US2030136A - Ship's davit - Google Patents

Description

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Jrvucndov G0RGE WILLIAM CARR,

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FATEN'E' ()FFIQE Application June 6, 1934, Serial No. 729,281 In Great Britain June 14, 1933 4 Claims.

This invention relates to ships davits, and has primarily as its object the provision of an improved construction of balanced lufling davit capable of swinging outboard by gravity even against a considerable opposing list of the ship.

A further aim of my invention is the provision of a balanced davit which is self-supporting in all positions as it swings outboard and inboard.

Further aims are the provision of automatic means for limiting the outboard swing of the davit according to the list of the vessel, an improved method of stowing boats suspended by davits according to my invention, and means for coupling two davits together so that they move outboard and inboard simultaneously.

With these and other objects in view, as will become apparent from the following description, my invention consists in the combination of members and parts as set out in the claims appended to this specification.

The accompanying drawings illustrate, by way of example, lufiing davits in accordance with my invention and also an improved method of stowing boats supported thereby. In the drawings:

Figure 1 is an end elevation showing the davit and boat in their inboard position and indicating one outboard position;

Figure 2 is an elevation, partly in section, looking on the outboard side of Fig. 1;

Figure 3 is a part similar view to Fig. 1 illustrating the movement of adjacent davit members; and

Figure 4 is a plan of the davit head and boat in the inboard position.

Figures 5 and 6 illustrate diagrammatically an improved method of stowing the boats in a double tier, Fig. 5 being an end elevation showing two adjacent davits and boats in the inboard position, and Fig. 6 an elevation looking on the out- 40 board side of Fig. 5;

Figures 7 and 8 are similar views to Figs. 1 and 2 respectively illustrating an alternative construction of davit; and

Figure 9 is a similar view to Fig. 1 illustrating another alternative construction.

Referring to Figs. 1 to 4 of the said drawings, the davit therein illustrated comprises an articulated framework consisting of a head member I I, five intermediate members l2 and a foot member l3, said members being hinged together in succession by pivot pins M. The head member comprises a pair of L-shaped side plates i5 rigidly connected together by crossbars I6 and stiffened by stays I! as shown in Figs. 1, 2 and 4. The head supports a pulley it! for the operating rope 19, the end of which is passedaround a sheave 20 and anchored to the head at 2| (Fig. 1). The intermediate members i2 each comprise a pair of flanged side plates 22 connected by brackets 23 to channel-section cross bars 24 to form rigid members, and the foot member I3 also comprises a pair of flanged side plates 25 which are provided with bearings 26 for the heel pivot pins 21 of the davit, said side plates being extended beyond the heel pivots and curved inboard and fitted with a stop rod 28. The heel pivot pins 21 are supported in brackets 29 depending from the boat deck plating 30 of the vessel near the side 3! thereof, said deck plating being slotted as shown to accommodate the side plates 25 of the davit foot member. The side plates of alternate intermediate members I2 are formed (as shown in Fig. 2) with eyes 32 to engage between corresponding pairs of eyes 33 on the adjacent intermediate members and on the head and foot members respectively, the pins i4 being passed through said eyes to form knuckle joints. The members Ii, l2 and i3 pivot about the pins M in succession from the head member II to the lowermost intermediate member i2 during the outboard movement, and vice versa during the inboard movement, and the abutting faces of the flanged side plates of said members are adapted to coact on either side of the pins M to limit the pivoting of the members thereabout, so that, when said members are in the inboard or outboard position shown in Fig. l, further inboard and outboard movement of the davit can occur only about the heel pivots 21.

The davit is thus self-supporting in all positions, and the davit and boat are retained in the inboard position by means of the rope l9 which is passed around a winch l9a on the deck. In the inboard position the davit lies adjacent to a pair of correspondingly shaped rigid girders 34 (Figs. '1 and 3) which carry a cross rod 35 on which is mounted a guide pulley 36 for the operating rope E9. The girders 34 also serve to support means for ensuring that the davit members pivot in correct succession. They may also support chocks for the boats, if desired. The lower ends of the girders are attached to the deck plating 30 by brackets 34a, and their upper ends may be connected to a convenient deck erection.

To ensure that the davit members II and I2 pivot in correct succession, a hooked projection 31 is provided on the lower inboard corner of each side plate of each of said members adapted to coact with a hooked projection 38 disposed immediately below it on the adjacent face of each of the girders 34, as shown in Figs. 1 and 3. The hooks 3T engage the hooks 38 when the davit members are in the inboard position and prevent premature movement of the lower members, the arrangement being such that, commencing with those of the head member II, the hooks 3! disengage the hooks 38 one after another in downward sequence as the davit members turn outboard as shown in the upper portion of Fig. 3. When the davit is swung inboard, the hooks reengage in upward succession commencing with those of the lowermost intermediate member I2.

The boat 39 is supported by rigid central slings 40 from a rod M the ends of which are adapted to engage forks 42 formed at the outer ends of the side plates 55 of the davit head, said rod being suspended by connections 43 from the sheave 26 of the operating rope I9. The boat is free to swing athwartships about the rod 4!, and in the inboard position is slightly canted, its inboard gunwale 44 being seated in the angle of the side plates I5 as shown in full lines in Fig. 1. During the outboard movement of the davit head, the boat assumes an even keel, and, about the time it reaches the position for embarkation of passengers (which is shown in dot-and-dash lines in Fig. l), the projecting portion of the davit head I I becomes approximately vertical and the weight of the boat is transferred from the forks 42 to the sling rods 4!, 43 and sheave 26. The coaction of the rod 4! with the forks 42 and the rigid slings 4% prevents any fore and aft or athwartship swinging of the boat while loading.

In order to stop the outboard movement of the davit and hold it in a position where the projecting portion of the davit head II is about vertical and the weight of the boat has been ransferred to the sheave 29 and also where the gunwale 44 of the boat is, in relation to the boat deck 30, at its nearest or most convenient position for embarkation of passengers as shown in dot-and-dash lines in Fig. l, or for lowering to the deck below it is necessary to limit the outboard movement of the foot member l3 about the heel pivots 21, according to the list of the vessel, and for this purpose I provide automatic stop gear comprising a pair of plates 41 (Figs. 1 and 2) freely suspended from pivots 48 mounted in brackets 48a below the deck plating 30, said plates being rigidly connected together by a crossbar 49 and being provided with notches 50 in their outboard edges to receive the stop rod 28 of the foot member of the davit. The notches 50 are so shaped and relatively positioned that the particular pair of notches into which the stop rod 28 enters depends on the list of the ship, the plates 41 being free to maintain their vertical suspension and being unaffected by the angle of the deck plating 36. When the stop rod 28 abuts against the plates 47, further outboard movement of the davit about its heel pivots 21 is prevented, and the davit is automatically stopped when the projecting portion of its head I I becomes approximately vertical. When the davit has turned out against an exceptionally heavy opposing list, the stop rod 28 may abut against a pair of notches 59a cut in the brackets 48a from which the stop plates 41 are suspended, said plates having swung inboard sufiiciently to allow of this.

The boat is supported so that, in the inboard position of the davit, the weight of the boat is normally opposed to the weight of the davit head i I and tends to automatically commence the outboard movement about the pivot I4 between the head and the uppermost intermediate member I2, the outboard movement of the davit being continued about each pivot in downward sequence. The outboard swing of the davit is thus, even under adverse conditions, entirely actuated by gravity, and may be readily controlled by suitable paying-out tackle, which may be the rope I9 or may be independent of the tackle for lowering the boat.

Pivoted pawls 21a coacting with toothed wheels 211) are fitted as shown in Figs. 1 and 2 on the heel pivots 21 to prevent upward and inward movement of the foot members I3 where the davit is working against a heavy opposing list and, on being relieved of the weight of the boat when the latter becomes waterborne, is balanced in such a manner as would tend to cause it to fall inboard. The pawls 21a are raised by hand off the toothed wheels while the davit is being returned inboard.

The davit described herein and illustrated in Figs. 1 t 4 of the accompanying drawings has been designed so that, even when its outboard movement is opposed by a heavy list of say 40 to 45, it will commence its outboard movement unaided, although after the head member I I and one or two of the intermediate members I2 have turned about their pivots I4, it may be necessary for a few members of the boats crew to enter the boat (which will then be almost on an even keel) and add their weight to the outboard half thereof to overcome the opposing weight of the davit head and continue the outboard movement by swinging the boat over the remaining pivots M. It will be understood however that it is only in the case of an exceptionally heavy list that it may be necessary for members of the boats crew to enter the boat before it reaches the embarkation position. Usually the weight of the boat is sufficient to automatically carry the davit outboard. The head member II of the davit is designed so that its projecting portion will not turn too rapidly from the horizontal to the vertical position, thus allowing the boat to reach the edge of the deck 30 in suitable position for loading.

The number of articulated members II, I2, I3 comprising my improved davit depends on the maximum list against which the davit is designed to operate and usually exceeds three. In order to obtain more strength when in the outboard position, the pivots I4 are disposed nearer to the inboard than to the outboard side of the davit, and the relative movements between the davit members are through only small arcs. B-y arranging that the boat is stowed in an inwardly canted position as shown in Figs. 1 to 4, the commencement of the outboard movement of the davit against a heavy list is facilitated and the projecting portion of the head member II may be made shorter and lighter and the number of pivots in the davit reduced, but, if desired, the boat may be stowed on an even keel, the height of the davit being increased accordingly.

The use of a central davit for each boat enables me to adopt an improved method of stowing the boats in which the boats 39 are arranged in a double tier as shown in Figs. and 6, the davits 5! for the upper tier of boats being higher and designed for a greater list than the davits 52 for the lower tier of boats. This method of stowage permits the ends of the upper boats to overlap those of the lower boats, the davits for the upper boats being disposed between and clear of the ends of the lower boats, and the davits for the lower boats being disposed between and clear of the ends of the upper boats. The lower boats are swung outward and lowered first, and the way is then clear for swinging outboard and lowering the upper boats, it being unnecessary to return the lower davits to their inboard positions before lowering the higher boats. By this arrangement, considerable saving in stowage space is obtained combined with the advantage of being able to lower the lower tier of boats,

lar parts.

The davits illustrated in Figs. 7 and 8 are substantially the same in construction and operation as the davit hereinbefore described and illustrated in Figs. 1 to 6, with the exception that the pivot pins 21 and 43 for the foot members I3 and the plates 4'! are mounted on the upper face of the ships deck 99, and the cross bars 24 and brackets 23 are dispensed with. In order to ensure that the members of the twin davits move outboard and inboard simultaneously, I provide a connecting member comprising a pair of curved channel bars 53 rigidly attached to the head members II and tied together by transverse beams 54 attached at their ends to the concave sides of the bars 53. The flanges of the curved bars 53 are on their convex sides, and they adequately stiffen the davits in lieu of the girders 24 of the construction illustrated in Figs. 1 to 3.

In the inboard position, the bars 53 project below the boat 39 as shown in full lines in Fig. 7 and in Fig. 8, the connecting beams 54 forming a platform on which boat chocks may be mounted. It will be noticed that the inboard ends of the flanges of the bars 53 overlap the uppermost intermediate members I2 when the davits are inboard, and, as the davits swing outboard, the bars 53 successively engage and overlap the succeeding members until, when the davit is fully outboard, the whole of said members and also the foot members I3 are overlapped by the flanges of the bars 53. Not only are the head members thus tied together so that they move simultaneously on slackening the ropes I9, but any tendency for individual lateral sway in the davits is checked.

Where a pair of davits is employed for each boat as illustrated in Figs. '7 and 8, the boat is supported by slings 49 from rods 4Ia which are engaged by hooks 55 on sheaves 56 disposed adjacent to the outer faces of the head members I I, said rods Ma being extended to engage the forks 42 in the outer ends of the head members and having the ends of their extended portions supported by brackets 51. The operating ropes I9 are passed around the sheaves 56, the guide sheaves I8 and 35 being mounted next the outer faces of the members II and 34 to suit.

The outboard and inboard movements of the davits of Figs. '7 and 8 are exactly the same as those of the davit of Figs. 1 to 4, and the stop rods 28 coact with the notches 50 in the plates 41 as hereinbefore described to limit the outboard movement of the davit heads, the outboard position of the davits being indicated in dot-and-dash lines in Fig. '7.

Figure 9 illustrates another modified construc- -member II respectively.

tion of my improved davit. -In this arrangement, each head member It, as well as being provided with the curved channel bar 53 of Figs. 7 and 8, has pivoted to it at 59 an arm 59 which takes the place of the rigid projecting portions of the side plates I5 of the construction shown in Figs. 1 to 4. The arm 59 carries the sheave 20 for the operating rope I 9, one end of the latter being anchored to the pivot 58. The other end, after passing around the sheave 29 coacts with the sheave 36 on the fixed girder 35, being passed between the side of the member II and a guide rail 65 in spaced relationship therewith, one end of said rail being carried by the pivot 59 and the other by the pin 66 of a sheave 6"! on the lower part of the head member II. The sheaves 29 and El are on the sides of the arm 59 and The outer end of the arm 59 is forked at 42 to receive the rod 4! from which the boat slings depend in the same way as in the construction of Figs. 1 to 4. Coacting faces 60, SI on the arm 59 and the head member II limit the movement of the arm towards the head member. The arm is however free to swing about the pivot 58 away from the head member.

The stop plates 41 of Figs. 1 and 2 are dispensed with in the construction of Fig. 9, and in their place I provide the foot member I3 of the davit with a transverse pin 62 working in slots 63 in two spaced parallel upstanding plates 54 (one only of which is shown) on the deck 39 of the ship.

In the inboard position illustrated in full lines in Fig. 9, the coacting faces 69, 6E hold the arm 59 so that the boat hangs vertically above the channel bar 53. When the operating rope I9 is slackened off, the davit head II, arm 59 and boat 39 swing outboard about the pivots I4 of the davit members I2 and finally about the pivot 21 of the foot member I3 of the davit until the pin 62 on the latter engages the upper end of the slots 63 in the stationary plates 64 whereupon the outboard movement of the davit is arrested and its position is that illustrated in dot-anddash lines in Fig. 9, the arm 59 being held by the rope I9 so that the boat is sufficiently close to the edge of the deck 39 for loading purposes, the rope I9 having been guided by the rail 55 to engage the sheave 61, as indicated. Further paying-out of the rope I9 allows the arm 59 to swing into the vertical position indicated in dotted lines in Fig. 9 where the boat is clear of the ships side and can be lowered by continuing the paying-out of the rope I9. On being returned inboard by winding in the rope I9, the sequence of operations is reversed. The actions of the channel bars 53 and the hooked projections 31 and 38 of the davit illustrated in Fig. 9 are the same as in the davit illustrated in Figs. 7 and 8.

My improved davits, being swung outboard by gravity, eliminate any necessity for electric or steam driven winches, and the constructions are such as to ensure maximum efiiciency when turning outboard'against a heavy list. They are particularly suitable for use with a boat of great beam in proportion to its depth. The usual boat gear would, with advantage, be stowed in the outboard portion of the boat to increase the weight tending to commence the outboard movement of the davits.

It will be understood that, while I have herein fully described three constructions of my improved davits, these particular constructions are described by way of examples, and their details may be modified as may be necessary or desirable without departing from the spirit of my invention. For example, the members I! of the davit may be extended down the ships side and the heel pivots 21 positioned at any suitable distance below the boat deck 30, thus giving a greater outboard reach where required.

What I claim as my invention and desire to secure by Letters Patent is:--

1. A davit comprising a series of members hinged together in succession, coacting faces on said davit members limiting their relative movements, a transverse pivot permanently connecting the lowermost of said davit members to the ships deck or side, boat supporting tackle coacting with the uppermost of said davit members, means for controlling the outboard swing of said davit members and for returning them to their inboard position, individual means associated with each of said davit members for ensuring that said davit members pivot in correct succession comprising hooked projections on the lower inboard edges of said davit members, a rigid girder on the ship immediately adjacent to the inboard side of the davit in its inboard position, and hooked projections on said girder with which the hooked projections on the davit members coact.

2. A davit comprising a series of members hinged together in succession, coacting faces on said davit members limiting their relative movements, a transverse pivot permanently connecting the lowermost of said davit members to the ships deck or side, boat supporting tackle coacting with the uppermost of said davit members, means for controlling the outboard swing of said davit members and for returning them to their inboard position, individual means associated with each of said davit members for ensuring that said davit members pivot in correct succession, and self-adjusting means for stopping the outboard swing of the davit members according to the list of the vessel, said means comprising a stop on the lowermost of the davit members, a pivot on the ships deck, and a notched plate freely suspended from said Pivot.

3. A pair of davits each comprising a series of members hinged together in succession, coacting faces on said davit members limiting their relative movements, transverse pivots permanently connecting the lowermost of said davit members to the ships deck or side, boat supporting tackle coacting with the uppermost of said davit members, means for controlling the outboard swing of said davit members and for returning them to their inboard position, individual means associated with each of said davit members for ensuring that said davit members pivot in correct succession, and means for stiffening the davit members of the two davits and ensuring that they move outboard and inboard simultaneously comprising a pair of curved bars rigidly attached to the uppermost of the davit members and transverse beams tying said bars together.

4. A pair of davits each comprising a series of members hinged together in succession, coacting faces on said davit members limiting their relative movements, transverse pivots permanently connecting the lowermost of said davit members to the ships deck or side, boat supporting tackle coacting with the uppermost of said davit members, means for controlling the outboard swing of said davit members and for returning them to their inboard position, individual means associated with each of said davit members for ensuring that said davit members pivot in correct suecession, and means for stifiening the davit members of the two davits and ensuring that they move outboard and inboard simultaneously comprising a pair of curved bars rigidly attached to the uppermost of the davit members and transverse beams tying said bars together, said curved bars being of channel section with their flanges projecting on their convex sides and overlapping the davit members.

GEORGE WILLIAM CARR.

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