A wall with a splittable and moveable construction, and a vessel comprising such a wall BACKGROUND OF THE INVENTION

The invention relates to a wall with a moveable construction that is retractable relative to the wall, in particular a vessel wall with a moveable construction such as a keel or a gangplank.

Retractable constructions, e.g. keels, are already known in the art. An example thereof is disclosed in international patent publication WO98/06621A1 in which the keel is retractable through the vessel wall into a space inside the vessel. The height dimension of the required space has been limited by retracting the keel along a curved trajectory such that the longitudinal axis of the keel is oriented vertically when fully extended but substantially horizontally when fully retracted. However, a huge disadvantage is that the construction to retract and receive the keel occupies valuable space inside the vessel.

Another example thereof is disclosed in Dutch patent publications NL1009784C1 , NL1009785C2 and NL1002990C2 in which a retractable keel is configured as a four-bar linkage seen in cross-sectional view to have a vertical extended orientation, in which two pairs of linkages are arranged vertically and parallel to each other, and a horizontal retracted orientation, in which two other pairs of linkages are arranged horizontally and parallel to each other and thus arranged substantially parallel to the vessel wall. Although an advantage is that the keel is not retracted inside the vessel and occupies valuable space there, a disadvantage is that the keel extends sideways in the horizontal retracted orientation effecting the sailing behavior. Further, it is not possible to have a fully functioning keel when retracting the keel to in between the fully extended and fully retracted orientation.

A similar example is disclosed in US patent publication US2,569,270A showing the same or similar disadvantages.

BRIEF SUMMARY OF THE INVENTION

In view of the above, it is an object of the invention to provide a moveable construction, such as a keel or gangplank, that is moveable in a direction from and towards an adjacent wall and which occupies less space in the retracted position on an opposite side of the wall and also allows to partially retract the construction without losing functionality. The object of the invention is achieved by providing a wall comprising:

an opening;

a first guiding path and a second guiding path, each starting at the opening and diverging therefrom;

a moveable construction that is moveable in a direction from and towards the opening;

a driving mechanism to move the moveable construction,

wherein the moveable construction comprises a splittable section and an end section connected to the splittable section, said splittable section comprising a first part to be guided along the first guiding path and a second part to be guided along the second guiding path, said first part comprising first interlocking members pivotally connected to each other about respective first pivot axes and said second part comprising second interlocking members pivotally connected to each other about respective second pivot axes extending in the same direction as the first pivot axes,

wherein the wall is configured such that moving the first and second interlocking members of the first and second part, respectively, towards the opening moves the first and second interlocking members into interlocking engagement with each other to form a substantially rigid splittable section portion,

and wherein the moveable construction is moveable between a retracted position in which the first and second part of the splittable section are arranged along the first and second guiding path, respectively, and an extended position in which the first and second part of the splittable section are interlocked for the most part, such that the end section of the moveable construction is closer to the opening in the retracted position than in the extended position.

A main advantage of the wall according to the invention is that the wall comprises diverging guiding paths allowing to arrange portions of the moveable construction inside or along the wall thereby minimizing or omitting the use of any valuable space on that side of the wall.

The possibility to arrange the moveable construction in or along the wall is based on the insight of the inventors that the moveable construction requires a splittable section, wherein the first and second parts of the splittable section are bendable when split apart and thus can go through the opening, be separated from each other and then move along different diverging paths, while the splittable section forms a substantially rigid cantilever or beam when the first and second parts are in interlocking engagement. Hence, it is also possible to partially retract the moveable construction as the portion extending from the opening is still forming a substantially rigid cantilever or beam and only has shortened in length without losing functionality of the moveable construction. The moveable

construction may thus still function as a keel or gangplank or any other structure depending on the application.

In an embodiment, the splittable section comprises a thickness, a width and a length, wherein the opening has a thickness and a width corresponding to the thickness and the width of the splittable section, respectively, wherein the width and the length of the splittable section are larger than the thickness of the splittable section, and wherein the first and second pivot axes extend parallel to the width direction of the splittable section.

In other words, the splittable section extending from the opening forms a cantilever.

However, it is also envisaged that the invention can be used for embodiments in which the width of the splittable section is substantially equal to the thickness of the splittable section, such that at least the splittable section extending from the opening forms a beam.

In an embodiment, the first and second interlocking members each have a first side and a second side, said first and second side facing towards or away from the opening, wherein the first side comprises a protrusion and the second side comprises a recess, and wherein the first and second interlocking members are interlockable by receiving the protrusion at the first side of a first interlocking member in the recess at the second side of an adjacent second interlocking member and/or receiving the protrusion of a second interlocking member in the recess at the second side of an adjacent first interlocking member. As a result thereof, the splittable section extending from the opening is mainly formed by alternating first and second interlocking members that are interlocked and thus able to withstand bending loads due to positive locking, alternatively referred to as a form fit.

Preferably, the opening plays an important role in maintaining the positive locking of the splittable section extending from the opening by constraining the movement of the first interlocked pair of first and second interlocking members although constraining the movement may also be provided by other components, e.g. components of the driving mechanism. Wherein the first interlocked pair of first and second interlocking members is the pair made of a first interlocking member that is interlocked with a second interlocking member and that is closest to the opening. Hence, at the opening, the first and second interlocking members are not able to be separated. Separation of the first and second interlocking members is then only possible at a distance from the opening inside or at an opposite side of the wall, possibly aided using a separation member forcing the first and second interlocking members to separate and continue along their respective guiding paths.

In an embodiment, the first and/or second interlocking members comprise moveable gripping members that are moveable between a locking position, in which the gripping member engages with an adjacent interlocking member, and a releasing position, in which the gripping member is disengaged. The gripping members may each be moved using a respective actuator, but it is also possible that a plurality of gripping members are moved using a common actuator, e.g. using a cable and a motor winding and unwinding the cable, where winding the cable moves the gripping members connected to the cable towards their locking position. Unwinding the cable may urge or move said gripping members towards the releasing position, possibly aided by gravity, movement of the moveable construction and/or springs.

Hence, interlocking or separating the first part and the second part may occur passively and/or actively depending on the embodiment.

In an embodiment, the first interlocking members of the first part are directly connected to each other with a first pivot axis being provided between adjacent first interlocking members. Preferably, the second interlocking members of the second part are also directly connected to each other with a second pivot axis being provided between adjacent second interlocking members.

In an alternative embodiment, the first interlocking members of the first part are indirectly connected to each other via an associated connecting member. Preferably, the second interlocking members of the second part are also indirectly connected to each other via an associated connecting member.

In an embodiment, the connecting member is formed by one or more cables, where the flexibility of the one or more cables to bend sideways forms the first or second pivot axis. The first interlocking members may for instance be clamped or connected to the same one or more cables, or separate one or more cable portions are provided between each adjacent first interlocking members. The same may hold for the second interlocking members. In another embodiment, the connecting member is a rigid component, wherein the connecting member is pivotally connected to both adjacent interlocking members, thereby forming the first or second pivot axis.

In an embodiment, the splittable section comprises a first portion and a second portion that in the extended position are pivotable relative to each other about a first operational axis parallel to the first and second pivot axes, and wherein a first actuator system is provided to pivot the second portion relative to the first portion.

The first part and the second part of the splittable section divide the splittable section in two such that they extend at opposite sides from the opening. In an embodiment, the first and second part of the splittable section are splittable along a plane extending parallel to the width and length direction. The first and second portion divide the splittable section in two such that in the extended position the first portion of the splittable section is closer to the opening than the second portion of the splittable section, i.e. the first and second portion are at opposite sides of a plane extending parallel to the width and thickness direction.

In an embodiment, the first portion and the second portion of the first part comprise first interlocking members pivotally connected to each other about respective first pivot axes, wherein the first operational axis is formed by the first pivot axis between the first interlocking member of the first portion that is adjacent to the first interlocking member of the second portion, wherein the first portion of the second part comprises second interlocking members pivotally connected to each other about respective second pivot axes, wherein the second portion of the second part comprises second interlocking members pivotally connected to each other about respective second pivot axes, and wherein the first actuator system is provided between one of the second interlocking members of the first portion of the second part and one of the second interlocking members of the second portion of the second part.

Although the above embodiments indicate that the splittable section can be split into two portions only, it is envisaged that the splittable section comprises a third portion, a fourth portion or even further portions, each being arranged at a larger distance from the opening in the extended position than the previous portion. The first actuator system may be provided between each of the portions so that the shape of the splittable section when looking at the splittable section in a direction parallel to the functional axes can be set by appropriate control of the first actuator system. When the splittable section contains only two portions, namely the first and second portion described above, the angle between the two portions can preferably be in the range of 180 ± a degrees or in the range between 180 - a degrees to 180 + b degrees, where a¹b, thereby enabling a straight splittable section for the angle being 180 degrees or a splittable section with a kink for all other possible angles.

With an increasing number of portions, the possibilities to set the shape also increase. Examples are mimicking a curved or bend shape or to only move the end section sideways without changing its orientation with respect to the wall.

In an embodiment, the interlocked portion of the splittable section is configured to allow rotation of adjacent interlocking members relative to each other while being interlocked to each other, wherein the driving mechanism and/or an actuator system set the orientation of adjacent interlocking members relative to each other. This also results in the creation of a relative large number of portions allowing to bend the splittable section.

In an embodiment, alternatively or additionally to the earlier described portions of the splittable section, the splittable section and the end section are pivotable relative to each other about a second operational axis parallel to the first and second pivot axes, and wherein a second actuator system is provided to move and position the end section relative to the splittable section. This alternatively or additionally provides the possibility to adjust the shape of the moveable construction extending from the opening.

In an embodiment, the driving mechanism comprises a first cable connected to the first part, a second cable connected to the second part, and at least one winch for winding and unwinding the first and second cable to respectively retract and extend the moveable construction. Such a driving mechanism is especially suitable when the driving

mechanism is mainly or only used to retract the moveable construction and extension of the moveable construction occurs due to other forces, e.g. gravity forces as in the case of the moveable construction being a keel hanging downwards from a bottom wall of a vessel.

In another embodiment, the driving mechanism is configured to provide both pulling and pushing forces to the first and second part of the splittable sections, which is especially suitable when no other forces such as gravity forces are present to aid in retracting or extending the moveable construction, such as a substantially horizontal gangplank extending from a side wall of a vessel.

In an embodiment, the driving mechanism comprises frictional elements, e.g. rubber shafts, that are in frictional engagement with the first and second part and configured to move the first and second part upon rotation.

In an embodiment, the wall is a vessel wall, e.g. the bottom wall or the side wall of a vessel.

In an embodiment, the wall may be straight, curved or comprising kinks. The orientation of the wall is not relevant. The wall may also form a deck or floor. It is also possible that the wall is formed by the combination of a side wall and a deck, wherein the first guiding path extends from the opening into the side wall and the second guiding path extends from the opening into the deck.

In an embodiment, the moveable construction extends substantially perpendicular from the wall, or when the wall is curved, the moveable construction extends in a radial direction. However, other directions, such as oblique are also envisaged.

In an embodiment, the moveable construction is a keel of a vessel. In another

embodiment, the moveable construction is a gangplank of a vessel. In yet another embodiment, the moveable construction is a barrier, e.g. a barrier extending from a floor wall that is adjustable in height.

In an embodiment, the first and second guiding paths are formed by respective first and second guiding channels inside the wall.

In an embodiment, the first and second guiding paths are formed by respective first and second guiding recesses in the wall.

In an embodiment, the first and second guiding paths are formed by respective first and second spaces arranged along or mounted to the wall.

Any of the first and second guiding channels, recesses and spaces may be easily, e.g. open, or may be closed so as to hide the first and second parts of the splittable section. In an embodiment, the opening is provided with a seal to prevent or at least minimize the amount of water from entering through the opening, e.g. when the wall is used in a vessel. When water is able to enter through the opening, a pump may be provided to remove said entered water. It is also possible that the first and second guiding paths are formed by respective first and second guiding channels or respective first and second spaces, which channels or spaces are closed to prevent water that has entered the channels or spaces through the opening from flowing any further.

The invention also relates to a vessel comprising a wall according to the invention, wherein the vessel preferably is a sailing boat, and the moveable construction is preferably a keel or a gangplank.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in a non-limiting way by reference to the

accompanying drawings in which like parts are indicated by like reference symbols and in which:

Fig. 1 schematically depicts a perspective partially cutaway view of a vessel

according to an embodiment of the invention with a retractable keel in its extended position;

Fig. 2 schematically depicts the vessel of Fig. 1 with the retractable keel in its retracted position;

Fig. 3 schematically depicts a perspective view of a wall portion of the vessel of

Fig. 1 and 2 with the retractable keel in its extended position;

Fig. 4 schematically depicts a cross-sectional view of the wall portion of Fig. 3;

Fig. 5 schematically depicts a perspective view of the wall portion of the vessel of

Fig. 1 and 2 with the retractable keel in an intermediate position;

Fig. 6 schematically depicts a cross-sectional view of the wall portion of Fig. 5;

Fig. 7 schematically depicts a perspective view of the wall portion of the vessel of

Fig. 1 and 2 with the retractable keel in its retracted position;

Fig. 8 schematically depicts a cross-sectional view of the wall portion of Fig. 7;

Fig. 9 schematically depicts a perspective view of a wall portion of a vessel

according to another embodiment of the invention with the keel in an extended position;

Fig. 10 schematically depicts a cross-sectional view of the wall portion of Fig. 9 with the keel in the extended position;

Fig. 11 schematically depicts a cross-sectional view of the wall portion of Fig. 9 and

10, but with the keel in the retracted position; Fig. 12 schematically depicts a cross-sectional view of a wall portion of a vessel according to a further embodiment of the invention with the keel in a vertical orientation and in an intermediate position;

Fig. 13A schematically depicts a cross-sectional view of the wall portion of Fig. 12 with the keel in an extended position and in a bend orientation;

Fig. 13B schematically depicts in more detail a connection and first actuation system provided between two portions of the splittable section;

Fig. 14 schematically depicts a perspective view of a wall portion of a vessel

according to yet another embodiment of the invention with the keel in an intermediate position;

Fig. 15 schematically depicts a cross-sectional view of the wall portion of Fig. 14 with the keel in the same position;

Fig. 16 schematically depicts a cross-sectional view of the wall portion of Fig. 14 with the keel in another intermediate position;

Fig. 17 schematically depicts a cross-sectional view of the wall portion of Fig. 14 with the keel in the retracted position;

Fig. 18 schematically depicts a cross-sectional view of the wall portion of Fig. 14 with the keel in the extended position; and

Fig. 19 schematically depicts a cross-sectional view of the wall portion of Fig. 18 with the keel in a bend orientation.

DETAILED DESCRIPTION OF THE INVENTION

Figs. 1-8 depict a vessel VE according to an embodiment of the invention. The vessel VE in the shown embodiment is a sailing boat including a hull HU, mast MA, main sail MS, head sail HS, cabin CA and keel KE. The invention will be explained with respect to the keel KE. The other parts and details of the vessel VE, which are commonly known, will not be elucidated here unless necessary for explaining the invention. Figs. 1 and 2

schematically depict a perspective partially cutaway view of the vessel VE such that an interior of the hull HU at the location of the keel KE can be seen.

The keel KE is configured as a moveable structure such that the keel is moveable between an extended position as shown in Fig. 1 and the Figs. 3 and 4, and a retracted position as shown in Fig. 2 and the Figs. 7 and 8. An advantage of the invention is that the keel can also be retracted to an intermediate position as for example shown in Figs. 5 and 6 while being fully functioning. Although not shown, any intermediate position between the extended position and the retracted position is possible in this embodiment. Details of the keel KE will be described below by reference to the Figs. 3 to 8 where a portion of a bottom wall BW of the hull HU is depicted. This bottom wall BW portion can also be seen in the cutaway views of Figs. 1 and 2.

Although the details of the invention will be described by reference to the keel KE, it will be clear for the skilled person that the same can be applied to any other moveable construction, e.g. a gangplank, and that the term keel in this description can thus be replaced by the more general term‘moveable construction’.

The keel KE is retractable through an opening OP in the bottom wall BW. The opening is only indicated using reference symbol OP in Fig. 3 for clarity reasons, where Fig. 3 schematically depicts a perspective view of the bottom wall BW portion of the vessel VE with the keel KE in the extended position. Fig. 4 schematically depicts a cross-sectional view of the bottom wall BW portion of Fig. 3.

The keel KE is moveable in a direction Z from and towards the opening OP using a driving mechanism DM.

The keel KE comprises an end section ES, which in this embodiment comprises ballast- filled bulb BU, and a splittable section SS connected to the end section ES.

The bottom wall BW defines a first guiding path GP1 and a second guiding path GP2, each starting at the opening OP and diverging therefrom along the bottom wall BW. The first and second guiding paths GP1 and GP2 are depicted in the cross-sectional view of Fig. 4.

The splittable section SS includes a first part FP and a second part SP, as clearly seen in the Figs. 5 to 8, wherein the first part FP is to be guided along the first guiding path GP1 and the second part SP is to be guided along the second guiding path GP2.

The first part FP comprises first interlocking members IM1 that are pivotally connected to each other about respective first pivot axes extending in the X-direction, allowing the first part FP to bend and follow the curves in the first guiding path GP1. Only a couple of first interlocking members IM1 are indicated using the reference symbol IM1 for clarity reasons.

The second part SP comprises second interlocking members IM2 that are pivotally connected to each other about respective second pivot axes extending parallel to the first pivot axes, allowing the second part SP to bend and follow the curves in the second guiding path GP2. Only a couple of first interlocking members IM2 are indicated using the reference symbol IM2 for clarity reasons.

The bottom wall BW is configured such that moving the first and second interlocking members IM1 , I M2 of the first part FP an the second part SP, respectively, towards the opening OP moves the first and second interlocking members IM1 , IM2 into interlocking engagement with each other to form a substantially rigid splittable section portion between the opening OP and the end section ES, while the remaining first and second interlocking members IM1 , IM2 are separate from each other and arranged along respective guiding paths, namely the first guiding path GP1 and the second guiding path GP2.

As a result, the first part FP and the second part SP of the splittable section SS are separate from each other and arranged along the first and second guiding paths GP1 ,

GP2 for the most part in the retracted position and are interlocked for the most part in the extended position. The end section ES is then closer to the opening OP in the retracted position than in the extended position.

The splittable section SS comprises a thickness T1 corresponding to a dimension in the Y-direction, a width W1 corresponding to a dimension in the X-direction, and a length L1 corresponding to a dimension in the Z-direction. The opening OP has a thickness T2 corresponding to a dimension in the Y-direction and a width W2 corresponding to a dimension in the X-direction. Hence, the thickness T1 of the splittable section SS corresponds to the thickness T2 of the opening and the width W1 of the splittable section SS corresponds to the width W2 of the opening.

Although the embodiment according to Figs. 1-8 shows a rigid splittable section portion extending between the opening OP and the end section ES as a stack of alternating first and second interlocking members IM1 , IM2, it is also envisaged that the rigid splittable section portion comprises a stack of first interlocking members IM1 and a stack of second interlocking members IM2 that are connected to each other substantially at a centre plane of the rigid splittable section portion.

The driving mechanism DM in this embodiment includes a first rotatable shaft RS1 that is in frictional engagement with the first part FP of the spittable section and a second rotatable shaft RS2 that is in frictional engagement with the second part SP of the splittable section. The first and second rotatable shafts RS1 , RS2 are rotatable about respective rotation axes extending parallel to the first and second pivot axes, respectively. Rotating the first and second rotatable shafts RS1 , RS2 in opposite directions, using for instance an electromotor and corresponding gearbox, allows to move the first part FP and the second part SP and thus the keel KE between the retracted position and the extended position. The first and second rotatable shafts RS1 , RS2 may be provided with a friction increasing element, e.g. made of rubber, to increase the friction between the shafts and the respective parts of the splittable section.

The spaces in which the first and second part FP, SP are received and which define the first and second guiding paths GP1 , GP2, respectively, are in this embodiment closed to prevent any water from entering the cabin CA through the opening OP. The delimiting walls of the spaces are not completely shown for clarity reasons, but the Figs. 3-8 depict a side wall SW as part of these delimiting walls.

It is also possible that the bottom wall BW is a double-wall structure, comprising guiding channels to define the first and second guiding paths GP1 , GP2, thereby hiding the first and second parts FP, SP in the bottom wall BW.

The way the first interlocking members IM1 and the second interlocking members IM2 interlock has only been shown schematically in Figs. 1-8. Figs. 9-11 schematically depict a bottom wall BW portion with a keel KE of a vessel according to another embodiment of the invention. This embodiment is similar to the embodiment of the Figs. 1-8, so that similar features and characteristics will not be unduly repeated here. Reference is therefore made to the corresponding above description. The description below will therefore mainly be directed to the differences between the two embodiments and/or details not shown in the embodiment of Figs. 1-8, which among others includes a way in which the first and second interlocking members IM1 , IM2 may interlock.

Fig. 9 depicts a perspective view of the bottom wall BW portion with an opening OP and the keel KE in an extended position. Fig. 10 is the corresponding cross-sectional view, while Fig. 11 is also a cross-sectional view but with the keel KE in a retracted position.

Similar to the embodiment of Figs. 1-8, the keel KE comprises a splittable section SS and an end section ES with a bulb BU connected to the splittable section SS. The splittable section SS comprises a first part FP to be guided along a first guiding path GP1 , and a second part SP to be guided along a second guiding path GP2. The first part FP includes first interlocking members IM1 while the second part SP includes second interlocking members IM2.

The first interlocking members IM1 are pivotally connected to each other to pivot about respective first pivot axes PA1. The second interlocking members IM2 are pivotally connected to each other to pivot about respective second pivot axes PA2.

The first and second interlocking members IM1 , IM2 are in this embodiment configured to interlock with each other using a protrusion PR on one side of the respective first and second interlocking members and a corresponding recess RE on the opposite side of the respective first and second interlocking members, so that the protrusion on one interlocking members (first IM1 or second IM2) is able to be received in a recess of an adjacent interlocking member (second I M2 or first IM1) thereby locking them together due to positive locking.

A driving mechanism DM is provided to move the keel KE between the extended position and the retracted position. As can be best seen in Fig. 9, the driving mechanism DM includes an electromotor EM and a gearbox GB to drive rotation of a first rotation shaft RS1 and a second rotation shaft RS2, which shafts RS1 , RS2 are visible in Figs. 10 and 1 1.

The first and second rotation shaft RS1 , RS2 are in frictional engagement with

respectively the first part FP and the second part SP of the splittable section SS. Moving the splittable section SS by the driving mechanism DM through the opening OP towards the retracted position separates the interlocked first interlocking members IM1 and second interlocking members IM2 that pass through the opening OP, while moving the splittable section SS in the opposite direction towards the extended position interlocks the first interlocking members IM1 and second interlocking members IM2 that pass through the opening OP.

A difference is that the first and second rotation shafts RS1 , RS2 in this embodiment are positioned at a larger distance from the opening OP than in the embodiment of Figs. 1-8, so that at the opposite side of the bottom wall BW, more space may be required to allow the first FP and second part SP to bend from the opening OP towards the adjacent bottom wall BW to follow the respective first and second guiding path GP1 , GP2. This can be best seen in Fig. 10. As a result thereof the side wall SW delimiting the space defining the first and second guiding paths at the opening OP, i.e. in the middle, is thicker than at the sides. However, an advantage may be that the driving mechanism DM can be easier mounted to the bottom wall BW and/or are easier accessible for e.g. maintenance.

In the embodiment of Figs. 1-8, only one side wall SWwas shown that delimits the space in which the first and second part are to be received. Fig. 9 now also shows the other side walls denoted here using reference symbol OSW. Although not shown, it will be clear that a wall or cover may be provided to close said space, i.e. delimit said space from the rest of the interior of the hull.

Figs. 12, 13A and 13B schematically depict in cross-section a bottom wall BW portion with a keel KE according to another embodiment of the invention. Shown are an opening OP, a first guiding channel GC1 defining a first guiding path GP1 , a second guiding channel GC2 defining a second guiding path GP2, a splittable section SS with a first part FP to be received in the first guiding channel GC1 and a second part SP to be received in the second guiding channel GC2, an end section ES with a bulb BU, and the first rotating shaft RS1 and the second rotating shaft RS2 as part of a driving mechanism.

The embodiment is similar to the embodiments of the Figs. 1-8 and Figs. 9-11 , so that similar features and characteristics will not be unduly repeated here. Reference is therefore made to the corresponding above description.

Fig. 12 depicts the keel KE at an intermediate position, Fig. 13A depicts the keel KE in the extended position and Fig. 13B depicts a detail of Fig. 13A indicated by the circle in Fig. 13A. The keel KE can also be retracted to a retracted position (not shown).

In this embodiment, it can be clearly seen that the first part FP of the splittable section SS comprises first interlocking members IM1 that are pivotably connected to each other to pivot about respective first pivot axes PA1 , and the second part SP of the splittable section SS comprises second interlocking members IM2 that are pivotably connected to each other to pivot about respective second pivot axes PA2. Only a few of the interlocking members and pivot axes are indicated using respective reference symbols IM1 , IM2, PA1 and PA2.

The first and second interlocking members IM1 , IM2 are in this embodiment configured to interlock with each other using a protrusion PR on one side of the first and second interlocking members and a corresponding recess RE on the opposite side of the first and second interlocking members, so that the protrusion on one interlocking member is able to be received in a recess of an adjacent interlocking member thereby locking them together. The opening OP keeps the interlocking members at that location in place thereby keeping all interlocking members between the opening OP and the end section ES in interlocking engagement.

In this embodiment, a separation element SM is provided aiding in the separation of the first and second interlocking members IM1 , IM2 and guiding the first interlocking members IM1 towards the first guiding channel GC1 and the second interlocking members IM2 towards the second guiding channel GC2.

In this embodiment, the splittable section SS is divided along its length (i.e. seen in the length direction) in three portions, namely a first portion P1 , a second portion P2 and a third portion P3, wherein in the extended position of Fig. 13A, the first portion P1 is closer to the opening OP than the second portion P2, and the second portion P2 in turn is closer to the opening OP than the third portion P3. The second portion P2 is pivotably connected to the first portion P1 to pivot about a first operational axis OP1 , which in this embodiment is formed by a first pivot axis PA1 provided between the adjacent first interlocking member IM1 of the first portion P1 and the first interlocking member IM1 of the second portion P2.

The third portion P3 is pivotably connected to the second portion P2 to pivot about a second operational axis OP2, which in this embodiment is formed by a first pivot axis PA1 provided between the adjacent first interlocking member IM1 of the second portion P2 and the first interlocking member IM1 of the third portion P3. This is shown in more detail in Fig. 13B.

The third portion P3 in turn is connected to the end section ES.

To pivot the second portion P2 relative to the first portion P1 , and to pivot the third portion P3 relative to the second portion P2, a first actuator system FA is provided. In this embodiment, the first actuator system comprises a plurality of hydraulic actuators HA provided between adjacent second interlocking members IM2 of the first and second portions P1 , P2 and between adjacent second interlocking members IM2 of the second and third portion P2, P3. This allows to bend the keel KE from a straight orientation indicated by dashed line DL1 in Fig. 10A to the right as shown in solid lines in Fig. 13A and indicated by arrow A1 , and to the left as shown in shown in dashed lines in Fig. 13A and indicated by arrow A2. Due to the presence of the first actuator system and the hydraulic actuators, which in this embodiment replace a second interlocking member compared to the embodiments shown in Figs. 1-11 , there is room between the different portions of the splittable section SS to allow the bending of the splittable section SS. As shown in more detail in Fig. 13B, a resilient member RM may be provided to fill the space between the portions while at the same time allows the portions to move relative to each other.

Figs. 14-19 depict a bottom wall BW portion of a vessel according to yet another embodiment of the invention with a keel KE. The keel KE, i.e. the moveable construction, is retractable and extendible through an opening OP in the bottom wall BW.

To this end, the keel KE comprises a splittable section SS and an end section ES with a bulb BU connected to the splittable section SS. The splittable section SS comprises a first part FP to be guided in a first guiding channel GC1 defining a corresponding first guiding path for the first part FP. The splittable section further comprises a second part SP to be guided in a second guiding channel GC2 defining a corresponding second guiding path for the second part SP.

As can be best seen in Fig. 16, the first part FP of the splittable section SS comprises first interlocking members IM1 and the second part SP comprises second interlocking members I M2 configured to interlock with each other to form a keel KE below the opening OP.

The first part FP is bendable due to the first interlocking members IM1 being pivotally connected to each other. In this embodiment, this is implemented by connecting the first interlocking members IM1 to first cables C1 , which first cables C1 due to their flexibility provide virtual first pivot axes between adjacent first interlocking members IM1.

Similarly, the second part SP is bendable due to the second interlocking members IM2 being pivotally connected to each other by connecting the second interlocking members IM2 to second cables C2. The second cables C2 due to their flexibility provide virtual second pivot axes between adjacent second interlocking members IM2.

The cable portions between adjacent interlocking members may alternatively be referred to as connecting members. The first and second cables C1 , C2 are in this embodiment not only used to connect the first and second interlocking members IM 1 , IM2 to, but also part of a driving mechanism DM. The driving mechanism DM further comprises a first drum DR1 to receive the first cables C1 , a first motor M1 to drive rotation of the first drum DR1 , a second drum DR2 to receive the second cables C2, and a second motor M2 to drive rotation of the second drum DR2. By rotating the first and second drum DR1 , DR2, the respective first and second cables C1 , C2 are wind on or unwind from the first and second drum DR1 , DR2.

The combination of the first drum DR1 and the first motor M1 may alternatively be referred to as the first winch. The combination of the second drum DR2 and the second motor M2 may alternatively be referred to as the second winch.

In Fig. 16, the keel KE has been retracted to an intermediate position compared to the situation in Fig. 15 by winding the first cables C1 on the first drum DR1 and winding the second cables C2 on the second drum DR2. Continuing this operation results in the situation of Fig. 17 in which the keel is in its retracted position.

Fig. 18 shows the situation after unwinding the first C1 and second C2 cables until the keel KE is in its extended position. In this position, the splittable section is formed of alternating first and second interlocking members IM1 , IM2 that are interlocked as protrusions PR of the interlocking members are received in corresponding recesses RE of the adjacent interlocking members thereby creating a formfit.

Fig. 19 shows the keel KE in the extended position with an asymmetric pull of the first and second winch on the respective first and second cables C1 , C2. The pull applied by the second winch is in this case larger than the pull applied by the first winch. As a result, the keel KE bends to the right in Fig. 19. Such bending is possible due to the configuration of the protrusions PR and the recesses RE that allow bending of the interlocking members about an axis parallel to the first and second pivot axes.