium when the anchor is dragged along the surface of the medium. This results in the anchor plates 2, 3 being rotated around the respective lateral (transverse) axis formed by the tooth-like members 53 or 54, whereby the anchor plates 2, 3 are urged against the anchoring medium, thereby promoting engagement of the pointed claw elements of the anchor plates, i.e., frontmost pointed claw elements 21, 31 and lagging pointed claw elements 22, 32, into the anchoring medium. 
     The pivot axle means 6 may be extended laterally outward to provide a crossrod 61, 62 to promote engagement of the flukes by urging a dragging anchor into a yawing rotation. 
     Each anchor plate 2, 3 may be provided with a plurality of additional pointed claw elements in addition to those illustrated by the numerals 21, 31 and 22, 32. The additional pointed claw elements should also have backwardly swept edges, and each successive additional claw element is disposed laterally outward of the preceding pointed claw element, thus farther from the longitudinal axis of the anchor. The disposition of the individual pointed claw elements and the details of the fluke configurations and, in particular, the longitudinal distance between the forwardmost pointed claw element and the various lagging pointed claw elements and the lateral distances between pointed claw elements, may be selected based on the specific requirements which the plate anchor must satisfy. 
     The material of construction of the described anchor is preferably steel or, in a lightweight version, aluminum. A lightweight version is possible because a high holding force is achieved as a result of the special engaging means and the enhanced digging effect of the four pointed claw elements 21, 31 and 22, 32. 
     The anchor plates 2, 3 may have reinforcing ribs and/or corrugations, in known fashion. Examples of reinforcing ribs 29, 39 are illustrated in FIGS. 1 and 2. The ribs extend perpendicularly to the plane of the anchor plates 2, 3, and are generally backswept at an angle from the leading edge, which edge is namely that generally closest to the anchored ship. Advantageously, the ribs 29, 39 are fastened, e.g., by welding, to the above-described stiffening web members 28 at the end face of the ribs 29, 39, respectively, which is generally farthest from the ship.