GB2170609A - Navigational triangle calculator - Google Patents

Abstract

A navigational calculator has a base scale marked radially representing angles and concentrically representing distance and speed. It has a central slot along a radial. The calculator has a transparent azimuth disc and transparent cursor with bearing and distance markings respectively. The markings on the cursor are to the same scale as the base scale. Both disc and cursor are free to rotate about a common central pivot. The pivot is fitted into the slot in the base scale so that the azimuth disc and cursor are free to slide along its length. The setting of the sliding azimuth disc and cursor to known navigational variables allows angular, distance, and speed information to be obtained from the base scale.

Description

SPECIFICATION Navigational triangle calculator The calculator allows the rapid solution of the triangle of velocities in navigation, which is otherwise achieved by plotting on a chart or paper, or by extensive trigonometry.

It is made of sheet material three parts; a base sheet with a scale graduated in degrees from 0-90 axially from its centre line on both sides and marked radially to represent distance/speed; a transparent disc marked as a bearing ring, and a cursor marked to the same scale as the distance/speed markings on the base sheet.

The disc and cursor are free to rotate about a central eyelet and this eyelet is fitted through a slot along the centre lines of the base sheet. Through this construction the cursor and disc parts are able to slide along the length of the base sheet scale. This allows vector triangles to be represented graphically.

Navigational data can therefore be used to set the calculator to account for the effects of tide or wind on craft motion. Directional and distance/speed information can then be obtained from the scales.

For example: To find the course to steer and the distance/speed which will be made good allowing for a particular tidal vector.

A/ Rotate bearing disc to the course required on the centre line of the base sheet.

B/ Set cursor to bearing of tide.

C/ Slide disc so that rate of tide on cursor crosses speed of craft on base scale distance/speed markings.

D/ Read off course correction angle from base scale in degrees and add or subtract from course required to obtain the course to steer.

E/ Read off the distance/speed made good from the base scale along the centre line.

Or: To find the course and distance/speed which has been made good after experiencing a particular tidal vector.

A/ Invert calculator.

B/ Rotate bearing disc to course steered on centre line of base sheet.

C/ Set cursor to tidal bearing.

D/ Slide disc so that disc centre is at craft's speed on base scale markings, along centre line.

E/ Read off course correction angle from the base scale in degrees at the point on the tidal cursor corresponding to rate of tide. Add or subtract from the sourse steered to obtain the course which has been made good.

F/ Read off distance/speed made good on the base scale speed/distance markings at this same point.

1. A navigational triangle calculator comprising a base scale, a transparent azimuth disc, and transparent cursor.

2. A navigational triangle calculator as claimed in Claim 1 wherein the azimuth disc and cursor rotate about a common pivot.

3. A navigational triangle calculator as claimed in Claim 1 or Claim 2 wherein means is provided for the pivot to slide along a slot in the base scale.

4. A navigational triangle calculator as claimed in any preceding claim, wherein the invertion of the calculator provides alternative deduced information, according to different input information.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Navigational triangle calculator The calculator allows the rapid solution of the triangle of velocities in navigation, which is otherwise achieved by plotting on a chart or paper, or by extensive trigonometry. It is made of sheet material three parts; a base sheet with a scale graduated in degrees from 0-90 axially from its centre line on both sides and marked radially to represent distance/speed; a transparent disc marked as a bearing ring, and a cursor marked to the same scale as the distance/speed markings on the base sheet. The disc and cursor are free to rotate about a central eyelet and this eyelet is fitted through a slot along the centre lines of the base sheet. Through this construction the cursor and disc parts are able to slide along the length of the base sheet scale. This allows vector triangles to be represented graphically. Navigational data can therefore be used to set the calculator to account for the effects of tide or wind on craft motion. Directional and distance/speed information can then be obtained from the scales. For example: To find the course to steer and the distance/speed which will be made good allowing for a particular tidal vector. A/ Rotate bearing disc to the course required on the centre line of the base sheet. B/ Set cursor to bearing of tide. C/ Slide disc so that rate of tide on cursor crosses speed of craft on base scale distance/speed markings. D/ Read off course correction angle from base scale in degrees and add or subtract from course required to obtain the course to steer. E/ Read off the distance/speed made good from the base scale along the centre line. Or: To find the course and distance/speed which has been made good after experiencing a particular tidal vector. A/ Invert calculator. B/ Rotate bearing disc to course steered on centre line of base sheet. C/ Set cursor to tidal bearing. D/ Slide disc so that disc centre is at craft's speed on base scale markings, along centre line. E/ Read off course correction angle from the base scale in degrees at the point on the tidal cursor corresponding to rate of tide. Add or subtract from the sourse steered to obtain the course which has been made good. F/ Read off distance/speed made good on the base scale speed/distance markings at this same point. CLAIMS

1. A navigational triangle calculator comprising a base scale, a transparent azimuth disc, and transparent cursor.

2. A navigational triangle calculator as claimed in Claim 1 wherein the azimuth disc and cursor rotate about a common pivot.

3. A navigational triangle calculator as claimed in Claim 1 or Claim 2 wherein means is provided for the pivot to slide along a slot in the base scale.

4. A navigational triangle calculator as claimed in any preceding claim, wherein the invertion of the calculator provides alternative deduced information, according to different input information.