GB2166547A - Collision avoidance by sailing vessels - Google Patents

Abstract

In order to identify which, of two sailing vessels approaching each other, is required to take action to keep clear in compliance with the International Regulations. Each of the two vessels is allocated a precedence rating determined by its point of sailing and its course relative to the other. The vessel with the inferior precedence rating is required to keep clear. <IMAGE>

Description

SPECIFICATION Collision avoidance by sailing vessels The invention relates to the avoidance of collisions between sailing vessels.

The International Regulations for Preventing Collisions at Sea, which have been in force since 15th July 1977, provide, inter alia, a set of rules which require that, when two sailing vessels are approaching each other so as to involve the risk of collision, one shall take action to keep clear and the other shall hold its course and speed.

The above rules further require that the action to keep clear shall be positive and made in ample time.

The relevant rules in the above International Regulations, hereinafter referred to simply as "the Regulations", prescribe that the vessel which is required to take action to keep clear shall be identified, in each potential collision situation, by reference to the points of sailing of the respective vessels or by their positions relative to each other.

It is known to provide diagrams in which the relative positions of a number of sailing vessels are represented together with their respective headings relative to an arrow representing the direction of the wind. Such diagrams are usually accompanied by notes which show which, of any pair of the vessels represented, is required to keep clear of the other in order to comply with the Regulations.

Diagrams of the above kind are appropriate for use ashore, for example, for initial training purposes. However, for more advanced training or, more particularly, for practical use at sea, such diagrams can be difficult to interpret correctly and, in some circumstances, do not enable a person in charge of a sailing vessel or an advanced student ashore to quickly determine the action required of him in compliance with the Regulations.

The object of the present invention is to overcome these disadvantages by providing a method and apparatus to enable an observer, for example, the helmsman of a sailing vessel approaching another sailing vessel so as to involve the risk of collision or a student ashore or afloat confronted with an imaginary or real potential collision situation to determine quickly and positively without the need to commit the regulations to memory, whether he is required to take action to keep clear or to hold his course and speed in order to comply with the Regulations.

It will readily be apparent that, when two vessels are approaching each other so as to involve the risk of collision, their respective directions of travel or, more correctly the courses made good (hereinafter referred to simply as their courses) will meet at a point.

For the purpose of the descriptions which follow, a convention will be adopted wherein the angle between the courses of two such vessels varies between 0 deg. and 360 deg. and has a value of 180 deg. when the vessels are approaching each other head on.

The present invention provides a method of determining which of two sailing vessels approaching each other so as to involve the risk of collision is required, in compliance with the Regulations described hereinabove, to keep out of the way of the other characterized in that, as a first step, the point of sailing of each vessel and the angle between their respective courses are determined from which, as a second step, each vessel is allocated a "precedence rating" and, as a third step, the precedence ratings are compared whereupon the vessel with the inferior precedence rating is identified as the vessel which is required to take action to keep clear while the vessel with the superior precedence rating is required to hold its course and speed.In accordance with the method of the invention: (a) when the angle between the respective courses of the two vessels is between 67.5 deg. and 292.5 deg. the precedence ratings are allocated as follows: (i) when each vessel has the wind on a different side, the vessel which has the wind on the port side is given the inferior precedence rating.

(ii) when each vessel has the wind on the same side, the vessel which is to windward is given the inferior precedence rating.

but, (b) when the angle between the courses of the two vessels is less than 67.5 deg. or more than 292.5 deg. the vessel which is overtaking is given the inferior precedence rating.

The invention provides apparatus for putting the method described above into practical effect.

In accordance with the present invention the apparatus comprises means for representing and storing the point of sailing of each vessel and the angle between the courses of the two vessels and further means which, when this angle lies between 67.5 deg. and 292.5 deg., determine and indicate to the user the precedence ratings of each vessel in accordance with item (a) of the method described above but, when the angle between the courses of the two vessels is less than 67.5 deg. or more than 292.5 deg. includes means for warning the user that an overtaking situation exists.

In preferred embodiments of the invention, the apparatus includes means for comparing the values of the precedence ratings and for indicating to the user which vessel has been allocated the superior rating and/or which vessel has been allocated the inferior rating.

Preferably, the precedence ratings provided by the invention will be expressed in terms of numbers, symbols or measurements which constitute one or more series having ascending values and, when more than one series is used, each of the numbers, symbols or measurements within the first series has a value which is superior to each of those in the second which in turn is superior to each of those in the third and so on.

The respective precedence ratings are preferably represented by any convenient feature or characteristic within the apparatus which can be read, interpreted or measured either directly by the user or by appropriate means preferably within the apparatus so that the superior and/or inferior rating can be readily identified.

Such features or characteristics include, for example, numbered scales or other indicia, or angular or linear distances defined by a boundary, a shaded area, an asperity or recess in or on a part of the apparatus; electical voltages or currents, magnetic fields and any such variable parameters as will readily occur to those skilled in the art.

The invention will now be described in greater detail by reference to the drawings attached hereto. In these; Fig. I is a plan view of an area of water in which a vessel is sailing.

Fig. II is a plan view of one form of apparatus provided by the invention.

Fig. III (a) is a exploded view of another form of apparatus provided by the invention.

Fig. III (b) is a plan view of the apparatus of Fig. 111(a).

Fig. IV is a schematic diagram of yet another form of apparatus provided by the invention.

The manner in which the precedence ratings for a particular vessel are determined in accordance with the invention will now be described by reference to Fig. I in which the vessel, 1, which is to be rated is encircled by a number of arrows such as 2 which, collectively, represent many different directions in which the wind may blow relative to vessel 1.

The precedence ratings in this particular example are denoted by letters of the alphabet and a convention has been adopted wherein the highest precedence rating is denoted by the letter A and succeeding letters of the alphabet denote progressively diminishing precedence ratings.

Thus, wind in the direction of the arrow marked with precedence rating "A" is such as to put vessel, 1, on a close-hauled starboard tack whereas the wind direction arrow labelled "K" is such as to put vessel, 1, on a port run. It will be seen that their alphabetical precedence ratings conform with the highest and lowest ratings prescribed by the method of the invention and noted in item a (i) above.

Intermediate letters provide precedence ratings for the vessel on intermediate points of sailing.

In Fig, I, no wind arrows have been provided in the. positions marked with broken lines. Neither of these wind directions is of any practical significance in interpreting the regulations and the precedence rating for these positions (dotted "F") is not required. One embodiment of apparatus provided by the invention will now be described by reference to Fig. Il.

In Fig. ll, three meshing gear wheels 21, 22 and 23 are rotatably mounted on spindles 24, 25 and 26 which pins are rigidly attached to base 27. The two larger gears 21 and 22 are each inscribed with scales 28 and 29 which, in this particular example incorporate numerical precedence ratings. These two gears are each inscribed with an arrow and they mesh together so that the two arrows lie in the same angular positions. In use, the two arrows are used to represent the direction of the wind relative to the user's vessel and the numerical precedence ratings inscribed or the gear wheels reflect the same orders of precedence as already described with reference to Fig. I.

A fixed bridge piece, 30, lies over pin 24 and is secured at each end to base 27 by screws (not shown). A second bridge piece, 33, is rotatably mounted over spindle 26.

The bridge pieces are each inscribed with emblems 31 and 34 to represent the hull of a boat in plan view. The bridge pieces each contain apertures 32 and 35.

Preferably, the apparatus is permanently fixed by base 27 aboard the user's vessel in a position close to the helmsman and is arranged so that the boat-shaped emblem 31 represents the heading of the user's vessel.

More correctly but usually without any practical effect, the emblem 31 should be aligned to correspond with the course of the vessel made good which may, as a result of the combined effects of leeway and tide, be different from the ship's heading.

In use, the gear 21 is rotated until the inscribed arrow thereon lies in the same direction relative to emblem 31 as the wind lies relative to the user's vessel.

When another sailing vessel approaches the user's vessel so as to involve the risk of collision, the user rotates bridge piece 33 so that emblem 34 represents the course of the approaching vessel.

The precedence ratings of the user's and the approaching vessel are now visible, respectively, through apertures 32 and 35. The precedence ratings in this particular example are 6 and 12 respectively. Thus, the precedence rating of the user's vessel is inferior to that of the approaching vessel from which the user can conclude that he is required, by the Regulations, to take action to keep clear.

The simple embodiment described above is purely by way of example. Many alternative forms of construction and many detailed refinements such as will readily occur to those skilled in the art are provided by the invention.

For example, gears 21 and 22 may be rotably connected to each other by a belt and the intermediate gear 23 may be omitted. Alternatively, a spring loaded pawl may be provided to engage the teeth of gear 21 or 22 and arranged to ensure that a precedence rating is always centralized within apertures 32 and 35 and to prevent the setting of the apparatus from being accidently disturbed. The user of the apparatus illustrated in Fig. II is required to remember that, when one of the vessels is overtaking the other by coming up at an angle greater than 22.5 deg. abaft the beam of the other the precedence ratings assigned by the apparatus must be ignored and the overtaking vessel is invariably required, to comply with the Regulations, to take action to keep clear.

To remind the user, an opague plate formed into a sector with an included angle of about 135 deg. (shown dotted in Fig. II) may be interposed between gear 22 and bridge 33 so that the precedence rating of the approaching vessel is obscured when one of the vessels is overtaking the other.

In.a preferred embodiment of the invention means are provided to ensure that the user cannot obtain a precedence rating for either vessel in the above circumstances as will now be described by reference to Figs. III (a) and (b).

In Figs. lil (a) and (b), a rigid plate, 40 supports a pin or screw 41. The pin 41 passes through three separate components as follows; 42, a disc preferably formed from a transparent material such as glass, PVC or polyester engraved or otherwise marked with a suitable emblem 46 and inscribed circle 52 to denote the course of an approaching vessel and labelled to this effect; for example, with the words "other boat". Preferably disc 42 incorporates an opaque sector of a ring 51 shown shaded in the Fig. 111(a). This lies on the same pitch circle as the circles 52 within emblem 46 and subtends the same angle as the sector-shaped component 43 described below.

43, a generally sector-shaped component formed from a thin sheet of opaque and preferably coloured material such as metal, wood or plastics such as PVC or polyester which is inscribed with a boat-shaped emblem 47 to denote the course of the user's boat and which contains an aperture 48 lying at the same radial distance from the centre of pin 41 as the circle 46. Preferably, the two straight edges of component 43 correspond with radii of a circle whose centre lies on the axis of pin 41 and the angle they subtend is less than 135 deg., preferably 135 deg. less the angle subtended by the emblem 46.

45, a thin disc formed, for example from transparent material such as glass or plastics, PVC or polyester. Disc 45 is engraved or inscribed with an arrowhead or other suitable emblem 50 to represent the direction of the wind in the area in which the two vessels are sailing. Disc 45 is also inscribed with precedence ratings which, in this particular example are in the form of numbers at intervals of 22.5 deg. lying on the same pitch radius as aperture 48 and circle 52. The numbers form two series. One series, containing the numbers 9 to 15 inclusive is disposed relative to arrowhead 50 so as to represent the precedence ratings of a vessel on a starboard tack.

The other series, containing the numbers 1 to 7 inclusive so disposed as to represent the precedence ratings of a vessel on a port tack all as previously described hereinabove by reference to Fig. I.

Preferably, pin 41 is shouldered and may be threaded or rivetted into base 40 such that, after fixing pin 41, the components 42 and 45 are free to rotate. Preferably resilient spacing washers, not shown, are disposed between components 42, 43 and 45 so that the rotating elements are not scratched in use and, after they have been moved into a particular position are retained by friction.

The sector-shaped element 43 is prevented from rotating by pin 49. The base 40 is inscribed with marks 53 spaced at 22.5 deg.

and lying on such a radius as to lie just within the periphery of disc 42 but outside the precedence ratings on disc 45.

The above apparatus is preferably carried aboard the user's vessel and should be handheld or fixed so that the emblem 47 represents the course of the user's vessel as discussed in connection with the embodiment of Fig. II. In this particular embodiment, when the angle between the course of the two vessels is less than 67.5 deg. or more than 292.5 deg. the opaque section 51 on disc 42 and the opaque component 43 obscure aperture 48 and circle 52. In these circumstances, no precedence ratings will be shown. It will readily be apparent that in these circumstances one of the vessels is "the overtaking vessel" as defined hereinabove and is required by the Regulations to take action to keep clear.

Which vessel is overtaking will readily be apparent to the user in any practical situation and he can therefore decide what action is required of him. As a reminder, the sector shaped element may usefully be inscribed with words such as "Beware! Overtaking boat keeps clear," (not shown on the drawings).

In apparatus of the above kind, the number of individual priority ratings which can conveniently be accommodated will be limited by the diameter of disc 45. In compact apparatus, the number may conveniently lie on any pitch circle diameter between 50 and 100 mms. In the apparatus of Figs. Ill(a) and (b), the above pitch circle diameter (not to scale) is 58 mms and precedence ratings appear at angular intervals of 22.5 deg. In smaller apparatus, these angular intervals may be increased to 30 deg., while, for apparatus in which the diameter of disc 45 is more than 58 mms, the angular intervals may be reduced, for example, to 18 deg.

Preferably, a precedence rating will be omitted from the angular position which corresponds to a situation in which the wind is directly behind either of the two vessels. Similarly, a precedence rating will preferably be omitted from the angular position which corresponds to a situation in which the wind is directly on the bow of one of the vessels. In these locations, instead of a precedence rating the words "not applicable" or an appropriate abbreviation may conveniently be inscribed on disc 45.

As already discussed, any convenient parameter or feature may be used to represent the precedence ratings provided by the method of the invention. For example, in Figs. lil (a) and (b), the numerical precedence ratings may be replaced by shaded or coloured areas on disc 45 whose boundaries lie at different radial distances from the centre of pin 41 which different radial distances represent different precedence ratings. In such embodiments of the apparatus of the invention, the two radial distances representing the precedence ratings of two vessels may conveniently be compared by reference to a series of concentric circles inscribed, for example on base 40 of the apparatus. Many other variations of detail may be incorporated into the apparatus of Fig lil (a) and (b) without departing from the provisions of the invention.

Finally, the invention provides apparatus for the same purpose but with many different constructions to those already described. For example, referring to the schematic drawing of Fig. IV, the precedence ratings may be represented by the varying voltages on two generally semi-circular resistance elements 60 and 61 interconnected by resistance 62 and supplied via resistance 73 from a source of current 63 earthed as shown. In apparatus of this kind, the resistance elements 60 and 61 are carried on an insulating disc 64 which is free to rotate on a metal pin 65 fixed to an insulating base 66. To leave the disc 64 free to rotate, the electrical connections are made by slip rings or pigtails 75 and 76 or any other suitable means. Two sliding contacts make electrical connection to elements 60 and 61.One such contact, 67, is fixed to base 66 and connected to terminal 68 and thence to terminal 74. The second contact, 69, is carried on a metal arm 70 supported by but free to rotate about pin 65.

From descriptions of other embodiments of the invention it will readily be apparent that, if the apparatus of, Fig. IV is mounted on the user's vessel so that the centre line 71 corresponds with the course of the user's vessel and the disc 64 is rotated so that arrow 72 represents the direction of the wind and movable arm 70 is moved to represent the course of the approaching vessel, then the voltages between pin 65 and earth and between terminal 74 and earth represent the precedence ratings of the approaching and the user's vessels respectively.

These two voltages and the precedence ratings may be indicated to the user by any one of a number of different means not shown, for the sake of clarity, in Fig. IV. For example, each of the voltages may be applied to a voltmeter. Alternatively, the two voltages may be applied to a centre-zero voltmeter whose reading will indicate the difference between the two voltages and the direction of swing of the voltmeter can be made to indicate directly to the user which vessel has the superior precedence rating.

In other embodiments, the two voltages may be compared and the results indicated to the user by electronic rather than simple electrical means as described above. Appropriate diode arrays or bridge networks capable of supplying indicator lamps will readily occur to those skilled in the art. Two lamps may, for example, be used and connected so that, when the user's vessel has a superior precedence rating a green lamp is illuminated and when the above rating is inferior, a red lamp is illuminated.

The present invention includes all such methods of indicating the precedence ratings or the comparision thereof.

The invention also provides means for warning the user when the angle between the courses of the two vessels is less than 67.5 deg. or more than 292.5 deg. i.e., when one of the vessels is, as defined by the Regulations, overtaking the other.

By way of example, one such means is illustrated in Fig. IV wherein extension 77 is fitted to contact 69 and when the angle between the courses of the vessels corresponds to an overtaking situation, makes contact with a conducting sector of a ring 78 so that the two voltages (i.e., precedence ratings) are equal. In such embodiments, the trimming resistance 73 may usefully be placed in series with a current limiting device.

Other means may be provided to warn of an overtaking situation. For example, an additional contact mounted on arm 70 but insulated therefrom may be used to collect voltage from a strip similar to 78 and apply it to an amber-coloured warning lamp.

Many other means of warning the user will readily occur to those skilled in the art and are included in the present invention.

The invention, as already noted, also includes other embodiments in which the precedence ratings, are represented by means which have not been described hereinabove.

For example, magnetic fields, measured by flux-sensitive devices such as Hall Effect probes, or represented by displacement transducers whose output is measured by voltmeters or ammeters.

Claims (7)

1. A method of determining which of two sailing vessels approaching each other so as to involve the risk of collision is required, in order to comply with the Regulations hereinabove described, to keep out of the way of the other characterized in that, as a first step, the point of sailing of each vessel and the angle between their respective courses is determined from which, as a second step, each vessel is allocated a precedence rating and, as a third step, the precedence ratings are compared whereupon the vessel with the inferior precedence rating is identified as the vessel which is required to take action to keep clear while the vessel with the superior precedence rating is required to hold its course and speed.

2. A method as claimed in claim I in which; (a) when the angle between the respective courses of the two vessels is between 67.5 deg. and 292.5 deg., the precedence ratings are allocated as follows: (i) when each has the wind on a different side, the vessel which has the wind on the port side is given the inferior precedence rating, (ii) when each has the wind on the same side, the vessel which is to windward is given the inferior precedence rating.

but (b) when the angle between the courses of the two vessels is less than 67.5 deg. or more than 292.5 deg. the vessel which is overtaking is given the inferior precedence rating.

3. Apparatus for determining which of two sailing vessels approaching each other so as to involve the risk of collision is required, in order to comply with the Regulations described hereinabove, to keep out of the way of the other characterized in that the apparatus includes means for representing and storing the point of sailing of each vessel and the angle between their respective courses and, when this angle is between 67.5 deg. and 292.5 deg, means for determining and indicating to the user the precedence rating of each vessel in accordance with the method claimed in claim 2 and, when the above angle is less than 67.5 deg. or more than 292.5 deg.

means for warning the user that an overtaking situation exists.

4. Apparatus as claimed in claim 3 wherein when the angle between the courses of the two vessels is between 67.5 deg. and 292.5 deg. means are provided for comparing the two precedence ratings and indicating to the user which vessel has been allocated the superior rating and/or which vessel has been allocated the inferior rating.

5. Apparatus as claimed in claims 3 and 4 in which the precedence ratings are expressed in terms of numbers, symbols or measurements which constitute one or more series having ascending values and, when more than one series is used, all the numbers, symbols or measurements within the first series have values which are superior to all of those in the second which, in turn, are superior to all of those in the third and so on.

6. Apparatus constructed substantially as hereinabove described with reference to and as illustrated in the accompanying figure II or figures lil (a) and (b).

7. Apparatus constructed substantially as hereinabove described with reference to and as illustrated in the accompanying figure IV.