Lifting Dry Dock

Abstract

A lifting dry dock for lifting a boat out of the water comprising a subsurface support, a cradle for cradling the boat, and a plurality of legs pivotally connecting the cradle to the subsurface support in a manner which permits movement of the cradle between a lowered position in which the cradle is below the surface of the water a distance sufficient to permit the boat to float thereover and a raised position in which the cradle is clear of the water. A winch is provided for effecting movement of the cradle between its lowered position and its raised position.

Description

BACKGROUND OF THE INVENTION

This invention relates to a lifting dry dock for lifting a boat clear of the water, and is particularly concerned with a lifting dry dock having a cradle for cradling the boat, and a pivoted linkage arrangement enabling raising and lowering of the cradle.

It is desirable to remove a boat, such as small pleasure craft, from the water when out of use to prevent marine life from accumulating on the hull of the boat and to reduce deterioration of the boat. Reference may be made to such U.S. Pat. Nos. as 2,885,987 and 3,412,702 which are in the general field of this invention.

SUMMARY OF THE INVENTION

Among the several objects of this invention may be noted the provision of an improved simplified lifting dry dock such as above-described which cradles a boat as the boat is lifted clear of the water; the provision of such a lifting dry dock which accommodates various sizes of boats; the provision of such a lifting dry dock in which the boat is moored to the cradle to hold the boat in position for engagement by the cradle; and the provision of such a lifting dock which is easy to operate and which is of economical construction.

In general, a lifting dry dock of this invention for lifting a boat out of the water comprises a subsurface support, elevator means for lifting the boat out of the water including a cradle for cradling the boat and pivoted linkage means pivotally mounted on the subsurface support and having pivotal connections with the cradle mounting the cradle for movement between a lowered position in which the cradle is below the surface of the water a distance sufficient to permit the boat to float thereover and a raised position in which the cradle is clear of the water. Means are provided for effecting movement of the cradle between its lowered position and its raised position. Other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of a lifting dry dock of this invention showing its cradle in its raised position supporting a boat clear of the water;

FIG. 2 is a side elevation of a lifting dry dock showing in solid lines the cradle with the boat cradled thereon in its raised position and showing in phantom the cradle in its lowered position;

FIG. 3 is a plan view showing the cradle associated with a floating dock; and

FIG. 4 is a vertical section on line 4--4 of FIG. 3 showing the cradle in its raised position.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, a lifting dry dock of this invention, indicated in its entirety at 1, for lifting a boat 14 clear of the water is shown to comprise elevator means generally indicated at 2 which includes a cradle 10 for cradling the boat. The cradle is carried by the lower portion of a floating dock 3, this lowered dock portion being disposed below the surface of the water and constituting a subsurface support 5 for the cradle. The cradle is movable by means of a pivoted linkage generally indicated at 7 between a lowered position (as shown in phantom in FIG. 2) in which the cradle is below the surface of the water a distance sufficient to permit the boat to float thereover and a raised position in which the cradle is clear of the water.

More particularly, floating dry dock 3 includes a pair of I-beams, each being indicated at 30, extending transversely of cradle 10, these I-beams being spaced apart from one another a distance slightly greater than the length of the cradle. A pair of cradle support members, each being indicated at 28, are spaced apart from one another a distance corresponding to the width of the cradle and are secured as by welding to I-beams 30. A transverse cross brace 31 is welded in place extending between support members 28, this brace member being adjacent the forwardmost I-beam 30 (i.e., the left I-beam as shown in FIG. 1). These support members 28, I-beams 30 and brace 31 together constitute subsurface support 5. The floating dock further includes upright members 34 which extend from I-beams 30 above the surface of the water for supporting a pair of side decks, each being indicated at 38, and a front deck 39 (see FIG. 3). These decks are arranged to form a boat slip 40 in which cradle 10 is mounted on linkage 7 for movement between its lowered position and its raised position. As shown in FIG. 2, the decks are at substantially the same elevation and permit access to boat 14 when the cradle is in its raised position. The upright members 34 of each deck have cross braces 36 extending diagonally therebetween to rigidize the dock structure. It will be understood that flotation means (e.g., empty 55 gallon steel drums, not shown) may be secured to the subsurface support to provide buoyancy for the floating dock.

Cradle 10 is shown to be a horizontal frame having a pair of spaced-apart side rails 11 which extend the length of the cradle, and a forward member 13 extending transversely between the forward ends of the side rails and being welded thereto. Forward and aft cross members 15a and 15b, respectively (see FIG. 2) extend between the side rails intermediate the ends of the cradle. Each side rail has a forward shoring member 12a secured thereto adjacent cross member 15a and an aft shoring member 12b secured thereto adjacent cross member 15b. These forward and aft shoring members each have a cradle member 9 secured to their upper ends, the lower end of each of these cradle members being secured to the adjacent cross member 15a or 15b. The cradle members are engageable with the hull of boat 14 for cradling the boat as the boat is lifted from the water upon raising of the cradle from its lowered position to its raised position.

A post 15 is secured (welded) to the top surface of forward member 13, this post being of a height sufficient to extend above the surface of the water when the cradle is in its lowered position for permitting mooring of one end of boat 14 (i.e., its bow) thereto in a manner as will appear. The post is securely held in its upright position by braces 16 welded to the sides of the post and to forward member 13. A vertical elongate slot 18 is provided in the post for purposes as will appear. A vertical column 22 is secured to forward I-beam 30 and extends above the elevation of front deck 39 for mounting a winch 24 at a convenient height.

Column 22 is braced in the fore and aft direction by a support brace 35 extending between the column and cross brace 31. The winch has a cable 26 wound thereon and the cable has a hook 27 on its free end. The winch is provided with a handle 29 for manual operation thereof and has a conventional pawl and ratchet mechanism (not shown) for preventing unwinding of the cable from the winch. Column 22 carries an adjustable stop 33 which is engageable by forward member 13 of the cradle when the cradle is in its raised position to prevent overcentering movement of the cradle. It will be understood that a power winch may be used in place of the manual winch 24.

Linkage means 7 includes four leg members, each of which is indicated at 42. These leg members are pivotally connected as indicated at 43 at their upper ends to the bottom faces of side rails 11 of cradle 10 adjacent forward and aft cross members 15a and 15b, respectively, and are pivotally connected at their lower ends as indicated at 45 to cradle support members 28 of subsurface support 7 to enable movement of the cradle between its lowered and raised positions. The leg members on opposite sides of the cradle adjacent the forward cross member constitute a forward pair of leg members and are braced laterally relative to one another by diagonal braces 32. Similarly, the leg members pivotally connected to the cradle adjacent the rear cross member are laterally braced relative to one another by other diagonal braces 32. The leg members are substantially the same length and together with the cradle constitute a parallel linkage arrangement whereby the cradle remains substantially horizontal as it is moved between its lowered and raised positions.

The boat 14 is shown as carrying a fitting or eye-bolt 20 on its bow, this eye-bolt being adapted to extend through slot 18 in post 15 (see FIGS. 1 and 2) when cradle 10 is in its lowered position (as shown in phantom in FIG. 2) for mooring the boat relative to the post when the boat is floating free above the cradle. Hook 27 on cable 26 is adapted to be hooked into eye-bolt 20 so that upon operation of winch 24 to retract the cable, the boat is pulled against post 15 to hold the boat in proper position for being engaged by cradle members 9 as the cradle is raised from its lowered position. Upon further retraction of the cable, the bow of the boat (or a shoulder (not shown) provided on fitting 20) bears against the post and thereby exerts a forwardly and upwardly acting force on the post to effect movement of cradle 10 to its raised position. As the cradle is moved upwardly relative to the boat floating thereabove, eye-bolt 20 moves down in slot 18 and the boat is held adjacent post 15 by the pulling of the cable on fitting 20, thus the boat is held in position for engagement by the cradle. The cradle may be held in any position between its lowered position and its raised position by engaging the pawl of the above-mentioned pawl and ratchet mechanism of the winch 24 to prevent unwinding of cable 26 from the winch.

In operation, the lifting dry dock of this invention permits a boat to be conveniently and quickly lifted clear of the water for storage, and permits the boat to be readily lowered into the water when desired. With cradle 10 in its lowered position, and with boat 14 floating adjacent floating dry dock 5, the boat is maneuvered for entry into slip 40. The bow of the boat is moved into position adjacent post 15 which projects up above the surface of the water and fitting 20 on the bow of the boat is guided into slot 18 of the post. Cable 26 is unwound from winch 24 and hook 27 on the free end of the cable is hooked in eye-bolt 20. Winch 24 is then operated by turning crank 29 to wind up cable 26 thereon. As the cable is retracted, the bow of the boat is pulled against post 15 to thereby exert a force on the post in a generally forward and upward direction. Thus, cradle 10 is caused to move on pivoted legs 42 from its lowered position to cradle the boat. Upon further retraction of the cable, the cradle is caused to move to its raised position against stop 33. A padlock (not shown) may be inserted in eye-bolt 20 to thereby prevent the eye-bolt from being withdrawn from slot 18 in post 15 for anti-theft purposes.

It will be understood that the length of slot 18 is sufficient to accommodate boats having fittings 20 installed thereon at various heights and to accommodate a boat in which its load may vary, whereby the height of the fitting above the surface of the water may vary depending on the load carried by the boat. It will be further understood that cradle members 9 may be adjustable to accommodate boats having various shaped hulls.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

What is claimed is:

1. A lifting dry dock for lifting a boat out of the water comprising a floating dock having lower portions adapted to lie below the surface of the water when said dry dock is floating on the water, these lower portions constituting a subsurface support, and a deck adapted to extend above the surface of the water, said lifting dry dock further comprising a cradle for cradling the boat, pivoted linkage means pivotally mounted on said subsurface support and having pivotal connections with said cradle mounting said cradle for movement between a lowered position in which the cradle is below the surface of the water a distance sufficient to permit the boat to float thereover and a raised position in which the cradle is clear of the water, said deck forming a boat slip in which said cradle is mounted for movement between its lowered position and its raised position, a winch positioned above and forward of the front end of said cradle, said winch being fixedly mounted relative to said floating dry dock at one end, constituting the forward end, of said slip and having a flexible cable for effecting movement of the cradle between its lowered position and its raised position upon operation of the winch.

2. A lifting dry dock as set forth in claim 1 wherein said cradle comprises a frame having means extending upwardly therefrom at one end thereof constituting its forward end for mooring thereto of one end of the boat prior to and during the raising of the cradle, whereby the boat floating above the cradle is held in position adjacent said mooring means to be lifted by the cradle as the cradle is raised from its lowered position to its raised position.

3. A lifting dry dock as set forth in claim 2 wherein said mooring means comprises a post secured to and extending upwardly from the forward end of said frame, said post having a vertical slot therein into which a fitting carried by the said one end of said boat is adapted to be inserted, said flexible cable being adapted to be attached to said fitting as inserted into said slot in said post whereby retraction of said cable by the winch holds the boat against said post and exerts a lifting force on said cradle to raise the cradle from its lowered position to its raised position.

4. A lifting dry dock as set forth in claim 1 wherein said pivoted linkage means is a parallel linkage means having a plurality of leg members pivotally connected at their ends to said cradle and to said support, whereby said cradle is maintained in a substantially horizontal position as it is moved between its lowered and raised positions.

5. A lifting dry dock as set forth in claim 2 wherein said frame includes a pair of spaced-apart side rails extending the length of said cradle, a plurality of cross members extending between the side rails, and a plurality of cradle members adapted to support the boat.