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ContinuousWave: Small Boat Electrical
|Author||Topic: Radio Tales|
posted 10-16-2010 10:58 AM ET (US)
In the summer of 2010 we happened to be aboard our boat in a harbor in Northern Lake Huron. We had come about 70-miles that day in some rough seas, and when we finally reached the harbor, I was quite glad to be there. We called the harbormaster on the VHF Marine Band radio on their working channel, and made arrangements for a transient berth for the night. Once we had the boat made fast to the pier, I relaxed in the cockpit and enjoyed a beer. The radio was left on the working channel.
In the next hour or so, I listened to a number of boats call the harbormaster with their VHF Marine Band radios. The quality of the radio transmission from these several boats was quite variable.
A rather large trawler-type yacht called the harbormaster. The voice modulation on this fellow's radio was about as loud as the alternator whine from his diesel engine's battery charging current. While the transmission was intelligible, the alternator whine was much too loud. Although this yacht was quite impressive, its radio signal was not.
A sailboat called in. Their signal was weak and broken. The harbormaster asked for a repeat and for the vessel to give their current position. The sailboat replied that they were just outside the harbor. Even allowing for a 1-watt transmission, their VHF radio range was extremely limited. If they were using an antenna mounted atop their main mast, I suspect they had a bad connection. While it is possible to receive with such a bad antenna connection, transmission range is often greatly reduced.
A third boat called the harbormaster. Their radio modulation consisted almost entirely of the wind blast hitting the microphone. The intelligibility of their transmission was very low.
Another boat called. The level of their modulation was very low, and the recovered audio from my receiver was barely audible.
These four boats demonstrated four common problems in installation and operation of a VHF Marine Band radio:
--poor power connections
When transmitting, a typical 25-watt VHF Marine Band radio will draw about 6- to 7-amperes. The radio should be provided with clean 12-volt power. The appearance of alternator whine on the modulation of the radio transmitter is often an indicator that the vessel battery is in poor condition and that the wiring of the radio to the battery is not proper.
The coaxial transmission line between the radio and its antenna should be kept in good condition, and the connection at the antenna periodically checked. It is possible for antenna and transmission line systems with very marginal performance to provide adequate reception. This is due to the large amount of reserve gain available in the receiver. Any transmission line loss will greatly reduce transmitter range. Transmitters are limited to a fixed gain. Often transmission line discontinuities produce a mismatch between transmitter and transmission line, which then can result in a reduction of transmitter power to prevent damage.
Some radios sold for marine service have microphones which are very susceptible to wind blast noise. When speaking into a microphone for any radio, the microphone should be oriented to reduce the wind blast hitting the microphone element. Some microphones appear to have a large area in which the microphone is located, but in actuality the microphone element is very small and located behind a small hole in the microphone with no blast filter from wind.
The technique of speaking into a radio microphone varies with the microphone design and the operator's notion of how to use it. My experience is that the manufacturers of VHF Marine Band radios often set the microphone gain rather low, anticipating that the operator will be speaking in a loud voice and from a short distance. For those radios, when an operator speaks softly and holds the microphone 6-inches away, the resulting modulation level is very low. Since it is not generally possible for an operator to make adjustments to the microphone gain of a transmitter, the operator must adjust his microphone technique to suit the radio, its microphone, and its microphone gain setting. The best way to discover proper microphone technique is to monitor your own transmission with a second radio. Set the audio gain of the receiver in the second radio to a reference level using a commercial station such as a weather radio broadcast. Then listen to your own radio transmission. Or, have another person listen and make comparisons. This is actually better, as most people will judge the sound of their own voice as having lower volume than perceived by another listener.
posted 10-16-2010 03:09 PM ET (US)
I often hear a rather nice polite sounding American female radio operator broadcasting from a coalition warship in the area.
The responses from the vessels she is inquiring about their destination, cargo etc are often quite poor reception even from large commercial ships.
I wish my SH2100 had a meter like the old VU's you had on 70 stereos. The needle would be bent over double when she broadcasts.
posted 10-17-2010 10:40 AM ET (US)
Government stations (or in Steve's example military stations) provide a good reference for properly modulated signals. A receiver can be set to a comfortable listening level when tuned to a government station (such as a NOAA Weather Radio broadcast or a Canadian Coast Guard continuous marine broadcast). This calibrates the receiver audio gain for a properly modulated signal. Tune this receiver to a vacant working channel, and make a test transmission from your own radio. Compare the audio level of your transmitter to the commercial or government station. The receiver audio level should be very similar. If your transmitter audio is lower than the reference station, you need to speak more loudly into the microphone of your transmitter.
posted 10-19-2010 02:41 PM ET (US)
I seem to remember my old Man telling me WWII stories about how the radio operators were all from the midwest, particularly, Nebraska. When I asked why, he said because they had no accent and everyone could understand their transmissions.
posted 10-19-2010 06:20 PM ET (US)
Funny you should say that but the post with link of Sal A being on TV, the presenter who introduced him I could not understand a word
posted 10-20-2010 08:23 PM ET (US)
Omaha, Nebraska probably was an important telephone center for voice operators because of the neutral, non-specific accent of speakers from that area and the central location. See
posted 10-25-2010 02:51 AM ET (US)
I use a Standard Horizon handheld VHF with a boom microphone and single earphone mounted on a headset to counter the noise of our 90hp 2 stroke. I have been told by my brother who listens on the fixed VHF on our boat that I over modulate as a result of trying to "shout" over the aforesaid noise of the outboard.
posted 06-19-2011 07:08 PM ET (US)
I am back from another week on the boat, and during that time we were underway about 20-hours. As required by the FCC rules and regulations, we had our radio on and maintained a radio watch on Channel 16. We heard a lot of interesting radio traffic and the usual variety of radio signals.
One of the strangest was the notice of marine broadcast from the United States Coast Guard. The USCG practice is to make a broadcast on Channel 16 to notify mariners that immediately following there will be a broadcast on Channel 22A. If we hear the notice, we usually switch to Channel 22A to hear the latest notice to mariners. The radio operator at the USCG who made the broadcast must have been in a hurry to get to lunch. I have never heard such a poorly read, poor enunciated, and unintelligible transmission from the USCG. I have about 50 years of experience in copy radiotelephone transmissions, and I have a rather good ear for it. I can usually copy signals that are in the noise which others might not be able to understand. But this Coast Guardsman was readable only about one word in five, not due to a problem with reception but due to very poor radiotelephone technique by the operator. He raced through the text, failed to pause at the end of sentences, paused for no reason at other times, and generally did a miserable job. I don't expect every Coast Guardsman to sound like Walter Cronkite, but I do expect them to at least read slowly and enunciate clearly.
Now for signal problems. Typically I set the volume on my receiver by listening to a weather radio broadcast. Weather radio stations generally have excellent modulation level. If you set the radio to a nice loud level on a weather station, your receiver volume should be adequate for most signals. That works until you get the boater who speaks softly, holds the microphone three feet away from his mouth, and transmits with about five-percent modulation. That sort of signal is barely audible unless you crank the volume. But there are plenty of boats out there whose transmissions sound like that.
I also noticed the usual lousy power supply problems. Some radio transmissions have so much alternator while on them that the alternator whine is louder than the voice modulation. These boaters would be amazed to hear how badly their radio transmits. Too bad they have never hear their own boat on another radio--if they did they'd fix the power problem right away.
I did notice one anomaly with my radio receiver. While in the Traverse City area, if I monitored Channel 9, my radio receiver would open squelch with a strange mishmash of signals. Traverse City is home to a very powerful NOAA weather radio transmitter, KIH22. Its tower is about two miles from the harbor on a hilltop. Some local public service radio service stations must have also been close to me. When the public service station--it sounded like a fire department communication--transmitted, my radio would open squelch and I would hear the NOAA weather radio AND the public service station, all appearing to come in on Channel 9. This is a classic case of receiver intermodulation distortion and overload. This makes me want to buy a new radio, with a better front-end.
If your homeport is Traverse City, I bet Channel 9 sounds like this on a lot of inexpensive VHF Marine Band radios. It was the first time I had ever noticed intermodulation products on my radio, other than when someone transmitted at 25-watts from the next boat slip.
posted 06-20-2011 07:34 AM ET (US)
While sitting in the harbor at Leland, I was able to receive several NOAA weather radio stations. As I had previously noted, I was again receiving WXN69 from Sister Bay, Wisconsin, with a good signal. Leland is at the fringe of the predicted coverage area for WXN69.
I also found I was receiving WNG684 from Manistique, Michigan. That transmitter is located at Smith Lake in the Upper Peninsula, and Leland is far beyond the predicted coverage area for the signal. The path length was over 78-miles. The signal was strong and no fading was observed.
For more reading on how to use NOAA weather radio transmitters as test signals for checking the performance of your radio receiver and antenna, see
posted 06-25-2011 05:30 PM ET (US)
You can also hear the police department frequencies if you're cruising the St. Joseph river in St. Joseph, MI near the courthouse/jail. Usually it's something like a deputy radioing in a vehicle license plate for more information, but I have heard them read people's names and driver's license information over the radio....which makes me drive very carefully in that county, and is a very important reason that I don't let states use my Social Security number on my driver's licenses.
I would imagine that if you had a slip at the Pier 33 docks nearest the mouth of the river, you could observe these transmissions regularly and if you were a less than honest person, you could get some very "useful" information.
|Tom W Clark||
posted 06-25-2011 10:19 PM ET (US)
Jim -- That is interesting. You seem to imply that FCC rules require that a VHF radio be turned on when one is operating a boat equipped with a VHF radio.
This is in contrast to my understanding that if a boat is equipped with a VHF, and if it is turned on, one must maintain a watch on channel 16 or channel 9, but there is no requirement that radio be turned on.
Would you please clarify and cite the applicable law(s)?
posted 06-26-2011 08:04 AM ET (US)
According to the U.S. Coast Guard (see http://www.navcen.uscg.gov/?pageName=mtWatch )
posted 06-26-2011 09:07 AM ET (US)
ASIDE: A few years ago I was stopped and boarded by the U.S. Coast Guard for a vessel safety inspection. On my REVENGE, my VHF Marine Band radio is located on a shelf in the locker under the helm. (This is the location recommended by Boston Whaler in their owner's manual.) On the shelf below the radio I keep a set of safety flares in an orange plastic case. When underway the door to the locker is kept open (in a not very elegant method) by a retainer cord. When the inspecting Coastie came aboard, the locker was open and the radio and flare case were in plain view. The radio was on and was tuned to Channel 16.
The Coast Guardsman glanced at the helm and noted, "Radio ON and tuned to 16--good." He also said, "I see your flares in the case."
Re the regulations: they make good sense to me. The more boats with radios listening to Channel 16, the more the chance that a distress call on Channel 16 will be heard by someone. It is only common sense to keep the VHF Marine Band radio ON and tuned to Channel 16 when underway.
posted 06-26-2011 09:32 AM ET (US)
Tom Hemphill--Thanks for the cite of the applicable regulations for keeping a radio watch on Channel 16. Here is the actual regulation mentioned which pertains to recreational vessels with voluntarily equipped radios:
TITLE 47 - TELECOMMUNICATION
CHAPTER I - FEDERAL COMMUNICATIONS COMMISSION
SUBCHAPTER D - SAFETY AND SPECIAL RADIO SERVICES
PART 80 - STATIONS IN THE MARITIME SERVICES
subpart g - SAFETY WATCH REQUIREMENTS AND PROCEDURES
80.310 - Watch required by voluntary vessels.
Voluntary vessels not equipped with DSC must maintain a watch on 156.800 MHz (Channel 16) whenever the vessel is underway and the radio is not being used to communicate. Noncommercial vessels, such as recreational boats, may alternatively maintain a watch on 156.450 MHz (Channel 9) for call and reply purposes. Voluntary vessels equipped with VHF-DSC equipment must maintain a watch on either 156.525 MHz (Channel 70) or VHF Channel 16 aurally whenever the vessel is underway and the radio is not being used to communicate. Voluntary vessels equipped with MF-HF DSC equipment must have the radio turned on and set to an appropriate DSC distress calling channel or one of the radiotelephone distress channels whenever the vessel is underway and the radio is not being used to communicate. Voluntary vessels equipped with Inmarsat A, B, or C systems must have the unit turned on and set to receive calls whenever the vessel is underway and the radio is not being used to communicate.
[68 FR 46967, Aug. 7, 2003]
In my particular case, I have a radio with digital selective calling (DSC), so perhaps I could satisfy the requirement for radio safety watch by my radio's DSC feature. However, I prefer to also leave the radio tuned to Channel 16.
Also, commercial vessels may be required to keep a radio watch on Channel 13 (Bridge-to-Bridge). It is typical on a commercial vessel that there are two VHF Marine Band radios, one dedicated for Channel 16 and a second dedicated to Channel 13.
|Tom W Clark||
posted 06-26-2011 10:52 AM ET (US)
So then 99.9 percent of recreational boaters are in violation of Federal Law (myself included)?
If so, I'll need to remove the two VHF radios from my boat to bring it into compliance with the law.
posted 06-26-2011 11:01 PM ET (US)
Tom--If you do, can I have your GAM antenna?
posted 06-27-2011 11:37 AM ET (US)
Do these regulations apply to handheld VHF radios? Since I carry it on board i don't think that the boat is "equipped" with the radio. Your thoughts?
posted 06-28-2011 08:05 AM ET (US)
I don't know if one can consider their recreational vessel to not be equipped with a radio if you just turn the radio off.
The radio watch requirement is nothing new. Here is a link to a website that has preserved some USCG content from 1998 on the subject of mandatory radio watch keeping. You can infer that the requirement has been around since at least 1998, or 13-years, which may be about as far back as one can go with internet resources for the U.S. Coast Guard.
posted 06-29-2011 09:27 AM ET (US)
The answer is contained in the link that Jimh just provided.
"Vessels not required to carry a marine radio (e.g. recreational vessels less than 20m length), but which voluntarily carry a radio, must maintain a watch on channel 16 (156.800 MHz) whenever the radio is operating and not being used to communicate."
It appears that you have to maintain a watch if the radio is operating and not being used to communicate. It also appears from that if you turn your radio off you don't have to maintain a watch.
posted 06-29-2011 09:37 AM ET (US)
I agree that the quoted passage appears in the website linked, but that is not authoritative. The passage refers to the federal regulations. I have quoted the current regulations previously verbatim. They do not provide for the option of having to maintain a radio watch only when the radio is operating. See the hyperlink and the quote of the actual regulations above. This is another case in which opinions about what the regulation says and what the regulation actually says are not in agreement.
posted 06-29-2011 09:53 AM ET (US)
The federal regulations, the military regulations, and the international regulations aside, it is just good seamanship to maintain a radio watch on the distress frequency when underway. I don't think the regulation is onerous and compliance should not be burdensome. Any voluntary radio-equipped boat with a digital selective calling (DSC) radio is in compliance just by having the radio turned on. You can tune the voice receiver to any channel you like; the digital selective calling receiver in the radio will be monitoring for distress calls on the DSC channel all the time the radio is on. In the U.S.A. most fixed-installation VHF Marine Band radios being sold now must have digital selective calling features rated to Class-D DSC. These are effective regulations which will tend to increase safety at sea for recreational boaters by providing for better distress signal monitoring. I think the concept of mandatory radio watch on certain frequencies began shortly after the TITANIC was lost.
posted 06-29-2011 11:02 AM ET (US)
This is a real situation that occurred a couple of years ago. We were fishing and area 30 miles SE of Atlantic Beach NC when we heard this conversation bewtween a US Navy guided missle destroyer and the USCG. The Navy vessel was relaying information in regards to a incident that occurred with a sport fishing boat returning from offshore. The fishing boat had entered the exclusion zone around the Navy vessel in excess of 35 mph. Efforts to raise the fishing vessel on channe 16 proved futile.
Here's the conversation between the Navy vessel and the Coast Guard. We were about 25 miles from the Navy vessel passing the information.
posted 07-01-2011 10:07 PM ET (US)
I heard another interesting call today. I could only hear the Coast Guard side of the call; the other station was not copyable at my receiver. The calls went like this:
CG: Vessel calling Coast Guard this is Sarnia Coast Guard Radio. Please state the nature of your emergency.
CG: Vessel with engine problem please state your location.
CG: Vessel with engine problems near Imperial Oil, please state how many people on board.
(This location is probably in the St. Clair River just south of Sarnia along the Canadian shore.)
CG: Vessel with engine problems near Imperial Oil, your radio transmissions are garbled and unreadable. If you have a cell-phone, please call [gave special three-digit dial sequence for quick-dial to Coast Guard].
CG: Vessel with engine problems near Imperiod Oil, your radio transmission is breaking up and unreadable. If you have a cell-phone please call [repeated speed dial number].
It occurred to me that a boater with engine problems is also probably likely to also have radio problems, too. The radio and the engine probably both need a battery to operate, and if the underlying cause of the engine problem is a dead battery, the radio probably won't be able to transmit for very long on a dead battery. On the other hand, if the battery is okay, maybe the radio is as unreliable as the engine.
posted 07-04-2011 11:15 AM ET (US)
On July 2 we were boating on Southern Lake Huron, again monitoring Channel 16. About 1545 (3:45 p.m.) local time we received a broadcast from Canadian Coast Guard, alerting us to a SQUALL WARNING for Southern Lake Huron. At the time we received the broadcast, we were already planning on making it to port in the next hour. The conditions at that time were ideal: sunny, no waves, very light winds, just a few clouds. The notion of a squall seemed a bit far-fetched.
About an hour later, we were tied up at the dock at the State of Michigan marina in Port Sanilac. The weather conditions began to deteriorate, and we could see a line of dark clouds coming toward us from the Northwest. Many boaters in the marina began to take down decorative flags they had been flying for the Fourth of July Holiday weekend, and dock lines were being snugged up. Another boater was going around the dock informing people aboard their boats that some serious thunderstorms were heading our way. The skipper of a much larger sailboat in the adjacent slip mentioned he had checked them on weather radar and the center of the storm cell appeared to be moving directly toward Port Sanilac.
Chris and I quickly put up our canvas windshield, side curtains, and drop cloth, and I added an extra dock line at the bow. We were tied in slip with the bow facing West.
A few moments after we got the canvas all snapped and zippered in place, the wind, which had been blowing lazily from the South, instantly switched to the North and increased to about 30-knots. A extremely dark line of low clouds with a great deal of swirling action in them appeared. It began to rain heavily. The wind began to gust even stronger, on occasion rapidly accelerating our boat in the boat slip to the limit of the dock lines. The peak of the gusts, a long sustained blast, caused the 41-foot sailboat next to us to take on a very significant heel for a boat tied to a dock.
The thunderstorm or squall lasted about an hour. It was not particularly terrible to experience while safely tied to a dock, but it would have been quire different if we were ten miles offshore in Lake Huron.
Receiving important weather information is another benefit of maintaining a radio watch on Channel 16.
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