1987-05-05
1989-02-07
Basinger, Sherman D.
Ships
Anchor
114301, B63B 2134
Patent
active
048024341
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to an anchor for mooring a floating object to a mooring bed.
A fixed fluke anchor having a cranked shank which is capable of orientating to an upright digging attitude automatically by rolling when dragged inverted over most mooring bed surfaces is known from UK Patents Nos. 1356259 and 1513453. However, in certain mooring beds of firm clay, the rolling action can be impeded by the flat sides of the shank bearing against the mooring bed surface when the anchor has rolled approximately 45 degrees onto its side.
It is an object of the present invention to obviate or mitigate this problem.
Marine anchors as described above have a fluke angle .theta. defined by the angle between a line extending from the anchor cable attachment point on the shank to the rear of the fluke and a fluke central line. The fluke central line is in fact constituted by the line intercept of a vertical symmetry plane of the anchor with the upper surface of the fluke, such a line intercept defining a forward direction. If the upper fluke surface is flat then the line intercept is a straight line: however if the fluke upper surface is longitudinally curved giving a curved intercept then the pertinent straight fluke intercept line would be the chord subtended by the "curved" intercept. In this specification, this chord is identified by the expression "fluke central line". Also, similar fluke longitudinal intercept lines could be obtained on the fluke by planes parallel to said vertical symmetry plane. The above defines the expression "central fluke line or longitudinal fluke line as hereinbefore defined" used in this specification. The fluke angle .theta. can be within the range 25 degrees to 55 degrees.
According to the present invention there is provided an anchor comprising a fluke member arranged transversely to a longitudinal plane of symmetry of the anchor, a shank adapted at one end for attachment to an anchor line and at the other end for attachment to said fluke member, said fluke member including an upstanding lug on each side of said plane of symmetry; auxiliary flukes each attached to a respective lug so as to be remote from the plane of symmetry, each auxiliary fluke extending substantially transversely to said plane of symmetry and providing a leading surface inclined upwardly at an acute forwardly opening angle .beta., to a plane at right angles to said plane of symmetry and containing the fluke central one or a fluke longitudinal line as hereinbefore defined; and support means about which the anchor may tilt when inverted on a firm horizontal mooring bed surface to bring a lug and/or an auxiliary fluke into contact with the mooring bed with said leading surface of the auxiliary fluke inclined upwardly at an obtuse forwardly opening angle .beta..sub.2 to the horizontal mooring bed surface.
Preferably said tilt is sustained under gravity on a firm horizontal mooring bed surface.
Preferably at least a portion of the surface of said lug facing the shank has a forward opening angle .gamma. measured in the forward direction at right angles to the plane of symmetry in the range -2 degrees +20 degrees with 4 degrees to 12 degrees preferred, and preferably additionally has an upwards opening angle .alpha. relative to the plane of symmetry in the range 0 degrees to 40 degrees measured in a plane orthogonal to the forward direction with 8 degrees to 18 degrees preferred.
Preferably the lug surface area facing the shank on each side of said plane of symmetry is in the range of 2 to 12 per cent of the area of the fluke member viewed at right angles to the forward direction parallel to the plane of symmetry and preferably is in the range 3 to 7 per cent of said area of the fluke member.
Preferably the said forward opening angle .alpha..sub.1 of the leading surface of the auxiliary fluke is in the range 20 degrees to 80 degrees with 55 degrees to 70 degrees preferred.
Preferably further the leading surface of said auxiliary fluke has a downwardly and forwardly opening angle .DELTA. relative to t
REFERENCES:
patent: 4173938 (1979-11-01), Covin
patent: 4577581 (1986-03-01), Puech
patent: 4706595 (1987-11-01), van den Haak
Avila Stephen P.
Basinger Sherman D.
BruPat Limited
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