WO2012025743A1

WO2012025743A1 - Wind indicator device, method and computer program product for sailing

Info

Publication number: WO2012025743A1
Application number: PCT/GB2011/051576
Authority: WO
Inventors: Jonathan Keith Anderson Abrahams; Stephen Puleston Williams
Original assignee: Jab Sailing Ltd
Priority date: 2010-08-23
Filing date: 2011-08-19
Publication date: 2012-03-01
Also published as: GB2471785B; GB2471785A; GB201014037D0

Abstract

A wind direction indicator comprises a base (1/1') on which is mounted a rotatable disc (2/2') with an anticlockwise scale (SC). Indicia in the form of sectors (S1 to S5) and sail plan diagrams (6, 6') indicate the points of sail for a given bearing. The device is used by rotating the disc so as to set the scale to indicate the wind direction and then simply reading off the bearing of the boat on the scale to find the wind direction experienced by the boat. Indicia such as sail plan diagrams (6, 6') show the points of sail needed for various wind directions. The wind direction indicator may be implemented electronically in a mobile device.

Description

Wind indicator device, method and computer program product for

sailing

The present invention relates to a wind indicator device, method and computer program product for indicating the wind direction relative to a sailing boat for any bearing.

Various indicator and calculator devices are known for assisting in sailing and navigation, eg from US 4,652,728, US 3,804,057, US 4,855,577, GB 1,121,620, FR 2,670,003A, GB 2,422,232A, DE 202007014108U, US 2009/287409A, GB 529,507,US 4,481,810 and FR 2,203,970A. In general, these devices, most of which are of complex construction, utilise angularly calibrated discs, the main angular scale being calibrated in the conventional clockwise sense, ie with angular markings increasing

10°, 20°, 30° 360° in the clockwise direction.

US 4,652,728 discloses in Figure IB two 180° angular scales, the left-hand scale being calibrated in the anticlockwise sense and being associated with points of sail for a port tack and the right-hand scale being associated with points of sail for a starboard tack.

US 3,804,057 discloses in Figure 1 a left-hand 30° to 60° scale (and also a 0° to 60° scale) calibrated in the anticlockwise sense and a right-hand 30° to 60° scale (and also a 0° to 60° scale) calibrated in the clockwise sense. These are subsidiary scales subtending much less than one revolution, the main 360° angular scale being clockwise.

None of the above prior art documents teaches or suggests that as the bearing of the boat varies, the wind direction relative to the boat (the parameter of main interest to the helmsman) varies in the opposite sense and can be read off a reverse angular scale. Accordingly in one aspect the invention provides a wind direction indicator for indicating points of sail for a sailing boat, the indicator comprising an angular scale which is rotatable relative to a set of indicia (eg lines or similar markings, or diagrammatic representations of sail patterns) angularly distributed about its axis of rotation, the indicia being associated with points of sail and said set of indicia defining a reference line associated with the longitudinal axis of the sailing boat, said angular scale being calibrated in the anticlockwise sense over substantially a complete revolution whereby on setting said reference line to indicate the wind bearing on said angular scale, the wind direction relative to the sailing boat corresponds to the bearing of the sailing boat on said angular scale.

For example if the wind direction were determined to be 0° (due N), eg by the boat facing due N and the sails ruffling, the angular scale would be set with its 0° mark aligned with the reference line. If the boat then sailed on a bearing of 90° (due E) the wind direction experienced by the boat would shift anticlockwise by 90°, ie a change of -90° which could be deduced by reading off the bearing of 90° on the anticlockwise scale.

More generally, if the bearing of the boat is 01 and the wind direction is 02, the wind direction experienced by the boat is 02 - 01. The setting of the angular scale to the wind bearing gives 02 and the negative (anticlockwise) scale adds (-01) to give the wind direction experienced by the boat.

Thus a simple manipulation of the device provides the information needed to set the boat's sails. Moreover it is not necessary for the boat to be sailing along the bearing indicated, so the point of sail for a hypothetical bearing (eg on a future leg of an Olympic course) can be established in advance. The device need not be aligned with the boat and in fact it is not necessary for a boat to be present at all, enabling the device to be used on a desktop for teaching.

Preferably said indicia are provided on a representation of a boat. This feature makes the device easier to read and understand.

Preferably said set of indicia defines sectors on the left and right sides of said reference line respectively which are differently coded (eg red and green) to represent port and starboard tacks respectively. This feature enables the sails to be set for port and starboard tacks more easily.

Preferably said set of indicia includes a representation of at least one sail configuration required for an indicated wind direction. This reduces the possibility of error.

Preferably said set of indicia indicates at least one leg of a standard sailing course (eg an Olympic sailing course), said standard sailing course having an orientation defined with respect to the wind direction. This feature emphasises to the user the point of sail for a given leg of the course. Conveniently, said angular scale is rotatably mounted on a base, said set of indicia being provided on the base surface facing said angular scale. The device is

conveniently hand-held.

Other preferred features are defined in the dependent claims.

In a variant, the device comprises an electronic display arranged to display said angular scale and/or said set of indicia and to rotate said angular scale relative to said set of indicia in response to an input signal. Preferably both the angular scale and the indicia are displayed, although it is within the scope of the invention to have the indicia marked permanently on the display.

The electronic version may include data entry means for enabling a user to generate said input signal. However the input signal may be provided by an electronic compass, navigation system or wind direction sensor to enable automatic operation

Preferably the electronic version is a hand-held mobile device.

In another aspect the invention provides a computer program product for operating the electronic version of the wind direction indicator, said computer program product comprising a computer readable medium embodying program code means executable by a microprocessor to display said angular scale and/or said set of indicia and to rotate said angular scale relative to said set of indicia in response to an input signal. The computer program product may be loaded onto a mobile telephone for example.

In another aspect the invention provides a method of sailing a sailing course wherein the angular scale of the wind direction indicator of the first aspect of the invention is set to indicate the wind direction and points of sail at different stages of the sailing course are read off from the wind direction indicator.

Preferred embodiments of the invention are described below by way of example only with reference to Figures 1 to 9 of the accompanying drawings, wherein:

Figure 1 is a schematic plan view of a wind indicator device in accordance with the invention;

Figure 2 is a diagrammatic representation of a sailing boat being turned into the wind to determine the wind bearing; Figure 3 is a diagrammatic representation of a yacht sailing an Olympic 60° sailing course, the wind directions experienced by the boat at positions Yl to Y7 being illustrated by corresponding arrows in Figure 1 ;

Figure 4 is a diagrammatic representation of an electronic wind indicator device in accordance with the invention;

Figure 5 is a schematic plan view of a preferred embodiment of a wind indicator device in accordance with the invention;

Figure 6 is a schematic rear end elevation of the wind indicator device of Figure

5;

Figure 7 is a diagrammatic illustration of the determination of start line bias using the embodiment of Figures 5 and 6;

Figure 8 is a diagrammatic illustration of the use of the embodiment of Figures 5 and 6 to indicate a Bear Away set as a sailing boat rounds a windward buoy, in the case that the wind bearing stays the same or increases, and

Figure 9 is a diagrammatic illustration of the use of the embodiment of Figures 5 and 6 to indicate a Gybe set as a sailing boat rounds a windward buoy, in the case that the wind bearing decreases.

Referring to Figure 1 , the device comprises base 1 in the form of a rectangular board of dimensions 140 mm x 90 mm and 2 mm thickness, the corners being rounded. The device can thus be kept in a jacket pocket. A hole H is provided to enable the device to be held on a lanyard.

A diagram B of a boat is marked on the upper surface of base 1 and has a central reference line RL along its longitudinal axis.

On each side of line RL, five sectors SI to S5 are indicated, and correspond to points of sail as follows:

51 is the dead air zone, in which the boat cannot sail because it is too close to the wind.

52 is in the sector 45° to 90° from RL where a typical yacht would use mainsail and head sails and is typically referred to as sailing a Close reach or Close Hauled. The line LI orthogonal to RL is the nominal orientation of the start line for any type of yacht race using a committee boat start as well as in an Olympic course, deviations from this line of interest to the yachtsman being shown as PORT END BIAS and STARBOARD END BIAS. These indications are shown only in the sectors S2 above line LI in Figure 1 for the sake of clarity but in practice could be shown in the sectors S3 below this line (but with "PORT END BIAS" in the left hand sector and "STARBOARD END BIAS" in the right hand sector).

S3 is broadly the Beam Reach sector. Line L2 is the course to sail for an Olympic course with 60° turns. Line L3 is the course to sail for an Olympic triangular course with 45° turns. A spinnaker can be used in this sector.

54 is a sector corresponding to a starboard tack (on the right hand side of diagram B) or a port tack (on the left hand side of diagram B) of legs 1 and 2 respectively of a triangular Olympic course. The sail plan for a starboard tack is illustrated by a diagram 6 and the sail plan for a port tack is illustrated by a similar diagram 6'. The Broad Reach point of sail extends from in front of the boundary of S4 and S5 into region S5 and thus is not explicitly marked.

55 is bounded by the rear portion of line RL which is marked RUN, indicating a dead run sail plan, typically involving mainsail, head sail and spinnaker.

A transparent angular scale disc 2, 85 mm in diameter, is rotatably secured to base 1 by a snap-fitting stub shaft 3 and has an anticlockwise scale SC. For ease of illustration and clarity, only the portion from 320° to 90° is shown, but in practice the scale SC covers a complete revolution ie 360°.

In a variant, the green and red coloured sectors could be replaced by green and red borders of the boat diagram B in order to improve readability, and/or two opposite sides, eg the long sides of the board 1 could include cutout portions extending within the circumference of disc 2 in order to enable the disc to be gripped and rotated more easily.

In a further variant the anticlockwise scale SC could be marked on the base 1 and the boat diagram B and its associated indicia could be marked on a flat rotatable transparent member (which could be boat- shaped for example). The preferred features of the invention could be combined with any of the above variants, which could themselves be combined if desired.

Arrows marked Yl Y5, Y3, Y7, Y4 and Y2 Y6 are shown in Figure 1 but do not appear on the device; they refer to wind directions experienced at various positions in the Olympic course of Figure 3. The setting up of the device will now be described with reference to Figures 1 and 2.

Referring to Figure 2, the yachtsman sails yacht Y into the wind so that the mainsail M and head sail H empty and flap equally from side to side ( a situation known as head to wind). At this point he reads the course bearing on a compass 5 (which could be separate or alternatively could be mounted on base 1 of the device, for example) and aligns disc 2 with the forward portion of reference line RL. For example in Figure 1 it is assumed that this bearing (the wind direction) is about 358°. The wind direction for any subsequent bearing of yacht Y can then be read off scale SC. For example, referring to Figure 1, at a bearing of about 43° the wind direction would be as indicated by arrow Y2 Y6. This would correspond to a close hauled point of sail, almost in the dead air zone.

The application of the device will now be described with reference to Figure 3. The course C shown in Figure 3 is a triangular Olympic course defined by a leeward buoy B3, and windward buoy Bl and a wing buoy B2, each defining 60° corners. The course is set up with the windward buoy Bl exactly to the windward of leeward buoy B3, in this case due North of B3 because the wind W is a north wind (bearing 0°). In general, the direction from Bl to B3 is defined by the wind direction rather than any point of the compass.

The yachts set off from a start line 10 (whose length and distance from line BIBS is greatly exaggerated for the sake of clarity) which is nominally orthogonal to direction B1-B3 but in this case happens to be slightly skewed to starboard, as shown. The start line 10 is normally defined by markers such as a buoy and a boat (not shown). The skew amounts to a port end bias ie it favours starting from the West (port) end of the line 10. A user of the device in Figure 1 can determine the bias by establishing the wind bearing and setting the angular scale disc 2 with said bearing as outlined earlier, then positioning his yacht behind one of the buoys (not shown) at either end of the start line, establishing the bearing along the start line and then comparing the orientation of the start line 10 with Line LI (Figure 1). In the event that the bearing of the start line 10 lies in the PORT END BIAS sector of the device, he concludes that it is advantageous to start from the port end of start line 10. The yacht, racing others (not shown) starts off on a starboard tack ST at Yl, using a head sail H and a mainsail M as shown. This tack, being on a bearing of about 310°, involves a close hauled point of sail as indicated by arrow (Yl Y5) in Figure 1. The device warns the helmsman that he is almost within the dead zone represented by sector SI (Figure 1). He tacks to a port tack PT, on a bearing of about 45°, and the device (see arrow Y2 Y6) warns the helmsman that he is again almost within the dead zone and that a close hauled point of sail is required.

The helmsman rounds buoy Bl and sets off on LEG 1 of the course (position Y3) on a bearing of about 60°. Consulting the device, he refers to sector S4 (Figure 1) which is labelled LEG 1 and uses the sail plan represented by diagram 6 in this sector.

He then rounds buoy B2 and sets off on LEG 2 (see also Figure 1), whose sail plan is indicated by diagram 6' (Figure 1). This is of course the correct sail plan for wind W.

He then rounds buoy B3 and follows a starboard tack ST (position Y5) followed by a port tack PT (position Y6) with points of sail as indicated by arrows (Yl Y5) and (Y2 Y6) respectively. These are as described above for the start of the race.

Finally he turns the last bend of the course and sets off on the final RUN (position Y7, bearing 180°) towards line 10, using a spinnaker SP in addition to the mainsail M and head sail H with the wind behind him as indicated by arrow Y7 (Figure 1).

Unless the wind changes, the yachtsman knows the required point of sail at each stage in the race and he and his crew can plan accordingly.

Should the wind shift one way or the other significantly during the race it is impractical to stop and put the boat head to wind again to obtain the true wind direction.

However with the device of Figure 1 it is merely necessary to wait until hard on the wind again (ie sailing at 45° to the wind), on either port or starboard tack, and make a note of the compass bearing on that tack, and then simply turn the angular scale disc 2 to that bearing on the 45° line from the reference line RL on the corresponding tack. This will then give the new true wind direction for re-planning the rest of the race. Example

True wind is set up as 270° on scale disc 2. The boat would be sailing hard on the wind at 315° on port tack and 225° on starboard tack.

The wind then shifts and it is found that the boat can only sail 300° on port tack and 210° on starboard tack. This is a shift of 315° - 300° (or 225° - 210°) = 15°. Hence the new true wind direction is 270° - 15° = 255° and scale disc 2 is set to this value accordingly.

Figure 4 shows an electronic version of the device of Figure 1, in the form of a mobile device (eg a mobile telephone or other communication device) with a screen SC (optionally a touch-sensitive screen) and optionally a keypad K (and/or other data entry means, not shown). The device includes a microprocessor (CPU) provided with volatile and non- volatile memory (ST) and arranged to display an anticlockwise angular scale as shown in Figure 1 or as shown in the embodiment of Figure 5 described below, the scale being rotatable relative to fixed indicia as shown (ie as in Figure 1 or Figure 5) either under the control of the user by means of eg keypad K or a touch-sensitive screen or under the control of a WIND DIRECTION input signal which could be provided by a wind direction indicator (not shown). The mobile device includes input/output circuitry (I/O) which is connected to the microprocessor (CPU) and which is optionally coupled to one or more input ports for receiving eg the WIND DIRECTION input signal and a BEARING input from eg a compass or navigation system (not shown) representing the bearing of the boat. This BEARING signal could control the orientation of a vector line V in relation to the angular scale. Accordingly the required point of sail is indicated by the sector or other indicia indicated by vector V. Vector line V indicates the wind direction experienced by the boat.

In a variant, either or both of the WIND DIRECTION and BEARING signals could be received wirelessly by means of an antenna included in the device.

In a variant, the indicia could be permanently marked on the screen SC and only the angular scale displayed electronically. The embodiment shown in Figures 5 and 6 (in which parts similar to parts of the embodiment of Figure 1 are indicated by primed reference numerals) differs from the embodiment of Figure 1 in that:

a) a rotary pointer P is mounted above and concentrically with scale disc 2', in order to enable adjustments to be made in response to shifts in wind direction; b) port and starboard sectors S5 are labelled GYBE and BEAR AWAY respectively, in order to enable pointer P to indicate these alternatives when rounding a windward buoy,

c) the device includes a compass 50, and

d) the directions of the port end bias and starboard end bias arrows are reversed with respect to the corresponding arrows in Figure 1 , reflecting a different mode of determining the starting line bias.

The above features are preferred but not essential and in intermediate variants any combination of one or two or three of features a) to d) could be employed. There are other minor differences including a slimmer shape with corresponding changes in the shape of sectors S 1 to S5 and also the labelling of sectors S4 as LEG 2 and LEG 3 rather than LEG 1 and LEG 2, since this embodiment is intended for use in eg a trapezoidal or Olympic type sailing course with legs 2 and 3 at 45° to 60°. In further variants, other leg labelling schemes can be employed to match any desired sailing course. However, the device can be used in the course of Figure 3 at the positions shown by arrows Yl Y5, Y3, Y4 and Y2 Y6.

It should also be noted that scale disc 2' projects laterally beyond the sides of base 1 ' to enable the latter to be gripped by the user while rotating the scale disc and its associated pointer P. This projection is exaggerated slightly in Figure 5 for the sake of clarity.

Referring to Figure 5, stub shaft 3', which like base 1 ' pointer P and scale disc 2' is suitably of eg transparent polycarbonate plastics material is provided with a regular circumferential array of four hooked spring fingers 11 which resiliently engage the underside of base 1 ' around the edge of a central aperture formed therein. A registering central aperture is formed in scale disc 2' and thereby locates scale disc 2' between pointer P and base 1 '. Mutually facing surface regions of base 1 ' and scale disc 2' and of scale disc 2' and pointer P are provided with lower and upper clickstop mechanisms CS in the form of resiliently engaging hemispherical projections and recesses as shown in the detail views. The mutual engagement of the projections and recesses of the upper clickstop mechanism CS is stronger than that of the lower clickstop mechanism, which ensures that rotation of pointer P also rotates scale disc 2', unless the latter is held by the user in which case the angular position of pointer P can be varied in relation to scale disc 2'.

The use of the device of Figures 5 and 6 to establish the start line bias will now be described with reference to Figure 7.

The wind direction W is assumed to be 140°, implying a nominal start line 10' at 50 230°. However the actual start line 10, the transit line between eg committee boats, is at 60 240° as shown, as a result of human error or a wind shift for example. This 607240° bearing is detected by the user of device by sailing to one end of start line 10 and taking the bearing on compass 50 of the other end of the start line.

The resulting 607240° reading is then transferred to scale disc 2' and compared with the 507230° bearing which is at right angles to the wind direction (previously found by the procedure of Figure 2). The 607240° bearing is displaced

anticlockwise relative to the nominal 507230° bearing, ie in the direction of the PORT END bias arrows as shown in Figure 7. Accordingly the user concludes that the start line 10 has a port end bias, ie it is advantageous to sail to the first upwind marker from the port end of start line 10.

For the sake of ease of illustration, only the PORT END bias arrows are shown in Figure 7, but it will be apparent from the above description and from Figure 5 that a STARBOARD END bias could be determined in a similar manner.

Figures 8 and 9 show the use of the device to indicate whether a gybe or a bear away set is appropriate when rounding a windward buoy Bl (ie moving between positions YA and YB). The original wind direction is assumed to be 140° in both cases but in Figure 8 the wind is assumed either to shift to a bearing of less than 140° or to remain at 140° during the turn whereas in Figure 9 the wind is assumed to veer to a bearing of greater than 140° during the turn. In the situation shown in Figure 8 the scale disc 2' is set to 140°, the original wind direction. Pointer P is also set to 140°. If there is a shift in the wind direction as shown by the dashed arrow then pointer P is moved to position P' so as to remain aligned with the wind, ie parallel to the dashed arrow-headed line in Figure 8. The tail end of the pointer then points to the BEAR AWAY portion of the base of device and accordingly, as shown by the sail positions at YA and YB in Figure 8 the boat bears away on a starboard tack. The boat also bears away on a starboard tack if the wind direction remains unchanged and pointer P remains at 140 320°.

In the situation shown in Figure 9 the scale disc 2' is again set to 140°, the original wind direction, as is pointer P. If there is a shift in the wind direction as shown by the dashed arrow then pointer P is moved to position P" so as to remain aligned with the wind. The tail end of the pointer then points to the GYBE portion of the base 1 ' of device and accordingly, as shown by the sail positions at YA and YB in Figure 9 the boat gybes as it rounds buoy B 1.

Claims

1. A wind direction indicator for indicating points of sail for a sailing boat, the indicator comprising an angular scale (2, 2') which is rotatable relative to a set of indicia (LI, L2, L3) angularly distributed about its axis of rotation, the indicia being associated with points of sail and said set of indicia defining a reference line (RL) associated with the longitudinal axis of the sailing boat, said angular scale being calibrated in the anticlockwise sense over substantially a complete revolution whereby on setting said reference line to indicate the wind bearing on said angular scale, the wind direction relative to the sailing boat corresponds to the bearing of the sailing boat on said angular scale.

2. A wind direction indicator according to claim 1 wherein said set of indicia (LI, L2, L3) is provided on a representation of a boat.

3. A wind direction indicator according to claim 1 or claim 2 wherein said set of indicia (LI, L2, L3) defines sectors (LEG 2, LEG 1; LEG 3, LEG 2) on the left and right sides of said reference line (RL) respectively which are differently coded to represent port and starboard tacks respectively.

4. A wind direction indicator according to claim 3 wherein said sectors (LEG 2, LEG 1; LEG 3, LEG 2) are differently colour coded.

5. A wind direction indicator according to any preceding claim wherein said set of indicia (LI, L2, L3) is associated with a representation (6, 6') of at least one sail configuration required for an indicated wind direction (W).

6. A wind direction indicator according to any preceding claim wherein said set of indicia (LI, L2, L3) indicates at least one leg (LEG 1, LEG 2, LEG 3) of a standard sailing course, said standard sailing course having an orientation defined with respect to the wind direction (W).

7. A wind direction indicator according to claim 6 wherein said set of indicia indicates (LI, L2, L3) at least one 60° or 45° leg of an Olympic sailing course.

8. A wind direction indicator according to claim 6 or claim 7 wherein said set of indicia (LI, L2, L3) indicating said at least one leg (LEG 1, LEG 2, LEG 3) includes a representation of at least one sail configuration required for that leg.

9. A wind direction indicator according to any preceding claim wherein said set of indicia (LI, L2, L3) defines a dead air zone (SI).

10. A wind direction indicator according to any preceding claim wherein said set of indicia (LI, L2, L3) includes a radial line (LI) orthogonal to said reference line (RL).

11. A wind direction indicator according to claim 10 wherein said set of indicia (LI, L2, L3) defines sectors (S2) located forwardly of said radial line and associated with Close Reach points of sail.

12. A wind direction indicatoraccording to claim 10 or claim 11 wherein said set of indicia (LI, L2, L3) defines sectors (S3) located rearwardly of said radial line

(LI) and associated with Broad Reach and/or Beam Reach points of sail.

13. A wind direction indicator according to any of claims 10 to 12 wherein said set of indicia (LI, L2, L3) defines a rearmost zone (S5) associated with the Run point of sail.

14. A wind direction indicator according to any of claims 10 to 12 wherein said set of indicia (LI, L2, L3) depicts a port end bias and/or depicts a starboard end bias adjacent said orthogonal radial line (LI).

15. A wind direction indicator according to any preceding claim wherein said angular scale (2, 2') is rotatably mounted on a base (1, 1 '), said set of indicia (LI, L2, L3) being provided on the base surface facing said angular scale.

16. A wind direction indicator according to any preceding claim which in use is hand-held.

17. A wind direction indicator according to any preceding claim wherein said angular scale (2, 2') is translucent or transparent and said indicia (LI, L2, L3) are viewable through it.

18. A wind direction indicator (1 , 1 ') according to any preceding claim wherein only said angular scale (2) is movable relative to said indicia.

19. A wind direction indicator according to any of claims 1 to 17 wherein a pointer (P) is rotatably mounted on a base and is movable relative to said angular scale (2').

20. A wind direction indicator according to claim 19 which includes at least one of a gybe and a bear away marking (S5) which can be indicated by said pointer (P).

21. A wind direction indicator according to claim 19 or claim 20 wherein said pointer (P) is coupled to said angular scale (2') by a click stop mechanism (CS).

22. A wind direction indicator according to claim 21 wherein said angular scale (2') is mounted on a base (1 ') and is coupled to said base by a click stop mechanism (CS) which is weaker than the click stop mechanism coupling said pointer (P) to said angular scale (2') whereby rotation of said pointer rotates said angular scale (2') relative to said base unless said angular scale is held in a fixed position while rotating said pointer.

23. A wind direction indicator according to any of claims 1 to 14 which comprises an electronic display (SC) arranged to display said angular scale and/or said set of indicia and to rotate said angular scale relative to said set of indicia in response to an input signal.

24. A wind direction indicator according to claim 23 comprising data entry means (K) for enabling a user to generate said input signal.

25. A wind direction indicator according to claim 23 or claim 24 which is a hand- held mobile device.

26. A computer program product for operating the wind direction indicator of any of claims 23 to 25, said computer program product comprising a computer readable medium embodying program code means executable by a microprocessor to display said angular scale and/or said set of indicia and to rotate said angular scale (2, 2') relative to said set of indicia in response to an input signal.

27. A method of sailing a sailing course wherein the angular scale (2, 2') of a wind direction indicator as claimed in any of claims 1 to 25 is set to indicate the wind direction and points of sail at different stages of the sailing course are read off from the wind direction indicator.

28. A method according to claim 27 wherein the bias of a starting line (10) of the sailing course is determined using said wind direction indicator.