The present invention relates to a submersible boat, comprising a diving tank for controlling buoyancy of the boat, wherein the diving tank has an inflatable buoyancy body and a housing adapted to at least partially cover the buoyancy body. In principle, the submersible boat of the present invention may be of any type, but the present invention is especially suitable to be used in the field of relatively small submersible boats which are used for purposes of recreation and underwater research, and which are designed for accommodating only a small number of people, for example, a maximum of three.

A submersible boat as mentioned is known, for example from US 6,321,676. An important issue in the field of submersible boats is buoyancy, and the design of means for taking the boat to a desired level in or on the water and keeping it there until another decision regarding the level is made. US 6,321,676 discloses that such means may comprise two buoyancy chambers which are arranged at opposite sides of the submersible boat. In a possible embodiment, each of the chambers comprises a resilient inflation bladder. To provide buoyancy, the bladder is filled with a fluid having a lower density than water. In a practical situation, the fluid may be air such as can be provided by standard scuba air tanks. To decrease buoyancy, the fluid is evacuated from the bladder. To this end, a valve may be used, which is put to an opened position when evacuation of the fluid is required. A consequence of being underwater which is advantageous in this context is that ambient pressure is relatively high and may operate to collapse the bladder, eventually forcing out any inflation fluid contained therein. It is possible to have a passive system, i.e. a system according to which only water pressure is used for emptying and collapsing the bladder.

Hence, when a chamber comprising a bladder as mentioned in the foregoing is used, a downward movement of the submersible boat is associated with deflation of the bladder, and an upward movement of_ the, submersible boat is associated with inflation of the bladder. Although the use of the chamber comprising the bladder has proved to be functional, there are disadvantages associated with it. A notable disadvantage resides in the fact that when the submersible boat is underwater and the bladder is in a deflated condition, the chamber constitutes a considerable portion of the total weight of the boat, as it is filled with water in that situation. On the basis of this fact, the mass inertia of the boat is higher than is desirable and its maneuverability is lower than is desirable.

It is an objective of the present invention to provide a submersible boat having improved maneuverability. This objective is achieved by a submersible boat comprising a diving tank having an inflatable buoyancy body and a housing adapted to at least partially cover the buoyancy body, wherein the appearance of the housing is adjustable, depending on the inflation condition of the buoyancy body .

According to the present invention, in a diving tank which is part of a submersible boat, the appearance of the housing for at least partially covering the buoyancy body is adjustable, i.e. the size and/or shape of the housing are adjustable. Adjustments are done on the basis of the inflation condition of the buoyancy body. Thus, in a situation in which the buoyancy body is in a deflated condition, the housing has a smaller appearance than in a situation in which the buoyancy body is in a fully inflated condition.

As is the case with conventional submersible boats such as the boat known from US 6,321,676, a fluid such as air is used for inflating the buoyancy body. To this end, the boat comprises a tank or other suitable means for containing the fluid, and a system for supplying the fluid to the buoyancy body. A controllable valve or the like may be provided for allowing the fluid to flow from the tank to the buoyancy body, or for blocking such a flow of fluid.

The present invention offers many advantages. As in the diving tank, the housing is made to follow the buoyancy body, as it were, wherein the appearance of the housing is adjusted to the inflation condition of the buoyancy body, it is achieved that in a situation in which the submersible boat is underwater and the buoyancy body is deflated, the housing is smaller than in a situation in which the submersible boat is floating on the water and the buoyancy body is fully inflated. Compared to underwater situations with conventional boats, the housing only contains a minimum amount of water, due to the fact that its appearance is smallest then. Consequently, there is hardly a contribution to the weight of the submersible boat, and there is hardly a decreasing effect on its maneuverability. In other words, in comparison with conventional cases, there is a minimal volume of surplus water when the boat is submerged, whereby handling characteristics of the boat are improved, since there is less weight to accelerate and decelerate.

It appears that there are even more advantages associated with the present invention, pertaining to a submerged condition of the boat. In the first place, the frontal area of the diving tank can be minimal, as a result of which drag is reduced. In the second place, due to the minimal dimensions of the diving tank, visibility is improved. People sitting in the submersible boat can see more when there is less of the diving tank that is in the way.

Furthermore, another advantage is that due to the possibility of decreasing the size of the diving tank, the submersible boat can be stowed or transported without _^ a need of dismantling the boat. With a deflated condition of the buoyancy body and an associated smallest appearance of the diving tank, the boat can be very compact .

In order to have minimal dimensions of the housing of the diving tank in practical situations, it is preferred if the housing is capable of snugly enclosing the buoyancy body in a deflated condition in one of its possible appearances, while the housing is also capable of offering room to the buoyancy body in a fully inflated condition in another of its possible appearances.

It is an advantageous option to have at least one coupling arranged between the housing and an exterior surface of the buoyancy body. On the basis of the presence of a coupling as mentioned, the buoyancy body may pull the housing to another, smaller appearance in case the buoyancy body is deflated. Within the scope of the present invention, the coupling may be realized in any suitable way, wherein it is an option for the coupling to comprise a resilient member.

In a practical embodiment, the housing may comprise at least one movably arranged element which is adapted to be rested against the buoyancy body in any inflated condition of the buoyancy body.

The housing may be designed in any suitable way. For example, the housing may comprise two elements which are hingedly connected to each other, wherein the buoyancy body is arranged between the elements, so that one of the elements covers one side of the buoyancy body, and another of the elements covers another side of the buoyancy body. In that case, in order to have the advantage of minimal drag when the boat is submerged, it is preferred if a hinge axis which is present between the housing elements extends in a direction in which the boat is movable, i.e. in a direction which is denoted as forward in a normal orientation of the boat.

One of. the housing elements may have a fixed position with respect to fixedly arranged components of the boat, including a capsule for accommodating living beings and/or things to be

transported by means of the boat. In that situation, the appearance of the housing changes along with a hinging movement of another housing element.

A surprising effect of the present invention is found when the following is considered. Normally, like a conventional submersible boat, the boat according to the present invention needs means for driving the boat, causing it to move when powered. For example, the boat needs to have a horizontal thruster for enabling the boat to travel forward or backward. In designing a submersible boat, a difficulty is found in the fact that in a surfaced condition of the boat, the thruster should be arranged at a level on the boat that is low enough for the thruster to be in the water. However, in a submerged condition of the boat, a low level of the thruster is disadvantageous. The fact is that in such condition, it would be ideal to have the thruster at the level of the centre of gravity of the boat , in order to avoid pitch behavior of the boat when the thruster is powered, and thereby to avoid measures for compensating such behavior.

The present invention allows for a most practical solution to the above-sketched problem of the positioning of a horizontal thruster or the like on the boat . In particular, the thruster may be coupled to the housing of the diving tank in order to realize an adjustable position of the thruster. For example, in case the housing comprises a hingably arranged element, the thruster may be coupled to that element. In that case, the housing element may have a main surface which is more or less in a horizontal position when the buoyancy body is fully inflated, and which may be moved to assume a more or less vertical position when fluid is allowed to flow out of the buoyancy body, and the buoyancy body is deflated. When the thruster is coupled to that surface, it may be realized that the thruster is at a relatively low level when the surface as mentioned is in the more or less horizontal position, i.e. when the buoyancy body is fully inflated and the boat is floating on the water, and that the thruster is at a relatively high level when the surface as mentioned is in the more or less vertical position, i.e. when the buoyancy body is deflated and the boat is submerged. In fact, automatic positioning of the thruster is realized, which is most advantageous in comparison with options existing in the art, like having more than one thruster in the boat, at different levels, or trying to have a compromised positioning of the thruster, wherein the characteristics of the movements of the boat are not ideal in both a surfaced condition and a submerged condition.

The housing does not necessarily need to cover the buoyancy body entirely. In order for the buoyancy body to be resistant to damage, it is advantageous if the buoyancy body has at least one fender strip on its exterior surface. Within the scope of the present invention, any suitable protective measure may be taken, including another measure for reinforcing the exterior surface of the buoyancy body.

In a practical embodiment, the submersible boat comprises two diving tanks, arranged at opposite sides of the boat. For example, like the buoyancy chambers known from US 6,321,676, the diving tanks may be mounted at a position which is generally beneath and to the side of the capsule in a normal orientation of the boat, in a pontoon- like fashion. Each diving tank may comprise one inflatable buoyancy body, but it is also possible that more buoyancy bodies, for example, two buoyancy bodies, are part of a diving tank.

With respect to the capsule, it is noted that this component of the submersible boat may be openable and closeable at at least two levels. In particular, the capsule may comprise a shell having three parts, wherein a relatively small shell part is hingably connected to a relatively large shell part, and wherein the relatively large shell part is hingably connected to yet another shell part. In this design of the capsule, the relatively large shell part as mentioned may be put to an opened position for embarking and disembarking only at a light sea state, in which there is no risk of high waves and water flowing into the capsule. The relatively small shell part as mentioned is used at a rough sea state, or when the boat has not surfaced properly. In case the shell of the capsule is shaped like a sphere, the relatively large shell part may be a part of the shell which is an upper half in a normal orientation of the boat, wherein the relatively small shell part is shaped like a hatch which is arranged at a top position of the upper half. , _g

On the basis of the design of the capsule as described, it is achieved that embarking and disembarking can take place under all possible circumstances. Normally, most convenient embarking and disembarking is possible by putting a relatively large shell part to an opened position. Embarking and disembarking is also possible when circumstances are not ideal, namely through the relatively small shell part, albeit somewhat less convenient. In any case, in comparison to conventional designs, in which opening and closing of the capsule can take place at only one position, the scope of use of the submersible boat is enlarged.

The present invention further relates to a submersible boat comprising a capsule as described in the preceding paragraphs, whether the boat has diving tanks comprising an inflatable buoyancy body, or not.

Also, the present invention relates to a submersible boat comprising means for driving the boat, causing it to move when powered, wherein a position of the driving means is adjustable with respect to fixedly arranged components of the boat, including a capsule for accommodating living beings and/or things to be

transported by means of the boat, and wherein the driving means are coupled to a movably arranged component of the boat. Preferably, the movably arranged component is a component which is movable on the basis of a particular function, wherein the movement is performed when the boat rises or submerges, as is the case with the element of the housing as described in the foregoing. However, the movably arranged component may also be a separate component which is dedicated to the function of moving the driving means only.

The present invention, will further be explained on the basis of the following description, wherein reference will be made to the drawing, in which equal reference signs indicate equal or similar components, and in which:

figures 1 and 2 show a side and a front view, respectively, of a preferred embodiment of the submersible boat according to the present invention;

figures 3 and 4, like figure 2, show a front view of the boat, wherein a diving tank of the boat is shown in different conditions; figures 5-7 illustrate different conditions of the diving tank, and associated different positions of a thruster of the boat; and _η

figures 8 and 9 illustrate two ways of opening a capsule of the boat .

Figures 1 and 2 show a preferred embodiment of a submersible boat 1 according to the present invention. The view shown in figure 1 is a side view, and the view shown in figure 2 is a front view, taking into account a normal orientation of the boat 1 as shown in the figures and a normal traveling direction of the boat 1.

The boat 1 as shown is a so-called midget submarine, i.e. a submarine which has little or no on-board living accommodation, which is suitable for accommodating only a limited number of persons, in most cases less than ten, which is therefore relatively light, and which is used for relatively short trips. It is also possible for a midget submarine to be unmanned, wherein the

submarine may perform a trip by following a certain programme and/or by remote control. The boat 1 shown in figures 1 and 2, however, is suitable to be manned by a maximum of three persons . A main

component of the boat 1 is a capsule 10, which is suitable for accommodating the persons.

The capsule 10 has a shell 11 which is made of a material which is both water-tight and resistant to pressure prevailing at depths where the boat 1 may be used. Furthermore, the material is

translucent, so that the persons traveling with the boat 1 may see as much of the environment of the boat 1 as possible. In view of pressure distribution issues, it is advantageous for the capsule 10 to be shaped like a sphere, as shown.

Besides the capsule 10, the boat 1 comprises means for

controlling the buoyancy of the boat 1. In general, the boat 1 needs to be capable of floating on water if so desired, and the boat 1 also needs to be capable of submerging and rising again. In the shown example, the means for controlling the buoyancy comprise two diving tanks 20, which are arranged on at a position which is generally beneath and to the side of the capsule 10 in a normal orientation of the boat 1, at two sides of the boat 1, in a pontoon- like fashion.

The diving tanks 20 of the boat 1 as shown have a most

advantageous design. According to this design, a diving tank 20 comprises at least one inflatable buoyancy body 21, and a housing 22 for at least partially covering the buoyancy body 21. The buoyancy body 21 may be shaped like a bladder, and may be made of a resilient material such as rubber. For the purpose of inflating the buoyancy body 21, a suitable fluid such as air may be used, and the boat 1 is equipped with suitable means for containing the fluid and supplying the fluid to the buoyancy body 21. Furthermore, means are provided for closing and opening the buoyancy body 21 to the fluid supply. Also, means are provided for allowing a discharge of fluid from the buoyancy body 21 when it is intended to deflate the buoyancy body 21. The way in which the buoyancy body 21 is used and the means which are required for a proper functioning of the buoyancy body 21 are known per se, for example, from US 6,321,676, and are therefore not further specified here.

In a fully inflated condition, as shown in figures 1 and 2, the buoyancy body 21 contributes to the buoyancy of the boat 1, whereas in a deflated condition, there is no buoyancy effect of the buoyancy body 21. Hence, a situation in which the boat 1 is floating on water is associated with the fully inflated condition of the buoyancy body 21, whereas a situation in which the boat 1 is submerged is

associated with the deflated condition of the buoyancy body 21.

Furthermore, a situation in which the boat 1 travels to a lower level is associated with deflation of the buoyancy body 21, whereas a situation in which the boat 1 travels to a higher level is associated with inflation of the buoyancy body 21.

In the shown example, the housing 22 for at least partially covering the buoyancy body 21 comprises two tray-shaped elements 23, 24, which are both open to the buoyancy body 21, wherein the buoyancy body 21 is positioned between the housing elements 23, 24. The housing elements 23, 24 are hingedly connected to each other, wherein a hinge axis 25 is extending in a direction which is practically the same as a forward-backward direction of the boat 1, and wherein the hinge axis 25 is positioned at a top side of the housing 22, close to capsule 10.

One of the housing elements 23, 24 is a fixedly arranged element 23 which has a fixed position with respect to the capsule 10 and other stationary components of the boat 1. This element 23 is positioned at a side of the diving tank 20 which is the inside, i.e. the side which is closest to the capsule 10, and has a more or less vertical orientation in a normal orientation of the boat 1.

Another of the housing elements 23, 24 is a movably arranged element 24 which has a variable position with respect to the capsule 10 and the fixedly arranged element 23. In particular, this element _g

24 is movable about the hinge axis 25, in such a way as to follow the inflation condition of the buoyancy body 21. To this end, the element 24 may be coupled to the exterior surface of the buoyancy body 21.

Figure 2 shows the fully inflated condition of the buoyancy body 21, and illustrates the fact that in that situation, the movably arranged housing element 24 is kept in a more or less horizontal orientation by means of the fully inflated buoyancy body 21. Hence, the housing 22 is partially opened, wherein a portion of the exterior surface of the buoyancy body 21 is left uncovered.

Figures 3 and 4 illustrate what happens to the configuration of the housing 22 and the position of the movably arranged housing element 24 when the boat 1 is submerging and the buoyancy body 21 is deflated. As the buoyancy body 21 gets smaller and smaller, the housing 22 is moved to a closed position as shown in figure 4. In the process, the orientation of the movably arranged housing element 24 is changed from more or less horizontal to more or less vertical. In the latter orientation, the movably arranged housing element 24 rests against the fixedly arranged housing element 23, and the housing 22 constitutes a kind of box in which the buoyancy body 21 is stowed.

In the process of deflation, when the boat 1 is underwater, the water pressure is used to press the fluid out of the buoyancy body 21. For this reason, a kind of dent as shown in figure 3 is present in the buoyancy body 21 during the process. As long as there is fluid in the buoyancy body 21, the housing 22 is not closed

entirely, and the buoyancy body 21 is freely accessible by the water for exerting the pressure in an optimal way.

By having the movably arranged housing element 24, it is achieved that the appearance of the housing 22 is adjustable, wherein the appearance is determined by the inflation condition of the buoyancy body 21. The fact that it is possible to have a situation in which the buoyancy body 21 is deflated and the housing 22 is compact has many advantages, including the advantages of minimal weight of the diving tank 20 when being in the water, minimal drag, and minimal hindrance of the view from the capsule 10. Naturally, the situation of optimal compactness is also very advantageous in view of storage and transport of the boat 1.

A further advantage of the shown design of the housing 22 for at least partially covering the buoyancy body 21 becomes clear upon consideration of figures 5-7. These figures illustrate a possibility of having a coupling 30 between the movably arranged housing element 24 and a thruster 40 which is used for driving the boat 1. In figures 5-7, for sake of clarity, only the buoyancy body 21, the housing 22 with the two housing elements 23, 24, the coupling 30 and the thruster 40 are shown. Figure 5 shows the buoyancy body 21 in a fully inflated condition and an associated more or less horizontal position of the movably arranged housing element 24, figure 6 shows the buoyancy body 21 in a condition between full inflation and deflation, and an associated inclined position of the movably arranged housing element 24, which is a position between a

horizontal position and a vertical position, and figure 7 shows a more or less vertical position of the movably arranged housing element 24, wherein the buoyancy body 21 in a deflated condition.

In the shown example, the coupling 30 is oriented as an extension of the movably arranged housing element 24, at the side where the hinge axis 25 is present. Consequently, when the movably arranged housing element 24 rotates about the hinge axis 25, the coupling 30 performs a rotation as well, wherein the thruster 40 is taken more and more upward as the buoyancy body 21 is more and more deflated and the movably arranged housing element 24 is moved more and more to a vertical position. When a comparison is made between figures 5 and 7, it can clearly be seen that the thruster 40 is shown at the lowest level in figure 5, and at the highest level in figure 7.

Hence, when a coupling 30 between the movably arranged housing element 24 and a thruster 40 is present in the submersible boat 1, a system for automatically taking the thruster 40 to a higher level when the boat 1 is submerged is realized. This is very advantageous, as having the thruster 40 at a relatively low level is desirable in a surfaced position of the boat 1, while having the thruster 40 at a higher level, preferably the level of the centre of gravity of the boat 1, is desirable in a submerged position of the boat 1. It is an important insight of the present invention that this is a

possibility existing within the basic concept of having a deformable housing 22.

Figures 8 and 9 illustrate another advantageous option, which is related to the design of the capsule 10. In the shown example, the capsule 10 can be entered in two different ways, wherein the capsule 10 can be opened at two different levels. In the first _∑1

place, the shell- 11 of the capsule 10 is divided in two halves 12, 13, namely a lower half 12 and an upper half 13. Figure 8

illustrates the fact that the upper half 13 is hingably connected to the lower half 12, and that a conveniently large opening is obtained when the upper half 13 is tilted. However, in actual use of the submersible boat 1, it is not always possible to have the relatively large opening for allowing embarking and disembarking, especially in case of a rough sea state, when there is a risk that water enters the capsule 10 through the opening. In order to solve this problem, it is proposed to have a second possibility of opening the capsule 10. In particular, a relatively small opening can be created at a higher level, namely on the basis of the fact that a hatch 14 is arranged in the upper half 13. Figure 9 illustrates the fact that the hatch 14 is hingably connected to the upper half 13, and that a relatively small opening is obtained when the hatch 14 is tilted. Due to the higher level and the smaller size of the opening, there is practically no risk of water entering the capsule 10, even at a rough sea state.

Naturally, it is only safe to submerge the boat 1 when both the upper half 13 and the hatch 14 are in a closed position. In a manner known per se, sealing means such as one or more O-rings need to be provided in order to guarantee water-tightness at the position where the upper half 13 contacts the lower half 12, and the position where the hatch 14 contacts the upper half 13.

It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims.

For example, the housing 22 for at least partially covering the buoyancy body 21 can be of a totally different design than what is shown in the figures and described in the foregoing, as long as the housing 22 is somehow deformable, in the sense that its shape and/or size are adjustable, and capable of following the inflation

condition of the buoyancy body 21. The housing 22 may comprise elements 23, 24 having a variable mutual position, as is ₇ the case in the shown example, wherein it is possible for the elements 23, 24 to be rigid. Furthermore, the present invention covers embodiments of the housing 22 having one or more deformable portions, for example, soft and/or resilient portions.

Details of the submersible boat 1 which are not directly related to the present invention can be chosen freely from options which are normally available in the field of submersible boats 1. For example, it is possible for the boat 1 to be equipped with an arm for taking samples .

In the foregoing, a submersible boat 1 is disclosed. The submersible boat 1 comprises a diving tank 20 which serves for controlling buoyancy of the boat 1. In particular, the diving tank 20 has an inflatable buoyancy body 21 and a housing 22 for at least partially covering the buoyancy body 21. The configuration of the housing 22 is adjustable to the inflation condition of the buoyancy body 21. Hence, when the buoyancy body 21 is inflated, the housing 22 can have a relatively large configuration, and when the buoyancy body 21 is deflated, the housing 22 can have a relatively small configuration. In the latter case, which is associated with a submerged condition of the boat 1-, or a condition of storage and/or transport, the housing 22 is compact, and the same goes for the overall appearance of the boat 1, as the extent to which the diving tank 20 constitutes a projecting component of the boat 1 is reduced. This offers many advantages, ranging from improved maneuverability of the boat 1 in underwater conditions to reduced need for space during storage and/or transport.