Fixed Mount VHF antenna recomendations

[Matt19020]

I am considering installing a fixed mount VHF in my Mac. I was holding out to do it "the correct way" and mount a mast top antenna. Well I am on my third year and still did not do it. I have a good handheld VHF and have always been in cell phone reach of land. I sail the Delaware river 90% of the time with no bridge openings necessary.
My questions:
Is it worth the trouble to run a Mast top antenna for extended transmit range?
Do you lose range by having a deck connection at the mast base?
Can I mount a good antenna off the mast support bar which I leave on the boat at all times? If this is adequet what height antenna should I mount?
What type of range can be expected with it?
What key features are most important in a VHF? Transmit power? DSC? Hailer?

[NiceAft]

Matt,

I'm sure you are going to get some replies, but I don't think it is worth the effort to do the mounting on the mast. Where you and I sail, we just don't have the need. Also, when raising and lowering the mast, it will become one more thing to worry about.

I have mine mounted on a starboard, aft stanchion. Just in front of a stern rail seat. I have contacted the Coast Guard on several occasions to notify them of assistance needed by other sailors. The reception has been fine. When five miles off the A.C. coast, I was receiving strong reception from them on channel16.

Again, I'm sure you will get a variety of responses, but I just don't think it is worth the effort for our sailing area.

Ray

[Hamin' X]

Just from my perspective from sailing mostly in the Monterey Bay and San Juan Islands areas, a mast mount antenna is more detrimental than beneficial. The reason is that with the higher antenna, your are receiving more stations. The chatter on 16 can become incessant and the tendency is to turn the volume down, the squelch up, or turn it off. You get real tired of listening to a Coast Guard station that is 50 miles away talking to boats that you can't hear. If you were sailing in more remote areas, you would want to go for all the range you could get, But if it's a nuisance, you won't use it. Think of it as a PFD that is to uncomfortable to wear.

~Rich

[Paul S]

Just from my perspective from sailing mostly in the Monterey Bay and San Juan Islands areas, a mast mount antenna is more detrimental than beneficial. The reason is that with the higher antenna, your are receiving more stations. The chatter on 16 can become incessant and the tendency is to turn the volume down, the squelch up, or turn it off. You get real tired of listening to a Coast Guard station that is 50 miles away talking to boats that you can't hear. If you were sailing in more remote areas, you would want to go for all the range you could get, But if it's a nuisance, you won't use it. Think of it as a PFD that is to uncomfortable to wear.

~Rich

^^^^^^^ is the reason I mounted my antenna on top of the mast. I want ALL those stations to hear my mayday or DSC emergency call! Range is a good thing! That being said, I do carry a handheld for local chatter with our sailing club and use the fixed station for getting those members that are just a bit further away.

I would always have a mast mounted antenna on a sailboat. I have seen powerboat antennas mounted on Ms (dealer didn't want to deal with the foam in the mast). Not the end of the world, and works well enough. Just looks a bit silly IMO.

I think carrying 2 radios is better than one! Redundancy is often a good thing.

[Chinook]

I'm a top of the mast antenna guy, liking the idea of greater range due to the remote places we seek. Of course, it's a bit easier to get the antenna wire up an X mast, which is hollow. I do have an antenna related question, though. Somehow I managed to lose the wire whip which sticks out of the antenna unit which sits atop my mast. I checked and was told I couldn't just order a new whip, but would have to replace the whole unit. Instead, I cut up a wire coat hanger and made a replacement whip from the wire. Any thoughts from you radio experts out there on whether my jury rigged antenna is a reasonable fix? Other suggestions?

[Graham Carr]

I agree with Paul, which is the reason I mounted my antenna on top of the mast. The VHR radio is a critical key to our safety. The best way to reach out and touch someone is with power and antenna height. According to the United States Coast Guard Auxiliary; the range you could broadcast is up to 20 nautical miles, but normally in the 5-10 mile category. Atmospheric conditions also play a role in your broadcasting range and of course the conditions are variable. I for one want the odds in my favor.

I also sail in the San Juan Islands and I like to tuck into some of the small coves for the night. The mast mounted antenna allows me to receive weather updates with out any problems. The other point to consider is your possible future cursing grounds. You may find yourself further away. Then the taller antenna would be of great value. When rigging my boat it only takes a few minutes to mount the antenna in its base.


I would also like to repost some very important information that I posted back in April 2005. We have had a lot of new members which some are new to boating.

Why your VHF radio is Sooooo Important!
And why knowing how to use it, is more important!

By Wayne Spivak
National Press Corps
National Marketing & Public Affairs Department
United States Coast Guard Auxiliary

On 11 May 1993, two vessels that were in the same general area (the waters off Fan Island, Porcher Peninsula, British Columbia.) transmitted MAYDAY messages at about the same time. The message, as received, read: "MAYDAY MAYDAY ... going down." The other message read: "MAYDAY MAYDAY we're going down."
Due to the proximity of the vessels, and the almost identical messages issued, both vessels were lost. The messages were transmitted on their VHF radios. However, the procedures used during the transmission of the message and the fact that they occurred almost simultaneously were the main reasons cited why the Canadian Coast Guard response was prematurely terminated.
This is an example, which highlights what can happen, when not properly using your safety equipment. This error caused one of the crew to die of, and the other crew members to suffer hypothermia. All because they didn't follow tried and tested emergency radio procedures.
All recreational boats should carry a VHF marine radio on board. While currently not a federal regulation, the Coast Guard Auxiliary, during their Vessel Safety Check (VSC) recommends this piece of safety equipment. More importantly, all members of the crew need to know how to use this important piece of safety equipment!
VHF Radio vs. Cell phone vs. Citizen's Band (CB) Radio
A marine radio (VHF) can be bought as a handheld radio or a base unit.
Fixed mount (base) units can broadcast at a maximum of 25 watts, with the ability of also being able to reduce power to 1 watt. Handhelds normally don't broadcast over 5 watts. Base units, given the correct tuning, height of antenna and atmospheric conditions, can broadcast up to 20 nautical miles, but normally in the 5-10 mile category.
Handheld radios have the advantage of being able to be carried while you move around your vessel or while on a dinghy. The disadvantage of this type of radio is the limited power (wattage per channel) that they are able to produce. The smaller the wattage, the weaker the signal becomes as it radiates from the antenna. Thus, the strength, and limited antenna size, makes long distance communication nearly impossible.
Cell phones have large number of disadvantages, starting with the inability of other mariner's to hear your call for distress, which may not be heard by a Coast Guard Units to the inability of the Coast Guard to use direction finding equipment to hone in on your signal, should you be unable to describe your location. Add to these factors the limited distances cell service extends into the ocean, and you have a generally unreliable service.
Citizen Band Radios, the rage in the early to mid 1970's, is for most intents and purposes useless as a vehicle in which to contact the Coast Guard. Most Coast Guard Units do not have, and thus are unable to receive CB radio broadcasts, and thus are not able to respond.
The safety conscious recreational boater will purchase the best safety equipment they can afford, and when it comes to a VHF marine radio (a fixed mount VHF-FM can be obtained for as little as $100), they will buy a radio which will provide quality transmission signal strength, and the ability to quickly listen and transmit on channels reserved for distress calls. In addition, most new units have the ability to continuously monitor multiple frequencies.
What to do in an emergency
Let's briefly go over the three main types of emergency calls you will hear, according to the Office of Boating Safety (OBS) of the United States Coast Guard, while monitoring CH16 on your VHF radio:
MAYDAY is a request for immediate assistance. LISTEN! DO NOT TRANSMIT!! Determine if you're in a position to help. If not, maintain radio silence. "MAYDAY" identifies an imminent, life-threatening emergency.
PAN-PAN (pronounced pahn-pahn) is used when the safety of a boat or person is in jeopardy. Man-overboard messages are sent with the PAN-PAN signal.
SECURITE (pronounced say-cure-e-tay) is used to pass navigation information or weather warnings.
According to the OBS, if you have an emergency, you should use your VHF radio in the following manner:
If you have an imminent life threatening emergency, transmit on Channel 16:

1. MAYDAY, MAYDAY, MAYDAY!
2. This is (name of boat three times).
3. Repeat once more, "MAYDAY", (your boat's name).
4. Now report your position (give as accurate a position as possible).
5. Report nature of emergency.
6. Report the kind of assistance desired.
7. Report number of people on board and condition of any injured.
8. Description of the boat and seaworthiness.

**Then wait for a response. If there is none, repeat the message**
So, if your vessel is named Blue Duck and you have an emergency, your broadcast may sound like this:

"Mayday-Mayday-Mayday
This Is Blue Duck - Blue Duck - Blue Duck
Cape Henry Light Bears 185 Degrees Magnetic-Distance 2 Miles
Struck Submerged Object
Need Pumps-Medical Assistance And Tow
Three Adults, Two Children Onboard
One Person Compound Fracture Of Arm
Estimate Can Remain Afloat Two Hours
Blue Duck Is Thirty Two Foot Cabin Cruiser-White Hull-Blue Deck House
Over"

You can view the original post here. This way you can see the other members that responded. I checked the links in that post and found they were dead. I did find a new link for the above story, just click here.

I followed Chip’s advice on printing the call info (original post)

Graham

[Highlander]

Well arcording to the guy's I talked too, and they really know their STUFF a good quality 8ft antenna mounted on my mast arch support will do just as good if not better in range than a 36" ss mast mounted antenna on an 28-30ft mast so I suggest you check out the specs as I did. its not the height thats important as the quality of the antenna
so I did not go with a mast mounted antenna
J

[puggsy]

I have mounted my aerial base on the starboard transom, and run the cable between the two 'skins' into the cabin area to the VHF radio. For security, I leave the actual whip aerial in the cabin and only mount it [ via a sngle thumbscrew] on ocean trips.
Here in Western Australia, a "Third Class Radio Operators Certificate" is required for VHF.
Most boats are fitted with 27 Meg radios [ Marine] with no certificate required. I have both fitted.
Puggsy

[hart]

Another vote for mast mounting here.

Of course I'm sailing in and out and around the ICW a lot. I like hearing the barge traffic announce where they are as most of them do. My handheld misses a lot of the calls I want to hear but my mast mount gets them. Granted, I do get some chatter I don't need such as calls for a Pilot on Mobile Bay etc. I can't decide if I like picking up the Coast Guard station out of New Orleans or not though, lol.

My handheld misses so much that a wireless remote for the fixed unit is high on my list for keeping in the cockpit. I'll still keep my handheld for emergencies though.

[kadet]

There are so many variables here it is not an easy question to answer.
If you trailer all the time you risk damaging the connection and the aerial and it might not work when you need it.
How are you going to run the wire? Most aerials are tuned to their connecting wire so if you cut then use a connector or plug and socket so you can disconnect the mast you run the risk of reducing your effective power by up to 50%. If you just run standard coax the aerial may not operate as well as a tuned aerial on the deck even if it is thirty feet high.

My is less than a year old and the mast light is already flaky (have to wiggle the plug) from corrosion on the connecting plug.

I mounted a tuned 8ft fibreglass whip aerial on the starboard rear quarter I have no problem transmitting and receiving calls over 100 kilometres (Cape Moreton - Gold Coast Seaway Tower)

Lastly you really won’t that radio to work in an emergency, unfortunately one of the first things that can be damaged in a yachting mishap is the mast, no mast no radio if the aerial is mounted on it.

[Hamin' X]

Somehow I managed to lose the wire whip which sticks out of the antenna unit which sits atop my mast. I checked and was told I couldn't just order a new whip, but would have to replace the whole unit. Instead, I cut up a wire coat hanger and made a replacement whip from the wire. Any thoughts from you radio experts out there on whether my jury rigged antenna is a reasonable fix? Other suggestions?

The coat hanger will fail in short order, either from corrosion, or metal fatigue. Also, the whip must be a specific length for the antenna to function properly. Failure to have the proper length will cause the radio to reduce output power due to protection circuits built into the radio and can lead to damage to the radio's output transistors.

What type of antenna do you have? If it is a Metz, Larson, or Shakespeare, there should be no problem getting a replacement whip. The next time that you are in the Seattle area, check with one of the marine electronics dealers on the waterfront.

If you know the antenna brand and model, I can look up the info and point you to where you can order the proper whip. They are common stock items in all ham radio stores. PM, or Email me and I'll try to help you sort it out.

~Rich

[Hamin' X]

There are many variables to the range of VHF communications. The article that Graham cites is a lot short on technical knowledge and confuses a lot of terms. The long and short of the matter is that VHF frequencies are "Line-of-Sight" + about 30%. Antenna height is the number one item in determining range. Actually power is quite a bit further down the list and antenna gain and orientation are more important.

The installation is also, very important. The more complex the installation, the more apt it is to have a failure at some point. For emergency communications, the KISS principle is king.

There are many myths and misconceptions about radios and antennas. When the subject comes up, I try and offer my opinion that is based on 40+ years of Ham Radio and commercial 2-way radio work. But in the end, it is only an opinion.

~Rich---N7ZH

[Don T]

Hello,
Also, a high gain antenna is more apt to drop out when the boat is rocking. The radio only puts out a certain wattage, high gain antennae concentrate that energy horizontally. It works well with fixed mounting but our boats are not fixed. The Coast Guard will miss many words as the boat rocks back and forth.

[Russ]

Everything I've read says height is the most important factor. That's why you can hear coast guard broadcasts from 50 miles away. They mount their antennas on top of tall towers on tall hills. They can't use more than the same 25 watts, so it's the height that gains the distance.

In an emergency, I want to be heard as far away as possible. Also, coves with tall hills might get better reception if they can get over them.

I own 2 VHF's. The 25 watt is mounted to the mast top antenna. The deck connection is an issue and area of potential loss, but keeping it clean isn't that hard. For close comms, I use a hand held. It's both easier to use (kept close to helm) and it's low wattage and antenna make it more suitable for short range. As mentioned above, redundancy is worth it and a VHF is the cheapest piece of safety equipment you can buy.

My vote is for mast mounting. I know power boaters were always envious of my height.

Also, a lower gain antenna has a wider beam, so healing and rocking isn't affected as much. A narrow beam will tilt up towards the sky during healing.

================================================
More
http://www.yachtworks.net/Store/antennas.htm

Even if you could increase your power, it wouldn’t help much. VHF radios operate on a “line of sight” principle between stations, meaning that the signals do not bend around obstructions or over the horizon (Okay, they do a little, but think of them as traveling about as straight as a light beam.)
This means that antenna height, more than any other factor, is responsible for determining how far you can transmit. An antenna mounted up high can “see” farther over the horizon.
So, the wattage of the radio is much less important than antenna height in determining range. Antenna gain is important, however. This is a measure of how much the antenna focuses the radio’s energy in the horizontal direction. If several otherwise equal radios try to contact a single receiving radio, the higher gain antenna is the one the receiving radio will hear.
It is also extremely important to have good, solid, low resistance connections between the cable and antenna and between the radio and the cable. Splices in the cable are not recommended! We are dealing with RF power here, and any discontinuity will cause power to be reflected back to the transmitter and lost.

The following table, taken from a special section on VHF radios in Motorboating & Sailing, gives typical reception distances for selected antenna heights. The antenna heights are given for a handheld in a small boat, a typical powerboat antenna height of 10 ft., and sailboat installations with 30 ft. and 60 ft. heights. Distances are in nautical miles.
Transmit Antenna Height
Receiving Antenna Height
...... 5'........10'.......25'........100'.......250'
5'----5 mi.----7 mi.----9 mi.----15 mi.----23 mi.
10'--9 mi.---10 mi.----11 m.----18 mi.----25 mi.
30'--10 mi.--12 mi.---13 mi.----20 mi.----28 mi.
60'--12 mi.--14 mi.---15 mi.----21 mi.----30 mi.

[Hamin' X]

Don and Russ are correct about antenna gain. However, antenna gain figures are very much manipulated by manufacturers. The best way to determine the antenna gain, is the length of the antenna. The best type of antenna for marine use is the 1/2 wave antenna and it is about 36". It requires no ground and has a moderately wide horizontal beam width. A 1/2 wave antenna has a maximum gain of 2.15 db(i). (Note: most are listed as 3db gain, but this is just paper horsepower).

Doubling the gain from 3db to 6db will not double the signal received by the other station and will result in barely perceptible performance increase and the narrower beam width is more likely to be detrimental.

~Rich