To review the waypoint page for a selected waypoint:
1. Press the T key. 2. To return to the Map Page, press T again.
The cursor can also be used to create new waypoints right from the map display.
A B A. Waypoints can be created from the map display by moving the cursor to the desired position and pressing the EDIT/ENTER key. B. The create new waypoint page will automatically assign the next available three-digit number as the default waypoint name. If you are creating a waypoint at an on-screen navaid, the navaid icon and name will be used as the default symbol and comment. To create a new waypoint using the cursor:
1. Use the R keypad to move the cursor as close as possible to the following position: N 35 02.129; W 076 26.106 (Use the data window to verify the cursor position.) 2. Press the T key to capture the cursor position. 3. Use the R key to highlight the waypoint symbol field. 4. Press T to access the symbol page. 5. Press the DOWN arrow of the R keypad twice to select the wreck symbol. 6. Press T to confirm, and T again to finish.
Now that were navigating to an actual destination, lets move on to the next page of the sounder, the Navigation Page: 1. Press the J key.

Page 15

Navigation Page
Data Fields Compass Tape Graphic Highway Pointer to Waypoint CDI Scale

Overview

The Navigation Page provides graphic steering guidance to your destination. The bearing (BRG) and distance (DIS) to the destination, with your current course (COG) and speed over ground (SOG), are displayed at the top of the page, along with a compass tape to indicate your cardinal heading. The estimated time enroute (ETE) and velocity made good (VMG, or the rate you are closing in on your destination) are displayed at the bottom of the page. As you head toward the destination, the middle section of the page gives you visual guidance to your waypoint on a graphic highway, which displays the route and nearby waypoints on screen. The moving arrow below the highway always points to the destination waypoint relative to the direction youre moving. The line down the center of the highway represents your desired track, while the bottom of the page provides a graphic indication of your crosstrack error (the distance and direction you are off course) according to the scale at the bottom right of the page. In simulator mode, you can adjust your speed and course from the Navigation Page using the R keypad. As you head toward each waypoint in the tour route, try adjusting your boat speed and course to get a feel for how the highway works.

Active Route Page

To reset the boat speed to zero:
1. Press the O key. 2. Highlight the Setup Simulator? option. 3. Press T. 4. Press T to access the SOG field. 5. Press the LEFT arrow of the R keypad to clear the speed entry. 6. Press T.
B A. To stop navigating the active route, select the Deactivate Route? option and press EDIT/ENTER. B. Use the left arrow key to clear the SOG field and press EDIT/ENTER to confirm.
As youve seen, the primary pages provide status, position, fishfinding, navigation and map information. The tours last page is the main menu page, which allows access to the sounders waypoint, route and planning functions, as well as various operational and navigation setup features. The main menu is available from any page, and is accessed through the O key.
To access the main menu page:
1. Press the O key twice.

Page 18

Main Menu Page

Main Menu and Power Off

The main menu pages eleven submenus are divided into categories by function. You can select a particular submenu by simply highlighting the desired option and pressing T. To get a feel for how the main menu page works, lets clear out the track log weve created during our simulated tour. Clearing the track log will ensure that you have a clean slate once you start navigating in your home waters.
To select the track submenu:
1. Highlight the Track menu option and press T.
The track log page allows you to specify whether to record a track plot and define how it is recorded. It also provides both an indicator of the total memory used and the individual functions to clear the track log and start a TracBack route.

To delete the track log:

1. Highlight the Delete Track option and press T. A confirmation page will appear. 2. Highlight the Yes prompt and press T to confirm.
B A. The sounders track page lets you clear the track log and start a TracBack route. B. To delete the track log, confirm the warning page by highlighting the YES prompt and pressing EDIT/ENTER.
3. Press J to return to the main page sequence.
Congratulations! Youve now gone through the basic operation of the GARMIN GPSMAP 235 Sounder. Your new digital chartplotter is a powerful tool with many advanced features not covered in the Getting Started tour. For detailed instructions on using these features or performing a specific task, please refer to the quick reference guide or the appropriate reference section of this manual.

B A. The status bar at the bottom of the page displays important status, alarm and map scale information. It also provides on-screen user and message prompts. B. The status bar will display an anchor symbol or PRX icon whenever the anchor drag alarm or proximity alarm has been triggered.

Page 21

Satellite Status Page Options The satellite Status Page features an options menu that provides access to functions and features relating to the Status Page.
Initialize Position, AutoLocate, North Up, and Setup Simulator
To display the Status Page options menu:
1. From the Status Page, press O.

There are four options:

Initialize Position?: Allows you to initialize the receiver graphically or by text. See page 1 for instructions on initialization. Start AutoLocate?: Allows the receiver to locate your position automatically. North Up SkyView?: Allows you to select between a north up or track up sky view display. Setup Simulator?: Allows you to define speed, course and position values while in simulator mode. See the getting started tour for more on using the simulator mode. To select a menu option:
1. Highlight the desired option and press T.
B A. Whenever the sounder is in simulator mode, the Setup Simulator? option will appear on the option menu for each of the main pages. B. The setup simulator page allows you to define your speed and course over ground, as well as your position, altitude, and depth. The Auto COG option will automatically steer the desired course to your destination. Your speed and course can also be selected from the Navigation Page using the rocker keypad (see page 13).

Page 22

Position Page

POSITION PAGE

Compass Tape Data Fields
The trip odometer can be reset from the Position Page options menu. To reset the odometer, select the Reset Trip Distance? option and press EDIT/ENTER.
The position page shows your position, direction, and speed. There is a graphic compass tape at the top of the page that shows the direction youre heading (you have to be moving), and four selectable data fields: course over ground (COG), speed over ground (SOG), distance traveled (TRP) and altitude (ALT). The bottom half of the page displays your present positions coordinates, along with the time of day (calculated using GPS satellites). The status bar at the bottom of the page displays important status, alarm and map scale information. It also provides onscreen user and message prompts. The units of measure for speed, distance, position and altitude are all userselectable through the navigation setup option on the main menu page (page 79). The time of day is shown in UTC (Universal Time Coordinated, or Greenwich Mean Time) and can be set to a 12- or 24-hour time format (with a local offset) through the system setup option on the main menu page.

To change the page display:
1. Highlight the Setup Page Display? option and press T. 2. Highlight the desired field and press T. 3. Select a page display option and press T.

Page 32

Data Fields and Restore Defaults
Change Data Fields?: Allows you to specify the data displayed in each data field on the Sounder Page. There are thirteen options: BRG: Bearing to active wpt SOG: Speed over ground ETE: Estimated time enroute XTK: Crosstrack error TRN: Turn angle to wpt DPT: Depth STW: Speed through water To change a data field:
1. Highlight the Change Data Fields? option and press T. 2. Move the field highlight to the desired field and press T. 3. Select a data field option and press T. 4. When finished, press Q. Restore Defaults?: Resets all Sounder Page options except sounder setup to the
DIS: Distance to active wpt COG: Course over ground ETA: Estimated time of arrival VMG: Velocity made good VDC: DC voltage TMP: Temperature
B A. The Sounder Page can be configured to display up to five data fields simultaneously. B. Any of thirteen information options may be shown in a designated data field.
factory settings. See page 38 for restoring defaults on the sounder setup page.

Page 33

Sounder Setup Page The next Sounder Page menu option is Sounder Setup? which accesses the sounder setup page. There are eight fields on the sounder setup page which allow you to customize the sounders features: Fish ID, Target Depth, Water Temperature, Water Type, Noise Rejection, Keel Offset, Frequency, and Speed Calibration.
To access the sounder setup page:
1. From the Sounder Page, press O to access the options list. Highlight the Sounder Setup? option and press T.

Fish ID Setup

Fish ID: The Fish ID determines how the GPSMAP 235 Sounder identifies and labels sonar targets on the viewing screen. The On and Fish Only settings display fish symbols on the screen in place of actual target echoes. There are three fish symbol sizes: small, medium, and large. These are used to point out the relative size between targets. In other words, the sounder displays a small fish symbol when it thinks a target is a small fish, a medium fish symbol on a larger target, etc. Sometimes you see fish symbols on the screen when actually there are no fish because, at times, the sounder may not be able to distinguish between fish and certain other suspended objects. Practice using the sounder with and without Fish ID to become more familiar with it.
B A. When FISH ID is turned off, all sonar target information is displayed in an unprocessed form. B. The range scale will be highlighted when using the arrow keypad to adjust manual range mode or when switching between auto and manual mode.

1. Press O to display the sounder options page. 2. Using the R keypad, highlight Sounder Setup? and press T. 3. Choose between auto and manual calibration (COG field).

Page 37

To use Auto Calibration:
1. Ensure Auto Calibrate? is displayed in the speed calibration field. If it is not, press O to display the calibration menu. 2. Highlight Auto Calibrate and press T. 3. Press T again and an instruction message will appear. 4. Read the instructions and press T when you are ready to begin calibration. 5. Slowly accelerate your boat to a maximum safe cruising speed and then back down to a stop and press T. The minimum and maximum speed which the unit is now calibrated for will be displayed in the calibrated range field. 6. Auto calibration is complete.
GETTING STARTSOUNDER PAGE ED Speed Calibration Setup

Using the GOTO Key

When manual calibration mode is selected, the speed calibration bar will appear as a white horizontal strip with a black slider bar. Before entering the calibration, you will need to compare the value shown on the speed calibration fields STW display, with your boats actual speed as determined by the speedometer or by using a stop watch. Accelerate to a safe speed and compare the two speed readings.
B A. When you are ready to begin calibration, read the instructions and press EDIT/ENTER. B. When manual calibration mode is selected, the speed calibration bar will appear as a white horizontal strip, with a black slider bar positioned in the middle.

Page 38

GETTING STARTSOUNDER PAGE ED Speed Calibration and
Simulator GOTO Using the Setup Key
To use manual calibration:
1. Ensure manual calibration mode is selected in the speed calibration field. If not, press O, highlight Manual Calibrate?, and press O. 2. Press T. The slider bar will turn black and the calibration range bar will turn white. 3. Use the R keypad to move the selector bar until the speed displayed in the STW field matches the speed of your boat. Move the bar to the left for negative values and right for positive values. 4. When the desired speed is displayed, press T. 5. Press Q to return to the Sounder Page.

B A. Position mode on inland water cartography. B. Cursor mode on inland water cartography.

Page 41

Using the Cursor The cursor allows you to pan away from your present position and scroll to other map areas (even outside of your current G-chart coverage). As you pan past the edge of the current map display, the screen will actively scroll forward to provide continuous map coverage.

To move the cursor:

1. Press the R keypad to move the cursor up, down, left or right.
GETTING STARTMAP PAGE ED Using the Cursor
As you move the cursor, the distance and bearing from your present position to the cursor will be displayed in the data window, along with the cursors position coordinates. Keep in mind that when the cursor is stationary, the distance and bearing from your present position will change as your boat moves. The cursor can also be used to snap to on-screen waypoints and navaids, allowing you to review a selected position directly from the map display.
To select an on-screen waypoint or navaid with the cursor:
1. Use the R keypad to move the cursor to the desired waypoint or navaid (if there are several waypoints grouped closely together, zoom in closer for a better view). 2. When a waypoint or navaid is selected, it will become highlighted on-screen, with the name and position displayed.
B A. To create a new waypoint at the cursor, move the cursor to the desired position and press EDIT/ENTER. B. The create new waypoint page will appear, where you may change the waypoint name, symbol and comment before saving the waypoint.
To eliminate the cursor and re-center your position on-screen:

1. Press the Q key.

The cursor can also be used to create new waypoints directly from the map.
To create a waypoint with the cursor:
1. Use the R keypad to move the cursor to the desired map position. 2. Press T. 3. Press T to confirm the new waypoint using the default three-digit name.

Page 42

GETTING STARTMAPED PAGE Map Scales
Selecting Map Scales The map display has 16 available range scales from 1/8th to 4096 nautical miles (1/4 to 7500 kilometers). The map scale is controlled by the I and H keys, with the current scale displayed at the bottom of the data window.

To select a map scale:

1. Press H to zoom out and I to zoom in.
The sounder has a built-in worldwide database to 64 (32 in U.S.) nautical miles (see Appendix D for a built-in coverage map), with more detailed coverage available through the use of G-chartTM data cartridges (see pages 84-85 for installing and using G-chartTM cartridges). The sounder will display cartography as long as there is chart information available for the range youve selected. Map coverage will conform to the following conditions: When the selected zoom range is covered by either the internal database or a G-chart data cartridge, cartography will be displayed. When the selected zoom range is covered by both the internal database and a G-chart cartridge, cartography will be displayed using the data with the best resolution. When the selected zoom range exceeds the resolution of the chart in use by up to two settings, overzoom cartography will be displayed. The display will not show any filled landmass areas, and an Ovr Zm warning will appear in the scale field. The lat/lon grid will also be turned on regardless of the map configuration setting. When the selected zoom range exceeds the resolution of the chart in use by more than two settings, all cartography will be replaced by a track plot display, and a No Map warning will appear in the scale field. The lat/lon grid will be displayed regardless of the map configuration setting. Additional caution should be used while navigating in track plot mode.

1. Highlight Configure the Map? and press T. The map configuration page will appear.
Waypt Names Active Rte/Trk National Hwy Local Hwy Local Road Road Labels
B A. The map configuration grid allows you to define what items appear on the display at each map scale. B. To turn an entire row on for the selected map item, highlight the Enable Row? option and press T.
2. Use the R keypad to select the desired map item and press T. A pop-up window will appear with the current settings displayed. 3. Use the R keypad to highlight the scale you want to change. 4. Press T to turn the setting on or off. 5. Press Q to finish.
The map configuration page also allows you to set the map display to a North Up, Track Up or Desired Track Up orientation.
To change the map orientation:
1. Use the R keypad to highlight the Orientation field and press T. 2. Select the desired setting and press T.

Page 45

Map Page Options (cont.) From the map configuration page, you can also access another options menu by highlighting any of the items and pressing O. There are five options:
Enable or Disable a Row?: Allows you to turn an entire row on or off. To turn an entire row on or off:
1. Use the R keypad to select the desired map item. 2. Press the O key. 3. Select the Enable Row? or Disable Row? option and press T.
GETTING STARTMAP PAGE ED Enable/Disable Rows
Using the GOTO and Map Calibration Key
Calibrate the Map?: The map configuration options page also features a map calibration feature that allows you to calibrate the map display using your exact physical surroundings or correct data from older charts. Before using the map calibration feature, check to make sure that your map datum selected on the GPS matches the datum on the chart you are using (see page 80). To calibrate the map display, you must know exactly where you are, and understand that the correction is generally valid only in a limited range from the point of correction.
Map calibration should only be performed while the vessel is still, and should never be used to attempt SA corrections, which can degrade accuracy up to 330 (100 meters). The maximum correction is 16,400 feet (5000m).

To calibrate the map:

1. Select the Calibrate the Map? option and press T. 2. Use the R keypad to move the arrow cursor from the satellite position (indicated by the satellite symbol) to your exact position. The bearing, distance and position will be indicated in the data window. 3. Press T to confirm the calibration offset.
B A. To calibrate the map, highlight the Calibrate the Map? option and press EDIT/ENTER. B. A satellite icon will remain on the map to indicate the GPS position, while the boat marker will reflect the calibration changes. CAUTION! The map calibration feature should never be used to attempt to correct Selective Availability errors.

Page 46

GETTING STARTMAP PAGE ED Map Colors, Restore
Defaults, the GOTO Using Page Display Key
Set Map Colors?: The next option available from the map configuration page is the set map colors option, which allows you to define the fill color (grayscale) of the land and water used on the map display. Three options are available: no color (no fills for land or water), gray land/white water (the default setting), and white land/gray water. To select a map colors option:
1. Select the Set Map Colors? option and press T. 2. Highlight the desired map color option and press T. Restore Defaults?: Resets all map configuration options to their factory settings.
To restore the map configuration options to the factory defaults:
1. Highlight the Restore Defaults? settings and press T. Press Q twice to exit the map configuration page and access the map display. Press O on the map display to once again access the main options menu. The next main menu option after Configure the Map is Setup Page Display.
B A. The color option allows you to define the fill color (grayscale) of the land and water used on the map display. Three options are available: no color (no fills for land or water), gray land/white water (the default setting), and white land/gray water. B. The default option resets all map configuration options to their factory settings.
Setup Page Display?: Allows you to specify what fields are displayed in the data window section of the Map Page by selecting one of the following display options: 2 Fields & Compass 2 Fields & CDI 4 Fields 4 Fields & Compass 4 Fields & CDI 6 Fields 6 Fields & Compass 6 Fields & CDI 8 Fields 2 Fields & Sounder 4 Fields & Sounder

Page 47

MAP PAGE

Split Screen Option

The last two display options make it possible to display both the Map Page and Sounder Page simultaneously in a split screen arrangement. The top half of the page will show a reduced-size Map Page while the Sounder Page is displayed in the lower half of the screen. Note: When the dual frequency 200 kHz/50 kHz is selected on the Sounder Page, 50 kHz only is shown in the lower half of the split screen Map Page, when 50 kHz/200 kHz is selected, 200 kHz only is always shown in the lower half of the split screen. To modify or access the Sounder Page display, press Q or T until the actual Sounder Page appears, make any desired changes, and then return to the split screen Map Page.

ROUTES

Page 66

Routes

Creating a Route Graphically
The last way to navigate to a destination is to create a user-defined route. The sounder lets you create and store up to 20 reversible routes (numbered 1-20), with up to 30 waypoints each. Routes can be created and modified right from the Map Page, allowing you to see each route graphically on-screen as you create, review, modify or navigate the route. All of the route features are accessed through the main menu.
To create a route graphically:
1. Press the O key twice to display the main menu page. 2. Highlight the Routes field and press T. The routes page will appear, showing all the routes currently stored in memory. 3. Press the O key to display the route options page. 4. Press T to select the Create New Route option.
The route edit page will appear, with the cursor displayed as an arrow pointer, and will allow you to select your route waypoints using one of two methods:
A B A. The route options page provides access to the sounders route functions. B. Use the arrow pointer and EDIT/ENTER to add waypoints to the route. The create waypoint page will appear whenever you have selected a position that is not already stored as a waypoint.
5. To add an existing waypoint or navaid to the route, use the arrow pointer to highlight the desired waypoint on screen and press T. 6. To add a new waypoint to the route, use the arrow pointer to select the desired map position and press T. Press T again to confirm the new waypoint.
As you add each new waypoint to the route, the data window at the top of the map display will show the route number you are creating, along with the first and last route waypoints of the route. A route line will appear on the map to indicate each completed leg, and a dotted line will appear to indicate the distance and bearing to the arrow pointer from the last route waypoint.
7. Repeat steps 5 and 6 until you have finished defining all route waypoints. 8. Press Q to finish and enter review mode, or J to return to the main page sequence.

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Routes (cont.) Once a route has been created graphically (and the Q key has been pressed to finish), the map display will automatically enter the route review mode. The arrow pointer will be replaced by the map cursor, located at the last route waypoint. The route edit mode allows you to review and modify the route displayed through a pop-up window menu for each waypoint. You can also use the cursor to select an individual route leg and insert a new route waypoint.
To edit a route waypoint:
1. Use the cursor to highlight the desired route waypoint and press T.

To enter a custom route comment:
1. Highlight the desired route and press T. 2. Press the left arrow key of the R keypad to clear the comment field. 3. Use the R keypad to enter the new route comment and press T.
Once you have selected a route from the route page, additional functions for that route are available from the route options page.
To display the route options:
B To select a menu option: A. The route list page displays each route stored in memory, along with a 16-character user comment. The default comment is the name of the first and last route waypoint. B. The route list options page provides quick access to many route functions, including activating and deactivating a selected route.
The following options are available from the route list page:
Create New Route?: Allows you to create a new route (see page 66). Activate Route?: Activates the selected route and begins navigation. Invert Route?: Activates the selected route in reverse order and begins navigation. Edit On Map?: Allows you to edit the selected route graphically (see page 67 for specific instructions). Edit As Text?: Allows you to edit the selected route by text (see page 68 for specific instructions).

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Route List Page Options (cont.)
Clear Route: Allows you to clear all waypoints from the selected route. To clear the selected route:
1. Highlight the Clear Route? option and press T. 2. Press T to confirm the clear route warning.
GETTING STARTROUTES ED Route List Options
Copy Route?: Allows you to copy the waypoints of a selected route to another route. The route copy function can be used to copy a TracBack route (route 00) to another route in order to prevent losing the route the next time a TracBack route is activated, or to save a modified version of an existing route without losing the original. To copy a route:
1. Highlight the Copy Route? option and press T. The selected route will appear as the copy from route, and the first open storage route will appear as the copy to route. 2. Press T to confirm. (If youd like to change the route number that is being copied or the open route which is being copied to, highlight the appropriate field and press T. Select the new route number and press T.
B A. To delete all waypoints from a selected route, highlight the Clear Route? option and press EDIT/ENTER. B. Once a route is cleared, all waypoints are removed from the route. They are still stored in memory, however.
Deactivate Route?: Stops navigation of the current route.

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B A. The data transfer options allow you to send or receive almanac data, proximity waypoints, routes, track log data and waypoints to another GARMIN GPS or PC Kit. B. The NMEA In setting allows you to accept NMEA data from a Yeoman plotter or other compatible device.
When the Data Transfer option is selected, youll need to specify what information to request or send to the remote unit through the Transfer Mode field. The slave setting lets you control all data transfer from the external GPS receiver, or PC, while the other settings request or send specific data from the primary unit.

Page 83

Using NMEA and DGPS Interface Settings If you are using an NMEA interface format, the NMEA format must be specified in the NMEA format field that will automatically appear when an NMEA option is selected. The appropriate baud rate will be set automatically. See page 96 for a list of NMEA supported sentences.
To select a NMEA format: 1. Select a NMEA IN/OUT format from the options page. 2. Highlight the NMEA Format field and press T. 3. Select a NMEA sentence format and press T. 4. The baud rate will automatically be set to the appropriate speed. If you have selected an NMEA IN/OUT setting, you must use the same NMEA format for both the input and output device.
GETTING STARTSETUP MENUS ED NMEA and DGPS Setup
Tuning DGPS Stations If the I/O Format is set to accept RTCM input/NMEA Output for connecting a differential-ready GPS beacon receiver, you will need to tune a frequency in the tuning field and select a bit rate. The default frequency is 304.0 kHz, with a bit rate of 100 bps, or the last DGPS frequency/bit rate selected.
To tune a DGPS frequency: 1. Select the RTCM In/NMEA Out format from the options page. 2. Highlight the beacon receiver frequency field and press T. Enter the desired frequency and press T. If you are using an automatically-tuned DGPS receiver, you can enter 000.0 for the frequency. 3. Press T to select a bit rate. Five bit rates are available: 0 (used for automaticallytuned DGPS receivers), 25, 50, 100 and 200 bps. Press T to confirm. The DGPS status, along with the signal-to-noise ratio of the tuned station, will be displayed at the bottom of the page. A B A. Select the desired format from the NMEA field. The baud rate will automatically be set to the appropriate speed. B. After entering a DGPS frequency, set the bit rate to the speed indicated on the USCG station chart. DGPS coverage, frequencies and bit rates are available from the Coast Guards automated FAX service (703-313-5920).

Using G-Charts

Whenever you zoom past the usable range of the current electronic chart, the range field will display Ovr Zm or No Map. These warnings indicate that although you may still have cartography, you should exercise extreme caution using the data. See page 42 for more information on Overzoom and No Map modes.
B A. Map outlines for G-chart offshore cartography.
When a G-chart cartridge is installed, the sounder will automatically use the best available chart for display. As you enter and exit various subcharts, the system will automatically display the appropriate chart for the area you are in. When you leave the area covered by the main map of a cartridge, the sounder will default back to using the built-in 64 nm database (32 nm in U.S.) if it is available at the current scale. If you are not seeing certain map items (navaids, depth contours, etc. on offshore cartridges; highways, boat ramps, etc. on inland cartridges), check the map configuration settings available from the map options page.
B. Map outlines for G-chart inland cartography.

Page 86

LORAN TDs

LORAN C Basics

LORAN C Basics LORAN C is a radio navigation aid operated and maintained in the United States by the Untied States Coast Guard. The name LORAN is an acronym for "Long Range Navigation". The LORAN system covers the entire United States and the U.S. Coastal Confluence Zone. From the perspective of a mariner, the system is used for ocean and coastal navigation. It can be used as a supplemental system for harbor and harbor approach navigation, and it is used for inland navigation by recreational vehicles. The LORAN C system is also used in civil aviation. The LORAN system consists of groups of land based transmitter stations called chains. A chain contains a master station (M) and at least two, but more commonly 4 or 5 secondary stations designated (M) Victor, (W) Whiskey, (X) Xray, (Y) Yankee, and (Z) Zulu. These stations are usually separated by hundreds of miles. Each station transmits radio pulses at precise time intervals. The receiver measures the difference in time it takes the pulsed signal from each Master/Secondary pair to reach the receiver. This time is quite small, generally in millionths of a second. These time differences are then displayed on the LORAN receiver as the TD (time difference) coordinates. Many of the transmitter stations serve multiple roles. A station can serve as a master station for one chain and a secondary station for another, or as a secondary station for multiple chains. An example would be the chain 9610 master station and the chain 8970 Zulu station. These operate on the same transmitter located in Boise City, Oklahoma. LORAN is being phased out as a primary source of navigation, but should remain active until after the turn of the century.

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The chart below gives an approximate UTC time offset for the various longitudinal zones. Check with local charts for more detailed information. If you are in daylight savings time, add one hour to the offset. Longitudinal Zone Offset
W180.0 to W172.5 W172.5 to W157.5 W157.5 to W142.5 W142.5 to W127.5 W127.5 to W112.5 W112.5 to W097.5 W097.5 to W082.5 W082.5 to W067.5 W067.5 to W052.5 W052.5 to W037.5 W037.5 to W022.5 W022.5 to W007.5 W007.5 to E007.5 E007.5 to E022.5 E022.5 to E037.5 E037.5 to E052.5 E052.5 to E067.5 E067.5 to E082.5 E082.5 to E097.5 E097.5 to E112.5 E112.5 to E127.5 E127.5 to E142.5 E142.5 to E157.5 E157.5 to E172.5 E172.5 to E180.0 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -11 12

Time Offset Chart

Page 106
2D Navigation.20 3D Navigation.20
Estimated Time of Arrival (ETA).103
.vi Acquiring Satellites.20 Active Route Page.17, 72 Addresses/Phone Numbers.Inside Cover Almanac Data.103 Anchor Drag Alarm.81 Arrival Alarm.81 Auto Calibration.37 Auto Range Mode.8 AutoLocate.20

Accessories

Fish ID.33 Getting Started.3
G-Charts, Installing and Removing.84 G-Charts, Using.85 Glossary.103 Going To A Destination.12 GOTO.62 GOTO Options.63 Graphic Compass Tape.22 Graphic Highway.15 Grid.103
Backlight Timer.78 Backlighting.3 Bearing (BRG).15 Cancelling a GOTO.63 CDI Scale.79 Chart Speed, Adjusting.30 Clock Alarm.81 Connecting the Power/Data Cable.95 Countdown Timer.81 Course (COG).15 Crosstrack Alarm.81 Crosstrack Error.15 Cursor, Using.41 Cursor, Using on Map.11 Cursor Mode.40 Data Field, Changing.16
Data Window.10 Depth Units.79 Differential GPS (DGPS).103 Display Contrast.78 Distance (DIS).15
Heading.79 Highway Scale.16 Highway, Configuring.51 Index
.106 Initialization.1 Input/Output Setup.82 Installation.90
Keel Offset.35 Keypad Usage.viii Latitude:
.103 Local/UTC.78 LORAN.86-89 Main Menu Page.52 Manual Speed Calibration.37 Manual Range Mode.8 Map Configuration, Enable Or Disable A Row 45 Map Calibration.45 Map Colors.46 Map Datum.80 Map Datums.94