Introduction Warnings and Cautions
Introduction Warranty and Serial Number
This Garmin product is warranted to be free from defects in materials or workmanship for one year from the date of purchase. Within this period, Garmin will, at its sole option, repair or replace any components that fail in normal use. Such repairs or replacement will be made at no charge to the customer for parts or labor, provided that the customer shall be responsible for any transportation cost. This warranty does not cover failures due to abuse, misuse, accident, or unauthorized alteration or repairs. THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLUSIVE AND IN LIEU OF ALL OTHER WARRANTIES EXPRESS, IMPLIED, OR STATUTORY, INCLUDING ANY LIABILITY ARISING UNDER ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, STATUTORY OR OTHERWISE. THIS WARRANTY GIVES YOU SPECIFIC LEGAL RIGHTS, WHICH MAY VARY FROM STATE TO STATE. IN NO EVENT SHALL GARMIN BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES, WHETHER RESULTING FROM THE USE, MISUSE, OR INABILITY TO USE THIS PRODUCT OR FROM DEFECTS IN THE PRODUCT. Some states do not allow the exclusion of incidental or consequential damages, so the above limitations may not apply to you. Garmin retains the exclusive right to repair or replace the unit or software or offer a full refund of the purchase price at its sole discretion. SUCH REMEDY SHALL BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY BREACH OF WARRANTY. To obtain warranty service, contact your local Garmin authorized dealer or call Garmin Product Support for shipping instructions and an RMA tracking number. Securely pack the unit and a copy of the original sales receipt, which is required as the proof of purchase for warranty repairs. Write the tracking number clearly on the outside of the package. Send the unit, freight charges prepaid, to any Garmin warranty service station. Online Auction Purchases: Products sold through online auctions are not eligible for rebates or other special offers from Garmin. Online auction conrmations are not accepted for warranty verication. To obtain warranty service, an original or copy of the sales receipt from the original retailer is required. Garmin will not replace missing components from any package purchased through an online auction. International Purchases: A separate warranty is provided by international distributors for units purchased outside the United States. This warranty is provided by the local in-country distributor and this distributor provides local service for your unit. Distributor warranties are only valid in the area of intended distribution. Units purchased in the United States or Canada must be returned to the Garmin service center in the United Kingdom, the United States, Canada, or Taiwan for service. Garmin International, Inc. Garmin (Europe) Ltd. Garmin Corporation 1200 East 151st Street, Liberty House, No. 68, Jangshu 2nd Road, Olathe, Kansas 66062, USA Hounsdown Business Park, Shijr, Taipei County, Taiwan Tel. (913) 397-8200 or Southampton, Hampshire, SO40 9RB UK Tel. 886/2.2642.9199 Tel. +44 (0) 870.8501241 (outside the UK) (800) 800-1020 Fax 886/2.2642.9099 0808.2380000 (within the UK) Fax (913) 397-8282 Fax +44 (0) 870.8501251

The Garmin GPSMAP 178/178C has no user-serviceable parts. and is fastened shut with screws. Any attempt to open the case to change or modify the unit in any way voids your warranty and may result in permanent damage to the equipment.
Designed for detailed electronic charting capability, the Garmin GPSMAP 178/178C Sounder is a powerful navigation device that can give you the information you need: Precision Performance (178) 10 level grayscale FSTN display with backlighting (178C) High-contrast, 256-color LCD screen with backlighting 12-channel parallel receiver tracks and uses up to 12 satellites for fast, accurate positioning WAAS Capable receive signals from the additional set of WAAS (Wide Area Augmentation System) satellites to give you better accuracy Differential-Ready just add an optional Garmin beacon receiver for better than 5-meter accuracy Fully gasketed, high-impact plastic alloy case, waterproof to IEC 529 IPX7 Advanced Navigating and Plotting 3000 alphanumeric waypoints with selectable icons and comments Built-in Worldwide marine basemap to 20 miles includes detailed ocean, river and lake coastlines, cities, interstates, US state highways, and local thoroughfares 50 reversible routes with up to 50 waypoints each Uploadable maps using Garmins MapSource PC products and BlueChart Data Cards Coordinates: Lat/Lon, UTM/UPS, Loran TD, plus over 20 grids, including Maidenhead TracBack route feature which allows you to quickly retrace your track log to a starting position Built-in simulator mode Built-in tide information from over 3,000 tide stations around the USA coastline, Alaska, Hawaii, western Canada and several Caribbean Islands Superior Fishfinding Ability Whiteline feature provides a clear image of both bottom hardness and structure See-Thru technology helps separate fish returns from thermoclines and structure Multiple zoom levels with a moving view window Underwater waypoint marking Map/Sonar split screen combines navigation and fishfinding information Fish and depth alarms
Introduction Capabilities
Introduction Packing List
Before installing and getting started with your unit, please check to see that your package includes the following items. If any parts are missing, please contact your Garmin dealer immediately. Standard Package: GPSMAP 178/178C Sounder Unit GA 29 Remote External Antenna and 30 cable* Internal Antenna** Single-Knob Tilt & Swivel Bracket Power/Data Cable Owners Manual Quick Reference Card Protective Cover

Getting Started Changing Data Fields/ Active Route Page
Press PAGE to see the last page appearing in the main sequence, which is the Active Route Page. Whenever you have activated a route or Follow Track, this page lists the names of the route points along with useful data for each point. As you navigate the route, the information automatically updates to indicate the next point along the route. For more detailed information on the Active Route Page, see page 64.
You may change the size of the data fields.

Current waypoint

Getting Started Main Menu Page/ Deleting Waypoints

Main Menu Page

As youve seen, the primary pages provide map, sonar, and navigation information. The tours last page is the Main Menu Page, which allows access to the GPSMAP 178/178C Sounders waypoint, route, and planning functions, as well as various operational and navigation setup features, and celestial and tide data.
The Main Menu is available from any page, and is accessed through the MENU key. To access the main menu page:
1. Press the MENU key twice (or hold down the MENU key for two seconds.).

Submenu Tabss

The Main Menu Page lists 16 vertical tabs that are divided into categories by function. You can view a particular menu by simply highlighting the desired tab, which shows any secondary (horizontal) submenu tabs and options for that tab. To get a basic feel for how the Main Menu Page works, lets delete the two waypoints you created during the simulated tour. This ensures that you have a clean slate once you start navigating in your home waters. To delete the practice waypoints:
1. Use the ARROW KEYPAD to highlight the Points menu tab. You see a list of stored waypoints appear to the right of the Main Menu list. 2. Press RIGHT one time on the ARROW KEYPAD to highlight the User submenu tab.

Main Menu Tabs

Main Menu
3. Press DOWN on the ARROW KEYPAD and highlight waypoint 001 with the shipwreck symbol. 4. You may delete the waypoint by either pressing MENU, then highlighting Delete Waypoint; or by pressing ENTER and then highlighting Delete from the Waypoint Edit Page. 5. Press ENTER to delete the waypoint, then ENTER again to confirm. Repeat the above steps to delete the Dock waypoint also.
Congratulations! Youve now gone through the basic operation of the Garmin GPSMAP 178/178C 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. The unit is still in Simulator mode for practice, but automatically returns to its Normal operation mode when you shut it off and turn it back on. To turn the GPSMAP 178/178C Sounder off:

1. Press and hold the POWER key for about 2 seconds, until the screen is blank. 2. When the screen is blank, release the POWER key.
Getting Started Powering Off Unit
The next section of the manual describes the pages and functions of the GPSMAP 178/178C Sounder in detail. If you are unable to locate a specific option or function, please refer to the Index.

Reference Map Page

Data Fields Land Map Item Water
User Waypoint Boat Icon Navaids
Geographic Name Map Page shown using optional MapSource data.
The GPSMAP 178/178Cs Map Page provides a comprehensive display of electronic cartography, plotting, and navigational data. When using the unit with the optional BlueChart data or MapSource software, the map display shows your boat on a digital chart, complete with geographic names, map items, navaids and a host of other chart features. It also plots your track and displays any routes and waypoints you create. An on-screen cursor lets you pan and scroll to other map areas, determine the distance and bearing to a position, and perform various route and waypoint functions. When the cursor is active, an additional data window appears below the data fields to indicate the position, range and bearing to the cursor or a selected waypoint or map item. The map scale displays at the bottom right of the page. The (ZOOM) IN and (ZOOM) OUT keys, combined with the ARROW KEYPAD, let you select zoom ranges and move the cursor. Two basic map operating modes, position mode and cursor mode, determine what cartography is shown on the map display. Position mode pans the cartography to keep the present position marker within the display area, while cursor mode pans the cartography to keep the cursor within the display area. The GPSMAP system always powers up in the position mode, with your vessel centered on the map display. When sufficient map coverage is not available to keep the boat centered, the boat icon moves toward the edge of the display. When the ARROW KEYPAD is pressed, the GPSMAP 178/178C enters cursor mode. In cursor mode: The cursor can be moved over the map display using the ARROW KEYPAD. Whenever the cursor reaches the edge of the display, the map scrolls forward under the cursor. Keep in mind that the boat icon moves with the map scrolling and may go off the display screen (you may not be able to see your present position). When the cursor is stationary, a fixed coordinate position appears in the position field. Note that the distance and bearing changes as the boats position changes.

Whenever you zoom in cursor mode, the cursor is centered on screen.
To return to position mode, press the QUIT key.
Reference Map Page: Cursor
When the cursor reaches the edge of the map, the unit may pause as it loads new map data.

Using the Cursor

The cursor allows you to pan away from your present position and scroll to other map areas around the world (even outside of your current detail coverage). As you pan past the edge of the current map display, the screen actively scrolls forward to provide continuous map coverage. You see an hourglass symbol by the pointer while the unit is busy drawing new map detail. To move the cursor:
1. Press the ARROW KEYPAD to move the cursor in an up, down, left or right direction.
As you move the cursor, the distance and bearing from your present position to the cursor is 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 changes as your boat moves. The cursor may also be used to snap to on-screen waypoints and map items, allowing you to review a selected position directly from the map display. To select an on-screen waypoint or map item with the cursor:
1. Use the ARROW KEYPAD to move the cursor to the desired waypoint or map item (if there are several waypoints grouped closely together, zoom in closer for a better view). 2. When a waypoint or map item is selected, it becomes highlighted on screen, with the name and position displayed. Press ENTER to show details of the map item. When using BlueChart or MapSource data, additional information tabs appears. Use the ARROW KEYPAD to highlight the individual tabs to display the information and additional options.
Move the cursor over an item on the map to highlight it.
Additional information tabs. Pressing ENTER/MARK while highlighting a map item brings up additional details and options. Option buttons
Reference Map Page: Cursor and Zooming
To eliminate the cursor and re-center your position on-screen:

1. Press the QUIT key.

The cursor may also be used to create new waypoints directly from the map. To create a waypoint with the cursor:

Zoom Adjustment

Range Adjustment
Split: shows two reduced-size sonar pictures at the same time. The right half of the display 2X screen shows the complete sonar picture at its original scale. The left half shows a portion of the original picture at 1/2 depth scale. Zoom: displays the 2X zoomed picture on the full screen and does not show the original 2X depth scale. Split: shows two reduced pictures; the right at the original depth scale and the left at 1/4 the 4X original depth scale. Zoom: displays only the 4X zoomed picture on the full screen. 4X (Bottom) Split: shows two reduced pictures; the right at the original depth scale and the left Btm showing sonar returns from the bottom up. All target depths read as a distance from the bottom. (Bottom) Lock: displays only the Bottom Lock picture (returns from the bottom up) on the Btm full screen.
4X Split Zoom Display (Dual Frequency Mode)
Once activated, the zoomed picture becomes the Sonar Page display. You may also cycle through the sonar zoom display levels by pressing the IN or OUT keys. The Zoom function can be deactivated by pressing the OUT key until the No Zoom setting appears.
V iew/Span available when a Zoom scale other than No Zoom is selected. The View or Span setting is used to change the viewing range of a zoomed display. If the Zoom is set to 2X split or 4X split, only the zoomed portion on the left side of the screen is affected by the change. If the Zoom is set to Bottom Split or Bottom Lock, Span adjusts how far off the bottom the unit displays data. In Zoom mode, you can control the view of the left side of the split. G ain allows you to control the sensitivity of the units receiver. This provides some flexibility in what is seen on the display. To see more detail, increase the receiver sensitivity by selecting a higher gain percentage. If there is too much detail or if the screen is cluttered, lowering the sensitivity may increase the clarity of the display. T arget Level adjusts the color range of a return (or target). A Color Bar (see also page 39) appears on the right side of the screen as you adjust this setting. A higher percentage setting results in stronger-signaled returns (see page14). This setting does not increase/decrease the unit Gain. W hiteline controls how the unit displays information about the bottom type (hard or soft). With the Whiteline Off, the bottom return displays as red and contains no information on bottom hardness. With Whiteline set at Normal or 1-100%, the bottom return becomes white with a red line indicating where the water meets the bottom. To turn the Whiteline Off, press the ARROW KEYPAD DOWN until the setting bar is all the way at the bottom of the range and reads Off. See page 114 for more detail on this feature. F requency allows you to choose a transducer frequency. Frequency refers to the pitch of the sound that the transducer sends and receives. You may choose 200kHz, 50kHz, or Dual frequency. D epth Line adds a horizontal depth line across the display which is used to measure the depth of underwater objects. The depth of the line appears in a box on the right side of the line. Press UP or DOWN on the ARROW KEYPAD to control the position of the line on the graph. The depth is displayed in a window on the right side of the line. To turn the Depth Line Off, press the ARROW KEYPAD UP until the setting bar is all the way at the top of the range and reads Off.

Proximity Waypoint List

The Proximity submenu of the Points tab lets you define an alarm circle around a stored waypoint position, and can be used to help you avoid reefs, rocks, or restricted waters. Up to ten waypoints may be listed, with a maximum alarm radius of 99.99 nautical or statute miles or kilometers. If a proximity alarm circle overlaps with an existing alarm circle, the message Proximity Overlaps Another Proximity Waypoint appears. Since the unit only alerts for one of the overlap points, use caution when navigating in these areas. If you enter an alarm circle overlap, you are only alerted to the closest proximity waypoint.
To add a proximity waypoint:
1. Use the ARROW KEYPAD to highlight an empty space on the Proximity list and press ENTER. The Find screen appears. Highlight Waypoints and press ENTER. 2. Use the ARROW KEYPAD to highlight the desired waypoint from the By Name or Nearest tab lists. The Waypoint Review Page appears for the selected waypoint. 3. With OK highlighted, press ENTER to confirm. The distance field is now highlighted. 4. Press ENTER to begin entry of the proximity radius. 5. Use the ARROW KEYPAD to enter a distance value (to 99.99 units) and press ENTER.
To turn proximity alarms on or off:
1. Use the ARROW KEYPAD to highlight the field below Proximity Alarm and press ENTER. 2. Select the desired ON or OFF setting and press ENTER.

Proximity Waypoints List

The following options are available from the Proximity submenu of the Points tab: Delete Alarm removes selected waypoint from proximity list. Delete All removes all waypoints from proximity list.
To display the waypoint menu options:
1. Using the ARROW KEYPAD, highlight the Proximity tab and press MENU.

Proximity Circle

Proximity Waypoint
To clear one or all proximity waypoint(s) from the list:
1. Use the ARROW KEYPAD to highlight the proximity waypoint to clear and press MENU. 2. To clear a single alarm, highlight the Delete Alarm option and press ENTER. 3. To clear all proximity waypoints, select the Delete All option and press ENTER.

1. Use the ARROW KEYPAD to move the arrow cursor to the desired position and press NAV. 2. With Go To MAP Point highlighted, press ENTER.
TracBack Navigation (Follow Track)
Go To MAP Point allows you to navigate to a spot on the map that is not a waypoint or map item.
The TracBack function allows you to retrace your path using the track log automatically stored in the receivers memory, which eliminates the need to store waypoints along the way. TracBack routes are created by reducing your track log into a route of up to 50 turns and activating an inverted route along those points. Once activated, a TracBack route leads you back to the oldest stored track log point, so its a good idea to clear the existing track log before you start your current trip. To clear the track log and define a starting point for a TracBack route:
1. Press MENU twice to display the Main Menu. 2. Using the ARROW KEYPAD, highlight the Track tab, then highlight the Active tab to the right. 3. Use the ARROW KEYPAD to highlight Erase and press ENTER. 4. Highlight OK and press ENTER.
Highlight Save and press ENTER to save an active track log.
You must first save the track log before you can use the Follow Track feature. The Save feature allows you to store up to 15 track logs from certain times and dates. To save a track log:
1. From the Main Menu, use the ARROW KEYPAD to highlight the Track tab, then highlight the Active tab to the right.
2. Use the ARROW KEYPAD to select Save and press ENTER. 3. On the Save Back Through window, highlight the desired time, date, or Entire Log and press ENTER. 4. Next, the track begins saving and then display the Saved Track window when done. The default name, distance, and number of points (700 maximum) are displayed. To change the name of the saved track, highlight the name field and press ENTER, make your changes and press ENTER again. To choose a color that is used to display the saved track line, highlight the field and press ENTER, choose a Color and press ENTER again. To display the track on the Map and Highway pages, highlight the check box to the left of Show on Map and Highway and press ENTER. To view the track on the map, highlight Review on Map and press ENTER. Press QUIT to exit the Track Map window.

Once a MOB has been activated, a MOB waypoint with an international MOB symbol is created and the unit is set on an active navigation to that point. Use any of the Navigation Pages to guide you back to the MOB point. The MOB waypoint is stored in the waypoint list and may be deleted like any other waypoint (see page 51). To stop navigation to the MOB position:
Highlight Stop Navigation and press ENTER to stop navigating.

Routes

The last way to navigate to a destination is to create a user-defined route. The Garmin GPSMAP 178/178C lets you create and store up to 50 reversible routes (numbered 1-50), with up to 50 waypoints each. Routes can be created and modified in two ways. The first way is to Edit on Map from the Route Edit Map Page, allowing you to see each route graphically on-screen as you create, review, or modify the route. The second way is to Edit as Text from the Route Review Page, allowing you to see a list of the waypoints as you create, review, or modify the route. All of the GPSMAP 178/178Cs route functions are accessed through the Main Menu Page or the NAV key. To create a route graphically:
1. Press the MENU key twice to display the Main Menu Page. Use the ARROW KEYPAD to highlight the Route tab. 2. Press the MENU key to display the route options page. Select New Route and press ENTER. Or, highlight the first available blank slot in the Route List and press ENTER. 3. To add an existing waypoint or map item to the route, use the ARROW KEYPAD to highlight the desired waypoint or map item on screen and press ENTER. Map items do not appear in the waypoint list. To create a waypoint from a map item, see page 45. 4. To add a new waypoint to the route, use the map cursor to select the desired map position and press ENTER. Press ENTER again to confirm the new waypoint. You may also change the name, symbol, and other properties of the new waypoint (see pages 48). As you add each new waypoint to the route, the data window at the top of the map display shows the waypoint/map item name, bearing and distance from your location, and coordinates of the cursor. The bottom of the display shows you the number of available and used points. A route line appears on the map to indicate each completed leg, and a dotted line appears to indicate the distance and bearing to the arrow cursor from the last route waypoint.
Reference Creating a Route
Main MenuRoute Tab and Route Options Menu
5. Repeat steps 3 and 4 until you have finished defining all route waypoints. 6. When finished press QUIT twice to return to the Route List Page; or press MENU, highlight Edit as Text and press ENTER to return to the Route Review Page.
You see ADD below the cursor as you add points.
Reference Creating a Route/ Following a Route
To create a route using text from the Route Review Page:

SNR and Distance shows data when signal is received.

To restart the scan:

1. Press MENU, highlight Restart Scan and press ENTER. The Status field shows one of the
following: Tuning unit is attempting to tune to the specified frequency and bit rate. Scanning unit is automatically scanning through the frequencies and bit rates. Receiving unit is receiving DGPS signal and ready for operation. Check Wiring unit is not making connection with DGPS receiver.
When the unit is receiving a DGPS signal, the SNR (Signal to Noise Ratio) and Distance fields shows data. The SNR range is 0dB to 30dB, with 30 being the best. The Distance may or may not show data, depending upon the signal being broadcast from the DGPS site.
You may also manually enter a frequency and bit rate.
The DGPS beacon transmitters are operated by the U.S. Coast Guard (or similar government agency in other countries), which is responsible for their accuracy and maintenance. For DGPS transmitter problems or to find the most updated list of frequencies and coverage areas, contact your local USCG, or see their web site at http://www.navcen.uscg.mil/

NMEA Interface

If you are going to interface the GPSMAP 178/178C with another piece of equipment (such as a radio or autopilot), the unit needs to be set to output NMEA data. More information on wiring and NMEA data may be found on page 96. To activate the NMEA data:
1. On either port of the Comm Tab, highlight the Serial Data Format field and press ENTER. 2. Select NMEA In/NMEA Out and press ENTER.
Advanced NMEA Output Setup
The GPSMAP 178/178C NMEA data transmission can be customized to change the precision of the Lat/Lon minutes, set up the waypoint IDs, and keep the output rate at two seconds. If the unit is set up to output all of the available NMEA sentences, the output rate may exceed two seconds. The Advanced NMEA Output Setup Page allows you to turn on/off the GPS status (GSA. GSV), Waypoint/Route (WPL, RTE), and the Garmin Proprietary sentences. See page 96 for more information on wiring and NMEA data. Lat/Lon Minutes Precision allows you to adjust the number of digits to the right of the decimal point for transmission of NMEA Output, either 2, 3, or 4 digits. The Waypoint ID setting lets you choose to output the waypoint identifiers as names or numbers. To set up the Advanced NMEA page:

On the Units Tab of the Main Menu, press MENU, then highlight Loran TD On and press ENTER to select Loran TD.
Or, highlight the Position Format field, highlight Loran TD and press ENTER to select Loran TD.
The LORAN TD Setup window contains the fields to select the Loran GRI-Chain Number, Primary and Secondary Stations, and TD Offsets. To setup Loran TD from the Main Menu:
1. Using the ARROW KEYPAD, highlight the Setup tab, then press RIGHT to highlight the Units submenu tab. Highlight the Position Format field and press ENTER. You may also press MENU from the Units tab to display the Loran TD On option. (If you use Loran TD On, skip to step 3.) 2. Highlight Loran TD, press ENTER, then highlight Setup and press ENTER. 3. To change the settings of any of the five fields, highlight the field, press ENTER, select/enter the desired setting and press ENTER. 4. When done, press the QUIT key to return to the Main Menu.
Appendix B Loran TD Setup
If the active GRI Chain, secondary stations or offsets have been changed since the waypoint was created, the waypoint now references the active GRI-chain and secondary stations and adjust the TD coordinates accordingly. Remember that the GPS is not relying on the LORAN signal for navigation and actually converts the TD coordinate to a useful LAT/LON coordinate (in the background) before storing the waypoint to memory or using it for navigation. Because of this the unit can navigate to a TD coordinate anywhere in the world. For more information on Loran TDs, you may download Garmins Loran TD Position Format Handbook from the Garmin web site.

Loran TD Setup Window

Appendix C Map Datums

Adindan Afgooye

Adindan- Ethiopia, Mali, Senegal, Sudan Afgooye- Somalia

Chua Astro Corrego Alegr

Chua Astro- Paraguay Corrego Alegre- Brazil
AIN EL ABD 70 EL ANBD 1970- Bahrain Island, AIN Saudi Arabia Anna 1 Ast 65 Anna 1 Astro 65- Cocos I. ARC 1950 ARC 1950- Botswana, Lesotho, Malawi, Swaziland, Zaire, Zambia, Zimbabwe ARC 1960 Ascnsn Isld 58 Astro B4 SorolSorol Astro Bcn E Astro Dos 71/4 Kenya, Tanzania Ascension Island 58- Ascension Island Atoll- Tern Island Astro Beacon E- Iwo Jima Astro Dos 71/4- St. Helena Astronomic Stn 52- Marcus Island
Djakarta Djakarta (Batavia)- Sumatra Island (Indonesia) Dos 1968 1968- Gizo Island (New Georgia Dos Islands) Dutch Easter Isld 67 Dutch Easter Island 1967
European 1950 European 1950- Austria, Belgium, Denmark, Finland, France, Germany, Gibraltar, Greece, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland European 1979 European 1979- Austria, Finland, Netherlands, Norway, Spain, Sweden, Switzerland Finland Hayfrd Gandajika Base GDA Geod Datm 49 Guam 1963 Gux 1 Astro Hjorsey 1955 Hong Kong 63 Hu-Tzu-Shan Indian Bngldsh Indian Thailand Indonesia 74 Ireland 1965 ISTS 073 Astro Johnston Island Finland Hayford- Finland Gandajika Base- Republic of Maldives Geocentric Datum of Australia Geodetic Datum 49-New Zealand Guam 1963- Guam Island Guadalcanal Island Hjorsey 1955- Iceland Hong Kong Taiwan Indian- Bangladesh, India, Nepal Indian- Thailand, Vietnam Indonesia 1974-Indonesia Ireland 1965- Ireland ISTS 073 ASTRO 69- Diego Garcia Johnston Island

Appendix G Understanding Sonar
This fish is currently in a dead zone and is not detected by the sonar. The fish is in the coverage area of the transducer, but remember the first strong return sets the bottom level. The fish is eventually detected when the first strong return sets the bottom level below the fish.
Appendix G Transducer Coverage

Transducer Coverage

The area covered by the transmitted sound waves is determined by the cone angle of the transducer and the water depth. Cone angles may vary between different types of transducers. For example, a 50kHz frequency may provide a wide 40 cone angle, with a coverage width that is approximately 2/3 of the water depth. As shown in the sidebar, the 40 cone angle (50kHz frequency) approximately covers the area of a 20 foot diameter circle at a 30 foot depth. A 200kHz frequency may provide a narrow 10 cone angle, with a coverage width that is approximately 2/10 of the water depth. As shown, the 10 cone angle (200kHz frequency) approximately covers the area of a 6 foot diameter circle at a 30 foot depth. When using the GPSMAP 178/178C in Dual frequency mode, the unit transmits both 50kHz and 200kHz signals at the same time. The Dual frequency capability of the GPSMAP 178/178C allows you to have a large coverage area and still retain good bottom resolution. When in Dual frequency mode the unit uses the narrow cone angle (200kHz) to display detailed bottom information, keeping Dead Zones to a minimum, and the wide cone angle (50kHz) for the large coverage area. Fish returns from the wide and narrow beams appears differently on the display. The wide beam tends to show longer fish returns than the narrow beam.
200kHz - 10 Cone Angle 72" coverage at 30'
50kHz - 40 Cone Angle 20' coverage at 30'

Wide Cone Angle

Narrow Cone Angle

Understanding the Graph

It is important to understand that the unit does not display a 3-D representation of the underwater environment. The unit can display multiple things at the same time, but cannot determine where the return originated only when it was received. Examples 1 and 2 provide a look at the underwater world from a top view, and illustrate how these views would be displayed on the graph. On both graphs it appears the fish and tree are side by side as shown in Example 1. However, when we look at Example 2, we see that the fish can be several feet from the tree. It is important to remember that the sonar cannot determine where in the coverage area the tree or fish are, only that the returns were received at the indicated depths in the same time frame.

Calibrate Water Speed 39, 40 Capabilities v Card Tab 82 Cautions iii Celes Tab 74 Change Numbers 18, 30, 40, 43 Cleaning 117 Clock Alarm 90 Color, Sonar Background 39 Color Bar 39 Color Mode 27 Communications Tab 86-90 Compass Page 16, 41 Compass Page options 41 Compass Ring 16, 41 Contrast 1, 6 Copying Routes 59 Course Line 29 Course Up 27 Creating Map Waypoints 13 Creating Routes 57, 58 Creating Waypoints 44-47, 50 Cursor 9, 13, 22-24 Product Support i
Background Color 39 Backlight 6 BACKLIGHT Key 1 Basemap 27 Battery Alarm 90 Bearing Line 29
Editing Routes 60-63 Editing Waypoints 48, 49 Elevation Units 85 Entering Data 3 ENTER Key 1 Erasing Tracks 75

GPS Tab 68-71 Grids 84

Heading 85 Heading Line 29 Hide Numbers 37 Hide Pointer 37 Highway Page 17, 18, 42 Highway Page options 42 Highway Scale 42 How To Index viii

Appendix I Index M

Magnetic North 85 Main Menu 20 Main Menu Page 67 Main Menu Tabs 67, 68 Main Pages 8 Map, Set Up 26 Map/Sonar Split Page 14, 32 MapSource 27 Map Cursor 9 Map Datums 85, 104, 105 Map Information Page 27 Map Item 11 Map Outlines 29 Map Page 8, 9, 22 Map Page Options 25 Map Scales 12, 24 Map Split Sonar Detail 39 Marking Position 44 Marking Waypoints 10 MARK Key 1, 44, 45 Measure Distance 26 119
FCC Compliance ii Find 65, 66 FIND Key 1, 65 Find Options 66 Fish Alarm 91 Fish Symbols 38 Flasher 39 Following Routes 58, 59 Follow Route 11 Follow Track 11, 54 Frequency 14, 15, 35 Full Screen Map 25
Initialize Position 71 Initializing 4 Installation 92-100 Interfacing 96 IN Key 1, 22, 24
Keel Offset 39, 40 Keypad 1, 2
Gain 15, 35 General Tab 27 Going to a Destination 11, 53, 54 Go To 53 Go To Point 11, 53 GPS Information Page 5, 6 GPS Status 5, 70
Language 83 Lat/Lon Grid 29 Light Sectors 28 Loran TD 84, 102, 103 Loran TD Setup 103

Appendix I Index

MENU Key 1 MENU key 20 Merge From Card 82 Messages 106, 107 MGRS 84 MMSI Number 77, 78, 81 MOB 56 MOB Key 1, 56 Moon Phase 74 Moon Rise/Set 74 Mounting the Transducer 98, 99 Move Waypoint 47 Moving Waypoints 49
Nearest To Next 66 Nearest To Other 66 New Waypoint 46 NMEA 86-90, 96 NMEA Interface 89 NMEA Output Setup 89 Noise Reject 15, 36 North Reference 85 North Up 27 Numbers 30, 40

QUIT Key 1

Range 15, 34 Receiver Status 69, 70 Registration i Replace From Card 82 Reset All 74 Reset Max Speed 74 Reset Odometer 74 Reset Trip 74 Retail Demonstration 7 Reviewing Routes 60 Reviewing Tracks 76 Reviewing Waypoints 48 Routes 57 Routes, Copying 59 Routes, Creating 57, 58 Routes, Deleting 59 Routes, Editing 60-63 Routes, Following 58, 59 Routes, Reviewing 58, 60 Routes, TracBack 54 Routes, Trip Planning 63 Route List Page 59 Route Review Options 60 Route Review Page 60