AU568821B2 - Tactical dinghy compass - Google Patents

Description

"TACTICAL DINGHY COMPASS" TECHNICAL FIELD This invention relates to an easy to read compass and a method of navigating a sailing dinghy. BACKGROUND ART

The crew of a sailing dinghy normally have considerable difficulty in reading a tactical compass while sailing. This is because the compass is generally mounted centrally within the dinghy yet the crew are on the side of the dinghy and leaning outwardly, or may be suspended by a trapeze, to balance the dinghy and prevent it from capsizing. Under these circumstances a traditional compass marked with numbers or letters or both is extremely difficult, if not impossible, to read. The crew of a sailing dinghy often must be preoccupied with positioning themselves so as to keep the dinghy upright so that a centrally mounted compass is simply visibly inaccessible. Even if the compass is mounted on the gunwhales of the dinghy, an outwardly leaning crew may not be able to read the numbers or letters on a compass card. These problems are particularly acute in single handed sailing craft such as Laser class dinghys or sail boards where the single crew has both his hands occupied in controlling the sheets and tiller and is often required to position himself well away from a compass.

Further, certain calculations require to be made during a sailing race, using a traditional compass. For example, determining the favoured end of the starting line, detecting wind shifts and calculating headings to the marks all require that the crew exercise mental arithmetic skills. The physical demands of dinghy sailing are such that it is extremely difficult to exercise the arithmetic skills needed to make these calculations. Again, these problems are particularly acute for single handed sailors in for example Laser class dinghys or sail boards.

Compasses having marked tacking angles on adjustable peripheral bezels have been used, however they still require the user to remember numbers and discern whether the numbers are increasing or decreasing as the compass swings, thus allowing the user to know if he is "lifting" or "knocking" on a particular tack.

DISCLOSURE OF THE INVENTION This invention provides a compass which allows for ease of reading in a sailing dinghy and which also obviates the need for mental arithmetic in making the necessary calculations during a sailing race.

The invention provides a compass comprising a moveable compass card, said compass card being marked into quadrants, each quadrant being subdivided into a plurality of differently coloured equal sectors comprising a colour sequence said sequence being repeated in each quadrant.

The preferred method of reading the compass card is from above but this does not exclude any arrangement whereby the compass card can be read on edge or from below.

It is also preferred that the coloured sectors are marked at 10 degree intervals in an annulus around the circumference of the compass card. Preferably the quadrants on the compass card are differently coloured and located separately from the coloured sectors in another annulus closer to the centre of the compass card.

It is also preferred that a plurality of coloured lubber lines are marked on the compass for ease of reading.

BRIEF DESCRIPTION OF DRAWINGS By way of example only, the invention is described below with reference to the accompanying drawings wherein: Figure 1 is a schematic representation of a compass according to the present invention; and

Figure 2 is a schematic representation of a method of navigating an Olympic course using the present invention. MODES FOR CARRYING OUT THE INVENTION Figure 1 shows a compass (10) compass card (11) mounted pivotally about substantially its centre point (12) in a non-magnetic housing (13) whereon a plurality of lubber lines (14) (15)(16) (17) (18) are marked. The compass (10) is mounted in a sailing craft with the lubber line (14), the "keel line" substantially parallel to the centreline of the sailing craft. The outer annulus (19) is divided into a plurality of coloured equal sectors. The colour sequence (21) within a quadrant is repeated in each of the quadrants. The inner annulus (22) is divided into four coloured quadrants (23).

Between the inner annulus (22) and the outer annulus (19) a middle annulus (24) is marked with the four cardinal points and a plurality of equally spaced bearings in degrees. The colour sequence (21) is designed to maximise the contrast between adjacent colours. Although the sequence exampled here achieves this purpose any suitable sequence may be used.

The colours of the quadrants (23) are also chosen for maximum contrast between adjacent quadrants.

Figure 2 shows a method of using the invention in navigating an Olympic course.

The boat is firstly pointed into the wind (25) and the crew note the colour of the sector (26) which is adjacent to the lubber line (14).

In order to determine the bias of the starting line, the boat is sailed along the starting line (27). If the starting line is square to the wind the colour (26) will be adjacent to the lubber lines (14) and (16) or (17). If the starting line is not square^" to the wind direction the favoured end is determined when the colour (26) is aft of the lubber lines (16) or (17).

When the boat is sailing into the wind it will tack through approximately 90°, each tack bearing approximately 45° off the mean wind direction. Therefore on a standard tack (28) the colour (26) will lie adjacent to either the lubber line (15), on a starboard tack, or lubber line (18) on a port tack.

A favourable wind shift on a tack (29) is indicated when the colour (26) moves aft of the lubber line (15) on a starboard tack, or the lubber line (18) on a port tack.

An unfavourable wind shift on a tack (29A) is indicated when the colour (26) moves forward of the lubber line (15) on a starboard tack, or the lubber line (18) on a port tack. The choice of contrasting colours in the annulus (19) enables these wind shifts to be easily detected.

On the starboard reaching leg (30), the wing mark (32) is found by bearing away 90° from the starboard tack on a port hand around course as the boat rounds the windward mark (31) to bring the colour (26) in the next quadrant adjacent to lubber line (18). The choice of contrasting colours in the annulus (22) enables unambiguous associations of colour and quadrant to be quickly made by the crew.

On the port reaching leg (33) in a port hand around course, the start mark (34) is found by gybing the boat through 90° as it rounds the wing mark (32) to bring the colour (26) in the next quadrant adjacent to the lubber line (15).

Finally to set the course for the square run (35) back to the start mark (34), the colour (26) is brought adjacent to the lubber line (14).

On the downward legs to determine the "lifted" and "knocked" leg, for tacking downwind, the colour system may be used equally to advantage.

By using this method the crew can navigate an Olympic sailing course without carrying out any arithmetic tasks. Navigation is performed simply by reference to a single colour relative to the appropriate lubber lines for the various legs.

Claims (5)

1. A compass comprising a moveable compass card, said compass card being marked into quadrants, each quadrant being subdivided into a plurality of differently coloured equal sectors comprising a colour sequence, said sequence being repeated in each quadrant.

2. The compass as defined in claim 1 wherein said quadrants are differently coloured and located on the said compass card separately from the said coloured sectors.

3. The compass as defined in claim 1 wherein said sectors are at 10 degree intervals.

4. The compass substantially as herein described with reference to the drawings.

5. A method of navigating a sailing dinghy substantially as herein described with reference to the drawings.