The present invention relates to a variable trim boat.

It is known that the hull is a decisive factor to the hydrodynamics and the stability of boats. Lately, several technical modifications of the traditional hulls have been made, based on theoretical and empiric research, in order to improve the trim, the aerodynamic lift, and the speed of boats.

Ideally, a boat ought to maintain a longitudinal horizontal trim when still, whereas it ought to present a longitudinal trim slightly leaning towards the stern when it is moving. Closest prior art document GB 26467-1909 discloses the features of the preamble of independent claim 1 and 11.

Figure 1 shows a boat, designated with the reference numeral 100, in the ideal static configuration, wherein the longitudinal axis of the boat is in horizontal position; figure 2 shows the same boat in the ideal dynamic configuration, wherein the longitudinal axis of the boat is slightly leaning astern.

Actually, several boats have trim defects, or they tend to diverge more or less from the ideal configurations. For instance, figure 3 shows a boat 100 in which the longitudinal axis is excessively leaning astern, and figure 4 shows a boat 100 in which the longitudinal axis is leaning towards the bow.

The defects described can appear when the boat is moving, causing a worsening of the hydrodynamic performances of the hull and an increase of the fuel consumption, as well as when the boat is still, causing a reduction of the stability of the hull and of the comfort of the passengers.

In order to overcome the cited drawbacks, the use of particular ribbings and/or curvature of the hull has been proposed, as well as the use of additional elements like stabilizing lateral or rear fins, applied on surfing and semi-displacement hulls, and at times even on displacement ones. Furthermore, in order to improve the stability of the boat, hulls with perimetrical inflatable hoses in fibreglass-reinforced plastic have been projected, of the type of those used on inflatables.

At present, the trim variation during navigation is achievable principally by operating in order to adjust the verticality of the drive shank, with the following rake of the propeller; it is likewise possible to vary the angle of attack of particular adjustable fins and to move the inner loads.

For instance, the international patent application WO 2004/067376 illustrates a method and an apparatus to improve the performances of the boats, which requires the use of a hull equipped with a plurality of fins, whose rake is adjustable according to a predetermined angle. The variation of the angle of attack of these fins allows, in particular situations, to increase the speed of the vessel and to reduce the fuel consumption, modifying the hydrodynamic features of the hull.

In any case, if it is true that the dynamic trim of a boat can be varied, it is not possible to modify the static trim, unless by shifting the centre of mass of the cargo.

The aim of the present invention is to overcome the cited drawbacks by devising a boat which has adequately variable trim both in static and in dynamic configuration.

Within this scope it is a further aim of the claimed invention to improve the stability of the boat.

A further aim of the present invention is to allow to realize a variation of the waterline in static configuration.

Another aim of the present invention is to provide a device applicable to existing boats in order to improve the static and dynamic trim of the same boats.

A further aim of the present invention is to provide a device to improve the trim of the boats of simple, constructive and functional conception, equipped with a certainly reliable functioning, of versatile use, as well as of relatively economical costs.

The cited aims are reached, according to the claimed invention, by a variable trim boat according to claim 1, and claim 1:2.

The boat is equipped with lateral hollow bodies, which serve both as reserves of buoyancy and as tanks that can be filled with seawater, to increase the stability of the boat and to improve its trim.

Description details of the invention will be further evident in the illustrations of preferred embodiments of the variable trim boat according to the invention, illustrated in the guideline drawings attached, wherein:

fig. 1 illustrates a side view of a boat in ideal static trim;

fig. 2 illustrates a side view of a boat in ideal dynamic trim;

fig. 3 illustrates a side view of a boat in which the centre of mass is excessively astern;

fig. 4 illustrates a side view of a boat in which the centre of mass is excessively forward;

fig. 5 illustrates a side view of a variable trim boat according to the claimed invention;

fig. 6 illustrates an axonometric view of the box-shaped flaps arranged on the boat;

fig. 7 illustrates a plan view of a detail of the claimed variable trim boat;

fig. 8 illustrates an axonometric view of the claimed variable trim boat;

fig. 9 and 10 illustrate two axonometric views of a different embodiment of the box-shaped flaps, in different operational situations;

fig. 11 illustrates an axonometric view of a further embodiment of the box-shaped flaps;

fig. 12 illustrates a schematic axonometric view of a boat equipped with box-shaped flaps, according to a different embodiment;

fig. 13 illustrates a schematic axonometric view of a boat equipped with box-shaped flaps, according to a further embodiment;

fig. 14 illustrates a side view of a canoe equipped with the box-shaped flaps according to the invention;

fig. 15 illustrates an axonometric view of a different embodiment of the box-shaped flaps.

With reference to such figures, 100 refers to the claimed variable trim boat. The boat 100 comprises two or more box-shaped hollow bodies 1, preferably pyramidal, which work as volumetric flaps. The volumetric flaps 1 are symmetrically arranged on the sides of the boat along the longitudinal axis. The volumetric flaps 1 basically stretch from a hull central position until the stern area. The peculiarity of the said box-shaped flaps 1, as will be better explained below, is that they are kept empty during the navigation, whereas they can be kept empty or adequately filled up with seawater when the boat is still, thus varying the underbody of the boat owing to its different dislocation.

The boat 100, preferably built in fibreglass-reinforced plastic, bears moulded the volumetric flaps 1, which create in this way a continuity with the hull, being part of it. The volumetric flaps 1 consist of respective no-leakage chamber box structures (see fig. 6), insulated from the boat, and are provided with one or more recloseable openings 2 on the back side. The said recloseable openings 2 allow, upon conductor's control, the inlet of the seawater, and also the containment and the outlet of the same seawater. The particular pyramid profile of the volumetric flaps 1, with rounded lines, is projected to improve the hydrodynamics, trying to eliminate as much turbulences as possible, facilitating in certain cases also the surfing, advantageously for the fuel consumptions, for the speed increase and the improvement of the stability in veering and/or in rough sea. Some possible ribs 3 are provided for, individual or multiple, which work as anti-leeway stabilizers.

Clearly, for each typology of boat and therefore of hull the pyramid flaps 1 can be structured in personalised way and according to the lines of the vessel. In the case illustrated in fig. 5, a small fishing boat is represented, which is a fishing boat suitable for the integration with the volumetric flaps 1 to limit the swaying either during the sailing or in still state and to enhance the speed reducing the consumptions.

The functioning of the variable trim boat according to the invention can easily be understood from the description above.

In stationary phase, it is possible to keep the volumetric flaps 1 empty or, alternatively, to partially or totally fill the said flaps 1 with seawater. In the first case, the underbody will be less extended due to the engaging to float of the volumetric flaps 1, which serve as reserve of buoyancy, thus keeping the boat more hauled astern. In this case, an improvement in the trim can be obtained against rolling; this condition is anyhow comparable with that of many boats with a body with similar volumetry. In the second case, with the flaps 1 filled up with water, the maximum advantages can be obtained stability-wise. In this case a considerable increase of the underbody occurs, for the following stern heaviness of the boat. It has been highlighted, in fact, an extraordinarily higher stability, compared to that of the case before. Basically, the volumetric flaps 1 give a new type of trim to the boat according to the innovative concept of hydro-variable trim. The filling and emptying procedure of the flaps 1 takes place according to the criteria and the modes explained below.

According to the normal operational phases, at the departure the boat can have its flaps 1 empty or already filled. In the first case, there will be no need of intervening for the navigation, the volumetric flaps 1 will be lightweight and will pursue their usual task to improve the dynamic trim. In the second case, having the volumetric flaps been previously filled with seawater, the acceleration phase will have to be started leaving the back outlet valves open, thus allowing the normal suction deriving from the depression that the seawater exerts assisted by the fall effect for the natural lifting of the hull from the static to the dynamic situation and to the inertial effect of the water mass in the acceleration phase. These three synergic effects entail that all the water present in the flaps 1 totally flows out (depending on the acceleration, in few dozens of seconds) leaving empty and thus lightened the said flaps 1. In this situation, if the boat does not have any automatic system, it will be required to intervene on the valves in order to close them to avoid that, during the phases of deceleration and down time, the seawater can re-enter the volumetric flaps 1 making them heavier again.

Suitable dedicated handles 5 for the opening and closing of the valves are also adequately provided and arranged laterally behind the conductor's seat (see fig. 7), in an easily reachable position. In a different embodiment of the invention, not illustrated, the said handles 5 can be arranged directly on the driving console, connected through a normal sliding cable. The variation of water inlet inside the volumetric flaps 1 can also be handled through a valve, favouring the outlet of the air contained.

The dynamic trim variation described implies, in static or dynamic condition, a marked improvement of stability and trim.

What has been examined so far is the general method for using the volumetric flaps 1. For certain situations it can be advantageous the filling of only one flap, for instance if, for certain operations of fishing, a significant shifting of the centre of mass on one side exists. By intervening on the filling up of only one flap, it will accomplish an adequate function of counterbalance on the opposite side from the position of the centre of mass, while the other flap will function as reserve of buoyancy, which will entail a thrust to compensate the closest centre of mass component. It is likewise possible to only partially fill one or both the flaps, in particular situations where the trim necessitates a modest variation or adjustment. In this context, it is useful to have separated water-level indicators for each flap; it is thus possible to install, also in series, floating level-detectors, mechanical, with led, electronics and similes.

In table 4 are illustrated further embodiments of the invention. In particular, in fig. 9 and 10 an internal inflatable hose is represented, which, through a compressor activated from inside the boat, can be inflated and deflated assuming the shape of the flap, which, in this case, will have more rounded lines on the outside, as can be inferred from the figures. By highlighting by means of instruments the pressure of the inflatable hose it is easy to determine the level of water filling in the flaps.

Fig. 11 illustrates a further embodiment of the invention, wherein the volumetric flaps 1 are installed, later or as optional, in already existing boats. This solution is advantageous to apply specific flaps built on purpose for any type of manufactured boat, providing the described advantages and in case eliminating trimming defects.

Fig. 12 illustrates another embodiment of the invention, wherein the volumetric flaps 1 are installed inside the boat, in opposite lateral positions. This version, even though it limits the described effectiveness, has anyway considerable advantages, in fact it maintains unvaried the aesthetic of particular hulls and it is easy to personalize by the manufacturer.

Fig. 13 illustrates a further embodiment of the invention, which consists of a hybrid solution wherein the volumetric flaps 1 are partly internal and partly external with respect to the lines of the hull.

Fig. 14 illustrates the possibility to apply the flaps 1, as reserves of buoyancy, to the hull of boats of the kind of canoes, improving the stability thereof and favouring the insertion of the canoeist on board from the sea, operation generally very complicated.

The filling and emptying of the volumetric flaps 1 according to what described take place through manual operations; it is anyway also possible to provide for electric controls, in order to further favour the facility of use. In particular, a much valuable solution can be represented by the electro-mechanical automatism of closure of the valves of the flaps 1 once the level of the water contained in each of the said flaps reaches the bottom; in this case, the input can be given by the level-detector instruments or more simply by a timer, which becomes operative once a determined speed of the boat is reached.

It is likewise possible to add a valve 4 (see in particular fig. 6), in lifted position, to favour the filling inside the chambers of the volumetric flaps 1. The valve 4 may usefully be equipped with an air-water separator filter, to avoid that during the filling, with the subsequent outlet of air, some water can penetrate inside the boat.

All the advantages described can largely come into use in various destinations; in fact the variable trim system is very useful for the boats arranged for fishing, but other categories may be interested in using this finding. For instance the sailboats, and in particular the catamarans, could make use of the volumetric flaps 1 according to the present invention, not only as reserves of buoyancy but also as counterweight in sailing, thus compensating the lateral rake under effect of the wind against the sail; in this case, at one side the respective flap could be empty for a better thrust in surface, and at the other side it could be filled with water for the cited counterweight action. In order to favour the inlet of water in sailing, it is, with this purpose, provided for an inlet valve 6 arranged on the front part of the volumetric flaps 1 (see fig. 15). Clearly, other sectors may valuably take advantage of this system, such as working boats, boats of the civil defence or of the fire brigades, lifeboats, yacht and other types of boats in which it would be possible to install the volumetric flaps 1.

The variable trim boat according to the claimed invention reaches the aim to improve the stability of the boat and, at the same time, to allow the trim variations in dynamic and static configuration.

An advantage of the claimed invention is that it allows to realize a variation of the height of the waterline in static configuration. A prerogative of the claimed invention is to provide a device, which can improve the trim of the existing boats, which show trim defects.

A further aim of the invention is to provide for a device of simple constructive functional conception, equipped with a certainly reliable functioning, versatile in use, and also relatively cheap in the costs.

Materials adopted for the actual realization of the invention, as well as their shapes and sizes, can be various, depending on the requirements.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.