US3547067A

US3547067A - Device for raising an anchor

Info

Publication number: US3547067A
Application number: US779122A
Authority: US
Inventors: Frederik J Jonkman
Original assignee: NEDERLANDSE OFFSHORE CO
Current assignee: NEDERLANDSE OFFSHORE CO; Nederlandse Voor Werken Buitengaats Netherlands Offshore Co Nv Mij
Priority date: 1967-11-27
Filing date: 1968-11-26
Publication date: 1970-12-15
Anticipated expiration: 1987-12-15
Also published as: NL6716116A; GB1246991A

Description

United States Patent 1 Inventor Frederik J. .Ionkman Driehuis, Netherlands Appl No, 779,122 Filed Nov. 26, 1968 Patented Dec. 15, 1970 Assignees Nederlandse Maatschappij Voor Werken Buitengaats (Netherlands Offshore Company) N.V. Netherlands; N.V. and Bureau Wysmuller Netherlands Priority Nov. 27, 1967 Netherlands No. 6,716,116

DEVICE FOR RAISING AN ANCHOR 3 Claims, 2 Drawing Figs.

U.S. Cl. 114/206,v

Primary ExaminerTrygve M. Blix Attorney-Sughrue. Rothwell, Mion, Zion and MacPeak ABSTRACT: An apparatus for multiplying the force exerted by a ship on an anchor line. A rotating drum having differential diameters is buoyantly carried on a float that is positioned above the anchor. When the anchor is raised, the rotating drum is capable of multiplying the force exerted at a distance by the ship and causes the buoyant float to submerge in an approximately vertical direction increasing the buoyant force until the anchor is freed from the bottom.

'PATENTEU DEC 1 5 I978 SHEET 1 BF 2 I DEVICE FOR RAISING AN ANCHOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an apparatus that safely and efficiently raises an anchor.

2. Description of the Prior Art Ships, barges, dredges and other floatable objects that must be transiently anchored into position generally require one or more anchors. These anchors are generally dropped by the vessel itself or are positioned by asecond vessel to retain an accurate positioning of the vessel. It has been known to position these anchors with a buoyant marker floating on the surface and secured to both the anchor and the ship.

Due to many factors it is often necessary to reposition anchors, for example, if one of the anchors is dragging. This repositioning of-the anchor is generally carried out-by either the vessel itself or a secondary vessel such as a tug andrinvolves hauling the anchor up with a winch on board one of the vessels. During'the raising of the anchor a considerable force will be exerted on the hauling mechanism or winch.'The force is not just the weight of the anchor and of the chain, but also the force necessary for initially breaking the anchor from its grip on the bottom. The conventional method of raising the anchor described above has proved satisfactory in favorable weather conditions. However, when the vessels are subject to high waves there is the disadvantage of an added force'being exerted on the already taut anchor line. This occurs when the vessel is lying above the anchor and has drawn in all the slack anchor line. If at this point, the vessel is'repositioned relative to the anchor on the bottom by a wave passing underneath the vessel, the anchor line and the winch are subject to an extreme tension force. This force will generally be sudden and create the danger of either the anchor line breaking or the ship being.

put in serious danger.

SUMMARY OF THE INVENTION The present invention provides an apparatus that will allow ships to raise anchors without the use of a secondary vessel or the accompanying dangers of conventionally hauling the anchor up itself. Further it will greatly reduce the danger of raising the anchor when a secondary ship, as a tug, is used. This is accomplished by providing a rotating drumthat will multiply the force exerted by the ship and positioning this rotating drum on abuoyant platform that has been buoyantly designed to incrementally increase the buoyant force as the platform is submerged. The fact that the floating platform can be submerged removes the danger created by high waves and in fact uses the waves to loosen the anchor.

The float generally has a construction that tapers in its downward direction, for example a reversed pyramid or cone shape. This unique construction allows the vessel to simply secure the line to the buoyant platform and then proceed on its destination, thus allowing a ship to reposition itself or embark with only a minimum amount of time. The foregoing is a desirable feature both with respect to .time and with removing a ship from a position of danger.

The rotating drum which is a simple form-of winchcan be motivated by an independent source of power, but in its preferred embodiment, it uses the cable that attaches the buoyant float with the vessel. With this arrangement any force exerted on the cable by the vessel will rotate the drum and cause the line attached to the anchor and the small end of the rotating drum to be raised. When the vessel itself is the source of power that drives the hoisting means, the invention provides the additional advantage that the vessel is increasing the distance between itself and the floating platform and by so doing minimizes the possibilities of colliding with it.

During the entire operation, only a horizontal force is acting on the vessel, thus eliminating any sudden jerking of the cable attached to the vessel that would be created bythe rise and fall of the vessel in rough water. This allows the vessel to remain fully steerable and eliminates the necessity of carrying a large winch for raising the anchor. This is particularly helpful in a small secondary vessel since it eliminates the necessity of carrying a winch capable of handling a large ship's anchor. It would be obvious to one skilled in the art to vary the diameters of the drum to provide a particular ratio of forces.

BRIEF DESCRIPTION OF THE DRAWINGS The best mode contemplated of performing the invention will be described in detail below in connection with the accompanying drawing in which:

FIG. 1 is a diagrammatic layoutof the invention showing the relationship of the vessel and the anchor;

FIG. 2 is a perspective view with a section removed to show the relationship of the rotating drums with the various anchor lines.

In FIG. 1, the anchor 2 is shown resting in a secured position on the bottom of the sea. The anchor is secured by an anchor chain 3 to the main vessel (not shown) and secured to the floating structure 6 by the combination of a cable 4 and chain 5. The securing line could consist entirely of a cable or a chain, but the preferred embodiment uses the combination of both. The securing line is attached to the means for hoisting the anchor, indicated at 7. This hoisting means 7 consists of a pocketed sheave 8 and a rope drum 9 disposed on the same axis. The chain 5 has been guidedto and from the pocketed sheave 8, via guiding shells l and 11, respectively. The chain is provided with

stoppers

12 and 13 for limiting the travel of the chain. A rope drum disposed on the same axis as drum 9 could be used in lieu of the pocketed sheave.

A cable 14 is secured on the rope drum 9 and has a free end 1 supported on top of the water by

pontoons

15 and 16. This arrangement facilitates the securing of cable 14 to the parent vessel or the secondary vessel 17.

In the preferred embodiment, shown in FIG. 2, the rope drum 9 has a diameter twice the size of the diameter of the pocketed sheave 8. This permits both a multiplication of force and further, operation of the secondary vessel 17 at a distance from the floating structure 6. This ratio, can be varied to meet subjective requirements. The geometric configuration of the floating structure is preferrably designed to progressively displace more water as the floating structure is forced downward.

The preferred embodiment shown in FIGS. 1 and 2 uses an inverted pyramid shape to accomplish this progressively increasing displacement. Other shapes such as cones, spheres, etc. can be used. The chain stopper 13 may be constructed as a weight for compensating part of the weight of the anchor. This will permit the rate of fall of the anchor and consequently the rate at which the cable 14 is wound on the drum to be kept within reasonable bounds.

In operation the tug or secondary vessel 17 would fasten itself to the line 14 and simply pull the line 14 in the particular direction that is desirable. Line 14 will rotate the hoisting means 7 which will take up the slack in the anchor line until the line is taut. At that point the buoyant floating structure 6 will be progressively forced underwater and the force on the anchor line will vary with the water displaced by the floating structure 6. If a wavesubmerges part of the floating structure the secondary vessel will not be effected by this sudden increase in buoyant force, but rather the anchor will only be subjected to a smoother application of increasing force than has been possible in the conventional method.

Iclaim:

1. An apparatus for raising an anchor, comprising:

a. securing means capable of being attached to a vessel;

b. an anchor attached to an anchor line, the anchor line consisting of a chain in its upper portion;

c. hoisting means including a drum engaging the securing means and a pocketed sheave driven by the drum and engaging the chain, the sheave having a smaller diameter than the drum;

d. a submergible buoyant structure supporting the hoisting means and containing a guide passage for the chain;

e. first and second stops on the chain cooperable with the adjacent ends of the guide passage to limit the travel of the chain, the first stop being of such a weight to balance a portion of the anchor weight to facilitate raising the anchor; and

. whereby movement of the securing means will activate the hoisting means to progressively submerge the buoyant structure until the anchor is freed.

2. In an apparatus for raising an anchor from the sea bottom including a submergible buoyant platform having a geometric shape which progressively displaces greater increments of water volume as it is submerged, a drum mounted on the platform, a first cable wound on the drum and adapted to be connected to a towing ship, and hoisting means mounted on the platform and driven by the drum, the improvements comprismg:

a. a second cable permanently connected between the hoisting means and the anchor; b. a releasable coupling on the first cable for releasably connecting the first cable to the towing ship; and c. a float attached to the first cable adjacent one end thereof for maintaining the cable on the surface of the water when it is disconnected from the towing ship. 3. An apparatus as defined in claim 2 wherein: a. the hoisting means comprises a pocketed sheave; and b. the upper portion of the second cable comprises a chain engaged by the sheave.