Session 10 ROUTES

A waypoint (WPT or WP) is a designated location with geographic coordinates.

A group of waypoints, linked together in a logical sequence on a GPS, is called a “route.”

Entering Waypoints 0001 Enter in name/icon. Enter LAT/LON. Enter message (not recommended) Waypoint number. (Keep it simple) Menu of waypoint options at bottom. Bearing and Distance 0001 Entering waypoints on a single screen is SO much easier than using a Lowrance “field at a time” GPS. Reference waypoints are not used very frequently, but they allow you to specify a waypoint in reference to another waypoint. Sometimes called Waypoint Projection. Note the nice little edit menu at the bottom.

This is not a compass reading! GPS Position Page This is not a compass reading! Direction bar at top of screen. Course and Speed Mileage and Altitude Position Clean presentation, with some user-modifiable data fields on the GPS II (which will become more common). Time

A simple waypoint entry screen

Verifying your present position as a waypoint WPT 4 Use a simple numbering system. Do not place your position on top of the Aid. Risk of collision! Validate every waypoint before using it as a permanent waypoint in a route. WPT 3 If you don’t name the waypoint when you store it, you’ll forget where you were when you stored it! Autoroute is very handy for retracing channels. Position averaging does not have a ton of marine applications, since the boat will tend to move while you average. More of a hunter/hiker application. In the GPS 12 XL, you can leave it on and averaging your position for hours if you like, which effectively eliminates S/A. WPT 2 WPT 1

Waypoints are used extensively in GPS navigation: As boundaries between voyage segments – LEGS. To mark turning points, destinations, and aids to navigation. To mark hazards to navigation.

Mark the boundaries between legs. Waypoint Use Rock Marks hazards to navigation or obstructions. Mark the boundaries between legs. WPT 4 Marks the turn in a channel WPT 3 If you don’t name the waypoint when you store it, you’ll forget where you were when you stored it! Autoroute is very handy for retracing channels. Position averaging does not have a ton of marine applications, since the boat will tend to move while you average. More of a hunter/hiker application. In the GPS 12 XL, you can leave it on and averaging your position for hours if you like, which effectively eliminates S/A. WPT 2 WPT 1

GPS receivers enable waypoints to be entered and stored in various ways. A sequence of waypoints can define a planned route. Most GPS receivers store routes as well as waypoints.

NEVER rely on one means of navigation. Select waypoints that can be easily verified by other methods--visual fixes, soundings, radar, etc. NEVER rely on one means of navigation.

It is important to check your chart before establishing WPTs. If your course crosses an island, the GPS receiver will direct you to navigate over this hazard. WPT 02 WPT 01

Why create a route? Routes are lists of sequential waypoints. GPS can automatically advance you to the next waypoint. Routes can be reversed to retrace your original track. Routes keep you from wandering into danger and shorten the distance that you travel. WP 4 WP 3 Pretty self-explanatory. Many boaters will get along fine by just using GOTO navigation. Route editing can be very difficult on some models. WP 2 WP 1

WP 4 Editing Routes GPS receivers should allow you to delete, move, or append waypoints. In this case: WPT 2 will be deleted and moved. WPT 3 will be changed. WPT 4 will be added. WPT 3 WPT 2 WPT 3 This is how it should be: you can do anything you want to a route, including copying it to another route so you can further modify it. WPT 2 WPT 1

ROUTE Navigation WPT 2 Used by boats under power when they have to stay in a channel or follow an exact course line Useful functions: Cross Track Error (XTE) Course To Steer (CRS) Time To Go (TTG) Automatic course change at next waypoint (WPT) Total distance to end of leg (DTG) Total time to end of route. Use ROUTE navigation when you don’t want to wander off-course due to dangers. WPT 1

On your nautical chart, stick small labels showing the Waypoint Number beside each WPT. Measure, plot, and label your course lines. Update your Trip Log. Determine the LAT/LON for each Waypoint and establish Waypoints in your GPS. Establish a XTE safety zone C 225 D 2.4 WP 2 C 224 D 3.1 1 Plan route 2 Check for obstacles between waypoints (Use the pen to draw in an island while talking about it, hit the letter “e” to erase when done) 3 Check ½ mile either side of track line for shallow water etc. to allow for possible leeway. Plot course in true or magnetic depending on how your GPS is setup if route clear of obstacles. Determine distance between waypoints. 6. Discuss why I like Lat and lon vs bearing and distance. It insures accuracy of waypoint in that you should see the same bearing and distance appear on you GPS display. If it does not something is wrong and it allows you to find the problem and correct it before getting underway and possibly running aground. Use of GPS Underway At each waypoint, check receiver indication of bearing and distance against those measured on chart--this is a both a receiver check and detects errors in entering waypoints WP 1 ANIMATION

Highway Page on GPS Added line showing vessel direction 095º T Next waypoint Difference between line and the center of the road is XTE (Cross Track Error) You can actually use this page walking to a near, say 150 yard, waypoint. You may wish to add it as an exercise. Turn to starboard to go to next waypoint

GPS Route Page Display Perspective view of upcoming waypoints Shows if you are heading for next waypoint Customized data fields not needed.

Arrival Alarm Alarm Sounds Sounds whenever the boat penetrates an adjustable ring around a waypoint. Initiates new heading data for the next leg in your route. Note that waypoint is positioned just off the ATON not on top of it. 1/2 M Alarm Sounds

AV Task 6-5 How routes are created and used by GPS – page 143. Any questions about: AV Task 6-5 How routes are created and used by GPS – page 143.