GB2210333A

GB2210333A - Deck construction

Info

Publication number: GB2210333A
Application number: GB8723002A
Authority: GB
Inventors: Roger Philip Adams
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-09-30
Filing date: 1987-09-30
Publication date: 1989-06-07
Also published as: GB8723002D0

Abstract

The deck of a vessel particularly a Ro-Ro-ferry comprises partitions 3 between an upper load-bearing water- permeable surface 1 and a lower water-retaining surface 2 which define separate cells 4 into which water can flow. The water retained in the cells 4 cannot flow unrestrictedly across or along the vessel. Each cell 4 preferably has an outlet 8, in the lower surface 2, displaced from the middle of the cell towards the nearer side and/or end of the deck, so that the lower part of a sloping swamped deck is drained more quickly than the upper part. <IMAGE>

Description

DECK CONSTRUCTION This invention relates to decks for vessels, particularly, but not solely, roll on/roll off vehicle ferries.

The commercial reason for building ferries with car decks that extend, uninterrupted by bulkheads, to the maximum plan of the vessel is abundantly clear.

However, this open plan construction greatly impairs the stability of the vessel should a volume of water enter the parking area, the water being totally unrestricted in its movement in a rolling situation or should the vessel pitch or yaw to any degree.

The proposed engineering solution to this problem has hitherto been to divide the vehicle parking area up into compartments by the use of watertight bulkheads with watertight doors, which greatly restrict the free flow of onboard water. Unfortunately this engineering solution runs head on into the commercial requirement, i.e. to have a maximum area available for parking, and the need to load and unload vehicles in the shortest possible space of time.

The present invention is based on the idea of restricting the free movement of water, in order to enhance the stability of the vessel in adverse conditions, while leaving the on-deck parking area unimpeded for vehicular parking and movement, by building the bulkheads underneath the load-bearing surface, not on top, and allowing any ingress of water to flow through the deck into cellular compartments.

Accordingly, the invention provides a deck for a vessel, comprising an upper load-bearing water-permeable surface, a lower water-retaining surface spaced from the upper surface so as to define an intermediate space, and water-retaining partitions extending between the upper and lower surfaces and dividing the intermediate space into separate cells into which water can flow through the upper surface.

Preferably, each cell has an outlet in the lower surface, so that water can be drained to the deck below or to the bilges. The outlet is preferably displaced from the middle of the cell towards the nearer side and/or end of the deck. This provides the advantage that, in an adverse situation, the drainage pattern will act as a self-levelling mechanism, the water on the downward side of a sloping deck being drained in advance of that on the highest side.

The upper surfaces may be regularly perforated, with holes or slots, but in a preferred embodiment combining strength and permeability, it comprises horizontal flanges associated with the partitions and horizontal gratings between the flanges.

In a particularly simple and effective arrangement the cells are substantially rectangular in plan view.

However, it is possible for the cells to be of other convenient shapes, e.g. hexagonal.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic isometric view of part of a deck of cellular construction, for a vehicle ferry; Figure 2 is a diagrammatic plan view of the partitions of the cellular deck construction; Figure 3 is an enlarged perspective view of part of the deck, viewed on line B-B in Figure 2; Figure 4 is a section on line A-A in Figure 2, showing retention of water by the level deck; and Figure 5 is a section on line A-A in Figure 2, showing retention of water by a sloping deck in a vessel with a 150 list.

The deck illustrated has a water-permeable load-bearing upper surface 1 and, spaced below it, a lower surface 2 which is similar to a conventional single-layer deck and is constructed of welded steel sheets. Shallow steel bulkheads or partitions 3 extending longitudinally and transversely of the deck are welded to the lower surface 2 to form rectangular cells 4 for entrapping any ingress of water. Each cell 4 has a length to width ratio approximately equal to that of the deck.

The upper surface 1 comprises steel margins or flanges 6, surrounding the cells 4 and welded to the partitions 3, and deck grillages 7 which are mounted on the flanges 6 and which consist of longitudinally extending bars spaced apart so as to allow water to flow freely into the cells 4.

A drainage duct 8 is provided in each cell, for draining water to the bilges of the vessel. The duct 8 is located near the outboard partition of the cell, i.e.

the lateral partition that is nearer the side of the deck, and is displaced from the middle of the cell towards the nearer end of the deck. Figure 5 shows the effect of the deck construction on water distribution with the vessel listing at 150. It can easily be seen that, because of the positioning of the drainage ducts 8, the lower part of the sloping deck will drain more quickly than the upper part, so that the remaining water will exert a moment tending to level the deck.

The advantages of the above-described construction are: Free movement of vehicles unrestricted by any bulkheads; Greatly increased stability due to containment of water ingress; Ease of construction and ability to introduce a cellular deck into existing vessels with comparative ease, only headroom being restricted after installation; Even without an extensive drainage facility the introduction of a cellular permeable deck is significantly effective in containing vast quantities of water and providing greater stability; The cellular structure is inherently strong.

Claims

CLAIMS:

1. A deck for a vessel, comprising an upper load-bearing water-permeable surface, a lower water-retaining surface spaced from the upper surface so as to define an intermediate space, and water-retaining partitions extending. between the upper and lower surfaces and dividing the intermediate space into separate cells into which water can flow through the upper surface.

2. A deck as claimed in claim 1, in which each cell has an outlet in the lower surface.

3. A deck as claimed in claim 2, in which the outlet is displaced from the middle of the cell towards the nearer side and/or end of the deck.

4. A deck as claimed in any of claims 1 to 3, in which the upper surface comprises horizontal flanges associated with the partitions and horizontal gratings between the flanges.

5. A deck as claimed in any of claims 1 to 4, in which the partitions extend longitudinally and transversely of the deck so that the cells are substantially rectangular in plan.

6. A deck substantially as described with reference to, and as shown in, the accompanying drawings.

7. A vessel including a deck according to any preceding claim.

8. A vessel as claimed in claim 7, being a roll on/roll off vehicular ferry, the deck constituting a vehicular parking deck.