WO2007069273A2

WO2007069273A2 - An improved hatch cover for improving cargo capacity

Info

Publication number: WO2007069273A2
Application number: PCT/IN2006/000429
Authority: WO
Inventors: Prerit Kailash Misra
Original assignee: Prerit Kailash Misra
Priority date: 2005-11-28
Filing date: 2006-10-20
Publication date: 2007-06-21
Also published as: WO2007069273A3

Abstract

The present invention is a hatch cover having, a novel construction for container ships . The present invention will obviate the need of lashing equipment as is currently used for the 'on deck' carriage of containers. It comprises a system involving the continuation of cell guides (1) direct from the hold (17) through to above the main deck to the required height. Individual hatch cover panels (2) for each row are then placed on each row to divide the hold stack from the deck stack; the hold stack being the stack of containers (7) inside the holds while the deck stack is the stack of the containers (7) on the deck of the ship. The individual hatch covers (2) are designed accordingly to fit into the cell guides (1) and also to considerably reduce water ingress to the hold. The construction of the hatch cover (2) is in such a way that it facilitates weather tightness .

Description

Title of the invention: An improved hatch cover for improving cargo capacity.

Field of invention: The present invention relates to a hatch cover for improving cargo capacity of the sea going ships. More particularly, it relates to stacking of the containers in the hold stack as well as in a deck stack in safe and convenient manner for better safety against loss of the containers in stormy weather and ease of loading and unloading the containers. Prior art: In the conventional system, single hatch cover is used to cover the opening of several rows and containership has been fitted with either twin, or as in the case of bigger ships, three hatch covers across for each hold. The containers in the hold are contained within cell guides. On the conventional container ships the cell guides do not extend further and are limited to the holds. The hatch cover is then placed on top of the opening and containers are then further stacked on top of the hatch cover. The containers that are stacked on hatch covers then require to be secured using different types of twist locks and then lashed with the aid of lashing bars and are subject to severe limitations such as stack weight distribution of the individual container. It is preferable to stack the reefer containers (the containers provided with the facility of refrigeration of goods) over the deck for ease of maintenance of the refrigeration system, which is often required. The loss of such containers and also of the other containers stacked over the deck, in stormy weather is always possible and such events do occur in practice. With container ships getting larger the maximum permissible stack weight of most hatch covers is a limiting factor in the optimum carriage of deck containers. This is due in part to the fact that, prior art hatch covers which cover an area of usually 3 or 4 containers across in the holds cannot be designed with a weight of more than approximately 40 metric tonnes due to the design of shore gantry cranes, which usually have a safe working load of 40MT. although the newer gantries have a larger safe working load. This limiting factor in turn affects the maximum permissible stack weight on the hatch cover as the same hatch cover has to accommodate 3 / 4 or more containers rows/stacks. Hence a hatch cover with standard dimensions as is currently the norm and if notched at spaces to slide over cell guides, it would not only be very awkward to handle, resulting in damage to cell guides but would restrict the permissible stack weight of the hatch cover and also reduce the advantage achieved as regards flexibility in cargo planning for port rotation.

Another method of carrying containers is hatch coverless container ships. In this method containers are constructed for a maximum stacking of 9 high, the greater loads being placed on the lower containers that results in damage to the lower tiers of containers and cell guides. Deficiencies of prior art:

1 In container ships wherein single hatch cover opening is used, containers are stacked on hatch covers, which requires huge amount of expenditure for securing the containers on deck. 2 Even though, in container ships having single hatch cover opening, the containers that are stacked on hatch covers are secured with twist locks and further lashed with lashing bars, the threat of losing containers at sea still exist. Also, the cargo planners have to spend lot of time on planning activity.

3 In case of hatch coverless container ships, the cell guides are continued straight through till the required height on deck that give rise to the problem of water ingress into holds.

4 Another flaw in the hatch coverless container ships is that, since the containers are constructed for a maximum stacking of 9 high, the greater loads being placed on the iower containers result in damage to the lower tiers of containers and cell guides.

The need is felt for ridding these problems not only by the ship's owners, but ship's officers, cargo planners and all concerned with the safe carriage of "on deck" container cargoes.

Summary of invention: The purpose of the present invention is to provide a hatch cover that eliminates the need of any of the usual lashing equipments of deck containers and associated equipment (semi automatic twist locks, lashing bars, automatic mid locks etc).

The objective of the present invention is to eliminate the perpetual threat of losing containers at sea.

Another objective of the present invention is to increase flexibility in cargo planning associated with the fact that each row of containers may be isolated for a particular port of discharge, thus reducing the need for expensive restows.

Yet another objective of the present invention is to increase the individual permissible maximum stackweights of each row of containers "on deck" as a consequence of having a single hatch cover for each row; the "on deck" stack and the stack in the hold being divided by the hatch cover in between them. Thus an increase in the amount of total weight capable of being loaded on the decks of container ships. This increase in deck stackweights will lead to increased cargo capacity. The limiting factor in this case will be ship stability.

Yet another objective of the present invention is to increase flexibility in planning also due to the fact that container weight distribution within a stack do not need to be as strictly adhered to, as compared to using prior art systems of container securing (twist-locks, lashing bars etc.)

Yet another objective of the present invention is to increase the number of reefer containers which may be carried on deck. This would be possible as a consequence of the support framework and walkways which would be required for deck cell guides and so enable the fitting of reefer plugs and ease the maintainance work of the refrigeration system, at higher tiers on the vessel from the standard 2 high.

Yet another objective of the present invention is to achieve faster turnaround as a result of the elimination of conventional lashings. Another major benefit of the present invention is that, it may also be retrofitted on existing Container ships and so is not only restricted to new buildings.

Yet another objective of the present invention is to provide a hatch cover, which is very easy to handle due to its weight within the handling capacity of the cranes available at most of the ports and would allow the operator to achieve maximum permissible stack weight of the hatch cover.

Present invention: The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention as described bellow in the preferred embodiment. The present invention is a hatch cover having a novel construction for container ships. The present invention will obviate the need of lashing equipment as is currently used for the "on deck' carriage of containers. It is the combination of cell guides, which continue on completely uninterrupted from the holds through to the decks, and a different type of hatch cover construction, with single hatch cover being used for each row.

Traditionally container ships have been fitted with either twin, or as in the case of bigger ships, three hatch covers across for each hold. The present invention provides to have a single hatch cover for each row and not one hatch cover for several rows, as used normally. This is done with a view to facilitate continuation of cell guides direct from the hold through to the main deck to the required height. Individual hatch cover panels are placed on each row to divide the hold stack from the deck stack. The individual hatch covers are constructed accordingly to fit into the cell guides and also to eliminate water ingress to the hold. Brackets to deck structures, which could include walkways to enable repairs to cell guides, support the cell guides on deck. This would also enable the fitting of reefer sockets for the connection of reefer containers and hence reefer containers could then be carried at even higher tiers on deck.

The construction of the hatch cover takes into account the cell guides, which go straight through the hatch cover openings. Hence the construction of the hatch cover is such that the cell guides guide the hatch cover at its corners. Also the hatch cover rests on athwart ships extension of the outer port and starboard of each hold. The construction of the hatch cover is in such a way that it facilitates water tightness. The main body of the hatch cover slides into the extended cell guides in the same way as a 40ft container and thus has similar construction as the top of a 40 ft container. The forward and aft end of the hatch cover is extended to rest on top of the hatch coamings. Additionally, the center part of the hatch cover is extended athwart ships in both directions to facilitate weather tightness between hatch covers. The athwart ships extensions of the extreme port and starboard hatch covers of a hatch cover opening would rest on the hatch cover coamings (coamings are the raised borders around the hatches/holds of the ship to keep out water) and longitudinal members. Weather tightness at the forward and aft ends (and also the outboard extreme port and starboard hatch covers of the hatch cover openings) is achieved with the conventional hatch cover packing and compression bar or sliding rubber packings resting on the hatch coaming. The area behind the cell guide is completely covered with steel plate. Stiffeners are used to strengthen the hatch covers. Accordingly, improving the cargo capacity and eliminating the problems of water ingress and use of lashing equipment is achieved. Advantages of present invention:

1. The present invention eliminates the requirement of lashing containers on the decks of container ships.

2. The present invention eliminates perpetual threat of losing containers at sea.

3. The present invention increase flexibility in cargo planning associated with the fact that each row of containers may be isolated for a particular port of discharge, thus reducing the need for expensive restows.

4. The present invention increases amount of weight capable of being loaded on the decks of container ships.

5. The present invention increases flexibility in planning also due to the fact that stack weight distribution do not need to be as strictly adhered to as compare when using conventional system container securing (twist locks, lasing bars etc.)

6. The present invention increases the number of reefer containers, which may be carried on deck. This would be possible as a consequence of the support of framework, which would be required for deck cell guides and enable the fitting of reefer plugs at higher tiers on the vessel from the standard 2 high.

7. The present invention increases the individual permissible maximum stack weights of each row of containers "on deck" as a consequence of the additional strengthening and weight of hatch cover panel, which would be possible with having a single hatch cover for each row.

8. The present invention achieves faster turnaround as a result of the elimination for conventional lashings.

9. The size of single hatch covers, which cover only one row, making them easy to handle and position.

Description of the figures: the present invention ^ΛλAn improved hatch cover for improving cargo capacity" is now described with help of following figures.

Fig. 1 shows the perspective view of the complete arrangement according to the present invention.

Fig. 2 shows the perspective view of the hatch cover according to the present invention.

Fig. 3 shows sealing arrangement on the hatch cover corners according to the present invention in its perspective view.

Fig. 4 shows the arrangement of the steel boxes between the cell guides and the hatch coamings in its perspective view.

Fig. 5 shows the arrangement of drain holes and the drain channels in the cell guides and the hatch coamings respectively in a perspective view.

Fig. 6 shows the arrangement of the drain plugs in the hold of the ship in a perspective view. Fig. 7 shows alternative sealing arrangement using hydraulically operated steel plate in the cell guides in perspective view. Fig. 8 shows the alternative water drainage arrangement wherein the drain channels are not required, in its perspective view. Description: With reference to the above figures, the present invention "An improved hatch cover for improving cargo capacity" comprises a system involving the continuation of cell guides (1) direct from the hold (17) through to above the main deck to the required height. Individual hatch cover panels (2) for each row are then placed on each row to divide the hold stack from the deck stack; the hold stack being the stack of containers (7) inside the holds while the deck stack is the stack of containers (7) on the deck of the ship. The individual hatch covers (2) are designed accordingly to fit into the cell guides (1) and also to considerably reduce water ingress to the hold. The construction of the hatch cover (2) is in such a way that it facilitates water tightness. The main body of the hatch cover (2) slides into the extended cell guides (1) in the same way as a 40ft container and thus has similar construction as the top of a 40 ft container viewed in its Otop view. The forward and aft end of the hatch cover has extensions (20) to rest on top of the hatch coamings. Additionally, the center part of the hatch cover is provided with extensions (21) athwart ships in both directions to facilitate weather tightness between cell guides (1). The athwart ships extensions (21) of the extreme port and starboard hatch covers of a hatch cover opening would rest on the hatch cover coamings (5) and longitudinal members (not shown in the drawings). Weather tightness at the forward and aft ends (and also the outboard extreme port and starboard hatch covers (2) of the hatch cover openings) is achieved with the conventional hatch cover packing and compression bar (not shown in the drawings) or sliding rubber packing (11) resting on the hatch coaming. The weather tightness is achieved between intermediate hatch cover panels (2) by double rubber lip with drainage or open joint with drainage in a known way. The area behind the cell guide (1) is completely covered with steel plate (13). The guide plates (23) are fitted to forward and aft section of hatch cover and locate the hatch cover in its proper position as they are guided within the hatch cover guides (6). Stiffeners are provided to strengthen the hatch covers (not shown in the drawings) and give it the required rigidity. Accordingly, improving the cargo capacity and eliminating the problems of water ingress and use of lashing equipment is achieved.

Partial weather-tight sealing between hatch covers (2) and coamings (5) (as accepted on container ships) is achieved by rubber packing of the sliding type (11) acting direct on the hatch coaming (5) or by rubber packing (10) acting on a compression bar (not shown in drawing). The corner rubber packings (10) are fitted in the recess (12) provided for the same in the hatch cover

(2).

A lattice of drain channels (15), which run around the gap between cell guide (1) and hatch coaming (5) and a drain channel which runs below hatch cover panels (2), is used to drain water which may pass through the rubber packings (10) and (11) as shown in figs. 5. The drain holes (14) in this case are positioned vertically displaced downwards from the lower most rubber packing as shown in figure 5.

Water ingress in the area between the cell guides (1) and hatch coamings (5) is blocked by fitting steel plates (13). Water that enters between the rubber packings (10) fitted in the corners of the hatch cover panel (2) and cell guides (1) is drained off with drain holes (14) made in the cell guides (1) as shown in the figure 5. This water will drain off into the drain channels (15) provided in the hatch coaming (5).

As an alternative method of achieving partial weather-tightness the drain holes are provided in both the cell guides and steel covering boxes between them and the hatch coaming and water is allowed to drain into the boxes themselves and then drained out of the boxes by the use of drain plugs. The drain holes (22) in this case are placed at positions between the pairs of the rubber packings as shown in fig.8. The need for the drain channels is obviated in this alternative.

Another alternative method of achieving partial weather-tightness as shown in fig.7, sliding plates (18) are fitted in groves cut into the cell guides (1). These grooves would be below the water ingress boxes (13) fabricated around the cell guide (1) and supported by another plate below them (not shown in the drawings) on which the sliding plates (18) rest. The sliding plates (18) are hydraulically operated, with an additional mechanical emergency mechanism. When retracted they do not hinder the movement of containers (7) within the cell guides (1). When they are in "closed " position, i.e. made to slide in the direction of the hold, they would provide compression to regular sliding type rubber packings (11) which would be fitted right around the bottom of the hatch cover (2) i. e. including the corner sections of the hatch covers (2). In this system the drain channel lattice (15), as described above, is not required and neither are the corner rubber packings on the vertical face of the hatch cover. Another alternative is to use inflatable rubber packings at the corners of the hatch cover (2). These may be inflated /deflated as required with a pneumatic system.

The contact between hatch cover (2) and hatch coamings (5) is with conventional rest pad systems. Hold-downs are fitted to secure the hatch cover (2) in position.

Hatch-coverless ships face problems such as excess water ingress into holds, requiring elaborate pumping arrangements. Another flaw in the hatch-coverless container ship design is that since most containers are designed for a maximum stacking of 9 high, the greater loads being placed on the lower containers often result in damage to the lower tiers of containers and cell guides. This problem is immediately eradicated by the present invention as the hold stack and the deck stack are divided with a single hatch cover.

The problem of hatch cover panel weights, keeping in mind the permitted handling capacity of shore cranes, is also eliminated; as single hatch covers are made considerably lighter than conventional hatch covers keeping the individual weight of the hatch cover (2) well within 40 tonnes to match the load carrying capacity of the cranes commonly available at the ports.

The cell guides (1) on deck are supported by brackets and other supporting and strengthening elements i. e. support frame work

(19) to deck structures, which would include walkways (3) and ladders (4) to enable repairs to cell guides (1). This would also enable the fitting of reefer sockets (not shown in the drawings), for the connection of reefer containers, to power supply at higher tiers and hence reefer containers could then be carried at even higher tiers on deck than is the current norm.

Container shoes (9) are provided on the hatch cover (2) on which the containers can rest. Hatch cover (2) is provided with the lifting sockets (8) to facilitate handling the hatch cover by means of the lifting tackles. The hatch covers (2) are provided with rest pads

(not shown in the drawings) to facilitate stacking them while in stored condition.

Thus the hatch cover according to the present invention eliminates the need for any of the usual lashing of deck containers and associated equipment, (semi automatic twist locks, lashing bars, automatic mid-locks etc).

Container planning would be tremendously simplified with the additional flexibility obtained regarding port rotation, as also the continuous problem associated with weight distribution within a stack.

The perpetual threat of losing deck containers at sea is practically eliminated as these containers are securely stacked on the hatch cover (2) and supported by the cell guides (1) even though they are stacked above the deck.

The above system would prove to be advantageous in several ways not just to ship's owners but ship's officers , cargo planners and all concerned with the safe carriage of "on deck" container cargoes.

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment.

Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or matter.

The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention; which is defined by the scope of the following claims.

Claims

I claim

1. An improved hatch cover for improving cargo capacity comprising hatch cover (2) and a system comprising continuation of cell guides (1) direct from the hold (17) through the hatch covers (2), to above the main deck; the said cell guides (1) being supported and strengthened by means of support frame work (19) including walk ways (3) and ladders (4); individual hatch cover panels (2), one for each row then being placed on each row of containers (7); individual hatch covers (2) accordingly made to fit in to the cell guides (1) slidably, dividing the hold stack and the deck stack; the hold stack being stack of the containers (7) in the holds (17) while the deck stack being stack of the containers (7) over the deck, supported in the cell guides (1); the hatch cover (2) having its main body of the same shape and size of that of the containers (7) to be stacked as seen in their top view and made to fit slidably in to the cell guides (1); the hatch cover (1) being provided with extensions (20) at both ends for support and extensions (21) to extend the hatch cover (2) athwart the ship in both directions so as to facilitate weather tightness between the hatch cover panels (2); the said athwart ship extensions (21) of the extreme port and starboard side resting on the hatch cover comings (5); the hatch covers (2) being strengthened with structural members and the contact between the hatch covers (2) and the said hatch coamings (5) being with rest pad system and the hatch covers being secured in position by hold downs; the hatch covers (2) being provided with at least one rubber packing (10) fitted in the recess (12); the hatch cover (2) is provided with hatch cover lifting socket (8) so as to facilitate lifting the said hatch cover (2) by means of the lifting tackle, and container shoes (9) on which the containers (7) rest; steel plates (13) being provided between cell guides (1) and coamings (5) so as to arrest water ingress through the gap between them; drain holes (14) and (22) are provided in the cell guides (1) and drain channels provided in the hatch coamings to drain off water that may enter through the rubber packings (10).

2. An improved hatch cover for improving cargo capacity as claimed in claim 1 wherein, as an alternative embodiment sealing arrangement comprises sliding plates (18) fitted in the grooves cut in the cell guides (1), the said grooves being positioned bellow the water ingress plates (13) fabricated around the cell guides (1) and supported by another plate bellow (not shown in the drawings); the said sliding plates (18) being operated by hydraulic system (not shown) with additional mechanical emergency mechanism; the said sliding plates (18) when retracted, not hindering the movement of the containers, while in the closed or extended position i. e. when made to slide in the direction of hold (17), providing compression to regular sliding type rubber packing being fitted right around the bottom of the hatch cover (2) obviating the need of the drain channel lattice (15).

3. An improved hatch cover for improving cargo capacity as claimed in claim 1 wherein, as an alternative embodiment the sealing arrangement comprises inflatable rubber packings at the corners of the hatch cover (2) which is inflated to seal and deflated to release the seal using pneumatic system (e. g. compressed air).

4. An improved hatch cover for improving cargo capacity as claimed in claim 1 wherein, as an alternative embodiment for the water drainage arrangement the drain holes (22) are provided in line through the cell guides (1), steel boxes (13) and the hatch coamings (5) together with the drain plugs (23) so as to drain out the water; obviating the need for the drain channels.

5. An improved hatch cover for improving cargo capacity as claimed in claim 1 as substantially described hereinbefore, with reference to the accompanying drawings.

Dated this 10 it™h day of October 2006

(M. D. BH ATE) AGENT FOR THE APPLICANT