Ships – Anchor – Fluke type
Reexamination Certificate
2001-02-09
2001-12-25
Sotelo, Jesus D. (Department: 3617)
Ships
Anchor
Fluke type
C114S293000
Reexamination Certificate
active
06332423
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to marine anchors and more particularly to an improved fixed shank plow anchor.
BACKGROUND OF INVENTION
With the increased use of remotely controlled anchor windlasses for deploying and retrieving the anchor automatically, anchors require the following characteristics for successful operation: (1) the anchor must exit and enter the retaining anchor roller or davit smoothly, (2) the anchor must set quickly in all types of bottoms, and (3) the anchor must penetrate deeply into the seabed to develop high holding resistance. While numerous forms of anchors have been developed over the years for use by small vessels, both pleasure craft and work boats, all have their disadvantages and as far as is known, none completely fulfill the criteria set forth above.
U.S. Pat. No. 1,974,933 to Taylor, in 1934, discloses the first plow-type anchor and consists of an articulated shank attached to symmetrical plow shaped flukes. While this anchor holds well when set, it has difficulty setting, particularly in a hard seabed, and the hinge in the articulated shank causes difficulty in stowing and releasing the anchor in an automated system.
U.S. Pat. No. 4,397,256 to Bruce, in 1983, discloses an anchor having symmetrical flukes and a fixed connection between the shank and the flukes. Bruce specifies a shank that is of a rotated L shape that results in an anchor that is difficult to stow, retrieve and release.
U.S. Pat. No. 5,138,967 to McCarron et al. discloses a one-piece plow anchor with the shank rigidly fixed to a symmetrical double bladed ploughshare fluke. The flukes are inwardly dish shaped and may be either curved or consist of two or more flat sections with the trailing end portion of the fluke extending substantially obliquely with respect to the central ridge and so that the fluke presents a substantial surface area facing in the direction of the pull on the anchor. The concave leading edge may be either a smooth curve or comprises at least two straight lined segments. In contrast, in the present invention, the flukes are portions of a cylindrical section with the leading edge having a down and outward pointing fin lateral from the joint between the shank and the flukes.
U.S. Pat. No. 5,188,055 to Kershner discloses one- piece plow-type anchor with flukes that have a relatively broad tail portion lateral to the direction of pull on the anchor.
U.S. Pat. No. 5,855,181 to Oxford discloses a fixed shank plow anchor with flukes consisting of flat sections devoid of any downward pointed projections.
U.S. Pat. No. 6,148,758 to Wilkins discloses a plow-type anchor with flukes consisting of triangular flat sections and a pivoting mechanism in the shank.
All plow-type anchors are of the burying type. That is, the anchor when pulled will continue to bury deeper into the seabed until a solid bottom is reached. In hard bottoms this usually occurs when the flukes are buried. However, in soft bottoms the anchor will continue to move downward until even the shank is below the surface of the seabed. Good holding power in all types of bottoms depends on whether or not the anchor will bury itself deeper and deeper when a forward pull is applied.
When the anchor is lowered to the seabed, the anchor will usually be on one of its sides, resting on the forward end of the shank, the forward tip of the flukes and on the aft edge of one of the flukes. When a forward pull is applied to the anchor the tip of the flukes must penetrate the surface of the seabed to start the burying action. As the anchor is buried, the forward motion will upright the anchor. In a hard seabed, such as packed sand or clay, many plow-type anchors have difficulty penetrating the surface.
OBJECT OF THE INVENTION
An object of the present invention is to provide an improved fixed-shank plow-type anchor that overcomes the shortcomings of the prior art and includes the following interrelated factors:
(1) The anchor is of the fixed-shank plow-type with a pair of symmetrical blades forming a fluke known as a double-bladed ploughshare fluke. The shank is attached to the fluke, with no movement permitted between the fluke and the shank;
(2) Each blade of the fluke is a portion of a cylindrical section. The two blades are joined along a central ridge that is on the median plane of the anchor;
(3) The leading edge of the fluke is shaped so that the forward half of each cylindrically shaped blade will sit flat on a surface when the anchor is upright, with the central ridge sloping upward and aft from this surface;
(4) The shank is attached to the central ridge of the fluke with the forward edge of the shank approximately 75 percent of the distance along the central ridge from the forward point of the fluke;
(5) Each blade has a lateral fin that projects perpendicular to the central ridge, lies within the cylindrical shape of the blade, and extends laterally from the aft of the central ridge of the fluke; and, preferably,
(6) The shank is constructed from thin, high strength, steel so as to permit a low profile in the fore and aft direction while maintaining strength when the anchor is pulled laterally. The leading edge of the shank consists of a section that extends tangentially to a circular curve that terminates at the connection between the shank and the flukes.
In the present anchor the flukes are portions of cylindrical sections with the axis of the cylindrical sections parallel to the central ridge of the flukes, which is the direction in which the anchor must move to bury itself, providing minimum resistance to the burying motion. Once set, the broad aft sections of the flukes provide the holding resistance.
In the present invention, the aft edge of each fluke has a fin that trips the anchor to start the burying action. These fins also act as stabilizers as the anchor is buried. Being well aft of the center of gravity of the anchor the fins provide additional drag on each side of the anchor preventing premature break-outs. In sea trials, anchors of the present invention have been found to set faster than any of the prior art anchors referred to above.
The curved leading edge of the shank, where it connects to the fluke, is a thin section which minimizes drag as the anchor is buried. In addition, the curved-forward edge of the shank permits the anchor to enter and leave an anchor roller smoothly, which is a highly desirable feature for modern automated anchoring systems.
BRIEF DESCRIPTION OF INVENTION
Thus, by one aspect of this invention, there is provided a marine anchor of the type that buries in the seabed when a longitudinal pull is applied, comprising a longitudinal shank having a proximal end connectible to an anchor rode, and a distal end having a double-bladed ploughshare fluke rigidly mounted thereon; and wherein:
a) said shank has a forward edge consisting of a straight section that is tangential to a curved section that terminates at the fluke;
b) said fluke comprises a pair of symmetrically mounted blades, each having partially cylindrical convex and concave surfaces, with a pointed end forward and a divergent rearward section, rigidly connected to each other along a central ridge and symmetrical about a longitudinal medial plane, and wherein the longitudinal axis of each said partial cylindrical surface lies parallel to the central ridge, and the forward edge of the fluke lies on the intersection of the cylindrical surfaces of the blades and a horizontal plane when in an upright position; and
c) each said blade of the fluke includes, along an outer edge thereof, a fin in a plane perpendicular to a longitudinal plane of the central ridge, spaced laterally from the aft end of the central ridge.
REFERENCES:
patent: 1974933 (1934-09-01), Taylor
patent: 2507563 (1950-05-01), Farren
patent: 4397256 (1983-08-01), Bruce
patent: 4827863 (1989-05-01), Scholz
patent: 5138967 (1992-08-01), McCarron
patent: 5188055 (1993-02-01), Kershner
patent: 5855181 (1999-01-01), Oxford
patent: 5970902 (1999-10-01), Francis
patent: 6038996 (2000-03-01), Giles
patent: 6148758 (2000-11-01), Wilkins
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Dowell & Dowell , P.C.
Kingston Anchors Limited
Sotelo Jesus D.
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