Position Tools

The Position Tools pane assists in calculating the ship's position using sighted geographic points, bearings and distances. If the Position Tools pane isn't displayed, show it by selecting Position Tools in the Tools menu.

Information for a maximum of three points can be entered to calculate the position.

Positions

Positions are entered in the point's Position field, where the latitude and longitude must be separated by a comma.
A wide variety of notations is supported.
Both latitude and longitude can be entered in decimal degrees, or degrees and decimal minutes, or degrees, minutes and decimal seconds. The ° (degrees), ' (minutes) and " (seconds) symbols are optional, but if not used a space separating the individual values is required.
To indicate the hemisphere the value can be preceded by a - or + sign, where the latter is optional, or followed by a compass direction, N or S for the latitude and E or W for the longitude. If no sign or compass direction is given + is assumed.

Examples of valid entries:

A white exclamation mark in a red circle at the far end of the field is shown when the entered position isn't recognised.

When the Enter key is pressed, or if the position field loses focus, and a valid position has been entered, a marker bearing the name and in the colour of the point will be shown on the map.

Instead of entering a position for a point, it can be selected from the map. Click thebutton for the appropriate point and click the map at the location where the point should be.

To cancel picking a point, click thebutton again, or press the Escape key.

A point's marker on the map can be dragged to a different position.
Click the marker and, whilst keeping the mouse button pressed, drag the marker to its new location.
The map will pan automatically when approaching the edge.
When the mouse button is released the updated position will appear in the Position field.

Bearings

Bearings to a point are entered in the point's Bearing field, either in degrees, as a bearing angle, or as a compass point.

A bearing in degrees can be entered in decimal degrees, or degrees and decimal minutes, or degrees, minutes and decimal seconds. The ° (degrees), ' (minutes) and " (seconds) symbols are optional, but if not used a space separating the individual values is required.

Examples of valid entries:

Bearing angles are case insensitive, and the angle can be entered in decimal degrees, or degrees and decimal minutes. The ° (degrees) and ' (minutes) symbols are optional, but if not used a space separating the individual values is required.

Examples of valid entries:

Compass points can be entered using the 256-wind, or 256-point rose, can be clockwise or anticlockwise, and are case insensitive.
The by in a compass point can be abbreviated to b or x.
The 256-wind rose allows for the fractions ⅛, ¼, ⅜, ½, ⅝, ¾ and ⅞, which can also be entered as 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, and 7/8.

Examples of valid entries:

Each bearing can be true or magnetic, and also relative to the ship's heading.
Setting the True check box assumes the given bearing is using true north, otherwise magnetic north is assumed.
Setting the Relative check box makes the given bearing relative to the ship's heading, otherwise the bearing is absolute, i.e. from the magnetic or true north.

A white exclamation mark in a red circle at the far end of the field is shown when the entered bearing isn't recognised.

If the point's marker is shown on the map, a line showing the bearing will be drawn on the map for a valid bearing.
The bearing line is drawn as agreat circle, so it might not appear as a straight line on the map.

Distances

The optional distances to a point are entered in the point's Distance field.
Distances are only required to calculate the position from a single point and are ignored for cross bearing calculations.

By default the distance is entered in nautical miles, but different units of length can be used as well. A space between the number and unit is optional; if no unit is entered nautical miles are assumed.
The following units can be used:

Examples of valid entries:

A white exclamation mark in a red circle at the far end of the field is shown when the entered distance isn't recognised.

If the point's marker is shown on the map, an area of equal distance will be drawn on the map for a valid distance.
The distance area will follow thegreat circle, so it might not appear as a perfect circle on the map.

Compass Correction

If one of the bearings, or if the ship's heading, is a magnetic bearing, the compass reading must be corrected to get a true north heading.
The correction consists of two parts, themagnetic deviationand themagnetic declination.

The magnetic deviation is the error induced in a compass by local magnetic fields. Local magnetic fields are caused by magnetized iron, e.g. the ship's structure, and are independent of location.
Leave the Deviation field empty if the magnetic deviation is not known.

The magnetic declination, or magnetic variation, is the error induced in a compass by the earth's magnetic field. The earth's magnetic field varies over time and also depends on the location.

If the magnetic declination is not known Journey Plotter can calculate it.
The calculation for dates from 1900 onwards uses the 13th generation ofInternational Geomagnetic Reference Fieldseries of models.
For dates before 1900 theGUFM1model, a model based on geomagnetic secular variation from historical records between 1590 and 1990, is used.

By default the magnetic declination is calculated automatically. The mean position of the entered points is used for the location, but the date has to be selected manually.

Dates can be selected by clicking the button next to the date, which will show a calendar from which a date can be selected. Use the left or right arrows in the calendar header to change the displayed month, or click on the month and select a month from the menu that will be shown. Click on the year to select a year from the menu.

Alternatively, dates can be changed using the keyboard. First click on part of the date, i.e. day, month or year, and use the Up, Down, Page Up, Page Down, Home and End cursor keys of your keyboard to change the value. Use the Left and Right arrow keys to step through the parts of the date.

To enter the magnetic declination in the Declination field, or to have Journey Plotter calculate it at your discretion by clicking the Calculate button, disable the automatic calculation by clearing the Automatic check box.

Both the magnetic deviation and declination can be entered in decimal degrees, or degrees and decimal minutes, or degrees, minutes and decimal seconds. The ° (degrees), ' (minutes) and " (seconds) symbols are optional, but if not used a space separating the individual values is required.

Bearing lines shown on the map will be adjusted automatically when the compass correction changes.

Ship

For relative bearings the heading of the ship is required; in other cases it is used as an indication only.
The heading must be entered in the ship's Heading field, and can be entered in the same manner as earlier described for bearings.

To calculate the ship's position, select a calculation method from the list of methods. This list is dynamic, depending on the entered point information, and therefore one or more of the following methods can be used:

  • Cross bearing Points 1, 2 and 3: calculate the position using the positions and bearings of all three points
  • Cross bearing Points 1 and 2: calculate the position using the positions and bearings of Points 1 and 2
  • Cross bearing Points 1 and 3: calculate the position using the positions and bearings of Points 1 and 3
  • Cross bearing Points 2 and 3: calculate the position using the positions and bearings of Points 2 and 3
  • Distance and bearing to Point 1: calculate the position using the position, bearing and distance of Point 1
  • Distance and bearing to Point 2: calculate the position using the position, bearing and distance of Point 2
  • Distance and bearing to Point 3: calculate the position using the position, bearing and distance of Point 3

Click the Calculate button to perform the selected calculation.
If the magnetic declination is set to automatic, you'll notice a warning message appear, asking whether the correct date is selected. The date is important for the magnetic declination; it varies over time, so the date has to be set before calculating the position.

The ship's position labelled Position will show the result of a successful position calculation, in the format set in the Map Options (see the{{manual.jp.root.options.title}}section). Also a ship marker labelled "Ship" will be shown on the map. If a heading was entered, the ship marker will have an arrow pointing in the direction of the heading.

In the case of a three-point cross bearing an area is drawn on the map, indicating where the ship's position could be. The ship marker will be positioned at the mean position of this area. Optionally three intermediate cross points are shown, indicating the cross bearing positions of the corresponding points.

The ship's position labelled NHN will show the calculated position rounded to the selected number of decimals, and is primarily added for thenaval-history.net(NHN) editors. Also a marker labelled "Ship (NHN)" will be shown on the map to indicate the location of the rounded NHN position.
The number of decimals can be decreased or increased using theandbuttons after the position.
Thebutton will copy the NHN position to the clipboard, after which it can be pasted into the document being edited. The copy is in the standardnaval-history.netformat, e.g. Lat 50.70, Long 0.40.

Example of a calculated position using one point, bearing and distance.

Example of a calculated position using two points and bearings.

Example of a calculated position using three points and bearings.

The appearance of Position Tools points and areas on the map can be customized, and whether or not to show intermediate point markers for three-point cross bearings can be chosen in the Tools Options (see the{{manual.jp.root.options.title}}section).

Gazetteer

Entering the position of points, or picking them from the map, is easy if the position or location of the point is known, but impossible for unknown geographic points. The gazetteer allows searching for geographic points in theGeoNamesdatabase.

In the Gazetteer Search pane, activated through the corresponding tab at the bottom, the geographic point to search for can be entered in the Search field. Searches are performed on all data items of a geographic point in the database. This means the search doesn't look at the name only; country, state, administration, alternative names and other data items of a geographic point are also searched.

It is not possible to use wildcards, but a search can be narrowed or widened using various options.

All words: if selected all words in the search field must be present in the result.

Any words: if selected one or more words in the search field must be present in the result.

Exact match: if selected the results must match the entered words exactly.

Starts with: if selected the results must start with the entered words.

At least one search term is part of the name: if enabled at least one of the entered search words must be part of the geographic point's name.
This is particularly useful if one of the other data items of the geographic point, e.g. state, is the same as part of the geographic point's name; it will filter out all other geographic points within the state.
For example, a regular search for Berlin will not only return the city of Berlin, but also every geographic point in the state of Berlin. The latter will be filtered out by enabling this option.

Fuzziness: Use theandbuttons to increase or decrease the fuzziness of the search in 10% steps, where 0% equals an exact match.
Fuzziness is useful if there is uncertainty about the spelling of the geographic point searched for.

Restrict to map boundary: search results must be within the current map boundary.

Countries: if the Selected option is chosen the search will be limited to the selected country or countries.

Continents: if the Selected option is chosen the search will be limited to the selected continent.

Features: if the Selected option is chosen the search will be limited to the selected feature class or classes.

Click the Search button to start the search process.
Please bear in mind that searches atGeoNamescan take several seconds to complete.

Instead of searching using the Search field, it is also possible to show all available geographic points within the current map boundary. Click the Show All Within Map Boundary button to do so.
The Countries, Continents and Features options are taken into account.
Because of the number of available geographic points, the Show All Within Map Boundary button is only enabled when the map is zoomed in far enough; the height of the map needs to cover less than 1°, or 60 nautical miles.

Gazetteer Results

The results of the search will be shown both in the Gazetteer Results pane and as markers on the map, where the selected result is indicated by a pulsating marker.
The colour of the markers indicates the feature class of the geographic points.
The Gazetteer Results pane will be shown automatically when search results arrive, but it can also be activated through the corresponding tab at the bottom.

Regular searches are limited to batches of 100 results, whereas Show All Within Map Boundary searches for up to 1000 results.
If more results are available, clicking the Load More button will request the next batch of results. When more than 5000 results have been fetched the Load More button will be disabled, a limit imposed byGeoNames.
The Clear button will clear the list of results and remove the map markers.

The upper half of the Gazetteer Results pane shows a list of results matching the search criteria. The list can be used to select the geographic point of interest.
It is also possible to click the map marker of a geographic point to select it, though this can be difficult if markers are close to or on top of each other.

Information about the selected geographic point is shown in the grid below the list. Click the + symbol next to Alternative Names, or double-click Alternative Names, to expand the list of alternative names of the geographical point.

To use the selected geographic point as one of the points for the Position Tools, right-click the list of results or information grid and selected which Position Tools point to set. If the right-click is performed on an information grid item containing an Internet link, the menu offers options to open the link in the default browser, or to copy it to the clipboard.
It is also possible to right-click the map marker of the geographical point for use in Position Tools.

Example of search results on the map.

The appearance of Gazetteer points on the map can be customized in the Tools Options (see the{{manual.jp.root.options.title}}section). By default the Gazetteer colour scheme uses the same colour scheme asGeoNames.

Check the{{menu.jp.pages.screenshots.title}}page for a video showing some of the possibilities Position Tools have to offer using examples taken from authentic log-books.