Field of the Invention

The present invention refers to a support vessel for use in offshore activities and, particularly, to vessels designed to accelerate the load- ing and unloading operations of supplies in the oil sector. Description of the State of the Art

In the oil sector, it is common to use support vessels, also called PSV (Platform Supply Vessel), having an optimized design to face adverse weather conditions (sea and weather over 5 on the Beaufort scale). Such design usually includes a free deck and maneuvering capacity with the latest generation resources (dynamic positioning), in which the vessel also has great dimensions so as to better withstand the adverse conditions.

However, it is noticeable that said vessels are the fruit of the oil industry of the North Sea in Europe, where this industry was originated. In this region, the environmental and geopolitical conditions differ to those found in Brazil and in various other places where oil is currently extracted.

In the North Sea, the occurrence of waves over eight meters in height is common, such that said support vessels are designed to sustain waves of up to ten meters, and which, consequently, need to be further rein- forced and larger. Said vessels are of the single hull kind, with average dimensions of 35 m in length and 220 m ² in deck area. Alternatively, current vessels can be from 60 to 70 m in length with deck areas that vary between 450 and 650 m ² .

In other regions of the planet, where offshore oil exploration also occurs, the climactic conditions are not so severe and, simply as a matter of making use of the existing technology, those same conventional support vessels are used, which results in an unnecessarily high investment to purchase and manufacture the vessels which are not optimized for the type of sea on which they navigate. Accordingly, there is a need for a vessel suitable for low latitude regions which correspond to most of the new world frontiers in the oil industry. In other words, there is a need for vessels that do not have to withstand such adverse conditions and so large waves, and which, certainly, will result in lower manufacturing and maintenance cost, among other aspects.

Another important fact is that a few years ago, oil was extracted from shallow waters, which allows boats to remain anchored while waiting to be called to service at the rig. Today, however, with new deep-water exploration technologies (up to 3,000 m water depth), the support boats need to remain connected without using anchors ("stand by"). Therefore, the conventional use of 2 main engines for this stand-by status results in a high consumption of fuel, associated with a high emission of pollutants. Hence, there is still a demand for a vessel that provides optimized fuel consumption for said stand-by periods, with lower fuel consumption and a reduction in the emission of pollutants.

Finally, it is noted that conventional support vessels usually moor sideways at the quays and rigs. This arrangement which occupies a signifi- cant extension of the quay is necessary so as to make best use of the reach of the jibs of the cranes installed at the ports. In turn, a potential stern- mooring by current vessels, so as to occupy less space along the quays, would severely compromise the reach of the crane jibs, since it would not be possible to reach the entire loading deck area. In practice, a vessel does not remain for more than eight hours at a quay. The quay needs to service over seventy boats every two days, such that a conventional vessel, on account of its limitations, occupies an excessively large space along the quays, which makes loading and unloading operations more expensive, and also increase the time spent there. Accordingly, the state of the art also lacks a vessel that, albeit stern-moored, allows optimized use of the loading cranes, to the extent that the entire loading deck area can be reached by the crane jibs without great difficulty.

Therefore, this conventional design of support vessels, although it has been used for many years on the market, is extremely limited, by presenting, among others, the following drawbacks:

- reduced flexibility in terms of adapting to natural conditions; - low maneuvering capacity;

- lack of stability due to its width;

- high fuel consumption and consequent high emission of pollutants into the environment; - occupation of significant extensions at mooring sites;

- low safety in hoisting and unloading activities at sea;

- slow loading and unloading operations; and

- high manufacturing and maintenance cost. Summary of the Invention The vessel according to the present invention was conceived to

(i) adapt to the climactic conditions of low latitude regions; (ii) provide optimized fuel consumption with a consequent reduction in emission of pollutants; and (iii) allow an optimized use of the loading cranes, by way of stern- mooring at quay and rigs. Said objectives are achieved by means of a support vessel for offshore activities according to the present invention, which comprises a loading deck and a command bridge which is of the double hull catamaran- type.

The support vessel of the present invention is further character- ized by comprising two engines for locomotion operations, such as trips and maneuverings, and two engines for stand-by periods. Brief Description of the Drawings

Figure 1 show a perspective view of the vessel according to the present invention. Figure 2 shows a front perspective view of the catamaran-type vessel that shows the double hull structure.

Figure 3 is a comparative picture in which a traditional vessel is juxtaposed with three vessels according to the present invention.

Figure 4 is another comparative picture showing two traditional vessels and the vessel of the present invention, in which all are stern- moored. Detailed Description of the Present Invention As can be seen in figure 1 , the vessel 1 according to the present invention is of the double hull catamaran-type, has a deck 2 and a command bridge 3.

The catamaran-type vessel includes two hulls 4 and 5 (figure 2), in parallel. The support vessel may have a length of approximately 35 m with a deck of about 450 m ² .

In turn, the width of the vessel according to the present invention is preferably about 20 m. Other characteristics may include, for example, a waterline of 35 m, draft (loaded) of 4 m, and depth of 9 m. To achieve the objectives of the present invention, the vessel should be able to support a maximum load of 1 ,500 tons, of which 150 m ³ is fuel, and 400 m ³ is freshwater. As stated, the deck has an area of 450 m ² , with a load capacity of 8 t/m ² .

Motorization of the vessel according to the present invention in- eludes four engines, wherein two of the engines 2000 Caterpillar® (not shown), or equivalent, for usual voyage and maneuvering activities; and the other two engines are of the Caterpillar® 980 type (not shown), or equivalent, for the stand-by periods, which correspond to 70% of its work. The use of more economical engines for the stand-by periods provides savings of up to 50% in fuel consumption, also with an optimization in the emission of polluting gases.

The above motorization makes the boat more economical than conventional ones that have just two main engines. This fuel savings can easily reach up to 60,000 liters per month per vessel. Hence, it is a consid- erable savings besides, as stated, providing a significant reduction in the e- mission of pollutants by companies of the sector which often have over 100 vessels freighted.

Other additional characteristics include a 400 hp tunnel thruster and a 600 hp bow buster (not shown); consumption of 600 l/h at cruising and 100 l/h during stand-by periods; and a maximum speed of 7.72 m/s (15 knots) and of 5.14 m/s (10 knots) for cruising.

Besides the four engines referred" to above, the vessel of the in- vention may also include other auxiliary maneuvering engines (not shown) which are common in conventional vessels having the same purpose.

Also provided is a dynamic positioning system, a deck crane with a capacity of 3 t, from 10 to 16 m and three generators, being two main ones of 250 kW (310 kVA) and an emergency one of 48 kw.

Since the savings in operating costs is in the order of 25% and the logistics capacity may increase by up to 100%, also considering the hydrodynamics of the catamaran, the vessel engines of the present invention are much more economical, without compromising speed, the performance of its functions, besides requiring fewer interruptions for maintenance since the vessels are smaller.

As can be seen in figure 3, the same space occupied by a conventional vessel may easily be occupied by three vessels of the present invention, which may increase the total mooring loading area from 650 m ² to up to 1350 m ² .

In figure 4, it is possible to note the exclusive easiness in the logistics of the present invention stern-moored to the quay, in comparison with other conventional vessels 6 and 7, also stern-moored. In conventional vessels, the cranes are restricted in the reach of their jibs, which does not allow the ships to be stern-moored, since the length x width ratio exceeds the operating capacity of the cranes.

In the present invention, the novel measures supporting catamaran-type vessels provide a favorable situation for this type of mooring, which means its logistics is more efficient and reduces the need for large installa- tions in the future.

It is important to point out here that with the new exploration technologies, in new oil basins (fields and borders) in association with the new demands of the oil industry market, there is no longer any need for many u- nits (rigs) to explore an oil field. With the adoption of rigs of the FPSO (Float- ing, Production, Storage and Offloading) type, and equipment such as the Christmas tree and integrated submarine pump systems, the number of rigs has been considerably reduced. Moreover, a catamaran-type support vessel also has proven efficiency in the absorption of the impact of waves and being 30% wider than other vessels, also facilitates the hoisting and unloading operations at sea, increasing the safety in this kind of activity, which accounts for 25% of work accidents in the oil sector.

The vessel according to the present invention also allows some constructive variations, with due adaptations, without straying from the scope of protection, such as: a) a vessel having smaller dimensions and greater speed of up to 10.28 m/s (20 knots), for oil spillage collection operations in offshore activities, diving support, wind turbine installation support, maritime and fishing activities in general; b) a vessel with larger dimensions for shipping large loads requiring larger cranes; or c) adaptation of the vessel for probing service operations to determine the characteristics of the sea bed.

Other modifications within the spirit and concept of this invention and evident to a person skilled in the art after consideration of this specification should also be considered within the scope of the invention, as defined in the claims attached hereto.