US2997011A - Ocean going combined ore carrier and tanker - Google Patents

Description

OCEAN GOING COMBINED ORE CARRIER AND TANKER Filed June 24, 195'? Aug. 22, 1961 D. F. M NAUGHT ETAL 6 Sheets-Sheet l INVENTORS Dona/o E Mac/Vauy/n Roberl 14- Jacobson Wm ATTORNEY Aug. 22, 1961 D. F. M NAUGHT ETAL 2,997,011

OCEAN come COMBINED ORE CARRIER AND TANKER Filed June 24, 1957 e Sheets-Sheet z w "3 '3 Q "Br Q o i k 3 v L 0 \r Q N i a N m 5 w) no :1 Q K,

m L a 0) m 0) P 3 Q, I:

INVENTORS L Dona/d E Mac/Vauybl Roberl A. Jacobson ATTORNEY Aug. 22, 1961 D. F. M NAUGHT ETAL 2,997,011

OCEAN some COMBINED ORE CARRIER AND TANKER Filed June 24, 1957 6 Sheets-Sheet 3 Aug. 22, 1961 D. F. M NAUGHT ETI'AL 2,997,011

OCEAN GOING COMBINED ORE CARRIER AND TANKER Filed June 24, 1957 6 Sheets-Sheet 4 I S v 5 mm x i i m w w s M b m m C a d M J E A f. M r a e 2 0 a 8G 0 R w% Y Q B wAwm Q Q v .TT\ N \N.@ TlNl l: O &3 0., mm mu k QQQW .mN Q R R? N ATTORNEY Aug. 22, 1961 D. F. M CNAUGHT EI'AL 2,997,011

OCEAN some COMBINED ORE CARRIER AND TANKER Filed June 24, 1957 6 Sheets-Sheet 5 b NJ 1N VENTORS Dona/a F: Mac/Vaug/rl Robe/1* ,4- Jacobson BY W.

ATTORNEY Aug. 22, 1961 D. F. M cNAUGHT ETAL 2,997,011

OCEAN GOING COMBINED ORE CARRIER AND TANKER 6 Sheets-Sheet 6 Filed June 24, 1957 [Q k u...

INVENTORS 0000/0 E Mac/Vauy/rl Robe/'2 A. Jacobson wi/e ATTORNEY 2,997,011 OCEAN GOING COMBINED ORE CARRIER AND TANKER Donald F. MacNaught, Hingham, and Robert A. Jacobson, North Abington, Mass, assignors to Bethlehem Steel Company, a corporation of Pennsylvania Filed June 24, 1957, Ser. No. 667,511 20 Claims. (Cl. 114-73) This invention relates to a combined dry bulk cargo and liquid cargo carrier, and more specifically to a combined ocean going ore and oil carrier. Where herein after the terms ore and oil charges are referred to it is to be understood to be interpreted broadly as dry bulk cargoes and liquid cargoes respectively.

This invention further relates more specifically to the use in a combined ocean ore carrier and oil tanker of one or more aligned groups of three correlated cargoholds to a group, wherein each said group of three correlated cargo-holds comprises one deck covered cargohold adapted for oil cargo only, and two hatch-covered cargo-holds each adapted for ore or oil cargoes. The said two hatch-covered cargo-holds each comprise a movable hatch-cover dually adapted to be watertight for ore service, and oiltight for oil service by special gasketing and bolting arrangements peculiar to each said type of service. The hatch-covers in ore service are designed to roll longitudinally of their respective group and horizontally clear of their respective cargo-hold hatches on suitable high and low coaming and track support means to superposed stowage one over the other and both over the said one deck-covered cargo-hold of their respective correlated group to permit the working of ore cargo in and out of their respective opened cargo-holds.

The hatch-covers are rolled to stowage and moved as required preferably by a line or lines from winches fitted as ship equipment, or fitted especially for hatch handling operations. (The hatch-cover handling gear per se is not a part of this invention, and may be developed by diverse means as required by the ship owner.)

When in oil service the hatch-covers are temporarily fixed at their respective hatches at an oiltight connection and serve as a tank top. Tank cleaning connections and manholes are built into the hatch-covers for oil service. The deck-covered holds for oil service only are also fitted with manholes and tank cleaning connections at the deck in the manner used in tankers.

This invention further relates to four alternatively and optionabiy usable group combinations of aforesaid three correlated cargo-holds to each group, wherein each group may as optionably selected be successively aligned longitudinally of the ships hull with respect to its bow or successively transversely thereof with respect to its port side; and from any selection of said four specific group combinations the two movable hatch-covers of each group thereof may be moved directly from their respective closed positions over their respective said hatches to their specific open stowed superposed positions over the one deckcovered cargo-hold of their respective three cargo-hold group in order to permit working of ore cargo in-andout of their respective cargo-holds. The four different specific group combinations of three correlated cargoholds in each group are when used functionally aligned in the ships hull as listed and are designated as follows:

(Group )High, Low, Stow (as exemplified in FIGS.

1 and 2),

(Group 11)-High, Stow, Low (as exemplified in FIGS.

6 and 7),

(Group 12)Stow, Low, High,

(Group 13)-Low, Stow, High:

wherein in each instance High designates a high coamiT nited States Patent Fatented Aug. 2 1961 ing cargo-hold, Low designates a low coaming cargohold, and Stow designates the deck-covered cargo-hold over which the respective High and Low hatch-covers of said cargo-holds of each group are stowable in their respective open superposed positions during the working of the ore cargoes in and out of their respective cargoholds.

In above four listed groups (10-13 inclusive) it is to be noted that groups 10 and 11 are basic; and that groups 12 and 13 are structurally considered merely the reverse of groups 10 and 11 with respect to the ships bow and/ or its port side. It is believed that the latter groups (12 and 13) require no further description or illustration for proper disclosure in this invention.

This invention further relates to two alternative and optionably usable designs of hatch-covers, each design being suitably dually adapted for said specific ore and oil services but each with different structural and operon flanged wheels supported in special housings fitted with hydraulic jacks for controlling the vertical engagement of the cover withor its release from-its sealed coaming contact with its respective hatch opening. The wheels of the reversible hatch-cover engage respective continuous tracks which are fixed in way of the hatch to the coaming shelf, which shelf in turn is fixed to the hatch coaming. Clear of the hatch the tracks are fixed to track foundations built up from the deck to suit the height of the tracks at the hatch coaming shelf. Six wheel assemblies are used at each reversible hatch-coverthree on each side thereof. The wheel assemblies are used to roll the reversible hatch-cover when in ore service, and are removable when the cover is in oil service. More or fewer wheels may be provided, depending on the weight and dimensions of the covers.

In order that all of the ore hatches may be opened simultaneously the coaming and track heights are Varied to permit each of the reversible hatch-covers of each group to roll under or over its adjacent reversible hatchcover of its respective correlated group to its stowage position.

The reversible hatch-cover has been designed for two types of gasketing service. One side of the reversible hatch-cover embodies a specific gasket arrangement for watertightness and is used when its respective cargo-hold at the oiltight faying surface of the hatch coaming inconjunction with closely spaced bolts to secure the oiltightness required when the cover is in oil service. The batch coaming flange is used in common for gasket contact surface for both services.

When the reversible hatch-cover is in its closed ore service position at its respective hatch opening, the cover structure bears on the coaming bar and the gasket is sealingly compressed under action of the dog bolts. When the hatch is to be opened-the reversible hatch-cover must be raised so that the gasket and structure are clear of the top of the hatch coaming in order that the re versible hatch-cover can be rolled on its wheels to its respective stowage position. When closing the reversible cover it must be lowered from its elevated clearance rolling position to contact the gasket seating surface at the top of the coaming for dogging and. gasket sealing. The required raising and lowering operations are accomplished by hydraulically operated wheel supports contained within each wheel housing as bolted to the hatch-cover structure. All. six wheels at each of the hatch-covers are thus fitted with the hydraulic jacking devices. The complete set of jacks at each reversible hatch-cover is. tied into a hydraulic system employing a hand-pump, a valve, and a reservoir at each reversible hatch-cover. The jacking system provides for simultaneous jacking of all six of these wheels at each reversible hatch-cover thus preventing racking of the reversible. hatch-cover when jacking. The hydraulic piping for. the jacking system has been permanently installed at the periphery of the reversible hatch-cover structure. Flanged. connections. at the wheel assemblies and pumping units have been utilized to permit the removal of these fittings when the cover. is in oil service.

When converting the reversible hatchfcover from oil service to ore service, or vice versa, it is necessary to reverse the cover from one specific sealing arrangement to the other. The reversing operations will be performed using dockside equipment.

Suitable known bumpers, stop chocks, and holdbacks are provided to control the lateral movement ofand to, position the reversible hatch-covers in their respective closed and stowed positions in their respective correlated group of three cargo-holds.

The structural framing of the reversible hatch-cover is disposed above and below an intermediate cover plate to suit the gasketing arrangements for ore and oil services. Drain holes and plugs used in alternate drain holes are provided to drain rain water or sea wash from the top of the cover plating in either ore or oil service.

The non-reversible hatch-cover herein disclosed embodies the use of movable track-end ramp means for effectuating the vertical movement of the respective cover to its gasketed engagement with and disengagement from its respective closed hatch due to its associated shipequipped power Winch-operated means for effectuating track-supported horizontal roll to-and-from single or stacked stowage clear of its respective hatch opening and over plural intermediate ramped track ends and on plural parallel supporting intermittent tracks alongside said respective hatch opening. Alternatively, retractable wheels may be provided, in association with fixed track ends.

The non-reversible hatch-covers are fitted at hatch coamings of varied height at the hatches making up a stacked stowage grouping. The non-reversible hatchcovers are rolled and stowed on tracks attached to the horizontal stiffener on the hatch coaming or to supports built up from the deck in fore and aft alignment with the horizontal hatch side coaming stiffener. The tracks and horizontal coaming stifiTeners are at the same height differing therein from that shown in the reversible hatchcover as described hereinabove, but similarly adapted to allow all the ore hatches to be opened simultaneously in that one cover may roll under or over its adjacent cover of its correlated group by reason of their superposed by-passing design. Six removable wheel assemblies three on each side of each coverare used to support the respective non-reversible hatch-covers when rolling on their respective co-level parallel tracks at the hatch sides. (More or fewer wheels may be used, as required.) The wheels are specifically flanged to procure transverse and vertical control of respective cover movement when rolling on the tracks. The wheel supports are of varying length to suit the height of the respective hatch-cover relative to its respective track. The wheels are used only when the cover is in ore service, and the complete wheel assemblies may be removed when the cover is in oil service.

Ramped track-ends are provided at the tracks to lower the wheels of each non-reversible hatch-cover simultaneously at its respective cover closed position, so that the cover gasketing contacts the compression bar at the top of its coaming, thereby transferring the load of the non-reversible hatch-cover from the wheels to the peripheral-gasketing and the peripheral compression bars. The ramped track-ends comprise toggle-operated sliding trackends to obtain the required vertical clearance of the wheels in way of the ramped track-ends for dogging down the non-reversible hatch-cover. The sliding track-end assemblies are built into the ramped ends ofthe tracks so that the end of the track can bepulled away from contact with the wheels to permit the vertical displace ment of the wheels required for gasket compression. When the non-reversible hatch-cover is to be opened, it is first undogged, and then the sliding track-end is adjusted forward or aft to contact the wheel by means of the toggle arrangement. The non-reversible hatch-cover is then rolled-up the ramps'by the power winch-means from its hatch-closed position to its rolling position on the tracks where the gasketing clears the coaming and the weight of the non-reversible hatch-cover is assumed by the wheels. When the non-reversible hatch-cover is to be closed it is rolled on the wheels along the tracks to its closed position where the wheels automatically lower the non-reversible hatch-cover to gasket contact by rolling down the ramped track-ends. The ramped track-ends are then withdrawn from contact with the wheels by means of the toggle arrangement to provide for the vertical clearance-betweenthe track and Wheel required for final gasket compression. The ramped track-ends serve to positionthe non-reversible hatch-cover at the closed position. Suitable known chocks, bumpers, and holdbacks are provided to control the movement and to position the non-reversible hatch-cover at the stowage position.

Intermittent tracks fitted adjacent to and parallel to the main tracks are adapted to support respective flanged hatch-cover wheels during the travel of contiguous wheels to their respective closed positions.

The respectivev hatch-cover wheels are each adapted Withspecific shouldered flanges which engage the intermittent tracks adjacent to the main tracks to permit the free horizontal travel of an oncoming wheel over the intermediate ramps for each rolling contiguous wheel to its final closed position.

The non-reversible hatch-cover has been designed for two typesof gasketing ser vicingore and oil. The ore service gasket arrangement for watertight scaling is built into the non-reversible hatch-cover structure and is thereby protected from damage. When the non-reversible hatch-cover is dogged down for watertightness a vertical plate fitted at the hatch periphery bears on the gasket seating face of the hatch coaming thus relieving the gasket of the load of the non-reversible hatch-cover. This vertical plate also functions to stop the gasket compression, thereby eliminating gasket damage from overdogging. The gasket here used is fabricated of oil impervious material and remains in place when the non-reversible hatch-cover is in ore or oil service.

When the non-reversible hatch-cover is in oil service, the wheel and dog assemblies may be removed, and a peripheral oil seal is effectuated to the closed nonreversible hatch-cover by an angle and a fibre gasket assembly which is bolted to the horizontal sealing face at the hatch coaming and the hatch-cover side and end plates. The tapped holes for the oil seal arrangements in the hatch-cover sides and end plates. and in the horizontal coaming member (not utilized in attaching dog bolt assemblies) are fitted with machine screws (preferably of brass) to protect the threads when the vessel is in ore service.

Further objects and advantages will be apparent from the following description wherein details of design and of operation will be given in full with reference to the accompanying drawings exemplifying constructional examples of our invention, wherein:

FIG. 1 is a plan view of a portion of a ships deck showing a specific correlated group of three axially aligned cargo-holds comprising two adjacent hatch-covered cargoholds-one high, one lowand one deck-covered cargohold adjacent said low hatch-covered cargo-hold and remote from said high hatch-covered cargo-hold.

FIG. 2 is a side elevation of FIG. 1 diagrammatically illustrating the relationship of the specific three cargohold group of FIG. 1 and their respective closure elements thereof.

FIG. 3 is a sectional view adaptable to the line 3-3 of FIG. 2, diagrammatically illustrating the superposed double-track stowed relationship of the removable and reversible hatch-covers of the two hatch-covered cargoholds in their stowed position over the one deck-covered hold of their specific correlated group of three cargo-holds during the loading or unloading of bulk cargo from their respective hatch-covered holds (i.e. adaptable to similar views of groups 10, 11, 12 and 13).

FIG. 4 illustrates a sectional view taken along the line 44 of FIG. 2 showing the gasketed and clamped relationship of a hatch-covered cargo-hold at its coaming disclosing a specific removable and reversible hatch-cover in its watertight for ore service position thereover.

FIG. 5 illustrates a sectional view of the removable and reversible hatch-cover of FIG. 4 in its reversed gasketed and clamped oiltight for oil service position over its respective hatch-covered cargo-hold, and with its hydraulically operated wheel supports removed.

FIG. 6 is a plan view of a portion of a ships deck showing a specific correlated group of three axially aligned cargo-holds comprising one deck-covered cargo-hold intermediate of two hatch-covered cargo-holds-one high, one low.

FIG. 7 is a side elevation (drawn to a smaller scale) of FIG. 6 'diagrannnatically illustrating the relationship of the specific three cargo-hold group of FIG. 6 and their respective closure elements thereof.

FIG. 8 is a sectional view taken on the line 8-8 of FIG. 7, diagrammatically illustrating the co-level-track stowed relationship of the removable and non-reversible hatch-covers of the two hatch-covered cargo-holds in their stowed position over the one deck-covered hold of their specific correlated group of three cargo-holds during the loading or unloading of bulk cargo from their respective hatch-covered holds (i.e. adaptable to similar views of groups 10, 11, 12, and 13).

FIG. 9 illustrates a sectional view taken along the line Q-9 of FIG. 7 showing the gasketed and clamped closed relationship of the hatch-covered cargo-hold at its coaming disclosing a specific removable and non-reversible hatch-cover in its watertight for ore service position thereover.

FIG. 10 illustrates the removable and non-reversible hatch-cover of FIG. 9 in its gasketed and clamped oiltight for oil service position over its respective hatchcovered cargo-hold, and with its wheel supports removed during said oil service use.

FIG. 11 illustrates in elevation one of the horizontally sliding ramped track-ends as assembled on its hatch coaming stiffener and as adapted as a unit for permitting the raising or lowering of a removable and non-reversible hatch-cover from-and-to its dogged closed position over its respective hatch-covered hold.

FIG. 12 is an illustrative plan view of FIG. 11 as assembled on its respective hatch coaming stiffener.

FIGS. 13, 14 and 15 diagrammatically illustrate the three variably flanged supporting wheels used when their respective removable and non-reversible hatch-cover is in ore service. (For descriptive purposes herein the three differently flanged wheels are further respectively desig nated as types I, II, and III.)

FIGS. 16 and 17 diagrammatically illustrate respectively plan and cross-sectional views of assembled sliding track-end and intermittent track for type I wheels in closed clamped position of hatch-cover.

FIGS. 18 and 18 diagrammatically illustrate respectively plan and cross-sectional views of assembled sliding track-end and intermittent track for type II wheels in closed clamped position of hatch-cover.

FIGS. 20 and 21 diagrammatically illustrate respectively plan and cross-sectional views of assembled sliding track-end for type III wheels in closed clamped position of hatch-cover. As noted hereinabove, retractable wheels in association with fixed track ends may be substituted for the non-retractable wheels and sliding track ends illustrated in the drawings.

Referring now to FIGS. 1 and 2 of the drawings which illustrate diagrammatically profile portions 14in plan and elevationof a ships hull structurally sub-divided for transporting at sea either a liquid cargo or a dry bulk cargo in one or more axially aligned groups of three correlated cargo-holds to a group, 'wherein each group of three correlated cargo-holds comprises one deck-covered cargo-hold adapted for liquid cargo only, and two hatchcovered cargo-holds each adapted for dry bulk or liquid cargoes. Our invention relates primarily to four different but alternatively and optionably usable group combinations of aforesaid three correlated cargo-holds to each group, wherein each group may as optionably selected be aligned in the ships hull with respect to its bow or transversely thereof with respect to its portside deck; and from any selection of said four specific group combinations the two movable hatch-covers of each group thereof may be moved directly from their respective closed position over their respective said hatches to their specific open stowed superposed positions over the one deck-covered stowage-hold of their respective three cargohold group-this stowage being required in order to permit working of ore cargo in-and-out of their respective cargo-holds. The said four difierent specific group combinations of three correlated cargo-holds in each group are functionally aligned in the ships hull with respect to its bow 18 or transversely to its deck 19. The said four group combinations are herein respectively designated as:

Group 10-High, Low, Stow. (Exemplified in FIGS. 1 and 2.)

Group 11High, Stow, Low. 6 and 7.)

Group 12Stow, Low, High. (Reverse of group 10.)

Group 13Low, Stow, High. (Reverse of group 11.)

The FIGS. 1 and 2. illustrate a specific three cargo-hold correlated group 10 comprising successively aligned in said group: one high coaming hatch-covered cargo-hold 15, one low coaming hatch-covered cargo-hold 16, and one stowage deck-covered cargo-hold 17-said cargoholds 15, 16, and 17 being axially and successively aligned in the ships hull relatively with respect to the ships bow 18 longitudinally, or transversely to its portside deck 19. The hatch-covered cargo-holds 15 and 16 are here shown as covered respectively with hatch-covers 20 (high-coaming) and 21 (low-coaming). The stowage deck-covered cargo-hold 17 is for oil service only and is fitted with a manhole 22 and Buttenvorth tank cleaning connections 23 at the deck in the known manner used in tankers. Similar fittings 22 and 23 are also applied for similar use to the hatch covers 20 and 21.

Additionally disclosing in FIGS. 3, 4 and 5 we have shown our specific novel correlated cargo-hold group 10 further characterized by having the said hatch-covers 2t) and 21 adapted with our novel reversible hatch-cover features with their specific structural and operable ar rangements now to be set forth. (Thereversible hatchcovers are equally understandably adaptable to each of (Exemplified in FIGS the four specific correlated cargo-hold groups 10-13 inclusive without need of further specific description herein other than as now follows.)

The reversible hatch- covers 20 and 21 are substantially identical in operation and in ma'ke-upthey vary in dimensional details only.

The reversible hatch- covers 20 and 21 are each dually adapted on opposite sides thereof to close and seal their respective cargo-holds and 16- watertight for ore service and oiltight for oil service by special gasketing and bolting arrangements peculiar to each said type of service. The reversible hatch- covers 20 and 21 are designed to roll horizontally to single or stacked stowage clear of their respective cargo-holds 15 and 16 to super posed stowage one over the other and both over the said one deck-covered cargo-hold 17 of their respective threehold group 10 on flanged support wheels 24. The rotatably mounted flanged support wheels 24 engage respective continuous parallel tracks 25 on the hatch coaming shelves 26 of the respective high and low coamings 27. Clear of the cargo-holds 15 and 16 the tracks 25 are fixed to track foundations 28 built up from the deck 19 to suit the respective heights of the tracks 25 at the respective hatch coaming shelves 26.

The hatch- covers 20 and 21 have been designed as reversible for two types of service in which the framing is disposed above and below the centrally disposed hatchcover plating '29 to suit the sealing arrangements for the two types of service-ore and oil. The peripheral framed facial member 30 of each hatch cover 20 and 21 embodies a peripheral removable gasket arrangement 31 for watertightness bolted thereto and is used when the respective cargo-hold is in ore service. The hatch-cover platting 29 is reinforced on both sides by structural frame members 32. The opposite peripheral facial side incorporates a peripheral flange 33 suitable for bolting and gasketing for oiltightness when the respective cargo-hold is in oil service. Swing dog-bolts 34 are fitted to provide for proper gasket compressionlimited by the peripheral facial member 30 of the cover contacting the respective faying surface of the hatch coaming shelf 26for peripheral watertightness when the hatch-cover is in ore service. A fibre gasket 35 is used at the oiltight faying surface in conjunction with closely spaced bolts 36 to secure the oiltightness required when the cover is in oil service. The hatch coaming shelf 26 is used in common for gasket contact for both ore and oil services.

When the reversible hatchcover is in its closed ore service position at its respective hatch opening, the cover facial structure 30 bears on the hatch coaming shelf 25 and the gasket 31 is sealingly clamped under the action of the dog bolts 34. When the hatch is to be opened, the reversible hatch-cover must be raised so that the peripheral gasket 31 and facial structure 31 are clear of the top of the hatch coaming so that the reversible hatchcover can be rolled on itsflanged support wheels 24 to its respective stowage position. When closing the reversible hatchcover it must be lowered from its elevated clearance rolling position to contact the top of the coaming shelf 26 for dogging and gasket sealing. The required raising and lowering operations are accomplished by means of extensible and retractable wheel supports 37 hydraulically operatedwhichare contained within each wheel housing 38 which are bolted to the respective hatchcover structure plate 39 by bolts 4%) having nuts 41 welded to the rear face of the plate 39 to assist assembly and disassembly of wheel housings 38 when removing for oil service and maintenance. All six wheels 24 at each of the reversible hatch- covers 20 and 21 are thus fitted with the hydraulic jack wheel supports 37. The complete set of six hydraulic jack wheel supports 37 at each reversible hatch-cover is tied into a known hydraulic system comprising a peripheral connecting piping 42, and (not shown), a hydraulic pressure source, a pressure control valve, and a reservoir for hydraulic liquid--with necessary connecting flange 43 and piping 44 connecting through elbow 45 and hole 46 to the hydraulic pressure cylinder 47 of each hydraulic jack wheel support housing 38 of each reversible hatch- covers 20 and 21. The jack wheel supports 37 are vertically movable relative to the wheel support housings 38 by the hydraulic jack piston 49 attached to each jack wheel support 37 and operable under hydraulic controlled pressure within the pressure cylinder bores 48 of each wheel housing 38. The pressure cylinders 47 are each provided with piston packing means 50, and the piston 49 is removably attached to the support 37 by securing screw 51. When in ore service the peripheral faying flange 33 and the peripheral fibre gasket 35 is provided with a removable peripheral guard plate or bar 52 for protection purposes. The guard bar 52 is secured in place by using the gasketing bolts 36 of FIG. 5. The wheel assemblies-wheel supports 37--are fitted within the Wheel housings 38. The wheel housings 38 are bolted to the hatch cover structure support plate 39. To remove the wheel housings 38, the bolts 40 are removed, the connecting pipes 44 disconnected, and the wheel housings 38 with the fixed tubing connection 44 attached thereto, and the wheel supports 37 contained therein are removed from the hatch cover as a unit. The wheel supports 37 are prevented from extending out of the housing 38 under the action of the pistons 49, by stop bolts 53 fitted at the housing 38. These bolts 53 engage slotted stop-pads 54 at the wheel supports 37. The stop bolts 53 are removed when it is necessary to withdraw the wheel supports 37 from the housing 38 for maintenance. The framed facial structures 30 and 32 of the reversible hatch-covers 2t) and 21 are adapted with spaced peripheral drain plates 55 having tapped drain plug holes 56 for drain plugs 57 alternately used to drain rain water or sea wash from the respective exposed tops of the reversible hatch-covers in either ore or oil service.

\eferring now to FIGS. 6 and 7 which illustrate diagrammatically added profile portions 14 of a ships hull comprising a specific three cargo-hold correlated group 11 disclosing one high coaming hatch-covered cargo-hold 58, One deck-covered cargo-hold 59, and one low coaming hatch-covered cargo-hold 60; said cargo-holds 58, 59, and 60 being axially and successively aligned in the ships hull relatively with respect to the ships bow 1.8 or to its portside deck 19. The hatch-covered holds 58 and 60 are here shown as covered respectively with our novel non-reversible hatch-covers 61 (high coaming) and 62 (low coaming). The stowage deck-covered cargo-hold 59 is for oil service only and is fitted with a manhole 63 and Butterworth tank cleaning connections 64 at the deck in the known manner used in tankers. Similar fittings 63 and 64 are also applied for similar use to the non-reversible hatch- covers 61 and 62.

Additionally disclosing in FIGS. 8, 9, and 10, we have shown our specific novel correlated cargo-hold group 11 further characterized by having the said non-reversible hatch- covers 61 and 62 adapted with features of our novel non-reversible hatch-cover and disclosing their specific structural and operable arrangements now to be set forth. (The non-reversible hatch- covers 61 and 62 are equally understandably adaptable to each of the four (4) specific correlated cargo-hold groups 10-13 inclusive without need of further specific description herein than as follows.)

The non-reversible hatch- covers 61 and 62 are substantially identical in operation and in make-up-they vary in dimensional details only.

The non-reversible hatch- covers 61 and 62 are designed to roll horizontally to single or stacked stowage clear of their respective cargo-holds 58 and 60 to superposed stowage one over the other and both over the said one deck-covered hold 59 of their respective three-hold group 11. The hatch covers 61 (high coaming) and 62 (low coaming) are fitted to the top of their respective hatch coamings with faying bars 65 of varied heighthigh hatch coaming 66 being adapted for hatch-cover 61, and low hatch coaming 67 being adapted for hatch-cover 62. The non-reversible hatch- covers 61 and 62 are rolled and stowed on parallel ramped tracksouter tracks 68 for hatch-cover 61 (high coaming), and inner tracks 69 for hatch-cover 62 (low coaming)-both tracks 68 and 69 being attached to horizontal stiifeners 70 on the hatch coamings 66 and 67 or to track supports 71 built up from the deck in alignment with the horizontal stifleners 70. The tracks 68 and 69 and the horizontal stiffeners 70 and track supports 71 are at the same height. Six removable wheel assemblies-three on each side of each of the nonreversible hatch covers 61 and 62are used to support the respective cover when rolling on its respective colevel parallel tracks 68 and 69. The non-reversible high coaming hatch-cover 61 requires high coaming wheel assemblies 72 to suit the by-passing height needed to pass over its associated non-reversible low coaming hatchcover 62 in rolling to stowage when in ore service, and for the same by-passing need the non-reversible low coaming hatch-cover 62 has low coaming wheel assemblies 73. The wheel assemblies 72 and 73 are used only when the respective cover is in ore service, and the complete Wheel assemblies may be removed when the respective cover is in oil service. The wheel assemblies 72 and 73 are attached to their respective hatch-cover structural bodies 75 by attaching bolts 74; and each Wheel assembly 72 and 73 comprises a specific one of rotatably mounted flanged wheels hereinafter separately described as wheels 91, 92, and 93, and said wheels function to procure vertical and transverse control of cover movement when rolling on the tracks 68 and 69.

The hatch-cover structural bodies 75 comprise a top plating member 76, vertical longitudinal and transverse beam members 77, and peripheral cover vertical support plates 78. The peripheral cover support plates 78 comprise, welded on the inside of their lower periphery, the attached gasket support angle plates 79, thereby providing retaining means for peripheral watertight gasket 80.

When the respective non-reversible hatch cover 61 and 62 are in ore service (see FIG. 9) and in closed position over their respective cargo-hold, the gasket arrangement for watertight scaling is protected from damage due to its location and may be dogged down for watertightness by removable swing-dog-bolt assemblies 81 mounted on hatch coaming faying bars 65 with machine screws 82 using certain tapped holes required for o-iltight gasket and bolting arrangements at the sealing face of the hatch coaming bars 65. For dogging down the respective nonreversible hatch- cover 61 or 62 their respective peripheral support plate 78 is adapted with slotted dog-pads 84 which are engaged by the respective swing dog bolt and nut 83. When the cover is dogged down for watertightness the vertical peripheral support 78 bears on the hatch coaming faying bar 65 thus relieving the watertight gasket 89 of the load of the cover. This vertical support plate 78 also functions to stop the gasket compression, thereby eliminating gasket damage due to overdogging. The watertight gasket 80 is fabricated of oil impervious material and remains in place when the respective hatch cover is in ore or oil service.

When the respective non-reversible hatch-covers 61 and 62 (see FIG. are in oil service, the respective wheel assemblies (72 or 73) may be removed, and the swingbolt dog assemblies are removed to effectuate a peripheral oil seal to the respective closed cover as shown by the arrangement in FIG. 10. A clamp angle 85 and a fibre gasket angle 86 assembly unit are attached with cap screws 87 to the horizontal sealing face of the peripheral hatch coaming faying bars 65, and to the lower outer face of the peripheral cover support plates 78. The tapped holes required for the oil seal gasketing arrangements in the support plate 78 and in the faying bars 65, and which are not used in attaching the watertight dogbolt assemblies 81 when in ore service are fitted with machine screws (not shown and preferably of brass) to protect the threads of the tapped holes when the respective hatch is in ore service.

Referring now to FIGS. 11 to 21 inclusive the nonreversible hatch- covers 61 and 62 are further disclosed as embodying the principle of the use of hand-wrench toggle operated slidable track-end ramp means 88 assembled as horizontally movable units in the fixed tracks 68 and 69 for effectuating the relative vertical movement of the respective hatch cover in its gasketing engagement with and disengagement from its respective hatch due to its associated ship-equipped power winch-operated means (not shown) for eifectuating track supported roll of said hatch-cover on specific functionally flanged wheels 91, 92, and 93 to-and-from single or stacked stowage clear of its respective hatch-opening, and over said plural intermediate track-end ramp means 88, and over plural parallel intermittent supporting tracks (single 89, and double 90) in said tracks 68 and 69 alongside said respective hatch opening.

The hand-wrench toggle operated slidable track-end ramp means 88 are shown in FIGS. 11 and 12. The three functionally flanged hatch-cover wheels 91, 92, and 93 are shown in FIGS. 13, 14, and 15. The two intermittent supporting tracks 89 and 98 are shown in FIGS. 16 and 18. The FIGS. 16 to 21 inclusive show the relative functional relationship of the respective hatch-cover wheels and their track supports in their closed and dogged coverand-hatch relationship as indicated in imaginary lines in FIG. 1l-as to wheel center and to its ramp-end relationship.

The slidable track-end ramp assemblies 88 as shown in FIGS. 11 and 12 are provided at the fixed tracks 68 and 69 for each of th six wheels of the respective hatch cover at its cover-closed position over its respective hatchthree on each side thereof as shown in FIG. 6 for the hatches 58 and 60, to provide the means to lower the respective cover supporting Wheels at their respective cover-closed position at said hatches. The slidable track-end ramp assemblies 88 each comprise the rampend 94 slidably mounted on the respective hatch horizontal stiifener 7t) and extendably slidable in its associated track- end 68 or 69. The ramp-end 94 is slidably extended or retracted with respect to its fixed track end 68 or 69 by a wrench operated double-threaded toggle means 95 mounted on the underside of the hatch stiffener 70 and is pivotally operatively connected to the slidable rampend 94 by pivot pin-bolt 96. The double threaded toggle means 95 comprises a double-threaded operative bolt 97 having RH. and L.H. threaded portions thereon extending outwardly from its mid-length. The said double-threaded portions of the bolt 97 mount operative opposite-threaded nuts-1eft 98 and right 99. The toggle nuts left 98 and right 99 are both pivotally connected to the slidable ramp-end 94 by two connecting links 181 pivotally mounted in said nuts 98 and 99 by link pivot screws 100 and to the pivot bolt 96 in the slidable ramp-end 94. The double-threaded operative bolt 97 is rotatably mounted in the outer structural flange 102 of the horizontal hatch stiffener 70, and in the inner supporting lug 103 on the underside of the horizontal hatch stiffener 711. The double-threaded operative bolt 97 is rotatably retained in its respective support bearings in the flanges 102 and lug 103 by pinned retaining nutsouter 104, and inner 105. A standard wrench may be used to function the operative toggle bolt 97 to position the slidable ramp-end 94 to its desired operative position (full lines 186) or to its negative position (broken lines 107) of FIG. 11.

Referring now to FIGS. 13 to 21 inclusive: The FIGS. 13, 14, and 15 show respectively the specific flanged wheels 91, 92, and 93 of each respective hatch-cover in the order of their arrangement on each said hatch-cover with respect to its forwardly moving front edge when rolling on its supporting ramped tracks 68 and 69 from an open off-hatch position to a lowered and closed-cover position over its respective hatch opening. The FIGS. 16, 1S, and show respectively in reverse the track relationship of ramped tracks 68 and 69 and intermittent tracks 89 and 90 supporting the hatch-cover as it rolls forwardly to its closed lowered position over its respective hatch opening. The FIGS. l7, l9, and 21 show respectively the closed and clamped relationship of the respective hatch-cover wheels at their closed and clamped gasketed position clear of the otherwise track supporting hatch stiffener 79 and its tracks 89 and 9t) and their rampends 83. (The FIGS. 17, 19, and 21 are as indicated cross-sectioned views respectively of FIGS. 16, 18, and 20.) From the views 17, 19, and 21 it is obvious that a forwardly rolling but rearwardly located wheel 91, type I, of FIG. 13, will lower to clearance of stiffener 70, and of track ramp-ends 83, and of tracks 68 or 69, at its eventual arrival in rolling to its closed position as indicated in FIG. 17. Likewise it is obvious that a forwardly rolling intermediate wheel 92, type II, of FIG. 14, will be supported in passing over intermittent track 90 of FIG. 17, but will lower to clearance of all local supports at its arrival in rolling to its closed position as indicated in FIG. 19. Likewise it is obvious that a frontal rolling wheel 93, type III, of FIG. 15, will be supported in passing over intermediate intermittent tracks 89 and 90, but will lower to clearance at its arrival in rolling to its closed position as indicated in FIG. 21,

Although we have described and illustrated our invention in considerable detail, we do not wish to be limited to the exact and specific details thereof as shown an de scribed, but may use such modification in, substitution for or equivalent thereof, as are embraced within the scope of our invention or as pointed out in the claims.

We claim:

1. In a ship, a first cargo hold for the transport of liquid cargo, second and third cargo holds for the trans port of liquid cargo or selectively for the transport of dry cargo, first fixed covering means overlying said first cargo hold and secured to said ship as a permanent part of the structure of said ship, second and third covering means over said second and third cargo holds respectively and movable in horizontal planes, the plane of horizontal movement of said second covering means lying below the plane of horizontal movement of said third covering means, said second and third covering means being movable to superposed stowage over said first cargo hold, said second and third covering means each comprising a first side, first means secured to said first side for sealing said second and third cargo-holds oil-tight, a second side, and second means secured to said second side for sealing said second and third cargo-holds water-tight.

2. In a ship for the transportation of dry cargo or selectively for the transportation of oil cargo and provided with a hatch, a hatch coaming and a coaming shelf, a reversibly usable hatch cover removably mounted over said hatch oil-tightly sealable against said coaming shelf or selectively water-tightly scalable against said coaming shelf and comprising -a first side and a second side, first gasketing means adjacent said first side oil-tightly sealable against said coaming shelf, and second gasketing means adjacent said second side water-tightly scalable against said coaming shelf.

3. Apparatus as in claim 2, further including threaded openings in said coaming shelf, removable swing-bolt dogging means threadable into said threaded openings when said hatch is in dry cargo service and operable to compress said second gasketing means, and removable bolting means threadable into said threaded openings when said hatch is in oil cargo service and operable to compress said first gasketing means, whereby said removable swing-bolt dogging means and said removable bolting means we positioned the same distance outboard the hatch when either is in operative position.

4. In a ship for the transportation of dry cargo or selectively for the transportation of oil cargo and provided with a hatch, a hatch coaming and a coaming shelf, a hatch cover removably mounted over said hatch oil-tightly sealable against said coaming shelf or selectively watertightly scalable against said coaming shelf and comprising a peripheral downwardly extending enclosing rim, said hatch cover directly engaging the coaming shelf through said rim when said hatch is closed, first gasketing means mounted interiorly to said rim and water-tightly scalable between said hatch cover and said coaming shelf, clampangle gasket-retaining means removably mounted exteriorly to said rim, and second gasketing means operatively interposable between said clamp-angle gasket-retaining means, said rim and said coaming shelf and oil-tightly scalable between said hatch cover and said coaming shelf.

5. Apparatus as in claim 4, further including threaded openings in said coaming shelf, removable swing-bolt dogging means threadable into said threaded openings when said hatch is in dry cargo service and operable to compress said first gasketing means, and removable bolting means threadable into said threaded openings when said hatch is in oil cargo service and operable to compress said second gasketing means, whereby said removable swing-bolt dogging means and said removable bolting means are positioned the same distance outboard the hatch when either is in operative position.

6. Apparatus as in claim 4, further including wheel means mounted to said hatch cover removable therefrom when said second gasketing means is opcratively engaged between said hatch cover and said coaming shelf.

7. In a ship, a first cargo hold for the transport of liquid cargo, second and third cargo holds for the transport of liquid cargo or selectively for the transport of dry cargo, first fixed covering means overlying said first cargo hold and secured to said ship as a permanent part of the structure of said ship, second and third covering means over said second and third cargo holds respectively and movable in horizontal planes, the plane of horizontal movemet of said second covering means lying below the plane of horizontal movement of said third covering means, said second and third covering means being movable to superposed stowage over said first cargo hold, said wheeled covers each comprising a peripheral downwardly extending enclosing rim directly engageable with said ship around its respective cargo-hold when said cargo-hold is closed, first gasketing means mounted interiorly to said rim and water-tightly scalable between said cover and said cargo-hold, clamp-angle gasket-retaining means removably mounted exteriorly to said rim, and second gasketing means operatively interposable be tween said clamp-angle gasket-retaining means, said rim and said ship and oil-tightly sealable between said cover and said cargo-hold.

8. In a ship, a first cargo hold for the transport of liquid cargo, second and third cargo holds for the transport of liquid cargo or selectively for the transport of bulk cargo, second and third covering means over said second and third cargo holds respectively and movable in horizontal planes, the plane of horizontal movement of said second covering means lying below the plane of horizontal movement of said third covering means, said second and third covering means being movable to superposed stowage over said first cargo hold, further including a plurality of double-flanged wheel means rotatably mounted to said second and third covering means and aligned in the direction of horizontal movement of said second and third covering means, first track means rollably supporting said double-flanged wheel means and extending from said first cargo hold to said second and third cargo holds, the continuity of said first track means being interrupted by gaps underlying the positions of said plurality of double-flanged wheel means when said second and third covering means overlie said second and third cargo holds respectively, a plurality of second track sections in said gaps and underlying said plurality of doubleflanged wheel means when said second and third covering means overlie said second and third cargo holds respectively, each of said second track sections corresponding in gauge to the flanges on the double-flanged wheel means overlying said second track section when the respective covering section overlies its respective cargo hold, said second track section not corresponding in gauge to the flanges on another of said double-flanged wheel means, the double-flanged wheel means of said second and third covering sections being adapted to roll on said first track means and on said non-corresponding second track sections, the bottoms of said double-flanged wheel means being lowered below the plane of rolling engagement with said first track means when each of said double-flanged Wheel means overlies its respective corresponding second track section.

9. In a ship, a first cargo hold for the transport of liquid cargo, second and third cargo holds for the transport of liquid cargo or selectively for the transport of bulk cargo, second and third covering means over said second and third cargo holds respectively and movable in horizontal planes, the plane of horizontal movement of said second covering means lying below the plane of horizontal movement of said third covering means, said second and third covering means being movable to superposed stowage over said first cargo hold, further including a plurality of wheel means rotatably mounted to said second and third covering means, wheel-like flanges concentrically mounted to each side of each of said wheel means, first track means rollably supporting said Wheel means and extending from said first cargo hold to said second and third cargo holds, the continuity of said first track means being interrupted by gaps underlying the positions of said plurality of wheel means when said second and third covering means overlie said second and third cargo holds respectively, a plurality of second track sections in said gaps and underlying said plurality of wheel means and wheel-like flanges when said second and third covering means overlie said second and third cargo holds respectively, each of said second track sections corresponding in gauge to the pair of wheel-like flanges secured to the wheel means overlying said second track section when the respective covering section overlies its respective cargo hold, said second track section not corresponding in gauge to another pair of said wheel-like flanges, the wheel means and associated wheel-like flanges of said second and third covering sections being adapted to roll on said first track means and on said non-corresponding second track sections respectively, the bottoms of said wheel means being lowered below the plane of rolling engagement with said first track means when each of said wheel means and wheel-like flanges overlies its respective corresponding second track section.

10. In a ship, a first cargo hold for the transport of liquid cargo, second and third cargo holds for the transport of liquid cargo or selectively for the transport of bulk cargo, second and third covering means over said second and third cargo holds respectively and movable in horizontal planes, the plane of horizontal movement of said second covering means lying below the plane of horizontal movement of said third covering means, said second and third covering means being movable to superposed stowage over said first cargo hold, said second and third covering means each having forward edges facing their respective cargo holds and rearward edges facing said first cargo hold, six supporting wheels rotatably mounted to each of said second and third covering means, three on 'each side thereof and paired to provide a 'forward pair, an intermediate pair, and a rearward pair, broad wheel-like flanges concentrically mounted to each side of each of said forward pair of wheels, a broad Wheel-like flange concentrically mounted to one side of each of said intermediate pair of wheels, first track means rollably supporting said wheels and extending from said first cargo hold to said second and third cargo holds, the

continuity of said first track means being interrupted by gaps underlying the positions of said wheels when said second and third covering means overlie said second and third cargo holds respectively, intermediate and rearward track sections in said gaps and underlying said intermediate and rearward wheels respectively when said second and third covering means overlie said second and third cargo holds respectively, the flanges on said forward pair of wheels engageable with the tops of said intermediate and rearward track sections, the flanges on said intermediate pair of wheels engageable with the tops of said rearward track sections, whereby said wheels are adapted to roll on said first track means, said flanges on said for ward pair of wheels are adapted to roll on said intermediate and rearward track sections, and said flanges on said intermediate pair of wheels are adapted to roll on said rearward track sections, the bottoms of said wheels being lowered below the plane of rolling engagement with said first track means when said second and third covering means overlie their respective cargo holds.

11. Apparatus as in claim 10, further including gasket means operatively interposed between said second and third covering means and their respective cargo holds, ramped track ends slidably mounted to said first track means and extendable into or withdrawable from said gaps in said first track means corresponding to the positions of said forward, intermediate and rearward wheels when said cargo holds are closed, whereby when said ramped track ends are extended into said gaps and said second and third covering means are rolled to closed position over their respective cargo holds, said forward, intermediate and rearward wheels roll down said ramped track ends to place said second and third covering means in weight-b alanced gasketed contact with the cargo holds.

12. In a ship provided with a hatch opening, the combination comprising a hatch cover, a plurality of double flanged wheel means rotatably mounted to said hatch cover, first track means rollably supporting said doubleflanged wheel means, said first track means extending from a position alongside said hatch opening to a position away from said hatch opening, the continuity of said first track means being interrupted by gaps underlying the positions of said plurality of double-flanged wheel means when said hatch cover overlies said hatch opening, a plurality of second track sections in said gaps and underlying said plurality of double-flanged wheel means when said hatch cover overlies said hatch opening, each of said second track sections corresponding in gauge to the flanges on the double-flanged wheel means overlying said second track section when said hatch cover is closed over the hatch opening, said second track section not corresponding in gauge to the flanges on another of said doubleflanged wheel means, the double-flanged wheel means of said hatch cover being adapted to roll on said first track means and on said non-corresponding track sections, the bottoms of said double-flanged wheel means being lowered below the plane of rolling engagement with said first track means when each of said double-flanged wheel means overlies its respective corresponding second track section.

13. The combination according to claim 12, said hatch cover comprising a first side and a second side, first gasketing means adjacent said first side oil-tightly scalable between said hatch cover and said hatch opening, and second gasketing means adjacent said second side watertightly scalable between said hatch cover and said hatch opening.

14. The combination according to claim 12, said hatch cover comprising a peripheral downwardly extending enclosing rim directly engageable with said ship around said hatch opening when said cargo-hold is closed, first gasketing means mounted interiorly to said rim and watertightly scalable between said hatch cover and said hatch opening, clamp-angle gasket-retaining means removably mounted exteriorly to said rim, and second gasketing means operatively interposable between said clamp-angle gasket-retaining means, said rim and said ship and oiltightly scalable between said hatch cover and said hatch opening.

15. In a ship provided with a hatch opening, the combination comprising a hatch cover, a plurality of wheel means rotatably mounted to said hatch cover, wheel-like flanges concentrically mounted to each side of each of said wheel means and extending from a position alongside said wheel means and extending from a position alognside said hatch opening to a position away from said hatch opening, the continuity of said first track means being interrupted by gaps underlying the positions of said plurality of wheel means when said hatch cover overlies said hatch opening, a plurality of second track sections in said gaps and underlying said plurality of wheel means and said wheel-like flanges when said hatch cover overlies said hatch opening, each of said second track sections corresponding in gauge to the pair of wheel-like flanges secured to the wheel means overlying said second track section when said hatch cover is closed over the hatch opening, said second track section not corresponding in gauge to another pair of wheel-like flanges, the wheel means and associated wheel-like flanges being adapted to roll on said first track means and on said non-corresponding second track sections respectively, the bottoms of said wheel means being lowered below the plane of rolling engagement with said first track means when each of said wheel means and wheel-like flanges overlies its respective corresponding second track section.

16. In a ship provided with a hatch opening, the combination comprising a hatch cover, six supporting wheels rotatabiy mounted to said hatch cover, three on each side thereof and paired to provide a forward pair, an intermediate pair, and a rearward pair, broad wheel-like flanges concentrically mounted to each side of each of said forward pair of wheels, a broad wheel-like flange concentrically mounted to one side of each of said intermediate pair of wheels, first track means rollably supporting said wheels and extending from a position alongside said hatch opening to a position away from said hatch opening, the continuity of said first track means being interrupted by gaps underlying the positions of said wheels when said hatch cover overlies said hatch opening, intermediate and rearward track sections in said gaps and underlying said intermediate and rearward wheels respectively when said hatch cover overlies said hatch opening, the flanges on said forward pair of wheels engageable with the tops of said intermediate and rearward track sections, the flanges on said intermediate pair of wheels engageable with the tops of said rearward track sections, whereby said wheels are adapted to roll on said first track means, said flanges on said forward pair of wheels are adapted to roll on said intermediate and rearward track sections, and said flanges on said intermediate pair of wheels are adapted to roll on said rearward track sections, the bottoms of said wheels being lowered below the plane of rolling engagement with said first track means when said hatch cover overlies the hatch opening.

17. In a ship for the transportation of dry cargo or selectively for the transportation of oil cargo, the combination comprising three cargo holds in directly and horizontally adjoining relationship and constituting a correlated group arnanged longitudinally of the said ship, one of said cargo holds being adapted solely for the transportation of oil; a fixed cover overlying said cargo hold 1 and secured to said ship as a permanent part of the structure of said ship; the remaining cargo holds being adapted for the transportation of oil cargo or selectively for the transportation of dry cargo; sliding one-piece hatch covers for each of said last-mentioned cargo holds of size sufficient to cover said cargo holds in one section and adapted to be rolled selectively to or from overlying relationship with said cargo holds and movable in horizontal planes to superposed stowage over the first mentioned cargo hold; the planes of horizontal movement of said hatch covers being at different elevations with respect to each other and with respect to the ship.

18. Apparatus as in claim 17, further including a pcripheral downwardly extending enclosing rim on each of said sliding hatch covers directly engageable with said ship around said last-mentioned cargo holds When said cargo holds are closed; first gasketing means mounted intcriorly to said rim and watertightly scalable between said sliding hatch covers and said ship; clamp-angle gasketretaining means removably mounted exteriorly to said rim; and second gasketing means operatively interposable between said clamp-angle retaining means, said rim and said ship and oil-tightly scalable between said sliding hatch covers and said ship.

19. Apparatus as in claim 18, said first gasketing means being relatively soft and resilient and said second gasketing means being relatively hard; further including threaded openings in said ship around said last-mentioned cargo holds; removable swing-bolt dogging means threadable into said threaded openings when said last-mentioned cargo holds are in dry cargo service and operable to compress said first gasketing means to Water-tight condition; and closely-spaced removable bolt means threadable into said threaded openings when said last-mentioned cargo holds are in oil service and operable to compress said second gasketing means to oil-tight condition.

20. Apparatus as in claim 17, further including threaded openings in said ship around said last-mentioned cargo holds; each of said sliding hatch covers comprising a first side and a second side; first relatively hard-gasketing means on said first side; a plurality of closely-spaced removable bolting means threadable into said threaded openings when said last-mentioned cargo holds are in oil service and operable to compress said first gasketing means to oil-tight condition; second relatively soft and resilient gasxeting means on said second side; and removable swin -bolt do gging means threadable into said threaded openings when said last-mentioned cargo holds are in dry cargo service and operable to compress said second gasketing means to water-tight condition.

References Cited in the file of this patent UNITED STATES PATENTS 2,150,763 Elliott Mar. 14, 1939 2,376,245 Prick May 15, 1945 2,394,607 Gray et a1. Feb. 12, 1946 2,587,863 Lambert Mar. 4, 1952 2,726,623 Jernstrom Dec. 13, 1955 2,804,039 Gray et a1. Aug. 27, 1957 2,831,448 Suderow Apr. 22, 1958 2,831,449 Suderow Apr. 22, 1958 2,840,027 Chapman et al June 24, 1958 2,869,502 Stransky Jan. 20,1959

FOREIGN PATENTS 611,848 Great Britain Nov. 4, 1948 UNITED STATES PATENT. OFFICE CERTIFICATE oF coRREc'HoN Patent N00 2 997 011 August 22 1961 Donald F. MacNaught et a i It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 6 line 7 for "FIGS. 18 and 18" read FIGS. 18 and 19 column 7, line 64, for "housing" read housings column l1 line 31, for "-an" read and column 15,- line 9 for "and extending from a position alongside read first track means rollably supporting line 10, for "alognside" read alongside Signed and sealed this 9th day of January 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Pate:

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