SE1651316A1

SE1651316A1 - Ship

Info

Publication number: SE1651316A1
Application number: SE1651316A
Authority: SE
Inventors: Ludwigsson Robert; Hellander Klas; Jonsson Dan
Original assignee: Bassoe Tech Ab
Priority date: 2016-10-06
Filing date: 2016-10-06
Publication date: 2018-04-07
Also published as: EP3523189A1; SE542010C2; CN109803882A; CN109803882B; WO2018067061A1; EP3523189A4

Abstract

The invention concerns a ship, said ship comprising a lower deck, such as a tank top, and an upper deck, such as a bulkhead deck, arranged above the lower deck, said lower and upper decks extending in a longitudinal direction of the ship,wherein the lower deck is provided with watertight walls (bulkheads) that extend vertically between the lower and the upper deck and define a plurality of separated watertight compartments distributed between the upper and lower decks, andwherein a first of said watertight walls extends in a transversal manner from side to side of the ship so as to separate two longitudinally adjacent first and second compartments.The invention is characterized in that the first watertight wall does not extend only in a transversal direction but also in the longitudinal direction so as to provide the first compartment with a first longitudinally extending portion that extends into the second compartment,wherein the first longitudinally extending portion is arranged at a first distance from a first side of the ship, andwherein the first distance is greater than a width or depth of a theoretical damage according to standard requirements for the type of ship concerned.

Description

2016-10-06P41604497SE00/|FG Ship TECHNICAL FIELD This invention relates to a ship according to the preamble of claim 1. ln particular, the invention relates to an arrangement of the buikheads of theship.

BACKGROUND OF THE INVENTION The design of ship is subject to various safety regulations. A ship that issubjected to a damage must meet certain criteria with regard toheeling/listing, height of freeboard, etc. This is mainly solved by designing theship with internal watertight bulkheads at specific distances. The distancesbetween these bulkheads are governed by Solas (Safety of Life at Sea,International Maritime Organization, IMO) requirements, in this case Solas 90regulation ll-1/B/8. ln addition there is a special damage requirement for ro-ro(roll-on/roll-off) passenger ship, trading in European waters, EU directive2003/25/EC. These requirements state that a ro-ro passenger ship can besubjected to water on the bulkhead deck. To meet both Solas and the EU directive a number of measures need to be taken.

Some of the terms used in this disclosure can be explained as follows: B “Breadth (B) is the greatest moulded breadth of theship at or below the deepest subdivision draught”. lnshort, this is the greatest moulded breadth of theship (without outer plates, shell plating etc.).

Bulkhead deck Bulkhead Damage Freeboard deck on a passenger ship. lnternal walls on a ship.

A damage to the ship. A ship is designed on thebasis of a theoretical damage, the extent of which isdefined in relevant standards, rules and regulations.

Double bottom Space between bottom plate/keel and tank top.

LS ”Subdivision length (Ls) of the ship is the greatestprojected moulded length of that part of the ship ator below deck or decks limiting the vertical extent offlooding with the ship at the deepest subdivision The approximately the same as the summer load line. draught”. subdivision length is often Shell plating Plates which form the external surface of the hull.Tank top 'Roof of double bottom space. This level is normally referred to as Deck 1.

The extent of a theoretical damage according to standard requirements is:Damage length (0.03*LS + 3) m or maximum 11 m, where LS is thesubdivision length.

Damage width > B/5 (i.e. the “depth” of the damage from the side ofthe ship towards the centre line of the ship).

Damage height The vertical extent of the theoretical damage is not restricted.

A ship is divided into a number of watertight compartments by means ofbulkheads. These bulkheads are arranged to provide strength and safety tothe ship, and the particular arrangement depends on the size and type of theship. Typically the arrangement includes a number of transversal bulkheadsextending from side to side across the space between the bottom and thebulkhead deck.

Apart from the obvious aim - to keep a ship afloat - the arrangement of thewatertight bulkheads is based on stability calculations and studies to optimisethe ship's behaviour should it be damaged. Depending on where a ship isdamaged, different compartments and combinations of compartments will beflooded. Any one of these damage cases must not sink the ship entirely, norcause it to list too much, let alone capsize. The latter is normally solved bycross-flooding, i.e. making sure that the loss of buoyancy is the same on both sides of the ship. This will cause the entire ship to sink a little deeper, but will minimize list.

A particular problem that sometimes arises, depending on the size and typeof the ship, is related to the fitting of the ship engine(s) in the watertightcompartments. A ship engine is relatively large and heavy, its length may be10-20 m or even more, and so it requires a large compartment. For safetyreasons, a single compartment is not allowed to have a too great volume as itmight be filled with water, which can have a too large impact on thebuoyance and stability of the ship. lf the ship is provided with two (large)engines, these are often fitted in two separate watertight compartments.Conventionally, this is accomplished by means of two rectangularcompartments arranged side by side, preferably at a central position of the ship.

However, in some cases the size of the engines (in relation to the size of theship) is such that it becomes difficult to meet the regulations stated above forthe separate compartments if they are arranged in the conventional manneras even the total volume of one of the individual compartments would be too great. ln the case of ro-ro ship a further difficulty often arises in that the location ofthe cargo space makes it necessary to place the engines more astern than inother types of ship.

This disclosure focuses on the problem of how to arrange the bulkheads soas to form compartments suitable for accommodating large elongatedequipment, typically ship engines but also LNG (liquid natural gas) tanks or other equipment, while still complying with the regulations.

SUMMARY OF THE INVENTION An object of this invention is to provide a ship that exhibit improvedcapabilities of housing large elongated equipment in watertight compartmentscompared to conventional ships. This object is achieved by the ship definedby the technical features contained in independent claim 1. The dependentclaims contain advantageous embodiments, further developments and variants of the invention.

The invention concerns a ship comprising a lower deck, such as a tank top,and an upper deck, such as a bulkhead deck, arranged above the lowerdeck, said lower and upper decks extending in a longitudinal direction of theship, wherein the lower deck is provided with watertight walls (bulkheads)that extend vertically between the lower and the upper deck and define aplurality of separated watertight compartments distributed between the upperand lower decks, and wherein a first of said watertight walls (a first bulkhead)extends in a transversal manner from side to side of the ship so as toseparate two longitudinally adjacent first and second compartments.

The invention is characterized in that the first watertight wall does not extendonly in a transversal direction but also in the longitudinal direction so as toprovide the first compartment with a first longitudinally extending portion thatextends into the second compartment, wherein the first longitudinallyextending portion is arranged at a first distance from a first side of the ship,and wherein the first distance is greater than a width or depth of a theoreticaldamage according to standard requirements for the type of ship concerned.

Such a design has the effect that a longitudinally extended space for anengine or other elongated equipment is provided in the first compartmentwithout making the total volume of the same compartment unnecessarily orunallowably large. The size and shape of the longitudinally extending portionis preferably adapted to the particular elongated equipment to be arranged inthe first compartment. The elongated equipment will typically occupy most of the space or at least most of the surface area of the longitudinally extendingportion and protrude into the remaining part of the first compartment. Tosimplify manufacturing, the first watertight wall may be an assembly ofstraight wall sections connected together, where each of the sections mayextend strictly in either a transversa| or a longitudinal direction. However, thefirst watertight wall may include parts or section that are bent and/or thatextend in a direction different from strictly transversa| or strictly longitudinal.

While keeping the total volume at an acceptable level, the first compartmentis at the same time still open from side to side of the ship, which means that ifthe first compartment is flooded in an accident the inflowing water can bedistributed evenly over the breadth of the ship so as to minimize listing.

Further, the side space formed between the longitudinally extending portionand the side of the ship will form part of the second compartment, or a thirdcompartment depending on the particular arrangement of bulkheads, andsince this side space is sufficiently large (width-wise) to protect the extendingportion and thus the first compartment from being damaged and flooded inthe event of a (theoretical) damage (provided that the first watertight wall isnot damaged in the region where it connects to the side of the ship), this canbe used to reduce the number of compartments flooded if the ship is subjectto a damage.

For instance, by arranging other bulkheads in suitable positions, includingfurther bulkheads delimiting the second compartment and additionalbulkheads below the lower deck, and in particular by arranging the otherto the firstbulkhead/watertight wall to provide room for a damage longitudinally between bulkheads in suitable longitudinal positions in relationthe bulkheads in the region where the “safety space” is formed between thelongitudinally extending portion and the side of the ship, the number ofcompartments flooded in the event of a damage can be reduced. The longitudinal distance between the bulkheads/walls should thus be greater than the theoretical damage length. Typically the width of the side space is atleast B/5 where B is “greatest moulded breadth of the ship” as describedabove.

The above design of the first compartment also provides for a correspondingarrangement of the second compartment, i.e. an arrangement where alongitudinally extending portion is provided also in the second compartment.This can done by arranging a section of the first watertight wall along acenterline of the ship and let this section act as a delimiting central wall ofboth the longitudinally extending portions. Alternatively, for instance if someother object is arranged at the centreline and prevents placing a bulkheadsection at that position, the bulkhead section may be placed some distanceat the side of the centreline or two central separate (but connected) bulkheadsections may be arranged on opposite sides of the centreline. ln addition tothe wall/bulkhead section(s) arranged in association with the centerline,further wall sections can be arranged to connect the central sections (if thereare two central sections) and to define the remaining parts of the firstwatertight wall and thus of the adjacent parts of the first and secondcompartment.

Using such a delimiting central wall (or pair of central walls), twolongitudinally extended spaces for two engines or other elongatedequipment, one space in the first compartment and one in the secondcompartment, can be provided close to the centreline and symmetricallyAs the longitudinally extending portions are open in opposite longitudinal directions, arranged around the centerline in the transversal direction.i.e. the first one towards the first compartment (e.g. towards the bow) and thesecond one towards the second compartment (e.g. towards the stern), theequipment arranged in the two longitudinally extending portions will belongitudinally displaced in relation to each other (if the equipment is longerthan the longitudinally extending portion and protrudes into the remainingpart of the compartment). Such a displacement can normally be accepted.

The maximum total length of the equipment is set by the longitudinal distancebetween the inner end part of the Iongitudinally extending portion and afurther watertight wall that defines the opposite end of the compartment in question. ln an example of the invention, each of the first and second compartmentshas the general shape of an F, where one of the F's is upside down andfacing in the opposite direction in relation to the other F as seen from above(i.e. one of the F's is rotated 180° in the horizontal plane) and where thelower horizontal bar of each F is placed in between the two horizontal bars ofthe other F. The first watertight wall forms a single delimiting wall thatseparates the two F-shaped compartments. Two additional and separatewatertight walls define the vertical bars of the two F's. The upper horizontalbar of each F corresponds to a part of the corresponding compartment thatextends along the side of the ship (one at each side of the ship). The lowerhorizontal bar of each F corresponds to the Iongitudinally extending portion ofeach compartment. The top and bottom portion of each F is delimited by thefirst and second sides of the ship. ln a variant of this example, a further watertight wall section is arranged in asubstantially transversal direction at each side of the ship so as to partly orfully enclose the part of the corresponding compartment that extends alongthe side of the ship, i.e. the upper horizontal bar of each F. This way eachenclosed part of the upper horizontal bar of each F-shaped compartmentforms a buoyancy compartment laterally delimited by the further watertightwall section, the side of the ship, and (a part of) the first watertight wall.Provided that these delimiting components are not damaged, these buoyancycompartments will not be flooded even if the first or second compartmentsget flooded when the ship is subjected to a damage. This reduces the totalvolume flooded, which is an advantage with regard to a damage buoyancyand stability perspective. ln case only a buoyancy compartment is damaged and flooded, but not the first or second main compartment, the arrangementwith buoyancy compartment is of course also an advantage in that flooding of the main compartments is avoided. ln an embodiment of the invention the first watertight wall is arranged toprovide the second compartment with a corresponding second Iongitudinallyextending portion that extends into the first compartment, wherein the secondIongitudinally extending portion is arranged at a second distance from asecond side of the ship, and wherein also the second distance is greater thanthe width or depth of the theoretical damage according to standard requirements for the type of ship concerned. ln an embodiment of the invention the ship comprises a space below thelower deck, such as a double bottom between a tank top and a bottomplate/keel of the ship, wherein said space is provided with further watertightwalls that extend vertically in said space and define a further set of separatedwatertight compartments including at least a first and a second void tank,wherein the first and second void tanks are arranged below the first andsecond compartments and extend at least along the first side of the ship overa longitudinal distance that intersects with the vertically projected position ofa section of the first watertight wall that extends from the first side of the ship,wherein the width of the first and second void tanks along the first side of theship is at least equal to the width or depth of the theoretical damageaccording to standard requirements for the type of ship concerned, whereinthe first and second void tanks are Iongitudinally separated at the first side ofthe ship by a void wall section that extends in a transverse direction from thefirst side of the ship, and wherein the longitudinal distance between the voidwall section and the section of the first watertight wall that extends from thefirst side of the ship is greater than a length of a theoretical damage according to standard requirements for the type of ship concerned.

This way it can be avoided that all four compartments and tanks, i.e. the firstand second compartments plus the first and second void tanks, get flooded ifsubjected to a theoretical damage. ln an embodiment of the invention the first watertight wall comprises aplurality of wall sections including first and second longitudinally extendingsections and a first transversally extending connecting section that connectsthe first and second longitudinally extending sections, wherein the first andsecond longitudinally extending sections and the first transversally extendingconnecting section form the first longitudinally extending portion of the firstcompartment. ln an embodiment of the invention the transversally extending connectingsection is arranged at end portions of the first and second longitudinallyextending sections. ln an embodiment of the invention the first longitudinally extending section extends along the side of the ship at said distance from the side of the ship. ln an embodiment of the invention the second longitudinally extendingsection extends along a centreline of the ship. ln an embodiment of the invention the first watertight wall comprises a firsttransversally extending outer section that connects the first longitudinallyextending section with the first side of the ship. ln an embodiment of the invention the first watertight wall comprises a thirdlongitudinally extending section and a second transversally extendingconnecting section that connects the third longitudinally extending sectionwith a further longitudinally extending section of the wall, wherein the thirdand the further longitudinally extending sections and the second transversally extending connecting section form the second Iongitudinally extendingportion of the second compartment. ln an embodiment of the invention the first watertight wall comprises asecond transversally extending outer section that connects the thirdIongitudinally extending section with the second side of the ship. ln an embodiment of the invention the first and second compartments extendtransversally over the width of the ship. ln an embodiment of the invention the first watertight wall extendstransversally over the width of the ship. ln an embodiment of the invention the ship comprises further watertight wallsthat, besides the first watertight wall, define an additional transversaldelimitation of each of the first and second compartments. ln an embodiment of the invention the wall sections are connected to eachother at end portions thereof. ln an embodiment of the invention the width or depth of the theoreticaldamage is one fifth of a greatest moulded breadth of the ship according tostandard regulations Solas 90. ln an embodiment of the invention a length of a theoretical damage is(0.03*LS + 3) m or maximum 11 m, where LS is the subdivision lengthaccording to standard regulations Solas 90. ln an embodiment of the invention the ship is a roll-on/roll-off (ro-ro) ship or a ro-ro passenger ship. 11 ln an embodiment of the invention a watertight wall section is arranged in a substantially transversal direction at the first side of the ship, said watertight wall section being configured to connect to said side of the ship and to the first watertight wall so as to partly or fully enclose a part of the second compartment that extends along the first side of the ship between the first side and the first Iongitudinally extending portion of the first compartment.

BRIEF DESCRIPTION OF DRAWINGS ln the description of the invention given below reference is made to the following figure, in which: Figure 1 Figure 2 Figure 3 Figure 4Figure 5Figure 6Figure 7Figure 8 Figure 9 Figure 10 shows, in a schematic and partly sectional side view, anembodiment of a ship according to the invention. shows a top view of the arrangement of bulkheads/watertightwalls between an upper deck (bulkhead deck) and a lower deck(tank top) according to a first embodiment. shows a top view of the arrangement of bulkheads/watertightwalls below the lower deck (tank top) according to theembodiment shown in figure 2. shows a magnified view of a part of figure 2. shows a magnified view of a part of figure 3. shows the magnified view of figure 4 with the bulkheadarrangement below the lower deck indicated with dashed lines.shows a magnified view corresponding to figure 4 but relating toa second embodiment. shows a magnified view corresponding to figure 5 but relating toa second embodiment. shows the magnified view of figure 7 with the bulkheadarrangement below the lower deck indicated with dashed lines.shows a sectional view A-A according to figures 2-9. 12 DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION Figure 1 shows, in a schematic and partly sectional side view, anembodiment of a ship 1 according to the invention. The ship 1 is a roll-on/roll-off (ro-ro) passenger ship and has a bow/stem 2 and a stern 3. The termlongitudinal direction refers to the longitudinal axis of the ship 1 that extendsbetween the bow 2 and the stern 3. The term transversal direction refers to the width of the ship 1 (a direction perpendicular to the plane of figure 1).

The ship 1 is provided a lower deck, a tank top 4, and an upper deck, abulkhead deck 5, arranged above the tank top 4. These decks 4, 5 extendmainly in the longitudinal direction of the ship 1 but, of course, also in thetransversal direction.

The tank top 4 is provided with watertight walls (bulkheads) 6 that extendvertically between the lower and the upper deck 4, 5 and define a plurality ofseparated watertight compartments 7 distributed between the upper andlower decks 4, 5.

A bottom plate/keel 9 is arranged below the tank top 4. The space formedbetween the bottom 9 and the tank top 4 is denoted double bottom. Thisspace is also provided with bulkheads/watertight walls that define various empty (air filled) void tanks and other tanks or compartments.

The ship 1 is further provided with, for instance, additional decks 8.

Figure 2 shows a top view of the arrangement of bulkheads/watertight walls 6between then upper deck (bulkhead deck) 5 and the lower deck (tank top) 4according to a first embodiment. Figure 2 thus shows the tank top 4 as seenfrom above with a centreline 19.

A particular bulkhead, a first watertight wall (bulkhead) 10, extends in generaltransversally between first and second sides 15, 16 of the ship1 and the tank 13 top 4. As will be described more in detail below, the wall 10 comprises anumber of sections, some of which extending in a transversal direction andsome in a longitudinal direction. However, in general the wall extends transversally across the breadth of the ship 1.

Together with additional watertight walls 6a and 6b (that in this exampleextend in the conventional manner, i.e. strictly transversally across the ship1), the first wall 10 defines and separates a first and a second watertightcompartment 11, 12. The first and second watertight compartments 11, 12are arranged adjacent each other in the Iongitudinal direction with the firstcompartment 11 located closer to the stern 3 of the ship 1.

Figure 2 also shows further bulkheads 6c that, for instance, define a cargospace 17. Propellers 18 are also shown in figure 2.

Figure 3 shows a top view of the arrangement of bulkheads/watertight wallsbelow the lower deck (tank top) 4 according to the embodiment shown infigure 2. Figure 3 thus shows the bottom 9 as seen from above with thecentreline 19.

Watertight walls 21, 22, 23, 26a, 26b define first and second void tanks 24,25 and another tank 27, which tanks are located below the first and secondcompartments 11, 12 located above the tank top 4. The details of thisarrangement are described further below.

Figure 3 shows also the propellers 18 and further walls 6d that define further tanks or compartments.

Figure 4 shows a magnified view of a part of figure 2. ln particular, figureshows the first and second compartments 11, 12 and the first watertight wall10. Figure 4 shows, for instance, that the first wall 10 in this example is made up of seven wall sections 10a-10g. lt is also shown that, in this example, 14 each compartment 11, 12 has a general shape of an F. The first and second compartments 11, 12 are unsymmetrical.

Figure 5 shows a magnified view of a part of figure 3. ln particular, figure 5shows the watertight walls 21, 22, 23, 26a, 26b, the first and second voidtanks 24, 25 and the other tank 27.

Figure 6 shows the magnified view of figure 4 with the buikhead arrangementbelow the lower deck 4 indicated with dashed lines. ln other words, figure 6shows the same things as shown in figure 4, but in addition, the walls 21, 22,23 located below the top tank 4. ln this example, the walls 26a and 26b onthe double bottom are located right below the walls 6a and 6b and so the former walls cannot be seen in figure 6.

The function and advantages of the above arrangement will now bedescribed mainly with reference to figures 4-6.

The first watertight wall 10 does not extend only in a transversal direction butalso in the longitudinal direction and provides the first compartment 11 with afirst longitudinally extending portion 11a that extends into the secondcompartment 12. The first longitudinally extending portion 11a is arranged ata first distance from a first side 16 of the ship 1. This first distancecorresponds to the (transversal) length of the wall section 10g and thelongitudinal wall section 10 f is thus located at least this distance from theside 16 of the ship 1 (see figure 4). This first distance is greater than a widthor depth of a theoretical damage according to standard requirements for thetype of ship concerned, which in this case is one fifth of a greatest mouldedbreadth of the ship 1, i.e. B/5 (according to standard regulations Solas 90).This means that the first longitudinally extending portion 11a will not be directly affected by a theoretical damage.

The first watertight wallarrangement with regard to the second compartment 12: a second is arranged to provide a corresponding Iongitudinally extending portion 12a is provided that that extends into the firstcompartment 11. The second longitudinally extending portion 12a (i.e. thewall section 10b, see figure 4) is arranged at a second distance (transversallength of wall section 10a, which in this case is the same as the length ofsection 10g) from a second side 15 of the ship 1. As to the width of atheoretical damage, what is said about the first compartment 11 aboveapplies also to the second compartment 12.

Elongated equipment (not shown in the figures), such as a ship engine, canbe arranged in each of the compartments 11, 12 by letting it partly bearranged in the longitudinally extending portion 11a, 12a and letting theremaining part protrude Iongitudinally into the remaining space of thecorresponding compartment 11, 12.

At least within a distance from the side 15, 16 of ship 1 subject to the width ofa theoretical damage, the longitudinal distance between the differentbulkheads, i.e. the distance between the rear bulkhead 6a and the wallsections 10a and 10g, respectively, as well as the distance between the frontbulkhead 6b and the wall sections 10a and 10g, respectively (see figure 4), isgreater than the damage length of a theoretical damage, which in this case is(0.03*LS + 3) m or maximum 11 m, where LS is the subdivision lengthaccording to standard regulations Solas 90.

This means that only one, or none, of the bulkheads 6a, 10a/10g and 6b willbe affected by a theoretical damage (see figure 4).

As an example, it can be assumed that the first side 16 of the ship 1 (i.e. the lower side in figure 4) is subject to a theoretical damage: 16 A) lf the damage occurs close to the rear wall 6a, the first compartment 11will be flooded (as well as a compartment to the left of the first compartment11).

B) lf the damage occurs in the middle between the rear wall 6a and the wallsection 10g, no bulkhead will be affected and only the first compartment 11will be flooded.

C) lf the damage occurs close to the wall section 10g, the first and second compartments 11, 12 will be flooded.

D) lf the damage occurs in the middle between the wall section 10g and thefront wall 6b, no bulkhead will be affected and only the second compartment12 will be flooded.

E) lf the damage occurs close to the front wall 6b, the second compartment12 will be flooded (as well as a compartment in front of the second compartment 12).

Accordingly, in all cases zero or one bulkhead/wall will be affected, not two.For symmetry reasons, the same applies if the second side 15 is subjected to the damage.

Since the first and second compartments 11, 12 are reasonably small, it canbe accepted that one of the above bulkheads arranged on the tank top 4 is affected by the damage.

The first compartment 11 (as well as the left compartment 12) extendstransversally to the opposite side 15 of the ship 1. lncoming water will thus bemore or less evenly distributed over the breadth of the ship 1 so that listingwill not be severe. The first and second compartments 11, 12 are somewhat 17 asymmetric around the centreline 19 but the asymmetry is sufficiently smallto be acceptable with regard to listing.

With regard to the space provided below the lower deck/tank top 4, i.e. thedouble bottom between the tank top 4and the bottom plate/keel 9 of the ship,it was mentioned above that watertight walls 21, 22, 23, 26a, 26b define firstand second void tanks 24, 25 and another tank 27, which tanks are locatedbelow the first and second compartments 11, 12 located above the tank top4.

The void tanks 24, 25 are simply empty and have a function of providingbuoyancy to the ship 1. The other tank 27 can be used for various purposes.

As can be best seen in figures 5 and 6, the first and second void tanks 24, 25are arranged below the first and second compartments 11, 12 and extend atleast along the first side 16 of the ship over a longitudinal distance thatintersects with the vertically projected position of a section 10g of the firstwatertight wall 10 that extends from the first side 16 of the ship 1. This meansthat the first and second void tanks 24, 25 are located at least in an areaalong the first side 16 of the ship and that at least one of the void tanks 24,25 is located straight below the first wall 10, and more precisely straightbelow a part thereof where it extends from the side of 16 of the ship, i.e.below wall section 10g (see figures 5-6).

As can be seen in figures 5 and 6, the first and second void tanks 24, 25extend in this example in a transversal direction along (in front of and at therear of) the other tank 27 and extend in a corresponding way also along theopposite side 15 of the ship 1 under the wall section 10a. The transversalextension of each of the void tanks 24, 25 is important for stability reasons incase a void tank is subject to damage and gets flooded (the flooding watercan be transversally distributed). 18 A purpose of the other tank 27, besides offering a storage or tank volumeinside, is to limit the total volume of the void tanks 24, 25. The tank 27 isarranged at a distance at least B/5 from each of the sides 15, 16 of the ship 1and is therefore not affected by a theoretical damage.

The width of the first and second void tanks 24, 25 along the first side 16 ofthe ship 1 (and in this case also along the second side 15) is at least equal tothe width or depth of the theoretical damage according to standardrequirements for the type of ship concerned, i.e. in this case B/5. Asexplained above and shown in figure 6, this is the same as for the first andsecond longitudinally extending portions 11a, 12a.

Further, the first and second void tanks 24, 25 are longitudinally separated atthe first side 16 (and in this case also at the second side 15) of the ship 1 bya void wall section 22 that extends in a transverse direction from the first side16 of the ship 1 (and in this example a further void wall section 21 thatextends in a transverse direction from the second side 15, see figure 5).

Further, the longitudinal distance between the void wall section 22 and thesection of the first watertight wall 10 that extends from the first side 16 of theship, i.e. the wall section 10g, is greater than a length of a theoreticaldamage according to standard requirements for the type of ship concerned,which in this case is (0.03*LS + 3) m or maximum 11 m, where LS is thesubdivision length according to standard regulations Solas 90.

Correspondingly, the longitudinal distance between the further void wallsection 21 and the section of the first watertight wall 10 that extends from thesecond side 15 of the ship, i.e. the wall section 10a (see figure 6), is alsogreater than the length of a theoretical damage.

The advantage of the particular arrangement of the void tanks 24, 25 is the following: 19 The vertical extent of the theoretical damage is not restricted. This meansthat if the ship is subject to a theoretical damage, the whole side of the shipwill be affected, from the bottom 9 and upwards. To meet the requirements(and, of course, to reduce the effects of a real damage), too manycompartments, a too large volume of the ship, cannot be allowed to beflooded, and the bulkheads in the double bottom should therefore preferablyinteract in an advantageous way with the bulkheads arranged between thetop tank 4 and the bulkhead deck 5.

Above has been described how the first and second compartments 11, 12are affected depending on the longitudinal position of the theoretical damage.As can be understood from in particular figure 6, by providing a longitudinaldistance between the first wall 10 and the void wall section at the side 15, 16of the ship 1 (within the width of a theoretical damage), i.e. between the walls21 and 10a and between the walls 10g and 22 in figure 6, it can be avoidedthat more than three of the four compartments/tanks (i.e. the first and secondcompartments 11, 12 plus the first and second void tanks 24, 25) are floodedif the ship 1 is subjected to a theoretical damage.

With reference to the examples A-E above, and to figure 6, the following willbe the effects: A) Damage occurs close to the rear wall 6a.- First compartment 11 and first void tank 24 will be flooded (as well as acompartment to the left of the first compartment 11).

B) Damage occurs in the middle between the rear wall 6a and the wallsection 10g.

- First compartment 11 and first void tank 24 will be flooded.

C) Damage occurs close to the wall section 10g.

- First compartment 11, second compartment 12 and first void tank 24 will beﬂooded.

D1) Damage occurs in the middle between the wall section 10g and the voidwall section 22.- Second compartment 12 and first void tank 24 will be ﬂooded.

D2) Damage occurs close to void wall section 22.- Second compartment 12, first void tank 24 and second void tank 25 will beﬂooded.

D3) Damage occurs in the middle between the void wall section 22 and thefront wall 6b.- Second compartment 12 and second void tank 25 will be flooded.

E) Damage occurs close to the front wall 6b.- Second compartment 12 and second void tank 25 will be flooded (as well as a compartment in front of the second compartment 12).

Accordingly, in all cases two or three compartments/tanks, out of the fourdiscussed here, will be affected and flooded, not all four. One of the fourcompartments/tanks will thus stay watertight and provide buoyance to theship 1. For symmetry reasons, the same applies if the second side 15 issubjected to the damage.

With reference to the figures, the arrangement of bulkheads etc. can be additionally described as follows.

The first watertight wall 10 comprises a plurality of wall sections 10a-10gincluding first and second longitudinally extending sections 10d, 10f and afirst transversally extending connecting section 10e that connects the firstand second longitudinally extending sections 10d, 10f, wherein the first and 21 second Iongitudinally extending sections 10d, 10f and the first transversallyextending connecting section 10e form the first Iongitudinally extendingportion 11a of the first compartment 11.

The transversally extending connecting section 10e is arranged at endportions of the first and second Iongitudinally extending sections 10d, 10f.

The first Iongitudinally extending section 10f extends along the side 16 of theship at said distance (at least the width of a theoretical damage) from theside 16 of the ship 1.

The second Iongitudinally extending section 10d extends along or in parallelto a centreline 19 of the ship 1.

The first watertight wall 10 comprises a first transversally extending outersection 10g that connects the first Iongitudinally extending section 10f withthe first side 16 of the ship 1.

The first watertight wall 10 comprises a third Iongitudinally extending section10b and a second transversally extending connecting section 10c thatconnects the third Iongitudinally extending section 10b with a furtherIongitudinally extending section of the wall 10 (in this example 10d), whereinthe third and the further Iongitudinally extending sections and the secondtransversally extending connecting section 10b form the second Iongitudinallyextending portion 12a of the second compartment 12.

As an alternative to what is shown in the figures, the first wall 10 maycomprise two centrally arranged longitudinal sections instead of the singlesection 10d as exemplified here. A reason might be that here is anotherobject arranged at the centreline. Two (typically parallel) central wall sectionsmay be arranged on opposite sides of such an object. Further wall sectionscan be arranged to connect these two sections and the other sections. 22 The first watertight wall 10 comprises a second transversally extending outersection 10a that connects the third Iongitudinally extending section 10b withthe second side 15 of the ship 1.

The first and second compartments 11, 12 extend transversally over thewidth of the ship, from the first side 16 to the second side 15.

The first watertight wall 10 extends transversally over the width of the ship 1.

The ship 1 comprises further watertight walls 6a, 6b, that, besides the firstwatertight wall 10, define an additional transversal delimitation of each of thefirst and second compartments 11, 12.

The wall sections 10a-10g of the first wall 10 are connected to each other atend portions thereof.

Figures 7-9 re|ate to another embodiment, or rather a variant of theembodiment described above. Most parts of the two embodiments are similarso the same drawing references are used for similar parts and focus is setbelow on the differences.

Figure 7 shows a magnified view corresponding to figure 4 but relating to the second embodiment.

Figure 8 shows a magnified view corresponding to figure 5 but relating to the second embodiment.

Figure 9 shows the magnified view of figure 7 with the bulkhead arrangement below the lower deck indicated with dashed lines. 23 ln this second embodiment, a further watertight wall section 31, 32 isarranged in a substantially transversal direction at each side 15, 16 of theship 1 so as to partly or fully enclose the part of the correspondingcompartment that extends along the side of the ship, i.e. in this case theupper horizontal bar of each F-shaped compartment. This way eachenclosed part of the upper horizontal bar of each F-shaped compartmentforms a buoyancy compartment 33, 34 laterally delimited by the furtherwatertight wall section (31 or 32), the side of the ship (15 or 16), and (a partof) the first watertight wall (10b or 10f). Provided that these delimitingcomponents are not damaged, these buoyancy compartments 33, 34 will notbe ﬂooded even if the first or second compartments 11, 12 gets flooded whenthe ship 1 is subjected to a damage. This reduces the total volume flooded.ln case only a buoyancy compartment 33, 34 is damaged and flooded, butnot the first or second main compartment 111, 12, the arrangement withbuoyancy compartments 33, 34 is of course also an advantage in thatflooding of the main compartments 11, 12 is avoided.

The further watertight wall sections 31, 32 may be regarded to form part ofthe first watertight wall 10.

The buoyancy compartments 33, 34 may be provided with watertight doors and work as, for instance, storage rooms.

The arrangement of the void tanks 24, 25 is principally the same for thesecond embodiment as for the first embodiment. As can be seen in figure 8,together with figures 7 and 9, the void wall sections 21, 22, which aredenoted 21a, and 22a in relation to the second embodiment, have both beenmoved in the longitudinal direction and are now arranged below the wallsections 10a and 10g. ln principle, the void wall sections 21a, 22a could bearranged as in figure 5, i.e. below the further watertight wall section 31, 32,but the positioning shown in figure 8 provides for a more even distribution of water in the transversal direction in some damage cases. 24 A comparison of the effects of the first and second embodiment (denoted 1and 2 below) for the two levels of bulkheads (below and above the tank top4) will now be given with reference to the examples A; B, C, D1, D2, D3 and E given above (see also figures 7-9): A) Damage occurs close to the rear wall 6a. 1: First compartment 11 and first void tank 24 will be flooded (as well as acompartment to the left of the first compartment 11). 2: Same as for 1, except that the part forming the second buoyancycompartment 34 will not be flooded.

B) Damage occurs in the middle between the rear wall 6a and the wallsection 10g. 1. First compartment 11 and first void tank 24 will be flooded. 2. Same as for 1, except that the part forming the second buoyancycompartment 34 will not be ﬂooded.

C) Damage occurs close to the wall section 10g. 1. First compartment 11, second compartment 12 and first void tank 24 willbe flooded. 2. First compartment 11 (except for the second buoyancy compartment 34),first buoyancy compartment 33, first void tank 24 and second void tank 25 will be flooded.

D1) Damage occurs in the middle between the wall section 10g and the voidwall section 22 (or the further wall section 31 ).1. Second compartment 12 and first void tank 24 will be flooded. 2. First buoyancy compartment 33 and second void tank 25 will be ﬂooded.

D2) Damage occurs close to void wall section 22 (or the further wall section31). 1. Second compartment 12, first void tank 24 and second void tank 25 will beﬂooded. 2. First buoyancy compartment 33, (remaining parts of) second compartment12 and second void tank 25 will be ﬂooded.

D3) Damage occurs in the middle between the void wall section 22 (or thefurther wall section 31) and the front wall 6b. 1. Second compartment 12 and second void tank 25 will be flooded. 2. Same as for 1, except that the part forming the first buoyancy compartment 33 will not be flooded.

E) Damage occurs close to the front wall 6b. 1. Second compartment 12 and second void tank 25 will be flooded (as wellas a compartment in front of the second compartment 12). 2. Same as for 1, except that the part forming the first buoyancycompartment 33 will not be flooded.

Accordingly, the second embodiment exhibits clear advantageous effects inmost of the damage cases. For symmetry reasons, the same applies if the second side 15 is subjected to the damage.

Figure 10 shows a sectional view A-A according to figures 2-9. The structureof the bulkheads and the decks is the same for the two embodiments in thesection A-A, but since wall sections have been added and moved some ofthe compartments defined by the bulkheads and decks shown in figure 10 differ between the two embodiments.

The arrangement of the voids in the double bottom under each largeunsymmetrical compartment, should be such as to never allow all four (ormore) spaces to be flooded in one damage case. For instance, if two enginecompartments are flooded, only one void in the double bottom should be 26 flooded. The voids in the double bottom shall, as in this case, generally becross-flooded.

The buoyancy compartment should be arranged to the ship's shell plating.The optimal longitudinal location of the buoyancy compartment is adjacent tothe bulkhead separating the two partially interleaved main compartments.The buoyancy compartment should be located on the most 'voluminous' sideof each engine room. This principle also works for other types of compartments than engine rooms.

Preferred dimensions of each buoyancy compartment:Transverse extent- (at least) B/5.

Longitudinal length - greater than damage length.Height -from tank top up to Bulkhead deck.

The invention is not limited by the embodiments described above but can bemodified in various ways within the scope of the claims. For instance, theabove described bulkhead arrangement between the upper and lower deck(the bulkhead deck and the tanktop) is advantageous also for otherarrangements (tanks etc.) below the lower deck. The lower deck may formthe bottom plate/keel of the ship.

Claims

1. A ship, said ship comprising a lower deck, such as a tank top, and anupper deck, such as a bulkhead deck, arranged above the lower deck, saidlower and upper decks extending in a longitudinal direction of the ship,wherein the lower deck is provided with watertight walls(bulkheads) that extend vertically between the lower and the upper deck anddefine a plurality of separated watertight compartments distributed betweenthe upper and lower decks, andwherein a first of said watertight walls extends in a transversalmanner from side to side of the ship so as to separate two longitudinallyadjacent first and second compartments,characterized inthat the first watertight wall does not extend only in a transversal direction butalso in the longitudinal direction so as to provide the first compartment with afirst that compartment, longitudinally extending portion extends into the secondwherein the first longitudinally extending portion is arranged at a first distance from a first side of the ship, andwherein the first distance is greater than a width or depth of atheoretical damage according to standard requirements for the type of ship concerned.

2. The ship according to claim 1,characterized inthat the first watertight wall is arranged to provide the second compartmentwith a corresponding second longitudinally extending portion that extendsinto the first compartment, wherein the second longitudinally extending portion is arranged at a second distance from a second side of the ship, and 28 wherein also the second distance is greater than the width ordepth of the theoretical damage according to standard requirements for thetype of ship concerned.

3. The ship according to claim 1 or 2,characterized inthat the ship comprises a space below the lower deck, such as a doublebottom between a tank top and a bottom plate/keel of the ship, wherein said space is provided with further watertight walls thatextend vertically in said space and define a further set of separatedwatertight compartments including at least a first and a second void tank, wherein the first and second void tanks are arranged below thefirst and second compartments and extend at least along the first side of theship over a longitudinal distance that intersects with the vertically projectedposition of a section of the first watertight wall that extends from the first sideof the ship, wherein the width of the first and second void tanks along thefirst side of the ship is at least equal to the width or depth of the theoreticaldamage according to standard requirements for the type of ship concerned, wherein the first and second void tanks are longitudinallyseparated at the first side of the ship by a void wall section that extends in atransverse direction from the first side of the ship, and wherein the longitudinal distance between the void wall sectionand the section of the first watertight wall that extends from the first side ofthe ship is greater than a length of a theoretical damage according to standard requirements for the type of ship concerned.

4. The ship according to any one of the above claims, characterized in that the first watertight wall comprises a plurality of wall sections includingfirst and second longitudinally extending sections and a first transversallyextending connecting section that connects the first and second longitudinally 29 extending sections, wherein the first and second Iongitudinally extendingsections and the first transversally extending connecting section form the firstIongitudinally extending portion of the first compartment.

5. The ship according to claim 4, characterized in that the transversally extending connecting section is arranged at endportions of the first and second Iongitudinally extending sections.

6. The ship according to claim 4 or 5, characterized in that the first Iongitudinally extending section extends along the side of theship at said distance from the side of the ship.

7. The ship according to anyone of claims 4-6,characterized inthat the second Iongitudinally extending section extends along a centre|ine of the ship.

8. The ship according to anyone of claims 4-7, characterized in that the first watertight wall comprises a first transversally extending outersection that connects the first Iongitudinally extending section with the firstside of the ship.

9. The ship according to anyone of claims 4-8, characterized in that the first watertight wall comprises a third Iongitudinally extending sectionand a second transversally extending connecting section that connects thethird Iongitudinally extending section with a further Iongitudinally extendingsection of the wall, wherein the third and the further Iongitudinally extending sections and the second transversally extending connecting section form thesecond Iongitudinally extending portion of the second compartment.

10. The ship according to anyone of claims 4-9, characterized in that the first watertight wa|| comprises a second transversally extending outersection that connects the third Iongitudinally extending section with the second side of the ship.

11. The ship according to anyone of the above claims, characterized in that the first and second compartments extend transversally over the width ofthe ship.

12. The ship according to anyone of the above claims,characterized inthat the first watertight wa|| extends transversally over the width of the ship.

13. The ship according to anyone of the above claims, characterized in that the ship comprises further watertight wa||s that, besides the firstwatertight wall, define an additional transversa| deiimitation of each of thefirst and second compartments.

14. The ship according to anyone of claims 4-10,characterized inthat the wa|| sections are connected to each other at end portions thereof.

15. The ship according to anyone of the above claims,characterized inthat the width or depth of the theoretical damage is one fifth of a greatest mouided breadth of the ship according to standard regulations Soias 90. 31

16. The ship according to anyone of the above claims, characterized in that a length of a theoretical damage is (0.03*LS + 3) m or maximum 11 m,where LS is the subdivision length according to standard regulations Solas90.

17. The ship according to anyone of the above claims,characterized in that the ship is a roll-on/roll-off (ro-ro) ship or a ro-ro passenger ship.

18. The ship according to anyone of the above claims, characterized in that a watertight wall section is arranged in a substantially transversaldirection at the first side of the ship, said watertight wall section beingconfigured to connect to said side of the ship and to the first watertight wallso as to partly or fully enclose a part of the second compartment that extendsalong the first side of the ship between the first side and the firstlongitudinally extending portion of the first compartment.