US2564966A

US2564966A - Ship and cargo deck construction

Info

Publication number: US2564966A
Application number: US61950A
Authority: US
Inventors: Valdemar C Farrell
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-11-26
Filing date: 1948-11-26
Publication date: 1951-08-21
Anticipated expiration: 1968-08-21

Description

1951 v. c. FARRELL 2,564,966

SHIP AND CARGO DECK CONSTRUCTION Filed Nov. 26, 1948 2 4 Sheets-Sheet 1 ATTOR N EY Aug. 21, 1951 V. C. FARRELL v SHIP AND CARGO DECK CONSTRUCTION 4 Sheets-Sheet 2 Filed NOV. 26, 1948 ATTO R N EY Aug. 21, 1951 V v. c. FARRELL 2,564,965

SHIP AND CARGO DECK CONSTRUCTION Filed Nov. 26, 1948 4 Sheets-Sheet 5 T (call 1L9) Valdemar EI'arr all,

ATTORNEY A g- 1 v. c. FARRELL 2,564,956

SHIP AND CARGO DECKCONSTRUCTION INVENTOR" Valdemar ELFELTI'Ell ATTORNEY Patented Aug. 21, 1951 UNITED STATES PATEN T "OF F lCE SHIP AND CARGO DECK CONSTRUCTION Valdemar C. Farrell, West Englewood, N. J. Application November 26, 1948, Serial No. 61,950

13 Claims. 1 This invention relates to ships and, more "particularly, to the construction and organization of ships, especially to cargo decks for ships.

Throughout the history of modern ships it has been the practice, inherited from the days of wooden sailing vessels, to provide the ships with relatively small .hatchways through the various decks thereof ,for the admission of cargo to the cargo decks within the :hold of the ship. This cargo is usually handled by means of hoisting machinery or derricks fixed on the top deck of the ship and which lifts and moves the cargo selectively through the hatchway and between the proper cargo hold or deck. When the cargo is loaded in or discharged from the cargo hold it must be moved, manually or mechanically, across the cargo deck between the recesses of the hold and the hatchway or square of the hatch as it is frequently called. As the hatchways have heretofore been relativelysmall .in comparison to the :size of the deck, it :has meant that the cargo has required extensive handling in both loading and stowing in the hold and unloading or discharging therefrom.

Having mind the defects of the prior art, it

is an object of the present invention to provide a ship construction and organization enabling greater facility in loading and unloading.

It is another object of this invention to provide a ship construction that will reduce to a minimum the distance that the cargo will have to be manually or mechanically moved from the ends of the hatch opening to the ends of the It is a further object of the invention to provide a cargo deck construction including mobile wing deck that may be moved between stowage position beyond the ,hatchway to loading and unloading position within the hatchway.

It is a still further object of the invention to provide a ship construction and organization,

and particularly a cargo deck construction and organization having simplicity of design, economy of construction and efliciency in operation.

The foregoing objects and others ancillary thereto are preferably accomplished, according to a preferred embodiment of the invention, by a ship construction including a hatchway, "or square of the hatch, having a width -.substantially equal to or slightly less than, half of the beam of the ship and locating the hatch so that the distances from its sides to the sides of the shipwill be substantia1ly-one-half the width of the hatch. The tween-decks plating on both sides of the hatch from approximately three feet outboardijof the coaming brow or ramp and the full length of the hold will be mounted on auxiliary beams supported for mobility by rollers directly over the stationary deck beams to provide mobile cargo wing decks that may be moved between stowage positions outboard of the hatchway and in the sides of the ship's hold and inboard loading positions with-in the hatchway and evenlyspa'ced on opposite sides of the centerline for loading to the full height of the overhead. Mobile wing decks are similarly installed in the lower hold on the tank tops tor similar operation. Means are provided for simultaneously moving the wing decks in opposite directions, that is simultaneously inboard and outboard, and a preferred form includes a cable system that may be operated by the hoisting machinery on the ship The'wing decks are preferably provided with. retaining battens fixed across their outboard and end edges and retainers removably mounted along their inboard edges. The hoisting machinery-is all arranged athw-art'ship above a transverse bulkhead with the winches between the king posts to clear the top deck and permit a greater length tothe hatchway.

The novel features that are considered characteristic of the invention "are set forth with particularity in the appended claims. The invention itself, however, both as to its organizationand its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, whereinlike reference characters indicate like parts throughout the several figures and in which:

Fig. 1 is a fragmentary view in perspective o! a ship with parts being broken away to show part of the top cargo hold and deck thereof Fig. 2 is a. fragmentary cross-sectional view taken on line 2--2 of Fig. 1 through the hold-of a ship showing a plan of a portion of one of the I cargo decks thereof;

k 3 versely of a ship and through a hatchway thereof;

Fig. 4 is a fragmentary cross-sectional view taken on line 4-4 of Fig. 2;

Fig. 5 is a fragmentary cross-sectional View taken on line 55 of Fig. 2 and illustrating a lower corner of a mobile cargo wing deck with its mobile supports and means for looking it in position;

Fig. 6:;is a fragmentary cross-sectional view taken on line I'! of Fig. 3 and showing an outboard corner portion of a wing deck in plan view;

Fig. 7 is an exploded fragmentary view in perspective of the inboard edge of a mobile cargo wing deck with removable cargo retaining means;

and

Fig. 8 is a cross-sectional plan view similar to Fig. 2 and showing a modification.

Referring now to the drawings, specifically to Fig. l, the usual ship comprises a hull I, including frames 2 supporting hull plates 3, and a top deck 4 which cooperates with the hull I in defining the hold of the ship. One or more cargo decks 5 extend horizontally through the hold and are usually divided into hold sections by transverse bulkheads 6. A hatchway" or square of the hatch I extends vertically through the hold of the ship for access to the various holds or decks and is defined by a hatch opening 8 surrounded by a hatch coaming 9 in the top deck 4 and a hatch opening I!) in each of the upper cargo decks. Hoisting machinery or cranes I I are provided on the top deck l of the ship for moving the cargo through the hatchway I to and from the cargo decks 5.

The hoisting machinery II. usually comprises king posts I2, preferably mounted above a bulkhead 6 and on opposite sides of a mast table or resistor house I3 for support, and cargo booms I4 pivotally mounted at their heels or lower ends to the bases of the king posts I2. The cargo booms I4 are angularly supported by topping cables I5 operated by topping lift winches I6 and guide cables or vangs I'I anchored" at the tops of the booms I4 and selectively secured to Vang posts I8 adjacent the sides of the ship.

' The topping cables are anchored at one end to the'spanner I9, between the king posts I2, or to suitable tackle supported by the spanner, and each extends through one sheave of a block 2I on-"the booms I4 to and around a single sheave block 22 on the respective king post I2 ,'back through a second sheave of the blocks" 2I,

through the spanner tackle 2H and down' to the respective topping lift winch I6.

The cargo is handled by cargo falls or cables 23 which are usually joined at their ends to a cargo hook or like member 24 and extend through suit able tackle 25 on the free ends of the booms I4, and tackle 26 on the king posts I2, to cargo winches 21.

This arrangement of the hoisting machinery is advantageous-in that the boom supporting tacklev has reduced friction and permits the booms I4 to gravitate inboard regardless of the load or lack thereof. "Furthermore, the cargo winches 21 and topping lift winches I6 are preferably mounted substantially athwartship. be= tween the'king posts I2 on top of themast table or resistor house I3 in order to free the top deck 4 and permit the square of the hatch I to. have a greater relative length. By this arrangement the ends 28 of the hatchway may extend to within six feet of the bulkheads 6, whereas in the prior art structures considerable space was needed for the mounting of the winches on the top deck 4 and for strengthening the deck to withstand their weight.

In loading or unloading from the cargo decks 5, the hatch Id of the selected cargo deck 5 is closed by its cover 29 and the cargo moved between the recesses of the cargo deck 5 and the hatch cover 29, where it is picked up or released from the hook 24 of the cargo falls 23. The movement of the cargo from the hatch cover to and from the recesses of the cargo deck is usually accomplished by the hand labor of the longshoremen and possibly with the assistance of winches mounted on the cargo deck. Obviously this has entailed a great deal of labor and consumed a large amount of time, which is overcome by the present invention by the provision of mobile wing decks 38 that are movable between outboard stowage positions in the sides of the hold beyond the hatchway I, as shown in full lines in Fig. l, and inboard loading and unloading positions adjacent to each other centrally of the hold and in the hatchway I, as shown in broken lines in Fig. l.

The heels of" the cargo booms are mounted about one foot above the level of the mast table and the cargo falls substantiall athwartship to the cargo winches mounted on the mast table and evenly spaced on either side of the centerline of the ship." The four electric cargo winches are mounted side by side and back to back so that the mast table or winch bed area requires only about twelve feet on the fore and aft line and, therefore, only six feet of overhead is required over each end of a cargo hold instead of eighteen to twenty feet as in existing ships. Consequently, with only six feet of overhead at each end of the hold. the hatchway may be extended to a length of fifty to sixty feet.

In order to avoid greater depth and weight in the hatch coaming and to compensate for the extra length of the hatch. this area may be divided into separate hatches by three beams and a five foot deck area between them with a centerline stanchion under each coaming. Such division between the two gangs of longshoremen working in the hold would also serve to eliminate the l5'%'to 25% now lost in production through'the interference of one gang with the other.

' 'To facilitate stowage of long lengths with such a divided hatch, one hatch could be longer than the other in order to gain the desired length for such stowage in one hatch of each hold. By installing the mobile decks 3B in each wing of the tween-decks in two sections, it will be possible to load in the tween-deck at one hatch while the other hatch is loading in the lower hold or next level below. This flexibility is desirable when a ship'is required to load in several ports for several discharging ports.

As better shown in Figs. 2 and 3, the wing decks 3!] comprise deck portions or plates 3! that are supported by auxiliary beams 32 on wheels or rollers 33 that ride on the beam 3 of the ship. Preferablychannel-shaped rails 35 are mounted on the beams 34 to form runways for the rollers 33. The hatches Ill of the cargo decks 5 are usually surrounded or framed by a hatch coaming including a brow or ramp 36 that extends above the level of the deck 5 and flush with the level of the hatch cover 29. Therefore the rails 35 not only guide the rollers 33 but also elevate their tracks to the height of the brow or ramp 36 and level with the surf ce of th hatch cover 29 so that'the wing decks 39 may be rolled on and off the cover 29.

As the deck portions 3! form the stowage surface, the usual deck plating across the beams 34 may be dispensed with on the side portions of the cargo decks that are covered by the wing decks 3%) when the latter are in stowed position. Consequently, only a narrow strip 5a of deck plating need be provided along the sides of the hatchway I, as best shown in Fig. 3, in addition to the plating 52) between the ends 28 of the hatchway and the bulkheads 6, as best shown in Figs. 1 and 2. The deck strip 5a need only be wide enough to form a catwalk along the hatch H] for use in seating and removing the hatch cover 29 and will usually be about threefeet in width.

The wing decks 3b are preferably provided with retainer walls 3'! along their outboard and end edges to prevent displaceranent of loose cargo during the loading, unloading and moving of these wing decks. The retainer walls 3'! may comprise stanchions 3-8 supporting horizontal sweat battens 39. The retainer walls 3? along the outboard edges of the wing decks 33 are preferably arranged with the stanchions 38 positioned to nest between the frames 2 of the hull l and thereby afllord the full amount of cargo space on the wing decks 39 by permitting the rear edges of the deck portions or plates iii to extend in abutting relation with the inner edges of the frames 2, as shown in Fig. 2.

When loose cargo is piled on the wing decks 38, it may bear against the retainer walls 31 and tend to warp them outwardly. This effect is overcome in the outboard retainers upon the stowing of the wing decks as the battens 39 will directly bear against the frames 2 of the hull l To preclude rubbing between the end retainer walls 31 and the bulkheads 6, however, rollers ii! may be horizontally mounted on the end stanchions As many of the rollers Llil may be employed as desired but in the average construction only one in each upper corner is necessary, as indicated in Figs. 2, 4 and 6.

If the bulkhead walls are smooth, the rollers 40 may traverse the wall itself, as shown in Fig. 4.

serve to maintain the supporting rollers 33 on center alignment with their tracks 35.

Skirt plates 43 are preferably provided around the bottom of the wing decks 38 to prevent debris from getting under the decks and into the tracks 35 and blocking the rollers 33. In order to anchor the mobile wing decks 36 in loading or stowage positions, heavy apertured brackets or lugs M may be fixed to each inboard corner of the decks 3B and extend laterall therefrom for cooperation with apertured spanner lugs fixed to the bulkheads G, as best shown in Fig. 5. The deck lug 44 fits between the arms of the fixed lug 45 and a pin 46 may be inserted through their coinciding apertures. Two of the fixed lugs will be provided for each deck lug, one at the inboard loading position and one at the stowed position of the deck.

In addition to the fixed retainer walls 3? around the end and outboard edges of the decks 36, they may also be provided with removable retainers along their inboard edges to hold the cargo on the means with the decks.

" through a sheave to a pull ring 55.

decks during movement and also to prevent interlooking or overlapping of the cargo as it is stowed on the adjacently positioned decks. Any suitableiorm of retainer may be employed such as nets supported in any suitable manner as by removable stanchions or. as shown in Fig. '7, by sectional retainer walls ti may be employed. The sectional retainer wall may comprise stanchions d3 supporting sweat battens 13S and adapted to be re movably inserted in sockets or brackets 50 fixed along the inboard edges of the decks 3b. The adjacent sections 3! may be interlocked in any desired manner, as for instance by providing the adjacent ends with stanchions 58 of half thick ness so that the two end stanchions may jointly fit into one of the sockets 56.

r The mobile wing decks 3E9 may be rolled or moved between their stowage and loading posi tions by any suitable reversible power means which are connected by suitable motion-transmitting Moreover, it is preferable, in order to coordinate the movement of the decks to maintain the trim of the ship, that the connections between the motion-transmitting means and the decks be in relatively reverse direction but in the same sense and the same ratio of motion transmission so that the decks are simultaneously moved in opposite directions but in the same sense (inboard or outboard) for the same distance and at the same rate. It is preferred to provide simple inexpensive means that will make use of a source of power which is readily available. Consequently, according to a preferred form of the invention, the wing decks 38 are operated by and connected through a cable or tackle system that may be powered through the use of the cargo falls of the ship.

A suitable cable system and its use is diagrammatically shown in 1 and 2, wherein it may be seen that one end of a cable 5! is anchored at 52 adjacent one end and near the inboard edge of one of the wing decks This cable extends inboard and through a sheave 53 and then longitudinally along the centerline of the ship and A companion cable 5| is likewise secured to the deck adjacent its other end and extends inboard through a sheave 54 to the pull ring 55. In order to move the deck 35] inboard, the pull ring 55 may be hooked to the cargo hook 24 which may then be pulled up by the cargo winches 21.

The

sheaves

53, 5d and 54 may be secured to the base of the usual centerline stanchions 56 that form supports between the decks adjacent the hatchway. Furthermore, the

sheaves

53, 54 and 56', as well as others hereinafter referred'to, may be in the form of single or multiple sheave snatch blocks to permit the removal and stowage of the cables when not in use. For simplicity of illustration, the cables are diagrammatically illustrated as running around individual sheaves and in Fig. 2 the centerline stanchions 55 are omitted.

Referring now to Fig. 2, a second cable system is provided for moving the deck outboard to stowage position. A cable 5'! is anchored at one end to the deck 38 at 58 near one end of the deck and adjacent its outboard side. The cable extends outboard and around a sheave 59 secured to the hull l and then inboard and around a sheave 60 and longitudinally of the ships centerline to a sheave 6i and then to a pull ring 62.

Similarly a cable 5'! is anchored at 58' near the opposite end of the deck 3i? and extends outboard and around a sheave 59', inboard to a sheave 5 l and to the pull ring 52. Thus, by pulling the pull ring 62, as by the cargo hook 24, the deck 30 may be moved outboard. Obviously, the cables and their pull rings 55 and 62 may be operated by any suitable power means. Due to the adaptability of the cargo hook 24 and the cargo winches 21, however, it is preferred to employ this immediately available source of power.

If desired, a similar set of cables l'--5l' and Eff-51 may each be rigged to the other of the decks 39 for separate operation or the may be also respectively joined to the pull rings 55 and 62 for simultaneous operation. However, in order to obtain more positive coordination of the movement of the wing decks 30 and to counterbalance the decks against each other, it is preferred to provide the operative cable system in connection with one of the decks and then to operatively interconnect the decks so that one will be operated from and with the other.

Accordingly, the decks are interconnected by duplicate cable systems at each end, cables 63 and 63' being connected to the powered deck 30 at 64 and 66 adjacent the inboard edge thereof and respectively extending athwartship and around sheaves 65 and 65, secured to the opposite side of the hull I, and then inboard to be anchored at 6568 to the other deck 30 adjacent its outboard edge. Likewise, cables 6ll-6l' are respectively anchored at 6858 adjacent the inboard edge of the other deck 39 and extend athwartship and around sheaves 6969', anchored to the hull I, and inboard to be anchored at 19Tll to the powered deck 30 adjacent its outboard edge.

By the foregoing cable system, both wing decks will be counterbalanced and coordinated to move simultaneously in opposite directions at the same speed and for the same distance. That is, they will be simultaneously moved outboard from inboard loading positions to stowage positions or simultaneously moved from outboard stowage positions to inboard loading positions. When the pull ring 55 is pulled, the cables 5l-5 l will draw the powered deck 39 inboard. The movement of the deck will pull the cables 6l6'l which will draw the other deck inboard while the cables 53-453 counterbalance the decks so that they will move the same distance and at the same speed, and cannot move independently of each other. Similarly, upon pulling the ring 62, the cables EFL-51 will draw the deck outboard, which will pull the cables 53-453 to draw the other deck while the cables til-61 counterbalance the decks. This interconnection which enables coordination of the athwartship movement of the wing decks counterbalances the decks relative to each other and will prevent their afiecting the trim of the ship; it will prevent either of them from gaining momentum and rolling fast tothe low side if the ship is listed, and it will prevent them from rolling or gaining momentum when the ship is rolling at sea in the event that they are not otherwise secured.

In the present instance, the mobile wing decks 3!! are shown and described as extending the full length of the hold sections and being movable athwartship. This construction is preferred for use, particularly in new ships, in conjunction with the enlarged hatchway that is enabled by the athwartship alignment of the hoisting machinery in accordance with the present invention and which permits the lengthening of the hatchway and reduction of the overhead. However, in old ships having relatively small hatchways and a large expanse of overhead at'each end of the hold section, it will be advantageous to reduce the length of the wing decks to accommodate a second set of mobile decks movable between the hatchway and the ends of the hold section so that manual handling of cargo can be reduced to that stowed in the corners of the hold sections.

The term cable as applied herein encompasses rope, wire, chain or any other type of line that is suitable for the use involved. For simplicity, the drawings are diagrammatic in nature and the parts are not to be restricted to this form of illustration, as for example, the mobile

wing deck stanchions

38, 48 and 48 are shown as of ordinary rectangular cross-section whereas they would probably comprise metal T-bars or the like in actual practice.

Although certain specific embodiments of the invention have been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not to be restricted except in so far as is necessitated by the prior art and by the spirit of the appended claims.

What I claim is:

1. In a cargo craft including a hull enclosed by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, cargo supporting mobile decks, mobile mounts interposed between said mobile decks and deck construction and supporting said mobile decks for movement on said deck construction between loading and unloading positions within the hatchway and stowage positions outside of the hatchway, and means for selectively moving said mobile decks between said positions and including interconnections between said mobile decks for moving said decks simultaneously in opposite directions at the same speed and for the same distance.

2. In a cargo craft including a hull enclosed by by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, cargo supporting mobile decks, mobile mounts interposed between said mobile decks and deck construction and supporting said mobile decks for movement on said deck construction between loading and unloading positions within the hatchway and stowage positions outside of the hatchway, and means for selectively moving said mobile decks between said positions and including interconnections between said mobile decks for moving said decks simultaneously in opposite directions at the same speed and for the same distance, said interconnections including connections to one deck for operation by a power source, and connections between said decks for moving the other deck from said one deck and counterbalancing said decks by each other.

3. In a cargo craft including a hull enclosed by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, cargo supporting mobile decks, mobile mounts interposed between said mobile decks and deck construction and supporting said mobile decks for movement on said deck construction between loading and unloading positions within the hatchway and stowage positions outside of the hatchway, and means for selectively moving said mobile decks between saidpositions and including interconnections between said mobile decks for movin said decks simultaneously in opposite directions at the same speed and for the same distance, said interconnections including a cable system for connection to a source of power and connected to one of said decks for selectively moving said one deck in opposite directions, and a cable system connected between said decks for moving th other of said decks from said one deck whereby said decks are counterbalanced and coordinated in their movement.

4. A craft structure as defined in claim 3 wherein said cable system includes a coupling element for removable connection to a cargo hook of cargo hoisting machinery.

In a cargo craft including a hull enclosed by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, cargo supporting mobile decks, mobile mounts interposed between said mobile decks and deck construction and supporting said mobile decks for movement on said deck construction between loading and unlOading positions within the hatchway and stowage positions outside of the hatchway, and retainer walls fixed around the ends and the outside edges of said mobile decks.

6. In a cargo craft as defined in claim 5, the combination of retainer walls removably mounted along the inboard edges of said mobile decks.

7. In a cargo craft including a hull having inner frames spaced longitudinally thereof, a top deck enclosing said hull to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, cargo supporting wing decks, mobile mounts interposed between said wing decks and deck construction and supporting said wing decks for movement on said deck construction between loading and unloading positions within the hatchway and stowage positions outboard of the hatchway, and retainers on said wing decks along their outboard edges and including spaced stanchions secured to the edges of said decks and sweat battens mounted on the inboard sides of said stanchions, said stanchions being spaced along the edges of said decks and in staggered relation to said frames to fit between said hull frames with the edges of said decks abutting said frames when said decks are in stowage positions.

8. In a cargo craft including a hull enclosed by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, cargo supporting mobile decks, and mobile mounts interposed between said mobile decks and deck construction and supporting said mobile decks for movement on said deck construction between loading and unloading positions within the hatchway and stowage positions on opposite sides and outside of the hatchway, said deck construction including beams and deck plates on said beams, the deck plates covering a limited area between and defined substantially by the inneredges of said mobile docks in the stowage positions thereof.

9. In a cargo craft including a hull enclosed by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, a pair of cargo supporting decks mounted on said deck construction and normally occupying positions beyond the hatchway and substantially contiguous thereto, said cargo supporting decks being of a size jointly providing a cargo supporting deck surface substantially as great as the area of the hatch, and means for positioning said cargo supporting decks under the hatch for loading and discharging, said means including mobile mounts interposed between the cargo supporting decks and the deck construction and supporting said cargo supporting decks for simultaneous opposite movement toward and away from the hatchway.

10. A cargo craft as defined in claim 9 wherein said cargo supporting decks normally occupy positions outboard of the hatchway in the wings of the hold.

11. A cargo craft as defined in claim 9 wherein said cargo supporting decks normally occupy positions beyond the ends of the hatchway in the ends of the hold.

12. In a cargo craft including a hull enclosed by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transvversely of said hold, a plurality of pairs of cargo supporting decks mounted on said deck construction and normally occupying positions beyond the hatchway and contiguous thereto, said cargo supporting decks being of a size jointly providing a cargo supporting deck surface substantially as great as the area of the hatchway, and means for respectively positioning each pair of said cargo supporting decks under the hatch for loading and discharging, said means including mobile mounts interposed between said cargo supporting decks and the deck construction and sup porting said cargo supporting decks for simultaneous opposite movement of the decks of each pair toward and away from the hatchway.

13. In a cargo craft including a hull enclosed by a top deck to define a hold, a cargo deck structure transversely of said hold, and a hatch opening through said top deck and defining a hatchway into said hold for access to said cargo deck structure, the improvement in said cargo deck structure which comprises a deck construction transversely of said hold, cargo supporting mobile decks, mobile mounts interposed between said mobile decks and deck construction and supporting said mobile decks for movement on said deck construction between loading and unloading positions within the hatchway and stowage positions outside of the hatchway, reversible power means mounted on the craft, and motion 11 transmitting means connected to the power means and with said mobile decks, the connections with the decks being relatively reverse but in the same sense and the same ratio of motion transmission thereby reversibly moving said mobile decks simultaneousl in opposite directions but in the same sense and the same distance and at the same rate,

VALDEMAR C. FARRELL.

REFERENCES CITED Number 12 UNITED STATES PATENTS Name Date Church et a1. Mar. 18, 1879 Alison May 22, 1883 Webber Oct. 22, 1895 Andrews 1 Jan. 13, 1925 Dietrich May 17, 1932 Olds Mar. '7, 1933 Brown Nov. 19, 1940 Whittelsey May 20 1941 Christoffersen July 25, 1944 Smith Apr. 2'7, 1948