GB2294665A - RO-RO ship/ferry with buoyancy tanks to prevent capsizing - Google Patents

Abstract

A Ro-Ro ship/ferry is provided with water-tight buoyancy tanks 1 along opposite sides and has further buoyancy tanks 3, 4, 5, 6 fitted under each of the decks 2 and covering the ship's width and most of its length. The side buoyancy tanks 1 can be filled by a system (see Fig. 3) comprising pumps (7, 8), pipes (9, 10, 13) and valves (11, 12, 14). <IMAGE>

Description

RO-RO FERRY'S CAPSIZE PREVENTOR THIS INVENTION RELATES TO SAVING LIVES AT SEA ONBOARD THE FERRIES.

The main issue of safety at sea is to save lives, environment and properties.

Despite the major efforts that have been made, disasters and catastrophies can not be avoided, but can be minimized.

Nowadays, a vastunumber of people are carried by ferries and liners, and to provide them with a safe trip, we should bear in mind the safety of the design of the vessel.

A Ro-Ro ferry's stability like other vessel's, is subject to the relative positions of: a) Centre of gravity b) Centre of buoyancy c) The metacentre point So the conditions necessary for a vessel to be in stable equilibrium are: 1- Displacement must be equal to the upthrust 2- Forces of gravity and buoyancy must be on the same vertical line 3- The centre of gravity must be below the metacentre point.

But the instability of a Ro-Ro ferry is a result of: a) The top load carried on the main deck b) The free surface effect of the sea water entering the lower vehicle's compartment due to side collision or leakage through the ramps c) Shift of cargo to one side of the ferry that may happen when she heels.

These factors cause the centre of gravity to rise above the metacentre point resulting in the instability.

When a vessel starts to heel over, her breadth at the waterplane increases, by which her buoyancy increases. That increase, keeps the metacentre point above the centre of gravity, she will then come to rest with positive stability at a certain angle called "Angle of Loll".

In a Ro-Ro ferry, when it heels over, her breadth at the waterplane increases too and gains extra buoyancy, but due to the great free surface effect, inspite of the mobile bulkheads fitted nowadays on modern ferries, and the vast mass of water entering the lower vehicle's compartment, that extra buoyancy cannot cooperate with the rapid rise of her centre of gravity above the metacentre point due to the reduction in her total buoyancy.

Therefore, I have designed the following idea to provide the Ro-Ro ferries with additional buoyancy to keep them afloat,with minimum angle of list,to provide an opportunity to rescue lives at sea as well as properties.

Figure (1) Cross section shows the buoyancy tanks arrangement.

Figure (2) Side elevation shows the buoyancy tanks and their divisions.

Figure (3) Plane view shows the side buoyancy tanks and the filling system arrangement.

Figure (4) Stability figures show the difference between a Ro-ro ferry (x) and a general cargo ship (y) when both heel over to their breadth.

Figure (5) Shows a Ro-Ro ferry at different positions when she is under the external forces and until she gains the additional buoyancy.

e The design consists of air and water-tight side tanks (1)Built in sections which are located above and under the deck. (2) In both top cargo and lower vehicles compartment's. They should be made of light elements with specific resistance to high water pressure. As is shown in figures (1) & (2) they cover most of the ship's length.

Top tanks similar to the side tanks are fitted under the decks 3,4,5 and 6.

In this design the ship has 4 decks. They cover the ship's width and most of the length as in figures (1) & (2).

Where it can be most accessible as shown in Fig.(3), two main diesel pumps 7 & 8, two main pipes 9 & 10, one pipe and a pump each side. Each line is branched to each side tank. Each branch is fitted with valve 11. Each pump is fitted with main valve 12 and the two pumps are connected by the by-pass 13. A gate valve 14 is fitted on the by-pass, each pump is capable to operate the whole system adequately.

Suppose a Ro-Ro ferry has got sea water in the lower vehicles compartment through one of the ramps, or due to a hole caused by a side collision in bad weather, and was force inclined by the forces of both the free surface effect and the cargo's shift. At the beginning , she will keep inclining until the side tanks reach the water Fig.5 Diag.A, she will then start gaining buoyancy gradually against the inclination until a point where she stops to incline any further Fig.5 Diag.B. Thereafter, she will sink bodily till the top tanks reach the water, she will then gain upthrust gradually against the sinkage Fig.5 Diag.C. She finally reaches and settles at a point where she has positive stability with a list and partially immersed, Fig.5, Diag.D.

To bring the vessel to the minimum list, the high side buoyancy tanks could be filled individually, or totally, by the filling system installed Fig.3.

Claims (1)

1- Side and top bouyancy tanks to provide additional bouyancy to keep both Ro- Ro ferries and Ro-Ro ships afloat with positive stability Amendments to the claims have been filed as follows Ref: GB 9422061.3 CLAIMS 1- RO-RO FERRY AND SHIP HAVING TOP AND SIDE BUOYANCY TANKS WITH A SYSTEM OF PIPEWORK FOR FILLING THE SIDE TANKS TO PROVIDE ADDITIONAL BUOYANCY 10 KEEP VESSELS AFLOAT WITH POSITIVE STABILITY.

2- ACCORDING TO CLAIM 1, WHEREIN,BUOYANCY TANKS ARE SUBDIVIDED 1TO IND IVIDUAL WATERTIGHT COMPARTMENTS.

3- ACCORDING TO CLAIM 1.2 WHEREIN ,THE TOP TANKS ARE LOCATED UNDER DECKS BULKHEADS AND THE SIDE TANKS ALONG THE SIDE WALLS.

4- ACCORDING TO CLAIM 1,2,3 WHEREIN, BOTH TOP AND SIDE TANKS COVEY MOST OF THE SHIP's LENGTH.

5- ACCORDING TO CLAIM 1,2,3,3,4 WHEREIN, FILLING SYSTEM LINES ARE BRANCHED TO THE SIDE TANKS AND USED TO BRING THE SHIP UPRIGHT SHOULD A LIST OCCUR.

6- RO-RO FERRY AND SHIP SUBSTANIALLY AS DESCR1BED WITH REFERENCE TO FIGURES

1-5.