GB2517230A - Vessel - Google Patents

Abstract

A set of a plurality of wingsail units for a vessel 20. Each unit in the set has a rotatable support, a plurality of substantially vertical elongate aerofoil sails (1, 2, 3, Fig 1) mounted on the support and a support frame (9, Fig 1) that maintains a given separation between the aerofoil sails. For each of the wingsail units in the set the height of the support frame relative to the rotatable support is the same. The length of the aerofoil sails from the support frame to an upper end differs for at least two wingsail units in the set. A method of designing a set of a plurality of wingsail units for a vessel is also disclosed.

Description

VESSEL

The present invention relates to vessels provided with wingsail units and to the construction and configuration of such wingsail units. A wingsail unit, or aerofoil sail unit, is an apparatus that includes one or more aerofoils that can be set to an angle of attack relative to the incident wind in order to provide thrust to the vessel.

It has previously been known to provide wingsail units to pleasure-craft, such as yachts, as an alternative to traditional sails, However, the applicant has recognised that it may be beneficial to provide wingsail units to other vessels, including relatively large ocean-going vessels, For example, the present application relates to the provision of such wingsail units to large bulk carriers and tankers, such as may be used to transport coal, ores, crude oil, products derived from crude oil and liquefied gas, all of which are transported in large volumes in such vessels. tS

It is presently expected that the provision of wingsail units to such vessels may be used in order to supplement the existing engines, for example to improve fuel efficiency and/or reduce fuel costs. It should be appreciated, however, that the present invention could be applied to a vessel that is solely driven by wingsail units and/or a vessel that is configured to be solely driven by wingsail units part of the time, In previously-known uses of wingsail units, namely on pleasure-craft, there have been limitations on how they can be used, for example due to the limited size of the vessel, Consequently, previously a single wingsail has been known to be provided to each vessel, However, providing wingsail units to much larger vessels, such as bulk carriers and tankers, enables new options for the use of wingsail units, Providing wingsail units to large powered vessels also imposes new constraints. Furthermore, it may be desirable to retrofit wingsail units to existing large vessels, which also introduces further opportunities and requirements, The present invention seeks to respond to some or all of the available options and requirements when wingsail units are provided to relatively large vessels.

According to the present invention there is provided a set of a plurality of wingsail units for a vessel, in which each wingsail unit in the set comprises: a rotatable support configured to be mounted to the vessel; a plurality of elongate aerofoil sails each formed from at least one aerofoil section 3 for providing thrust to the vessel, mounted to the rotatable support such that the leading edges of the aerofoil sections are all substantially vertical; and a support frame, set apart from the rotatable support, configured to maintain a given separation between adjacent aerofoil sails at the location of the support frame; wherein, for each of the wingsail units in the set, the height of the support frame relative to the rotatable support is the same; and the length of the aerofoil sections of the aerofoil sails from the support frame to the end furthest from the rotatable support differs for at least two wingsail units in the set relative to each other, In an arrangement of the set wingsail units for a vessel according to the present invention, the length of the aerofoil sails from the support frame to the end furthest from the rotatable support may be different for each of the wingsail units in the set. Consequently, the height of each of the wingsail units may be different even though the height of the support frame for a plurality of the wingsail units may be the same. In tum, the construction of the wingsail units, from the rotatable support up to the support frame may be the same for each of the wingsail units within the set, Alternatively, the configuration of the wingsail units may also vary, for example the number of aerofoil sails within each wingsail unit. In that case, the configuration of each aerofoil sail within the set of wingsail units may be the same for the section of the aerofoil sail between the rotatable support and the support 23 frame notwithstanding the differing lengths of the aerofoil sails for respective wingsail units, The wingsail units may frirther comprise a tail section that may be used to drive the wingsail unit to set the aerofoil sails to a desired angle of attack relative to the incident wind, The tail section may also include one or more elongate aerofoil sections that are also configured such that the leading edge is substantially vertical.

Optionally, if a wingsail unit includes multiple aerofoil sections within the tail section, the cross section of each of these may be the same. Alternatively or additionally, all of the aerofoil sails within a wingsail unit may share a common cross section.

Within the set of a plurality of wingsail units, a plurality of the wingsail units maybe configured such that the aerofoil sections of the tail sections of those wingsail units have a common cross section. Alternatively or additionally, a plurality of the wingsail units may be configured such that the aerofoil section of the aerofoil sails of the wingsail units have a common cross section.

Within the set of wingsail units, the heights of the wingsail unit may differ from each other.

The present invention may, in particular, be applicable to large commercial vessels, such as bulk carriers or tankers and, in particular, maybe applicable to vessels having a displacement that is greater than 10,000 tonnes dwt, optionally greater than 100,000 tonnes dwt, optionally greater than 200,000 tonnes dwt.

The present invention also provides methods for designing plurality of such sets of wingsail units for a vessel, methods for preparing such a set of wingsail units for a vessel and methods of providing such a set of wingsail units to a vessel.

In an aspect of the present invention, at least two aerofoil sections having different lengths may be successively manufactured in the same mould because, although they may differ in length for the portion of the aerofoil section beyond the support frame, their configuration may be the same for the part of the aerofoil section between the rotatable support and the support frame.

In particular, the mould may have a first section for forming parts of the aerofoil section that connects to the rotatable support and the support frame, together with a fixed length of aerofoil section between those parts, and a section in which a variable length of aerofoil section may be formed for the part of the aerofoil section beyond the support frame.

The invention will now be described by way of non-limiting examples, with reference to the accompanying drawings, in which: Figure 1 schematically depicts an example of a wingsail unit; Figure 2 depicts a single aerofoil sail in three different positions; Figure 3 depicts a vessel having six wingsail units mounted thereon; Figure 4 is an enlarged view of the vessel depicted in Figure 3; and FigureS schematically depicts in plan view an arrangement of a wingsail unit having four aerofoil sails.

Figure t schematically depicts an example of a wingsail unit that may be used in an aspect of the present invention. In the example shown, the wingsail unit is formed from three elongate aerofoil sails 1, 2, 3, mounted such that the leading edges Ia, 2a, 3a, of each of the aerofoil sails are substantially vertical. The aerofoil sails are mounted to a rotatable tS support that in turn may be secured to a vessel. Accordingly, by rotating the wingsail unit, the aerofoil sails I, 2, 3 may be arranged to have a suitable angle of attack relative to the incident wind, generating thrust that is transmitted to the vessel.

The rotatable support of the wingsail unit depicted in Figure 1 may be configured to permit rotation of the wingsail unit relative to the vessel, As shown in Figure 1, each of the aerofoil sails 1, 2, 3 may be mounted to the rotatable support, directly or via a lower frame 4, such that the thrust generated by the aerofoil sails may be transferred via the rotatable support to the vessel.

In the arrangement depicted in Figure 1, the wingsail unit includes a tail section 5 that is provided downwind of the aerofoil sails 1, 2, 3. The tail section may be formed from an additional elongate aerofoil section and may be configured such that it can be actuated to have a different angle of attack relative to the incident wind from the angle of attack of the aerofoil sails. Such a tail section may be used in conjunction with a freely-rotating rotatable support in order to control the wingsail unit. In particular, control of the tail section may be used to rotate the wingsail unit on the rotatable support in order to set the angle of attack of the aerofoil sails 1, 2, 3 relative to the incident wind.

In the arrangement depicted in Figure 1, the aerofoil sails I, 2,3 are each formed from a leading part ib, 2b, 3b and a trailing part ic, 2c, 3c, each formed from an elongate aerofoil section. As shown in Figure 2, which depicts a single aerofoil sail t in three different positions, the trailing part Ic of such a configuration may be rotated relative to the leading part lb. In a wingsail unit having aerofoil sails of this configuration, rotation of the trailing parts of the aerofoil sails may be used effectively to change the shape of the aerofoil sails, providing control of the level of thrust generated for a given angle of attack of the aerofoil sail relative to the incident wind. As shown in Figure 2, an intermediate flap 6 maybe provided between the leading part th and the trailing part Ic of the aerofoil sail.

Depending on the precise configuration, this may provide a sufficient improvement in the thrust generated for a given size of wingsail unit to justify the additional manufacturing cost. In other specific configurations, it may not be required.

As shown in Figure 1, a link 7 maybe provided between the trailing parts of each of the tS aerofoil sails 1, 2, 3 of a wingsail unit, In such an arrangement, actuating the trailing portion of one of the aerofoil sails 2 using an actuator 8 may set the trailing portion of the other aerofoil sails 1, 3 to a corresponding position.

As further shown in Figure 1, a support frame 9 may be provided, set apart from the point at which the aerofoil sails are mounted to the rotatable support, to provide rigidity to the wingsail unit and maintain the separation of the aerofoil sails, 2, 3 along their length. As shown, this support frame 9 may also maintain the separation of the tail section from the aerofoil sail.

As discussed above, the applicant has recognised that wingsail units, such as those described above and as depicted in Figures t and 2, need not be limited to pleasure-craft, In particular, appropriately configured wingsail units may be provided to commercial vessels, such as bulk carriers and tankers and be commercially beneficial, In particular, the applicant has determined that, when applied to such commercial vessels to supplement the existing drive systems of those vessels, the use of wingsail units in line with the present invention may reduce fuel requirements by approximately 10% to 20%. To put this into perspective, the applicant has determined that, depending on specific configurations, fluctuations in fu& prices and the routes used by the vessels, the payback period for installing the wingsail units, namely the period within which the fuel cost savings will exceed the cost of installing the wingsail units, may be between one and four years. This is considerably less than the expected lifetime of such vessels.

However, there are considerable differences between the use of such wingsail units for pleasure-craft, as already known, and their use for commercial vessels such as bulk carriers and tankers. Firstly, these vessels may be very large and, in particular, relatively long.

Accordingly, in contrast with a pleasure-craft, there may be sufficient space to install multiple wingsail units to a single vessel without interfering with the aerodynamic performance of each unit.

The larger the vessel, the greater the number of wingsail units that may be provided to the vessel and the greater the benefit of the present invention. In particular, the wingsail units of the present invention may be provided to vessels having a displacement of greater than 10,000 tonnes dwt, optionally greater than 100,000 tonnes dwt, optionally greater than tS 200,000 tonnes dwt in order to yield the greatest benefits of the present invention.

In order to be able to provide wingsail units to a commercial vessel such as a bulk carder or a tanker, it is desirable that the provision of the wingsail unit does not change its ability to operate. This is particularly true if the wingsail units are to be retrofitted to an existing vessel, For example, the highest point on a vessel such as a bulk carrier or tanker may be the aft masthead light. The height of the aft masthead light above sea level may determine the port to which a vessel may gain access due to obstructions such as bridges to be passed under on the vessel's route to the port. Therefore, although maximising the height of wingsail units may be desirable to maximise the aerofoil sail area and therefore maximise the thrust delivered to the vessel, in practice the tops of the wingsail units provided to a vessel should be below the aft masthead light, Furthermore, it is now recognised by the applicant that the top of the wingsail units provided to a bulk carrier or tanker may need to be significantly lower than the aft masthead light if it is to comply with collision regulations, permitting the vessel to have access to the national waters and ports of many countries around the world. In particular, the forward wingsail unit may be provided with a height lower than the aft masthead light in order that the aft masthead light is visible at sea evel at a point 1,000 metres in front of the bow of the vessel.

Given the substantial length of many bulk caniers and tankers, this may require that the height of the forward wingsail unit may be significantly below the height of the aft masthead light. For ease of configuration and to minimise manufacturing costs, one may expect all the wingsail units for a vessel may be the same, namely the height of the forward wingsail unit. However, the thrust generated by each such wingsail unit may be substantially less than the thrust generated by a wingsail unit the height of the aft masthead light. Therefore, it is now appreciated that having all wingsail units the same height may result in lost thrust.

However, the applicant has also recognised that, although it may be simpler and/or cheaper to provide all of the wingsail units to a vessel having the same height as the forward wingsail unit, providing wingsail units of different heights to one vessel enables the maximum thrust to be generated by the combination of the wingsail units. In particular, the further rearward the wingsail unit is provided, the taller it may be provided. In an arrangement, the wingsail units provided to a vessel may be configured such that they become taller as one travels more rearward on the vessel. However, in an aspect of the invention, each of the wingsail units may be configured such that its top is below a line extending from the aft masthead light to a point at seal level 1,000 metres in front of the bow of the vessel, ensuring suitable visibility of the aft masthead light.

In order to maximise the thrust available, the wingsail units may be configured such that the tops of the wingsail units are as close as possible to the line between the aft masthead height and a point at sea level 1,000 metres in front of the bow of the vessel. For example, the height of each wingsail unit provided to a vessel, measured from the deck of the vessel at the point at which the wingsail unit is mounted may be greater than 80%, optionally greater than 90%, optionally greater than 95% of the height of the line above the deck of the vessel at that location. Such an arrangement is schematically depicted in Figure 3, which depicts a tanker 20 having six wingsail units 21,22,23,24,25,26 mounted thereon.

As shown, each wingsail unit is just below a line 30 extending from the aft masthead light 31 to a point 32 at sea level 1,000 metres in front of the bow of the vessel. As shown, the height of each of the wingsail units is different.

It may be appreciated that, depending on the size of the vessel and the load it caries, the position of the line extending from the aft masthead light may change significantly depending on whether or not the vessel is fully laden or ifilly unladen. In particular, if the vessel is fully unladen and therefore riding higher in the water, the angle of the line extending from the aft masthead light relative to the horizontal is steeper, resulting in the wingsail units needing to be slightly shorter to remain below it. Therefore, during the analysis of a vessel to determine the required sizes of the wingsail units, the line extending from the aft masthead light maybe defined for a fully unladen vessel.

As discussed above, in such an arrangement for a large vessel, it may be desirable to optimise the configuration of each wingsail unit on the vessel. However, this must be balanced with the desire to ensure that the cost of providing multiple different wingsail units to a vessel is not unnecessarily increased as a result of providing a plurality of different wingsail units to the vessel. tS

In the case of designing a new vessel to include wingsail units according to the present invention, the layout of the vessel may be selected to provide appropriate locations at which to place the plurality of wingsail units, for example evenly distributed along the length of the deck of the vessel, Once the locations of the wingsail units are determined, the height of each may be selected in order to be as high as possible and below the line between the aft masthead light and a point at sea level 1,000 metres in front of the bow of the vessel.

Alternatively, the wingsail units may retrofitted to an existing vessel, In that case, the vessel may be analysed in order to identify locations at which wingsail units may be mounted, for example to avoid existing equipment provided on the deck of the vessel and also to provide an appropriate structural point at which to mount the wingsail unit, For example, possible wingsail unit locations may be arranged along the centre line of the vessel so that the wingsail units may be mounted to the centre-line girder. Alternatively or additionally, the wingsail units may be mounted at the point of a bulkhead or transverse frame of the vessel. In general, it will be appreciated that the locations at which to mount the wingsail units may be selected such that the structure of the vessel can provide appropriate support to the wingsail unit and also to ensure that, in use, the delivery of the thrust from the wingsail unit to the vessel does not result in deformation of the vessel. As with the selection of wingsail units for a new vessel, once the location of the wingsail units has been determined, the height of the wingsail units to be retrofitted to the vessel may be determined. Subsequently, an appropriate set of wingsail units may be designed, manufactured and installed to the vessel at the available locations.

As explained above, where a plurality of wingsail units are to be provided to a commercial vessel, it may be desirable that the wingsail units will each have different heights.

However, to design, provide tooling and manufacture multiple different wingsail units for a single vessel may be undesirable due to the additional costs involved. In order to address this, a set of wingsail units for a vessel may be configured such that they have common components even though they have different heights. In particular, all of the wingsail units within a set may be configured such that the height of the support frame relative to the rotatable support is the same for each of the wingsail units but the length of aerofoil tS sections, of the aerofoil sails and/or the tail sections, extending beyond the support frame, differs from wingsail unit to wingsail unit.

Such an arrangement may facilitate the formation of wingsail units of different heights.

For example, wingsail units of different height may be made with the same tooling, in particular, an aerofoil section for a wingsail unit may be formed within a mould, for example if the aerofoil section is to be made from a composite material, In that case, the mould may have sections for forming the parts of each aerofoil section for connecting to the rotatable support and the support frame at a fixed separation from each other, together with a section for forming the fixed length of aerofoil section between the connection parts. In addition, the mould may have a section in which a variaNe length of aerofoil section may be formed, corresponding to the part of the aerofoil section that in the wingsail unit will extent beyond the support frame, thus enabling different lengths of aerofoils to be made for wingsail units in the same mould, In the case of an aerofoil section being formed from a composite material, it will be appreciated that the composition material being used to form the aerofoil section may be laid up in the mould up to the desired length. In any case, a moveable and/or removable end for the mould may be provided in order to define the size of the variable length section of the mould to be used when forming each aerofoil section, With the arrangement described above, it should be appreciated that aerofoil units may be provided of different heights, namely having aerofoil sails and tail sections of heights that differ from wingsail unit to wingsail unit using common tooling. As shown in Figure 4, which is an enlarged view of the vessel 20 depicted in Figure 3, in a set of wingsail units formed in this manner, the plurality of wingsail units 21, 22,23,24,25,26 provided to a vessel may have different heights but the support frame 9 of each, set apart from the respective rotatable support, may be at the same height for all the wingsail units relative to the deck of the vessel 20.

As also depicted in Figure 4, it should be appreciated that although in arrangements, such as discussed above, the tail sections 5 of each wingsail unit may be the same height as the aerofoil sails 1, 2,3 of that wingsail unit, this need not be the case.

tS In particular, the tail section 5 only needs to be sufficiently large to provide sufficient thrust to set the angle of attack of the aerofoil sails. Accordingly, for some configurations of wingsail units, the tail section may not need to be as tall as the aerofoil sail of that wingsail unit. Accordingly, two or more wingsail units in a set of wingsail units provided to a vessel may have tail sections 5 of identical heights even if the aerofoil sails 1, 2, 3 have different heights, ifirther facilitating the manufacture of the tail sections. In such an arrangement, the tail sections of taller wingsail units may be shorter than the aerofoil sails of that wingsail unit while shorter wingsail units may have taller tail sections than is necessary to provide sufficient thrust to set the angle of attack of that wingsail unit.

In the example depicted in Figure 4, all of the wingsail units 21, 22, 23, 24, 25, 26 have different heights, namely the aerofoil sails 1, 2, 3 of each of the wingsail units are different from each other, However, the forward three wingsail units 2, 22, 23 have tail sections 5 of a first common height and the rearward three wingsail units 24, 25, 26 have tail sections 5' of a second common height, different from the first common height. It will be appreciated that, depending on the number of wingsail units to be provided to the vessel, any appropriate number of common heights of tail sections may be included in a set of wingsail units.

As discussed above, and as depicted in Figure 1, a known wingsail unit may have three aerofoil sails 1, 2, 3 provided in a row and a tail section 5 downwind of the aerofoil sails.

The separation of the aerofoil sails, which determines the overall size of the wingsail unit and the space required for the aerofoil unit on a vessel, given that it may rotate to any angle relative to the vessel, is determined by the cross section of the aerofoil sections used.

In line with the present invention, a plurality of wingsail units may be provided to a single vessel. For a given design of wingsail unit, there may be a preferred separation between the wingsail units. This preferred separation provides a balance between ensuring that the separation is sufficiently large that each wingsail unit does not affect the operation of an adjacent wingsail unit, thus maximising the thrust from each, but also filling as many wingsail units to a vessel as possible, thus maximising the total thrust provided to the vessel.

tS For a vessel being designed to accommodate wingsail units, it may therefore be appropriate to configure the vessel such that wingsail units may be mounted to the vessel as appropriate locations to be as close as possible to the preferred separations.

However, in accordance with the present invention, wingsail units may be retrofitted to existing vessels. In that case, a pre-existing vessel may be assessed in order to identifkj locations at which wingsail units may be mounted, predetermining the separations between adjacent wingsail units. Wingsail units may then be designed in order to suit the separations between adjacent wingsail units that have been determined for a particular vessel.

For example, the cross section of each aerofoil section within wingsail units may be selected to maximise the thrust generated by a wingsail unit given the restriction of its separation from an adjacent wingsail unit. However, undesirably, for a vessel in which a plurality of wingsail units are to be retrofitted to the vessel, the variations in separations between wingsail units that may be required may in this manner result in the requirement to provide wingsail units each having aerofoil sections of different sizes of cross section.

This would undesirably increase the cost of producing such a plurality of wingsail units for a given vessel.

An aspect of the present invention provides an alternative solution. In particular, under the circumstances, it may be desirable to provide a wingsail unit that has four or more aerofoil sails instead of three aerofoil sails. Figure 5 schematically depicts in plan view an arrangement of such a wingsail unit 40 having four aerofoil sails 41, 42, 43, 44, Such a wingsail unit having four aerofoil sails may produce less thrust than a wingsail unit having three larger aerofoil sails. However, it is now recognised that this arrangement may be preferable overall if it is required to provide a set of wingsail units for a vessel. In particular, the aerofoil sections for the wingsail unit having four aerofoil sails may have the same cross section as the aerofoil sections of other wingsail units in the set of wingsail units to be provided to a vessel. This may significantly reduce the cost of production because, for example, the same tooling may be used, as explained above.

In particular, this may be appropriate when retrofitting wingsail units to a vessel if the structure or configuration of the vessel requires a relatively large separation between some t5 wingsail units in comparison to others. In that case, a wingsail unit having four aerofoil sails may provide more thrust than a corresponding wingsail unit having three aerofoil sails, while not interfering with the operation of the adjacent wingsail units.

It should further be appreciated that in some situations, wingsail units having a larger number of aerofoil sails, such as five or six aerofoil sails may be used. Accordingly, in general, a set of wingsail units for a vessel may have a plurality of wingsail units having a variety of numbers of aerofoil sails within each of the wingsail units. However, the cross section of each of the aerofoil sections used to form the plurality of wingsail units may be the same within a set of wingsail units for a particular vessel.

It should further be appreciated that the use of wingsail units having four or more aerofoil sections may only be practical for commercial vessels such as bulk carriers and tankers, This is because the space required for a wingsail unit significantly increases for four or more aerofoil sails due to the separation required between each aerofoil sail within a single wingsail unit. Accordingly, a wingsail unit having four or more aerofoil sails may be very wide, requiring a significant amount of space on the deck of the vessel in order to provide sufficient space for the wingsail unit to be able to rotate freely relative to the vessel.

As explained above, the tail section of the wingsail units may include an aerofoil section used to provide thrust in order to set the angle of attack of the wingsail unit relative to the incident wind, If a larger wingsail unit is to be used, for example a wingsail unit having four or more aerofoil sails, the thrust required to be provided by the tail section in order to set the angle of attack may be increased, As explained above, some variation in the thrust provided by the tail maybe provided by adjusting the total height of an aerofoil section used to form the tail section. However, this may be limited by the total height permitted for the wingsail unit.

A larger cross section aerofoil section may be used for a tail section on a larger wingsail unit, However, this is undesirable if a plurality of wingsail units of different configurations are to be provided for a vessel. In particular, it is preferable that all of the cross sections of the aerofoil sections used to form the tail sections of a plurality of wingsail units for a vessel are the same in order that, for example, common tooling may be used. tS

Therefore, as shown in Figure 5, a wingsail unit 40 such as one having four or more aerofoil sails 41, 42, 43, 44 may be configured to have two or more aerofoil sections 45, 46 within the tail section 5 in order that the combined thmst of the tail section is sufficient. In this way, a set of wing sail units for a vessel may be provided in which different sizes of wingsail units, namely having different numbers of aerofoil sails, can be provided for a vessel without requiring the production of a plurality of different sizes of aerofoil sections in order to form the tail.

In line with the above, it should therefore be appreciated that a vessel may be retrofitted with a plurality of wingsail units that maximise the total thrust that can be provided to the vessel even though there may be substantial variations in the separation between adjacent wingsail units due to limitations on locations to which wingsail units may be mounted to a vessel, without the need to manufacture different sizes of cross-section of aerofoil sections for the aerofoil sails and the tail sections of the wingsail units to be provided for that vessel, Thus the thrust provided by a plurality of wingsail units retrofitted to a vessel may be maximised without incurring substantial increases in the manufacturing cost.

It shou'd also be appreciated that, based on the above, one or more standard cross-sections for the aerofoil sections used to form aerofoil sails and tail units for wingsail units may be provided and any vessel to be retrofitted with wingsail units may then be assessed and appropriate wingsail units designed for that vessel using the standard cross-section.

Alternatively, an optimised single cross section for all of the aerofoil sections of the aerofoil sails and tail units, respectively, may be selected for each vessel, such that each vessel does not require an unduly large number of cross sections of aerofoils to be formed but still providing a degree of optimisation for each vessel. t5