CA2235286A1 - A vessel with a hull supported by totally submerged ellipsoidal floats - Google Patents

Abstract

This invention relates to a vessel whose hull or useful volume is above the surface of the water, and whose submerged and semi-submerged parts are oblong antirolling propelling floats, whose axis is parallel to the longitudinal axis of the vessel; at least it comprises two floats, designed in such a way that driving resistance is minimum, righting moment is increased, and the vessel is more stable and easier to maneuver.

Description

CA 0223~286 1998-04-20 A VESSEL WITH A HULL SUPPORTED BY TOTALLY
SUBMERGED ELLIPSOIDAL FLOATS

This invention is a solution to a usual problem in the field of navigation: how to reduce water resistance and at the same time how to navigate stably at high speeds both in calm and rough waters.

BACKGROUND OF THE INVENTION.

Attempts have been made to solve this problem, but for different reasons none of them has been a real solution as they lack stability or describe a structure which considerably reduces the effect to be achieved.
The Argentine patent number 213.661 discloses submerged floats, revolution-ellipsoid shaped, however it fails to mention stabilizing means such as the ones mentioned in this invention.
The Japanese patent KOKAI 52-31486 includes submerged floats; however, it does not disclose their shape, and includes perpendicular leveling means between two floats (at the rear end of said f]oats) joined to them, as well as a horizontal and vertical rudder system, also positioned between the two floats (at the front end of said floats) and joined to them. Both this leveling system and the rudder system, increase the navigation surface because of their features, and because their shape is incompatible 2'; with the design characteristics required to reduce shape resistance, they cause a significant increase in driving resistance.
The European patent number 0080308 includes removable CA 0223~286 1998-04-20 semisubmerged floats, fixed both at their front and rear ends to partially submerged columns which are perpendicular to the water surface.
The submerged ends of said columns include pairs of quarters which function as stabilizing means. As indicated in the previous specifications, this vessel has been designed for low speeds and to be at rest.
This is obvious, as the columns which are located near the ends of the floats dramatically reduce the shape effect achieved by said floats; at the same time these columns produce wave resistance, :increase driving resistance and require a solid structure to drive the float removing means.
Now that the background has been reviewed, it will be noticed that no appropriate stabilizing means have been found that can be combined with the floats supporting a vessel, and that said vessel can not navigate stably in either rough or calm waters.

SUMMARY OF THE INVENTION

The main object of this invention is a vessel or boat whose hull or useful volume (1) is above the surface of the water, and whose submerged part (2) and semi-submerged part (3) comprises anti-rolling floats (2,3), basically oblong, the axis of which is parallel to the longitudinal axis of the whole set, supporting columns which are a series of ellipses, and at least two, designed in such a way that they minimize the driving resistance, increase righting moment and make maneuverability and stability easier.

DESCRIPTION OF THE INVENTION

This vessel, as basically designed, offers a plurality of advantages if compared to conventional vessels, as it CA 0223~286 1998-04-20 reduces wave formation resistance significantly; reduces driving resistance; makes it possible to use propelling power better; saves fuel; rnakes transport at higher speeds possible; has a limited draught and a wider breath;
achieves optimum balance between surface resistance and shape resistance in order to achieve the least driving resistance and the maximum stability and maneuverability;
solves stability problems as it produces righting moment (response to the vessel rolling) with a minimum of ondulating movement; it does not use energy to produce "gliding effect" as the vessel buoyancy is basically is static instead of dynamic; and moreover it can transport heavy loads.
Let's analyze now the performance of a vessel using this invention under variable conditions of speed and in both rough and calm waters.
There are basically three kinds of resistances that use propelling power, that is: surface resistance, shape resistance and wave formation resistance. At relatively low speeds (scopeless standard related to Froude number) (between 0 and 1,5) friction forces comprising between 80 ~ and 85~ of total resistance are more commonly observed.
At relatively high speeds without gliding (from 1,5 to 3) friction forces comprise 50~ of the total resistance, and said resistance (from 1,5) increases much more rapidly than at low speeds, specially because of wave formation.
As a reference for relative speeds, it can be said that a cargo boat sails at 0.8; a warship, at 2.0; and an off-shore boat, at 7.0 or more.
As practically the entire anti-rolling floats (2,3) are submerged (80~ - 100~ of their volume), and considering the way they are arranged - as described in the Argentine patent number 213.661, the only patent in which the shape of the floats is totally used - flow is almost perfect and complete, the contact surf-ace, air-water, is much smaller CA 0223~286 1998-04-20 than in conventional vessels and boats because of the floats, and the corresponding resistances are much lower, which consequently makes it possible to use propelling power better, specially at high speeds.
In order to achieve the required level of stability in calm waters, the floats wi:Ll be equipped with stabilizers, both in the bow and in the stern. Said stabilizers are controlled by any known means, e.g. manually hydraulic drives or drives controlled by microprocessors, will offset both pitch and roll of the vessel.
At high speeds and as the waters become rough, the stabilizers are not enough to achieve the desired level of stability of the boat. This invention makes the best out of the floats shape in order to minimize shape resistance as well as wave formation resistance, and however increase stability gradually as the boat requires so.
The conformation of each antirolling float (2,3) according to revolution ellipsoids, is an excellent condition to make the best of propelling power, as it has been proved that the higher the ratio between the bigger and the smaller axis is, or in other words, the more oblong the float is, the higher the speed the boat can reach.
It is known that the body that has the smallest surface for a certain volume is a sphere. This is the case of a bubble. So as to know what shape a bubble would adopt when affected by a field of external and uniform forces, we can compare a bubble to the electron cloud of a hydrogen atom. When this cloud is under the effect of a field of force that can deform it in a given direction, for example a uniform external elect:rical field, said cloud will deform, and give way to an induced electrical dipole. The shape this cloud will adopt in space is a revolution ellipsoid.
Apart from the above mentioned, when a body moves in fluid, it produces an ondu]ating disturbance. If a particle CA 0223~286 1998-04-20 is placed under the effect of the first whirl of said disturbance, its path equation is sine or cosine.
When said particle defines a semiwave, the points reached during the corresponding path, for example corresponding to the sine, coincide with one of the points given by the equation of a semiellipse. If instead of taking a particle a group of particles is selected, so that the plane they are contained in is normal with respect to the direction of the forces of the field, and the symmetry center coincides with the intersection of said plane with the path direction, we will obtain the equation corresponding to a revolution ellipsoid in space.
According to the above mentioned, we conclude that for our case in particular, the best shape of a body having a given volume, and that moves in water at regular speed and that produces the least disturbance is a revolution ellipsoid.
Moreover, if we cut this revolution ellipsoid with a horizontal plane, so that it contains the main axis of the ellipsoid, we can see that the fluid drains not only in the low part, but also in all of the top part. This means that the fluid flows all around the body.
In order to provide the boat with an adequate righting moment, the antirolling floats (2,3) are not totally revolution ellipsoids, as they would be in the boat described in the Argentine patent 213.661. If we cut the antirolling float (2,3) according to a plane normal to its longitudinal axis, the latter will be shaped as shown in figure 3, and if we cut the float at any horizontal plane we will find an elliptical shape, which means shapes similar to an ellipse and not exclusively a geometrical ellipse, which preferably will keep the radious ratio both in its propelling section and its anti-rolling section.
When the vessel racks (figures 5 and 6), the floating plane changes and grows larger, and consequently the moment CA 0223~286 1998-04-20 of inertia opposing the rolling increases too. In the same way, the submerged volume increases as much as V' so that this extra volume produces a push at a L distance from the center of the vessel, generating a moment contrary to the movement. The exact shape and dimensions of the section which is not submerged (2) of the antirolling float (2,3) will depend on the antiro]ling characteristics the vessel may require; the response can be either slow or sudden, and the section which is horizontal to the longitudinal axis of the unsubmerged volume (3) will be ovoid or ellipsoidal.
After designing the floats in this way and after selecting the measures of the axis of the ellipses that generate the former, it is possible to reduce driving resistance and undulating movements. In fact, if we call the larger semiaxis of the generating ellipse "R" and if we call the semiaxis of the same ellipse "r", the quotient R/r will determine in each case a value having a corresponding speed for which said driving resistance and undulating movement are slight.
Given a supporting volume "T", there will be a large number of ratios between "R" and "r", and an optimum speed "V" will correspond to each of them. If the quotient R/r increases, so will "V". Therefore, if "T" is kept constant, "V" will be increased by only increasing "R" with respect to "r" for the same number of floats; or given a "R"
determined by the length of a vessel, the optimum speed will be successfully increased if the number of floats is increased for the same volume.
If the floats are longer, or if the number of floats is increased, their external surface will be increased too, which will lead to more contact with water, and therefore, a decrease in speed. If motive power is always constant, speed will reach a maximum value for each volume "T", and then will decrease if the surface is larger. Said maximum speed will be use~ul to determine the number of and the CA 0223~286 1998-04-20 size of floats for a volume "T" which will support a given weight, for which the motive power required will be the least.
Therefore, it is possible that once the cargo and speed are fixed, a vessel according to this invention will use less motive power for said cargo at that given speed.
The antirolling float (2,3) if this invention can be designed without taking into account the shape restrictions that a conventional hull or the previous models have; in this way the undulating movement generated by the part of the float that is in contact with the air-water surface can be minimized; it is possible to provide the necessary righting moment and achieve lateral resistance for a better maneuverability of the vessel. The floats can be totally hollow and/or divided into watertight compartments, which is advantageous in case of accident or damage.
Said compartments can be made by means of cross-sectional supports. Also, they can be divided into compartments where loads or fuel can be stored, or else they can be used to place the propelling engines. They can be provided with propellers, directional rudders, rolling stabilizers, etc.
In another embodiment, the anti-rolling floats (2,3) can be provided with supports so as to minimize resistance.
Therefore, the supports of the floats that are not external can be oblong, or else a series of curves of elliptical shape, but the side walls are separated forming an angle which is smaller than that of the external floats, or a slight angle. In this way, a new embodiment of the antirolling float divides it into two sections: the inside antirolling section and the distal antirolling section.
It is also convenient to add endings to these sections that do not correspond exactly to an ellipse, but which can be points, furmann bows, or any other hydrodynamic or airdynamic design, which can be useful to reduce driving resistance.

CA 0223~286 1998-04-20 Another important aspect is that the floats will be semi-submerged, and that the submerged volume will be about 80 - 100~ of the float. In this way, the level of stability is better, and the driving resistance increase is slight.
Preferably, this leads to align the propelling section of the float so that the total submerged volume is in the same range as each unit of the propelling section.
Bearing in mind that there should be at least two floats, it is advisable to embody the invention with more than two floats; said float:s will be symmetrically arranged in the same horizontal plane with respect to the vertical plane which passes by the longitudinal axis of the vessel so as to balance the propelling sections.
The surface that is in contact with the water will always be defined by the total of the external areas of the submerged volume of all the floats (2).
The directional devices, usually rudders, will preferably be placed at t:he rear of the floats, and if there were more than two floats, said rudders will be placed behind the external floats.
In case of a storm and if the antirolling means are not enough, the hull of the vessel will be conventionally shaped, and means will be provided to fix the waterline at the hull. Said means will be, among others, means that make it possible to fill the floats with water, to increase the cargo of the vessel, float elevating means, etc.
Though the invention has been described with respect to certain embodiments it is apparent that alterations and modifications will occur to the users and those skilled in the art. For a better understanding of the vessel invented, reference is made to the accompanying examples, which are schematically illustrated without a specific scale in the pictures enclosed. Said examples are neither limiting nor protected exclusively by the scope of this letter patent.

CA 0223~286 1998-04-20 DESCRIPTION OF THE DRAWINGS
Figure 1 shows a front view of the vessel.
Figure 2 shows a side, schematic view in elevation of the same vessel shown in figure 1.
Figures 3 and 4 correspond to a longitudinal section and a cross-section of a generic antirolling float, according to a preferred embodiment of the invention.
Figures 5 and 6 show the effect of the floats when the vessel racks, it shows how the floating area of the float and the volume submerged change.

In all the figures, same numerals correspond to the same or equivalent parts of, according to the examples chosen for this explanation of the vessel object of the invention.
As it can be seen in :Eigure 1, the vessel illustrated is provided with a superior set corresponding to the hull (1) and at least two floats (2) which are related to the hull by antirolling means (3), oblong inverted truncated-conical bodies, whose superior base is fixed to the inferior part of the hull (1), and whose lower base is fixed to the top part of the float (2), preferably forming only one body (2,3).
The frontal end (7) and the back end (6) of said antirolling means (3) comprise tapered ends defining sharp edges (8 and 9) of hydrodynamic profile for a better displacement. The total of the floats volumes is such that it supports the hull (1) and its cargo, above the surface of the water.
Figures 3 and 4 show a longitudinal section and a cross-section of an antirolling float (2,3) which is formed by an inferior revolution body (2) with a top longitudinal opening (a-a) from whose opposing ends two diverting walls protrude (12 and 13) whose top endings have horizontal sections (10 and 11), which are useful to join said body to CA 0223~286 1998-04-20 the hull (1), and besides the structure of the truncated-conical section they define is an antirolling means.
Having described this vessel and the examples, modifications and improvements will occur to those skilled in the art, all of which must be considered within the scope of this letter patent; this scope is limited only by the claims that follow.

Claims (13)

1. A vessel whose hull or useful volume is above the surface of the water and is provided with floating means joined to said vessel, characterized in that said floating means are at least two oblong floating bodies arranged in parallel fashion to the longitudinal axis of the vessel, including said antirolling floats in the upper part of said floating means.

2. A vessel according to claim 1, characterized in that the antirolling means form an oblong body, whose larger base is joined to the hull and whose smaller base is joined to the floating means.

3. A vessel according to claim 1, characterized in that the antirolling means form an inverted truncated-conical body, whose larger base is joined to the hull and whose smaller base is joined to the floating means.

4. A vessel according to claim 1, characterized in that the antirolling means are the joining means between the floats and the hull.

5. A vessel according to claim 1, characterized in that the endings of the antirolling means form an airdynamic edge for water displacement.

6. A vessel according to claim 2, characterized in that when the float is cut by a horizontal plane an elliptical area is defined.

7. A vessel according to claim 1, characterized in that the float volume that is submerged is about 80 - 100%
of its total volume.

8. A vessel according to claim 1, characterized in that the radious ratio between the revolution ellipsoids of the float propelling section and the elliptical forms of the antirolling section is the same.

9. A vessel according to claim 1, characterized in that the ends of the propelling section of the antirroling floats form a hydrodynamic edge for water displacement.

10. A vessel according to claim 1, characterized in that the floats comprise watertight compartments.

11. A vessel according to claim 1, characterized in that it comprises means that modify the waterline and fix it at the hull of said vessel.

12. A vessel according to claim 1, characterized in that antirolling floats comprise stabilizing means.

13. A vessel according to claim 1, characterized in that it comprises means for filling and emptying the floats.