GB2135940A - Semi-rigid inflatable boat - Google Patents

Abstract

The inflatable boat, comprising a hull 1 to which there are fastened two lateral floats 2 forming stabilisers, is characterised in that the hull 1 is in at least three parts 17, 18, normally made fast with one another, for navigation, by fixing and stiffening means, the lateral floats 2 being carried respectively by the said hull parts 17, these being capable of being turned over for the folding of the boat upon itself, about at least one longitudinal axis. <IMAGE>

Description

SPECIFICATION Semi-rigid inflatable boat The invention relates to semi-rigid inflatable boats.

Taken as a whole these boats comprise a rigid part or hull which is bordered on each side by an adjacent lateral float extending over all or part of the hull and possibly even extending to the rear beyond the hull.

The rôle of the rigid hull is to ensure the mechanical behaviour and floating capacity of the boat. The lateral floats are in fact stabilisers the role of which is firstly elastically to absorb the hydraulic impacts due to the waves and also to prevent an excessive momentary list.

These boats are used for pleasure purposes or for specific activities at sea such as supervision, lifesaving or services to oil-rig platforms. Thus they are likely to encounter heavy or even very heavy seas.

The purpose of the invention is to propose a boat which can be foldable fortransportwhile having good hull rigidity during navigation.

The boat according to the invention is characterised in that the hull is in at least three parts, normally made fast with one another transversely for navigation, the two lateral hull parts each carrying one of the lateral floats and the hull parts being capable of being turned over one on to the other, for example when the lateral floats are deflated.

According to one embodiment the central hull element is bolted on to the marginal zones of the lateral hull elements but it can also be retained by these by means of hooks or dogs or even protruding profiles carried by these lateral elements and engaging in corresponding lodgements provided on the sides of the central hull element, when the boat is unfolded, the boat being stiffened for navigation by at least one cross-member and/orthe stern board and/or an upper arch. The boat preferably comprises an axial internal float forming a seat, the inflation of which causes the opening out, in the manner of a book, of the two lateral hull elements about an axial line materialised by the float-seat.

According to another embodiment, applicable in particular to boats of great length, for example up to 20 metres, the boat comprises a rigid central hull element extending over the entire length of the central part of the boat, two rigid lateral hull elements each carrying one of the floats and extending on each side over a part of the length of the central hull element, water-tight articulation means between the respective adjacent sides of the central element and of the lateral hull elements, and means for controlling the angular position of each lateral hull element in relation to the central hull element.

The axis of articulation of each lateral hull element is substantially parallel to the longitudinal axis of the boat and extends over only a part of the length thereof.

As the boat is narrowed forwards, the articulation means extend towards the bow from the common rear extremity of the central element and the corresponding lateral hull element over only a part of the said adjacent sides, and are prolonged forwards, between their forward extremities and the forward extremity of the boat, by water-tight, flexible and deformable connection means connecting the central hull element to each lateral hull element and to the associated lateral float, the whole being arranged so that on pivoting of a lateral hull element in relation to the central element the articulation occurs about the rectilinear axis of the said articulation means, with deformation of the said connection means forward.

According to one variant of this embodiment the articulation spindles of the rigid lateral hull elements are articulated to the rigid central hull element each about an axis inclined in relation to the horizontal and to the longitudinal axis of the boat, the two axes extending from the stern of the hull to the forward point of the hull where they meet. With such an arrangement each of the lateral hull elements can be folded as a single assembly, with its float inflated.

Further characteristics of the invention will appear on reading of the following description and on reference to the accompanying diagrammatic drawings, wherein : Figure lisa view in lateral elevation of the boat according to one form of embodiment of the invention; Figure 2 is a plan view of the boat according to Figure 1; Figure 3 is a view of the boat according to Figure 1 from beneath; Figures 4to 7are sections along the lines IV - IVto VII - VII respectively in Figure 1; Figure 8 is a half-section analogous with Figure 6, on a iarger scale; Figure 9 is a plan view of a part of the stern board; Figure 10 is a view in rear elevation of the boat without its central hull element; Figure 11 tis a partial diagrammatic view, in perspective and seen from astern, of the boat when folded;; Figure 12 is a cross-section analogous with Figure 7 and on a larger scale, showing two variants of fastening of the central hull element on the lateral elements; Figure 13 is a plan view of a boat according to another form of embodiment of the invention; Figures 14 and 15 are two lateral views showing the boat according to Figure 13, for two pivotal positions of the floats and of their respective lateral carrier hull elements; Figures 16 and 17 are two lateral views showing the boat according to Figure 13 for two pivotal positions of the floats, equipped with rear air-planes and hydroplanes; Figure 18 is a partially broken-away diagrammatic perspective view of the boat according to Figure 13, and shows especially the constitution of the lateral floats; Figures 19 to 22 are cross-sections of the boat according to Figure 13 in four pivotal positions of the lateral hull elements;; Figure 23 is a diagrammatic plan view of a boat according to another form of embodiment of the invention; Figure 24 is a diagrammatic lateral view of the boat according to Figure 23, and Figures 25 and 26 are half-sections along the lines XXV - XXV and XXVI - XXVI of the boat according to Figure 24.

In the following description the same numerical references are utilised to designate the analogous or identical elements.

The boat as represented in the drawings comprises a rigid hull 1. This hull extends over the entire length of the boat. It is tapered and raised forward in order to terminate at a point. As shown in Figures 4 to 7, it is in the form of a V with concave flanks and evolutive profile, from the stem (Figure 4), where the V is very sharp, to the stern (Figure 7) where the V is very open.

The hull 1 is provided on each side with a longitudinal float or stabiliser 2 which extends over the entire length of the boat. The floats 2 terminate forward in a point and they may protrude to the rear in order to terminate likewise in a point. They are fastened to the upper longitudinal sides of the hull by any appropiate known means, for example by direct glueing in a channel 3 (Figures 8 and 12), reinforced by glued strips.

As may be seen from the Figures, the floats 2 are slightly superelevated in relation to the hull in such manner as to intervene only as lateral stabilsers, and not to brake the boat by their drag.

The V-profile of the hull ensures good penetration into the water and throws the water aside thanks to its flaring from the front to the rear.

The sustaining effect is reinforced at high speeds bythe air currents flowing overthe hull along concave surfaces 4 of evolutive profile, formed between the V-profile, which terminates with a lateral lip or nose 5, and the respective upper edges of the hull. Towards the rear (Figures 6 and 7) these air currents are imprisoned on each side in a passage 6, of rearwardly decreasing section, formed between the hull 1 and a V-shaped keel 7 fixed beneath each float 2 by bolting on plates 20 of the floats 2 and directly on the lower face of the hull.

The lower edge of each keel 7 carries a sustaining skidS; by way of variant the skid can be placed under the hull or astride between the latter and the associated float. The skid 8 has a plane or downwardly concave lower face.

The boat thus constituted can be surmounted by at least one longitudinal central aerial float 9 extending from the vicinity of the bow towards the stern of the boat.

This float is pointed forward and of rearwardly increasing section. It is connected to the bow and stern of the boat. Forward it can extend to the right to the bow but for preference it commences for example only at the second quarter of the boat. Its forward point is connected by an elastic or inelastic cable 10 to the rear part of a cockpit 11 which is supported on the stabilisers 2 by bolting on plates 12. The float 9 is slightly downwardly concave to come down to above the stern of the boat.It is fixed to the boat at the stern too, for example by a detachable rigid central mast 28 disposed between the stern board 13 and the extreme rear extremity of the float, and by at least one arch 14, two in the example under consideration, which is supported on the rear extremities of the lateral stabilisers, forward of the mast 28, by bolting on plates 15 and on the float 9 with which it can be in pneumatic communication.

The arch 14 is advantageously of pneumatic type, so that it can absorb shocks due to waves, while the rear mast 28 avoids complete crushing of the aerial float 9.

Along the axis of the boat and on its upper face, the hull 1 carries a pneumatic cushion 16 extending from the forward part to the stern board 13 to constitute for example a seat on which the passengers are seated astride.

According to one variant in place of a single aerial float 9 it is possible to provide a plurality of linked aerial floats distributed in an arc of a circle. It is also possible to eliminate the longitudinal float 9 and retain only the arches 14, suitably braced.

In known manner the set of pneumatic structures as described above can be formed with separate compartments and/or contain cellular structures.

In the event of a capsize, which is always possible in heavy seas, the aerial float 9, or the multiple aerial floats, is or are immersed; thus they are subjected to an upward hydraulic thrust which creates a sufficient correcting force to return the boat automatically into the normal floating position. For this purpose it is sufficient to give them the appropiate volume, which is variable according to the characteristics of the boat.

Furthermore, thanks to the form of the hull with V-profile widening from front to rear, to the keels 7, to the skids 8 and the exploitation of the air currents against the hull, the boat lifts off easily, which gives it, for the same motor power, speed performances much superior to known boats.

The boat is arranged to be capable of being partly dismantled and folded upon itself about a longitudinal line.

As indicated above, the forward cockpit 11, the aerial float 9 and the arches 14 are fixed by bolting; thus they are detachable.

As regards the hull 1, it is in at least three parts: two lateral elements 17 and a central element 18 which extend from front to rear of the boat. Each lateral element 17 is constituted by a profiled blank of plastic or metallic material. In its external marginal zone it receives the associated lateral float 2 by glueing in the channel 3, possibly with reinforcing strips. In the vicinity of its inner edge it is bolted at 19 to the central hull element 18 (Figures 1 to 11). The lateral elements 17 are united by water-proof flexible cloth 21 (Figure 8) glued on the lower face of the internal marginal zone of each element 17, the glueing being reinforced by a longitudinal strip 22 glued stride over the upper face of the said marginal zone and over the cloth 21 itself. The cloth 21 extends from stem to stern of the boat, rising over the inner face of the stern board 13 (Figures 10 and 11). The cloth 21, in its axial part, receives the inner seat-float 16 by glueing, the bond being reinforced by two lateral V-strips 23 glued astride the float 16 and the cloth 21.

The central hull element 18 is a laminated monob loc piece the lower face of which forms the evolutive V of the hull. Each of its longitudinal sides is fixed to the lateral element 17 by bolting at 19 and defines the cavity 4. Its central part presents a longitudinal channel 24 for the reception of the seat-float 16 glued on its cloth 21. At the front the point of the central element 18 can be received in a cap 29 fastened to the floats 2 and preferably flexible to permit folding.

As regards the stern board 13 (Figure 9), it comprises two lateral elements 25, 26 permanently fastened, each by its lower edge to the associated lateral hull element 17, by its outer edge to the associated lateral float 2, and by its inner edge to the cloth 21.

The lateral elements 25,26 of the stern board are in planes offset axially by a distance approximately equal to their thickness and by a central stern board element 27 detachably fixed to the lateral elements 25,26 on the inner side of the boat in relation to the cloth 21.

For the folding up of the boat the forward cockpit 11, the aerial float 9, the mast 28, the keels 7, the central hull element 18 and the central stern board element 27 are removed and the lateral floats 2 and the float-seat 16 are deflated, these remaining connected respectively to the lateral hull elements 17 and to the cloth 21 and being folded upon themselves. As shown in Figure 11, the two halves of the boat are turned over one on to the other about the flexible hinge constituted by the clath 21, the stern board element 26 coming to lodge before the element 25. Before the folding the deflated and flattened aerial float 9 can have been placed on one of the lateral hull elements 17.

After folding the boat occupies a restricted space of width compatible with road transport on a trailer.

For inflation the converse procedure is adopted, the inflation of the float-seat 16 being capable of being simultaneous with that of the lateral floats 2 and causing the automatic unfolding of the hull in the manner of a book about the inflating hinge formed by the cloth 21 and the float-seat 16.

By way of variant (not shown) it would be possible to provide a detachable canvas or awning, preferably transparent, which can cover the boat on both sides of the aerial float, to constitute a shelter against sun, rain or wind.

In Figure 12 there are shown two variants (one on each side) for the fixing of the central hull element 18 on the lateral elements. The bolt fastenings 19 according to Figures 1 to 11 are replaced in both cases by a mechanical hook attachment due to the very fact of the unfolding of the boat.

In Figure 12 there are entered the same numerical references as in Figures 1 to 11 for the identical or analogous elements; thus reference may be made to the description given previously thereof.

In the left half of Figure 12 the lateral hull element 17 carries, on its lower face, detachable or fixed spaced hooks 30, substantially at right angles, the respective free arms of which can come into engagement in associated cavities 31 of substantially horizontal axes, formed on the edge of the central hull element 18. The hooks 30 are directed towards the axis of the boat.

In the right half of Figure 12 the central hull element 17 carries on its lower face a detachable or fixed profiled section 32 which is shaped according to the contour of the central element 18. This section 32 is equipped with separate protuberances 33, the section of which decreases towards the free end, which can come into engagement in associated cavities 34 formed on the edge of the central hull element 18. The axes of the protuberances 33 are substabtially horizontal and directed towrds the axis of the boat. By way of variant the section 32 can carry a continous rib engaging in an associated groove of the central hull element.

In the two variants according to Figure 12 the hooks 30 or protuberances 33 penetrate of their own accord into the lodgements 31,34, while the edges of the central hull element 18 come to abut on the hooks 30 or sections 32.

For navigation the boat is stiffened by the stern board 13 and/or by the arches 14 and/or by rigid or pneumatic cross-members represented diagrammatically by a bench 35 resting on the floats 2 through footings 36.

In the variant according to Figures 13 to 22 the hull 1 is again in at least three parts: - two rigid lateral elements 17 and a rigid central element 18 which extend from the bow to stern of the boat. Each lateral element 17 is constituted buy a profiled blank of plastic or metallic material. In its outer marginal zone it receives the associated lateral float 2 by glueing in the channel 3, possibly with reinforcing strips 3a shown only in Figure 19.

The central hull element 18 extends throughout the length of the central part of the boat. Its lower V-form is prolonged on the sides by side pieces which have an upwardly widening course. From its rear extremity, common with that of the central hull element 18, each ofthe lateral hull elements 17 is articulated on the central element 18, along the adjacent edges, about a rectilinear line 40 substantially parallel with the longitudinal axis of the boat.

These material articulations 40 extend over only a part of the boat. They cease at a distance from the pointed bow and thence are prolonged forward by water-tight and deformable connection means which connect the central element 18 to the lateral elements 17 and to the floats 2. These connection means can be constituted by pneumatic floats but for preference, as represented in Figure 14, they are constituted by a cloth 41 glued over the lower faces of the central element 18 and of the associated lateral element 17 in order likewise to cover the lateral floats 2 at the extreme forward part. The cloth 41 is advantageously prolonged to the stern of the boat in order to ensure water-tightness of the articulation 40.

As shown in Figures 19 and 22, the articulations are constituted by mechanical hinges. By way of variant they can be constituted by strips glues astride over the adjacent marginal zones of the central element 18 and of each lateral element 17.

In known manner the floats 2 are of pneumatic type, preferably having separate compartments.

They advantageously enclose sheets 42 (Figure 18) carrying a plurality of gas cells.

Means are provided to conrtrol and maintain at will the angular position of each lateral element 17 in relation to the central element 18. In Figures 19 to 22 there is represented a transverse pneumatic tube 43 which is supported on each side on one of the lateral hull elements 17, at a distance from the articulation 40, and the state of inflation of which defines the angular position of the lateral elements.

Figure 19 shows the tube 43 inflated to the maximum and upwardly convex. For this condition the floats 2 are in the low position, corresponding to navigation on a calm sea permitting high speeds.

Figure 20 shows the tube a little less inflated and substantially horizontal. In this condition the floats 2 are in the horizontal or midway position, corresponding to navigation on a medium sea.

Figure 21 shows the tube 43 inflated to the maximum and downwardly convex. In this condition the floats 2 are in the high position, corresponding to navigation in a heavy sea.

Finally Figure 22 shows the tube 43 totally deflated. In this condition the floats 2 are in the extreme upwardly folded transport position, reducing the overall width of the boat and permitting road transport. The floats 2 are retained in this position by return means, for example elastic cords 52.

It is possible to provide several tubes such as 43, spaced over the length of the boat.

By way of variant it would be possible to use jacks for the positive control of each lateral element 17, as in the embodiment according to Figures 23 to 26.

In the pivoting of the lateral elements 17 in relation to the central element 18, the rear part of each element 17, in line with the articulation 40, is displaced wihout deformation of the float 2, while in the forward part, by reason ofthe narrowing and raising of the boat, there is deformation of the floats, the movement in the forward part being rendered possible by the deformable connection means 41.

The fore part of the boat is advatageously equipped with a deflector 44 (Figures 13 to 15) constituted by two identical flat triangular panels 45 glued by one side on the upper part of the forward extremity of each lateral float 2, united by two adjacent sides by a separable hinge 46 and together forming a downwardly open, rearwardly rising obtuse dihedron. As may be seen from Figures 14 and 15, this deflector 44 has the purposes of facilitating the penetration of the boat through the waves and of creating a force depressing the fore part of the boat, preventing the latter from rearing up exessively at high speeds. The disengageability of the hinge 46 has the purpose of permitting raising of the lateral elements into the position according to Figure 22.

The bottom of the boat has a floor 47. Between the floor 47 and the V-shaped part of the central hull element 18 there are advantageously disposed sheets 42 (Figure 18) analogous with those of the floats 2.

The floor 47 can carry a longitudinal pneumatic tube 16 forming a seat, which is fixed to the floor by strips 23 glued over the tube and the floor.

The lower longitudinal edge of the central hull element 18 carries on its lower face a rib 48 of upwardly open V-shape extending throughout the length of the boat. The rib 48 is either obtained in moulding, or added. This rib has the purpose of permitting the boat to split the water better and avoiding its "slapping" when it drops again after having cleared a wave.

Another advantageous characteristic of this invention is shown in Figures 16 and 17. At the extreme rear part of each lateral float 2 there is longitudinally articulated a rib or panel 49 of rectangular general form which carries, on its free edge opposite to the articulation 50, a skid 51 of V-form open towards the articulation and widening towards the rear. The ribs can be set either in the low position (Figure 16) so that the skids 51 may be supported on the water and facilitate lift-off at high speed, or in the high position to form supporting wings.

Fortransportthe ribs are either removed or turned over towards the interior of the boat.

In Figures 23 to 26 there is shown another embodiment which differs from that according to Figures 13 to 22 essentially in that the articulation of the lateral hull elements 17 to the central hull element 18 is effected over the whole length of the boat. Forthis purpose each hull element 17,18 is in one single piece. The central hull element 18 has two symmetrical rectilinear longitudinal edges 53, 54 and the lateral hull elements 17 each have a rectilinear longitudinal edge 55, 56, the edges 53,55 being in coincidence, as are the edges 54, 56, to receive the associated articulation 40.

As may be seen from Figures 23 and 24, the articulations 40, which are symmetrical in relation to the median longitudinal plane of the boat, extend throughout the length of the hull 1 and converge forward, rising to the point 57 where they meet.

With such an arrangement it is easily possible to fold and unfold the boat with the floats 2 inflated, which is particularly useful for emergency operations.

For the actuation of the hull elements 17 at least two jacks 58, 59 are provided on each side, which act between the central element 18 and the lateral element 17. Atthe same time these jacks ensure the movement and locking of the elements 17 in relation to the element 18.

In Figures 25 and 26 the floats 2 are shown in the midway position (in solid lines) corresponding to high-speed travel, in the low position (in chain lines) corresponding to low-speed travel, and the raised storage or transport position (in chain lines).

As shown in Figure 25 only, this characteristic being applicable however to the other forms of embodiment, a protective plate or shield 60 can be provided over the whole length of the floats 2, utilisable in applications in which floats can receive shocks or impacts. The shields 60 wrap around the floats by at least 180 .

Claims (25)

1.) Semi-rigid inflatable boat, comprising a hull (1) to which two lateral floats (2) forming stabilisers are fastened, characterised in that the hull (1) is in at least three parts (17, 18) normally made fast with one another, for navigation, by fixing and stiffening means, the lateral floats (2) being carried respective ly by the said hull parts (17, 18), it being possible for the latterto be turned over for the folding of the boat upon itself about at least one longitudinal axis.

2.) Boat according to Claim 1, characterised in that it comprises a rigid central hull element (18) extending throughout the length of the boat and detachably fixed by its longitudinal edges to two lateral hull elements (17), the outer edge of each of which carries an associated float (2).

3.) Boat according to Claim 2, characterised in that the central hull element (18) is fixed by bolting on the lateral hull elements (17).

4.) 2/3Boat according to Claim 3, characterised in that the lateral hull elements (17) carry on their lower faces protuberances, especially hooks (30), dogs or ribs (33), adapted to penetrate into associated lodgements (31,34) formed on the edges of the cantral hull element, the protuberances being directedx towards the axis of the boat.

5.) Boat according to Claim 4, characterised in that it comprises at least one stiffening crossmember (35), rigid or pnueunmtic.

6.) Boat according to one of Claims 2 to 5, characterised in that the inner edges of the lateral hull elements (17) are united by a cloth (21) which extends over the whole length of the boat, rising over the stern board (13).

7.) Boat according to Claim 6, characterised in that the lateral floats (2) are permanently fixed on the hull (1 ) and in that an internal central float (16) forming a seat is permanently fixed on the cloth (21), to constitue an inflating hinge for automatic opening of the boat on inflation.

8.) Boat according to one of Claims 1 to 7, characterised in that the stern board (13) is in at least two parts (25, 26) offset axially so that in the folding of the boat one can pass in front of the other.

9.) Boat according to Claim 1, characterised in that it comprises a rigid central hull element (18) extending throughout the length of the central part of the boat, two rigid lateral hull elements (17), each carrying one of the lateral floats (2) and extending, on each side, over at least a part of the length of the central hull element, water-tight articulation means (40, 41 ) between the respective adjacent edges of the central hull element and the lateral hull elemants, and means (43,52,60) for controlling the angular position of each lateral hull element (17) in relation to the central hull element (18).

10.) Boat according to Claim 9, characterised in thatthe axis of articulation of each lateral hull element is substantially parallel to the longitudinal axis of the boat.

11.) Boat according to one of Claims 9 and 10, characterised in that as the boat is narrowed forward, the articulation means (40) extend, forward, from the common rear extremity of the central element and the corresponding lateral hull element over only a part of the said adjacent edges, and are prolonged forward, between their forward extremities and the forward extremity of the boat, by water-tight, flexible and deformable connection means (41 ) connecting the central hull element to each lateral hull element and to the associated lateral float, the whole being arranged so that on pivoting of a lateral hull element in relation to the central element the articulation takes place about the rectilinear axis of the said articulation means, with deformation of the said connection means at the front.

12.) Boat according to Claim 11, characterised in that the connection means (41) are constituted on each side by a cloth glued over the central hull element and over the corresponding lateral hull element, and possibly over the extreme forward part of the floats (2).

13.) Boat according to one of Claims 9 to 12, characterised in that the central hull element (18) is in the form of an evolutive V widening to the rear and comprises, beneath and along its lower longitudinal edge, a smail rib (48) in the form of an upwardly open V intended especially to split the water and throw it to the sides.

14.) Boat according to one of Claims 9 to 13, characterised in that it comprises a front deflector (44) in the form of a downwardly open obtuse dihedron inclined upwards from front to rear, which extends from the forward point of the boat over a part of the length of the lateral floats to which it is fixed by its edges.

15.) Boat according to Claim 14, charactrised in that the deflector (44) is constituted by two panels articulated along the ridge of the dihedron by a detachable hinge (46).

16.) Boat according to one of Claims 9 to 18, characterised in that each of the lateral floats (2) carries in its rear part a rib (49) provided on its free longitudinal edge with a profiled skid (51).

17.) Boat according to Claim 16, characterised in that each skid (51) is in the form of a V open towards the float (2) and widening towards the rear.

18.) Boat according to one of Claims 16 and 17, characterised in that each rib (49) is articulated on the associated float (2) about a longitudinal axis so that it can be either lowered so that the skid (51 ) may act upon the water in order to cause the boat to lift, or raised for transport or so that the skid (51) may act as a supporting aerial wing.

19.) Boat according to Claim 9, characterised in that each lateral hull element (17) is articulated on the central hull element (18) about an articulation (40) extending from the stern to the bow of the hull, the hull elements (17, 18) possessing facing pairs of rectilinear edges (53, 54, 55, 56), the two articulations (40) being symmetrical in relation to the median longitudinal plane of the boat and being inclined forward and upward in order to intersect at the forward point of the boat.

20.) Boat according to one of Claims 9 to 19, characterised in that it comprises pneumatic means, especially transverse inflatable tubes (43), acting between the lateral hull elements (17).

21.) Boat according to one of Claims 9 to 19, characterised in that it comprises jacks (58, 59) acting between the central hull element (18) and the lateral hull elements (17).

22.) Boat according to one of Claims 9 to 21, characterised in that the lateral hull elements (17) are adapted to pivot from a low, calm sea high-speed navigation position to an extreme high position for transport.

23.) Boat according to one of Claims 1 to 22, characterised in that it comprises at least one transverse pneumatic arch (14) overhanging it and connected to the lateral floats (2).

24.) Boat according to one of Claims 1 to 23, characterised in that the lateral floats (2) are at least partially covered with a protective plate (60).

25.) A semi-rigid inflatable boat substantially as described herein and with reference to the accompanying drawings.