WO1992012431A1

WO1992012431A1 - Impending gybe detector and indicator

Info

Publication number: WO1992012431A1
Application number: PCT/GB1992/000033
Authority: WO
Inventors: Iain Bruce Webber
Original assignee: Iain Bruce Webber
Priority date: 1991-01-09
Filing date: 1992-01-08
Publication date: 1992-07-23
Also published as: EP0563242A1; GB9100395D0

Abstract

A self-contained or wire connected wind angle indicator which is mounted on or in a mainsail boom of a sailing vessel and detects the wind angle relative to the boom, with a view to alerting the crew as to the fact that the boom is getting close to the point of gybe, and someone had better do something about it, or at least be prepared for it. Alternatively, the indicator can alert by means of a remotely mounted alarm system, or even control the vessel by means of instructing the autopilot to turn away from the possibility of an accidental or uncontrolled gybe.

Description

IMPENDING GYBE DETECTOR AND INDICATOR

This invention relates to a detector and indicator of an im¬ pending gybe, for sailing vessels.

Sailing vessels with the mainsail supported by a boom have to sometimes turn through the wind. If the turn is executed with the vessel^'s bow passing through the wind, this is known as a TACK. If the turn is executed with the vessel^'s stern passing through the wind, this is known as a GYBE. During a tack, the boomed mainsail will point away from the wind and moves from side to side at the speed of the vessel^'s turn. During a gybe however, the boomed mainsail will point towards the wind and, at the moment when the wind passes the centreline of the boom, will begin to generate full power immediately on the opposite side of the mainsail. The result of this is that the boom will swing from one side of the vessel to the other with a lot of force. If this swing is correctly anticipated and controlled, this is known as a CONTROLLED GYBE. If however, this swing is not anticipated and controlled, it is known as an UNCONTROLLED GYBE. The consequences of an uncontrolled gybe can and have been, failure of the vessel^'s rigging, including the mast, injury, (either directly from contact with the boom, or being knocked overboard), or death, (from the same causes). One way to prevent an accidental gybe is to rig a line from the outer end of the boom leading forward to the bow of the vessel. This line, commonly called a ^'preventer^', is made taught and physically prevents the boom from swinging back¬ wards. The disadvantage with this method is that it is not easy to rig, has to be released for a controlled gybe and re- rigged on the other side, and in severe weather conditions, can itself cause equipment damage, should the boom-end be immersed in the water when the vessel rolls.

According to the present invention, there is provided an early warning detector and indicator of an impending gybe comprising an outer container on which is mounted an electrical or me¬ chanical means of detecting the wind angle relative to the boom and an electrical or mechanical means of indicating the detected wind angle, inside which is an electrical or mechani¬ cal means for converting the detected wind angle into a means of indication of the detected wind angle, and upon which is the means for releaseably securing it to the mainsail boom of a sailing vessel.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:-

Figure 1 shows in orthographic projection the wiπdvane con-' trolled impending gybe detector and indicator. Figure 2 shows in orthographic projection the windflap con¬ trolled impending gybe detector and indicator. Figure 3 shows in orthographic projection the windflow con¬ trolled impending gybe detector and indicator. Figure 4 shows in orthographic projection the wind pressure controlled impending gybe detector and indicator.

SUBSTITUTESHEET Referring to the drawing on figure 1, the detector comprises container (1); in this case it is box shaped. The container is mounted on the underside of the boom of a sailing vessel. It may be mounted anywhere along the boom, as the wind angles are the same throughout the length of the boom. The container is held to the boom by, for example, two ^'Velcro^' straps, at¬ tached to similar ^'Velcro^' strips which have been pre-stuck to the boom with adhesive. Through the underside of the container is mounted a windvane (2) . The windvane is free to rotate through 360 degrees. The angle of the windvane converted into an electrical signal by means of the electrical circuitry inside the container. This circuitry can be arranged so as to switch on or off a means of indication (3) when the vane prescribes an arc within a settable limit, either side of the centre line of the boom. This means of indication can either be (a) audible, using a sounder, or (b) visual, using a lamp or beacon. Alternatively, the means of indication could be remote from the unit, and mounted in a position of choice. This would neccesitate fitting a cable between the container and the vessel, which could have the inherent advantage that the entire unit could be powered from the vessel^'s own supply, thus obviating the need for batteries. Conversely, this would rob the unit of some of it^'s total ^'portability^'. Another simple electrical circuit could convert the wind angles from the windvane into a digital signal; (there is currently a standard digital ^'language^' for the maritime industry, called NMEA 0183). Using a cable, as previously mentioned, this digital signal may be interfaced with a cen¬ tralised alarm system on the vessel, and/or interfaced direct¬ ly with an automatic pilot whereby the automatic pilot may, on receiving the appropriate signal, be instructed to turn the vessel, (and by implication, the boom), in such a direction as to obviate the possibility of a gybe; i.e. away from the wind.

SUBSTITUTESHEET

Referring to the drawing on figure 2 the detector comprises a container (1); in this case it is in the shape of a ^'date bo ' . The container is mounted as described on page 2. On the rear quarters of this container are mounted a pair of ^'wind flaps^', (2) each free to pivot about a fulcrum. Each wind flap has a restricted angle of movement; in this case between 30 and 40 degrees to the centreline of the vessel^'s boom. Each wind flap is in effect a miniature boom with it^'s own ^'mainsail'. One wind flap has it^'s ^'sail^' mounted above it^'s boom, while the other wind flap has it^'s ^'sail^' mounted below it^'s boom. At the other side of the fulcrum, each wind flap boom is allowed to move between the stop at the outer end of it^'s travel, and operating a switch at the inner end of it^'s travel; i.e the switch is operated when the flap is outermost.

In operation, when the vessel is heading into wind, both flaps are pushed back by the wind pressure and both switches are off. As the vessel turns through the wind, the wind will eventually get to a point where it is pushing the nearest flap back, but pushing the farthest flap forward. The electrical circuitry is arranged so as to only operate a means of indica¬ tion (3) when both switches are operated, so that means of indication will not in this instance be activated. As the vessel^'s boom passes the angle that the flap is set to, (in this case, as mentioned, 30 degrees), the flap itself ^'gybes^', and switches on it^'s switch. Now both flaps are held open at 40 degrees by the wind pressure, both switches are on, and the means of indication is activated. This condition will persist until the vessel^'s boom moves 40 degrees either side of the direction of the wind, when the wind will then cause the appropriate flap again to ^'gybe^' , turn off it^'s switch, and consequently the means of indication. If a digital signal is required, it would be a simple matter to detect which of the two switches were operated first, thereby arriving at the correct conclusion as to which side of the wind the boom came from, and which way to steer in order to take preventative action.

SUBSTITUTE SHEET

Referring to the drawing on figure 3 the detector comprises a container (1); in this case it is cylindrical in shape. The container is mounted as described on page 2. Inside the container is a tube (2) which enters the container at a point, (point A), on the periphery of the container, and exits the container at the middle of the bottom surface, (point B). Inside the tube is fitted electronic equipment (3) capable of sensitively measuring the direction of low of air through the tube. The container is mounted in such a way that point A of the cylinder faces the rear of the boom. Below point A is fitted the means of indication (4), and inside the container is contained all the necessary electrical circuitry to convert the detected wind direction in the tube (2) into energizing the means of indication ( ).

In operation, when the vessel is heading into wind, there will be a natural negative pressure in the area just behind the container. The air flowing across point B is to all intents and purposes neutral in pressure; therefore point B will be at a higher pressure than point A and there will be a slight movement of air through the tube (2) from point B to point A. The airflow direction detection circuitry (3) is designed not to energize the means of indication (4) when the airflow in the tube is in this direction. As the vessel turns through the wind, the boom, together with the container, will be subject to a changing angle of relative airflow. When this angle of airflow reaches a point which occurs naturally roughly at an angle of about 40 degrees around the periphery of the contain¬ er from point A, the natural negative pressure around point A will turn positive. Point A will now be at a higher pressure than point B and there will now be a slight movement of air through the tube (2) from point A to point B. The airflow detection circuitry (3) is designed to energize the means of indication (4) with the airflow in the tube (2) in this direc¬ tion. This condition will persist until the boom of the vessel is turned away from the wind by an angle of about 40 degrees to the centreline, at which point the air pressure around point A will turn negative, reverse the airflow in the tube (2), and switch off the means of indication(4) .

SUBSTITUTESHEET Referring to the drawing on figure 4 the detector comprises a container (1) ; in this case it is cylindrical in shape. The container is mounted as described on page 2. Inside the container is contained a pressure sensor (2) . On the outside of the container is fitted the means of indication (3).

In operation this device works in almost exactly the same way as the device described in page 4; the difference being that whereas that device is operated by air flow through a tube, which itself is a result natural air pressure distribution around a cylinder, the device described on this page is oper¬ ated by the pressure sensor as a direct result of the natural air pressure distribution around the cylinder.

SUBSTITUTESHEET

Claims

1- A detector and indicator of an impending gybe comprising a container mounted on or in the boom or any other part of a sailing vessel, means for releaseably securing the container to the boom or any other part of the vessel, the container having mounted on it or in it an electrical or mechanical means of detecting the wind angle relative to the boom or to the vessel, or an electrical or mechanical means of indicating the wind angle relative to the boom or to the vessel, or an electrical or mechanical means of both detect¬ ing and indicating the wind angle relative to the boom or to the vessel, the container having on it or inside it an electrical or mechanical means of converting the detected wind angle into an electrical or mechanical signal in order to generate an indication of the detected wind angle. - A detector and indicator as claimed in claim 1 wherein the electrical circuit is powered by one or more batteries. - A detector and indicator as claimed in claim 1 wherein the electrical circuit is powered by one or more solar cells. - A detector and indicator as claimed in claim 1 wherein an electrical cable connects the indicator to an external power supply in order to supply power to the circuit. - A detector and indicator as claimed in claim 1 wherein the electrical circuit is powered by the wind. - A detector and indicator as claimed in claim 1 wherein the electrical circuit is powered by any combination of the means stated in claims 2, 3, 4 and 5. - A detector and indicator as claimed in any preceding claim wherein the electrical cable may also be used to transfer an electrical signal to or from the indicator. - A detector and indicator as claimed in any preceding claim where a light beam may be used in order to transfer a signal to or from the indicator. - A detector and indicator as claimed in any preceding claim where a sound beam may be used in order to transfer a signal to or from the indicator 0- A detector and indicator of an impending gybe substantially as described herein with reference to figures 1, 2 , 3 and 4 of the accompanying drawings.

TE SHEET