OUPV / Six Pack Captains License Course

NAVIGATIONAL GENERAL - Electronic Navigation

Navigation General

Electronic Navigation and Marine Radiotelephone

Electronic Navigation can be an extremely precise method of navigating, providing that the mariner’s equipment is working properly.  It can be limited by the equipment’s range and accuracy.  Electronic navigation includes the use of GPS, the Global Positioning System.  GPS technology can determine a vessel’s position anywhere on earth.  It is a system of 24 satellites operated by the Department of Defense.  It operates worldwide, 24 hours a day, in all weather conditions.    Besides indicating latitude and longitude positions, GPS can provide other navigation information, especially with route planning. 

 are locations with geographic coordinates and can be set on a GPS.  Once set, they can be accessed for future trips.  Most GPS receivers can store numerous routes as well as numerous waypoints.  A route can be plotted on a nautical chart to make sure there are no hazards along the way.  The GPS can then take your vessel from waypoint to waypoint in a straight line.  A waypoint mark can also be used to mark a hazard to avoid.  Many GPS systems are equipped with alarms to indicate when the vessel is off track, when a waypoint is within range, and if a vessel at anchor moves from a waypoint.

The Global Positioning System (GPS) was designed by the military and therefore can be detuned during times of war to prohibit others from using it. There is no direct cost to the user for this service. Most GPS receivers require four or more satellites to fix a position and their advertised accuracy can be from 1 to 100 meters, depending on the brand. Mariners should never assume that the GPS position will be the same as the charted position.  Differential GPS is used by the military and uses a network of ground stations as well as the satellites to further refine the signals.  Its accuracy is 1-3 meters.  You should have backup to GPS.  Prudent navigators should not rely solely on electronic navigation systems, but should carry charts and other up to date navigation publications.  Many GPS instruments contain a Man Overboard button that can be activated by holding the button in until activation.  A Man Overboard waypoint is created to assist in retrieving the person by recording the last known position.

The Marine Radiotelephone is a vessel’s most important piece of safety equipment.  It is important for all crew members to be proficient with radio operations and appropriate radio protocol.  Most marine communications are done by radio transmissions.  Typically, when one person speaks, the second person must wait and not talk over the other person.  VHF is used for local, short-range marine communication and usually has about a 20 mile range.  The range depends mainly on the height of the antennas for both the receiving and transmitting stations.  The VHF radio should be checked daily and a log kept.  Newer VHF radios contain a distress button that transmits the GPS location of the distressed vessel after the button has been pushed until activated.  The manual must be followed for proper installation as it must interface with the GPS through an NMEA port.  It must be programmed and registered properly.  All crew members and passengers should be shown this critical piece of safety equipment.

The single side band (SSB) range is 100 miles or more and requires a license.  A vessel cannot carry a SSB unless it also has a VHF radio.  The VHF must be the first radio used to ease SSB traffic.  The SSB operates on the frequency 2182 kHz and is equivalent to Channel 16 on the VHF radio 156.8 Mhz. The U. S. Coast Guard is broadcast on 2670 kHz (SSB) or the equivalent VHF Channel 22A.  Small pleasure craft and OUPV (six pack vessels) with a VHF radio are not required to have a station license but may elect to have one as it is optional for these vessels.  However, the FCC requires that certified vessels have a radio station license. The FCC also requires that SSB, radar, SATNAV, Global Marine Distress Signaling System (GMDSS) have a station licenses.  Inspected vessels are required to have a crew member licensed as a Marine Radio Operator (MROP License) through the FCC and can be obtained through Captains Marine.  It is currently good for life.  Loran C has been phased out completely.  The GMDSS system is a fax machine tied to satellites that tells where and who you are, and why you are calling, at the push of a button.

Be sure your radio is set on the proper frequency.  Use the squelch control to adjust the level to allow stronger signals to be heard and reduce static noise on the speaker.  As mentioned above, do not talk over other transmissions.  Keep the microphone 1 -2 inches from your mouth and use your body to block other boat noises from being transmitted.  Keep all transmissions short and to the point, thinking about what you are going to say prior to keying the microphone.  Speak clearly and concisely.  Use proper terminology such as “over” at the end of each transmission.  Messages are not private and can be heard by anyone with a radio or scanner.  Profanity or other inappropriate comments are not permitted to be transmitted. Speak English clearly as indicated by the following video.

The term seelonce means silence and the term feenee means finished.

Distress radio calls include MAYDAY, which means imminent danger of sinking or a life or death situation, PAN, which means urgent, and SECURITE, includes weather and navigation warnings.  MAYDAY is a distress of the highest nature and takes absolute priority over all other transmissions.  It indicates that a person or vessel is in grave or imminent danger or a person has a life threatening injury and requires immediate assistance.  All transmissions that could interfere with the MAYDAY call should stop.   Other stations should be on alert in case they need to assist in some way.  All vessels should write down any coordinates and other essential information that is broadcast from the distressed vessel as the vessel may not be able to broadcast them again.

To make a MAYDAY call, the first step is to say MAYDAY three times.  The caller then should state the name of the vessel and call sign three times.  The most important information, the location of the vessel, should be given next.  This could be latitude and longitude, or information based on a known landmark, light or buoy. Latitude is always given first followed by the longitude.  The more accurate and detailed the location is transmitted, the easier it will be for assistance to find the vessel.  The next piece of information should be the nature of the distress and type of assistance desired, the number of people on board and the condition of any injured people.  When giving medical information, the person should use the word “possible”, such as a “possible heart attack”.  Next, a description of the vessel, including her length, type and color of hull should be transmitted.  Lastly, any helpful information that might simplify the rescue can be transmitted.  Keep in mind that the most important information should be given first in the event that radio transmission is interrupted.  A person hearing a MAYDAY call should refrain from answering allowing the Coast Guard to answer.  If the vessel is out of range, you may need to relay the information to the Coast Guard.  All information should be repeated back Verbatim to insure accuracy.  Remember that a positive attitude can make all the difference in this type of situation.  

Practical Exercise
:   Without actually keying the radio microphone, practice a MAYDAY call with another person until you feel comfortable with the procedure and cover all of the information in the correct order.


Repeat at intervals until an answer is received.

Certified vessels must have an Emergency Broadcast Placard displayed near the radio, which gives detailed instructions on how to make a MAYDAY call.  These can be purchased at a marine hardware store and must be filled in with the appropriate vessel information.  Ship station logs must identify the vessel name, country of registry, and official number of a vessel.  The station licensee and the radio operator in charge of the station are responsible for the maintenance of station logs.  The licensee must retain the logs for a period of one year from the date of entry.  Logs relating to a distress situation or disaster must be retained for a period of three years from the date of entry.  Station logs are legal documents.

 stands for Radio Direction and Ranging.  A radar unit sends out an electronic pulse that is reflected off land and other ships or any other object large enough to be detected.  The radar antenna sweeps around in a circle to plot any object surrounding a vessel in any direction.  Radar can be used to measure the bearing and range from the vessel to the object that it is picking up.  If an approaching vessel’s bearing does not appreciably change, you are on a collision course.  A course change would be required to prevent a collision.  It is important to note that just because an object is not detected by a vessel’s radar that there is no danger in hitting something on the water.  Floating debris, for example, could cause severe damage to a vessel if hit.  The useful operational range of radar is limited primarily by the height of the antenna above the water and by its power.  A low mounted antenna would not have as great a range due to the curvature of the earth.  In spite of its range limitations and the possibility of electronic malfunction, radar has many advantages.  The greatest advantage is the ability to work at night or in restricted visibility, like fog or rain.  With its potential for accurate fixes, radar can provide tremendous assistance in preventing collisions.

Radio Direction
 Finder (RDF) picks up radio signals so you can triangulate or follow the signal in to shore or towards a light or radio beacon.

RACONS or Radar Beacons are transponder devices used as a navigational aid to identify landmarks or buoys on a radar display.  Racons are used in the U.S. to identify aids to navigation (buoys and lighthouses), inconspicuous coastlines, offshore oil platforms or other structures, and to indicate the navigable spans under bridges.  The use of a racon for any purpose other than as an aid to navigation is prohibited.

fathometer, or depth recorder, also needs to be maintained. Keep the transducer clean.  The transducer converts the electrical signal to a sound signal and sends it to the sea floor.  It bounces back and that is how the depth is recorded.  This shows the depth of water that you are in, not the depth of water where you are headed.  These devices can also serve as a fish finder, operating in the same manner.  Some transducers are mounted through the hull and extend out a short distance.  If it is not mounted at the lowest point of the hull that distance needs to be taken into account when determining the depth.  When reading the depth, draft may have to be added. A muddy bottom may indicate two depths.

Commercial fishing vessels are required to have an isolated power source located on the bridge for their electrical systems.   Electrical systems should be properly maintained.  Check for corrosion, chafing, and wear.

Practical Exercise:  Check your own electronic navigation and safety equipment or the equipment on boats that you operate from for chaffing or corrosion and insure that they are in proper working order.  Measure the fathometer’s transducer in relationship to the waterline to determine the appropriate adjustment.  Make sure that you know how to use all equipment properly.  Refer to equipment manuals for further information.