Did you know that your nautical GPS offers a way to warn you if you sail too close to rocks, coral, or other “ship killing” dangers. Make tough sailing navigation passages much easier with the magic of proximity circles. Put these five easy steps into play today on your small cruising or racing sailboat.
Most handheld marine GPS receivers (or chart plotters) have a proximity function that allows you to set up a waypoint surrounded by a circle. You can set an alarm to sound if you touch the circle’s edge. This gives you time to take action and turn toward deeper water. Follow these five steps for navigation safety.
1. Look over your nautical chart
Plot your course lines onto your paper navigational chart. Even with the great accuracy of GPS and chart plotters, vector displays often do not give enough detail when sailing close to hazards.
2. Set up hazard waypoints
Measure the navigation latitude and longitude of the center of the hazard. For a cluster of rocks or coral, use the approximate center of the cluster as the center waypoint. Write each hazard waypoint down into a logbook along with the lat and long.
3. Determine your “circle-of-safety”
Use a plotting compass to measure the radius of the circle. Push the needle point into the waypoint. Scribe a circle that surrounds the danger. Add at least 1/2 of that radius for safety.
For example, if the radius of the circle that surrounds the hazard was 1 nautical mile, then your proximity circle should have a radius of at least 1.5 nautical miles. Increase this distance as you see fit, based on maneuverability, point of sail, wind, and current.
4. Program each hazard waypoint
Enter each hazard waypoint into your gps. Label each hazard waypoint so that it cannot be confused with a non-hazard waypoint. For example, you might use Z-1; Z-2, or any other unique name. Double check each hazard waypoint’s latitude and longitude with the navigational chart before going to step 5.
5. Set up and test your proximity circles
Check your manual for directions to access and set up “proximity” waypoints. Access the proximity menu and set the alarm toggle to “on”. Go to the menu to select each of your hazard waypoints.
Set your circle radius with the toggle (up-down) key. Finish one hazard waypoint; then page over to the route screen. Check to make sure the computer has drawn the correct size proximity circle. Repeat this method for all other hazards.
Use these five easy steps to set up proximity “circles-of-safety” in your nautical GPS. Boost your sailing navigation skills to the next level for worry-free sailing wherever in the world you choose to cruise.
Captain John Jamieson shows small boat cruising skippers how to reach their sailing dreams today! Get his popular free report “Ten Top Boat Safety Checks for Cruising Boat Skippers” at http://www.skippertips.com/public/242.cfm.