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VHF Antenna for a bay boat?

Old 09-04-2017, 06:00 AM
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Default VHF Antenna for a bay boat?

Just had a hard t-top installed, and want to add a vhf radio/antenna.

Typical fishing is 10-20 miles from "civilization", and there is often another boat or three within sight... of course, not always, and who knows if they'll have a radio on.

I need to measure, but I think the top is about 4.5' long, and would prefer the antenna to not extend too far past the top when lowered.

What's the ideal length? And what would I be sacrificing using a shorter vs. longer antenna?

Is fiberglass the best antenna, vs. some type of steel/alloy?
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Old 09-04-2017, 06:15 AM
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I would go with the Shakespeare 5225XT 8' antenna, its fiberglass and works very well. I use it on all my boats. You should easily get 20miles or more. On my "Small bayboat" (20') I used the Shakespeare 5420XT 4' Antenna and I can get about 17-25 miles. I always choose the Fiberglass antennas, they look nicer and I believe do better
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Old 09-04-2017, 08:14 AM
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Antenna length has little effect on range. Range is determined mainly by the height the antenna is mounted above the water, measured from the sea to the center of the radiating element. The higher an antenna is mounted and the more in the clear it is mounted with respect to other conducting materials, the better the antenna will work and the longer its range of communication.

By necessity, all antennas are made from conductive materials. Some antennas are encased in fiberglass radomes which are fragile, and the fiberglass radome can fracture easily if hard contact is made with an obstacle or too much stress is applied to the radome. Antennas with exposed steel whip radiators are very durable, can flex and tolerate impacts, and are generally much lighter weight than fiberglass-encased antennas, creating lower stress on their mounting bases.

I have used and recommend the GAM SS-2 antenna mounted atop a 4-foot extension mast. See my detailed description at

http://continuouswave.com/whaler/ref...HFAntenna.html

I have been involved professionally in radio communications for over 40-years, so my recommendation of the GAM SS-2 is based on that background and also on my actual first-hand installation and use of the GAM SS-2 for over ten years on my boat.

Regarding necessary radio range to make communication in distress: if you are boating in the coastal waters of the USA, on the Great Lakes of the USA, or on the so-called Western Rivers, the Coast Guard RESCUE 21 radio system will be able to communicate with you at a range of at least 20-miles from shore and often at much greater distances. For details about RESCUE 21 coverage and sites, see

http://continuouswave.com/whaler/ref...1Stations.html

Regarding an influence of the boat on antenna selection, a "bay boat" sounds like a smaller boat. Smaller boats are not as stable as very much larger boats. As a result, any radio antenna on a smaller boat will be in motion due to the waves. All radio antennas have some pattern or directivity, so on smaller boats the best antenna to use is an antenna with a broad radiation pattern. Use of antennas with narrow radiation patterns on small boats can produce disappointing results, as the narrow main lobe of radiation won't be directed at the horizon very often due to the motion on the boat. For this reason, on small boats it is generally better to use an antenna with a broader pattern; this is a characteristic of antennas with lower gain. In marine antenna marketing, antennas described as having "3-dB" gain will have the desired broader radiation pattern.
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Old 09-04-2017, 09:48 AM
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The Digital 529 or 528 are my suggestions and I also suggest going with an 8 footer when ever possible.
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Old 09-04-2017, 10:00 AM
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jhebert pretty well summed it up...bottom line: don't go with excessive gain for a smaller, less stable boat, or you will be talking to the fish and stars. Stainless antennas have an advantage, in that they will flex rather than crack, and the whips alone are fairly inexpensive to replace.

A fiberglass radome, if accessible, is a constant temptation for guests to use as a hand-hold in rough water...causes early failure. And as they age, produce painful fiberglass whisker splinters, very hard to remove from a hand (hint: try Gorilla tape to extract them).

For a small boat, you want a "donut" radiation pattern, not a "pancake" one.

And, if you do choose a fiberglass one, don't mount it at a fashionable rakish angle...it should be vertical, not at 30° angle as so often seen.
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Old 09-04-2017, 10:23 AM
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Thank you gentlemen, for all of your suggestions.

jhebert, if I wanted to use the GAM SS-2, without an extension (on top of my ttop), with a ratchet mount, would I need a female/female adapter? Looks like the ratchet and GAM are both male.
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Old 09-04-2017, 10:49 AM
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Originally Posted by Brokenline View Post
...if I wanted to use the GAM SS-2, without an extension (on top of my ttop), with a ratchet mount, would I need a female/female adapter?
No. Use the GAM ADAP mounting adaptor. The GAM SS-2 antenna is never attached directly to the typical 1-inch thread pipe mount. The GAM SS-2 does not have a captivated feedline. The feedline is part of the ADAP mounting adaptor. To see the individual components of the system, follow the links in the article, which I repeat here:

SS-2 antenna:
http://www.defender.com/product3.jsp...29060&id=69674

ADAP-II bottom exit mount:
http://www.defender.com/product.jsp?...066&id=2893657

--or if you prefer the transmission line to exit sideways--

ADAP-I side exit mount
http://www.defender.com/product.jsp?...066&id=2893758

Originally Posted by Brokenline View Post
Looks like the ratchet and GAM are both male.
The SS-2 antenna has a SO-239-type jack; it threads into an ADAP mount with a matching PL-259-type plug. The ADAP mount has a pipe-thread receiver or socket that can thread onto the standard ratchet mount. The mount's threads are standard and are 1-14 threads.

The GAM ELECTRONICS SS-2 antenna can be mounted in several ways. If desired, the transmission line can connect directly to it using an 83-1SP or PL-259 plug. For mounting on a ratchet mount with a 1-inch pipe thread, use the ADAP adaptors.

All of this information--and more--is presented in the illustrated article I mentioned initially. If you read the article, you should have a good understanding of how the antenna consists of a whip, a matching coil, and a mounting adaptor with captivated transmission line to mount to a standard ratchet mount.

The GAM SS-2 antenna is not something magic. There are several very similar designs. What appeals to me about the antenna is the well-designed mounting adaptor that permits the antenna to be installed on an extension mast and have the transmission line come down the inside of the extension mast. This is not particularly possible with all 3-foot whip antennas. I also like the separation of the antenna into three parts, which can be replaced separately if the need arises.

While I do not ascribe magic to the SS-2, it has been tested (by me and others) and found to work well. This quality is not intrinsic in all antennas. There are plenty that do not work well. The SS-2 does work very well. The SS-2 is well made and durable. These are additional desirable qualities that are not always found. And it is made in the USA. What more could be asked for in an antenna?

There is one minor problem with the GAM antenna: it is not always available at your local boat store or at your favorite on-line retailer. However, at least one large retailer with an on-line presence has the antenna in inventory now. Ten years ago I had to buy it directly from GAM.
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Old 09-04-2017, 11:01 AM
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Originally Posted by jhebert View Post
Antenna length has little effect on range. Range is determined mainly by the height the antenna is mounted above the water, measured from the sea to the center of the radiating element. The higher an antenna is mounted and the more in the clear it is mounted with respect to other conducting materials, the better the antenna will work and the longer its range of communication.

By necessity, all antennas are made from conductive materials. Some antennas are encased in fiberglass radomes which are fragile, and the fiberglass radome can fracture easily if hard contact is made with an obstacle or too much stress is applied to the radome. Antennas with exposed steel whip radiators are very durable, can flex and tolerate impacts, and are generally much lighter weight than fiberglass-encased antennas, creating lower stress on their mounting bases.

I have used and recommend the GAM SS-2 antenna mounted atop a 4-foot extension mast. See my detailed description at

http://continuouswave.com/whaler/ref...HFAntenna.html

I have been involved professionally in radio communications for over 40-years, so my recommendation of the GAM SS-2 is based on that background and also on my actual first-hand installation and use of the GAM SS-2 for over ten years on my boat.

Regarding necessary radio range to make communication in distress: if you are boating in the coastal waters of the USA, on the Great Lakes of the USA, or on the so-called Western Rivers, the Coast Guard RESCUE 21 radio system will be able to communicate with you at a range of at least 20-miles from shore and often at much greater distances. For details about RESCUE 21 coverage and sites, see

http://continuouswave.com/whaler/ref...1Stations.html

Regarding an influence of the boat on antenna selection, a "bay boat" sounds like a smaller boat. Smaller boats are not as stable as very much larger boats. As a result, any radio antenna on a smaller boat will be in motion due to the waves. All radio antennas have some pattern or directivity, so on smaller boats the best antenna to use is an antenna with a broad radiation pattern. Use of antennas with narrow radiation patterns on small boats can produce disappointing results, as the narrow main lobe of radiation won't be directed at the horizon very often due to the motion on the boat. For this reason, on small boats it is generally better to use an antenna with a broader pattern; this is a characteristic of antennas with lower gain. In marine antenna marketing, antennas described as having "3-dB" gain will have the desired broader radiation pattern.


That right there ladies and gents is a detailed, knowledgable answer.
You certainly know your antennas.
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Old 09-04-2017, 11:14 AM
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Originally Posted by spraynet 1 View Post
That right there ladies and gents is a detailed, knowledgable answer.
As a general rule, I advise being cautious about accepting advice about antennas, as a lot of bad advice is passed around. And, of course, that could apply to my advice, too.
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Old 09-04-2017, 01:42 PM
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Originally Posted by jhebert View Post
As a general rule, I advise being cautious about accepting advice about antennas, as a lot of bad advice is passed around. And, of course, that could apply to my advice, too.
Any idea why USCG has standardized on a GAM competitor, the Metz?
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Old 09-04-2017, 03:37 PM
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I took jhebert's advice and bought a GAM SS-2 and mounted it on an extension. Very pleased.
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Old 09-04-2017, 04:55 PM
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Originally Posted by InternationalMarineBrian View Post
The Digital 529 or 528 are my suggestions and I also suggest going with an 8 footer when ever possible.
This is the way to go.
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Old 09-04-2017, 09:37 PM
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Originally Posted by Badbagger View Post
This is the way to go.
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Old 09-05-2017, 06:11 AM
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Originally Posted by Karl in NY View Post
Any idea why USCG has standardized on a GAM competitor, the Metz?
They're in wider distribution, so easier to get a replacement when they break one.

Also, selling into a government procurement channel can be tedious for the vendor. Maybe GAM has not bothered to get into direct sale to government agencies.

I don't feel bound to only buy the same stuff the Coast Guard buys, like HONDA engines or all-round floatation equipped small boats.
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Old 09-05-2017, 07:30 AM
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As JHebert said, either the GAM or Metz are excellent options. I have not used the GAM personally, but have used the Metz. It performed just fine for inshore and near shore.
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Old 09-05-2017, 09:14 AM
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Originally Posted by Parthery View Post
...either the GAM or Metz are excellent options.
The METZ antenna is probably a nice antenna, but the mounting options are not suitable for attaching to 1-14 pipe threads that are found on the usual ratchet mounts. The GAM mounting is much cleaner.
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Old 09-05-2017, 11:20 AM
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Originally Posted by jhebert View Post
The METZ antenna is probably a nice antenna, but the mounting options are not suitable for attaching to 1-14 pipe threads that are found on the usual ratchet mounts. The GAM mounting is much cleaner.
Not sure I see a typical need to put a 34" flexible whip on a rachet in the first place. I drag my Metz under a garage door every time I move the boat, It's a 8" interference.
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Old 09-05-2017, 11:50 AM
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Either the Metz or GAM (can't remember which) I believe needs trimming to resonance on Chan. 16.
A real inconvenience, and beyond the skill and equipment level of the average user.

I've never personally examined either brand, but I assume the trimming is done from the bottom end, as most stainless whips have an anti-corona ball at the top, and you make very small cuts and then use an accurate SWR meter.

I assume both brands do have an anti-corona ball at the tip, both to dissipate static, and for limited physical eye protection (?). Again, confusing both brands, I recall that if ordered direct from factory, they would pre-tune it to chan. 16, since the antenna is longer than need be to accommodate land-mobile services, not just marine VHF.

Would someone clarify?
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Old 09-05-2017, 11:56 AM
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Originally Posted by Karl in NY View Post
Either the Metz or GAM (can't remember which) I believe needs trimming to resonance on Chan. 16.

I've never personally examined either brand, but I assume the trimming is done from the bottom end, as most stainless whips have an anti-corona ball at the top, and you make very small cuts and then use an accurate SWR meter.

I assume both brands do have an anti-corona ball at the tip, both to dissipate static, and for limited physical eye protection (?). Again, confusing both brands, I recall that if ordered direct from factory, they would pre-tune it to chan. 16, since the antenna is longer than need be to accommodate land-mobile services, not just marine VHF.

Would someone clarify?
I've tested the Digital and the Metz with an antenna analyzer. The whips are quite different but the same length. The metz is tempered and can take quite a bend without taking a set. The Digital is thicker, and stiffer, but takes a set with almost any bending. The Metz has a plastic tip cap over a cut end, no ball.

The SWR 1.5 max bandwidth covers 156 to 162 no issue, but the Metz does seem tuned a bit high.
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Old 09-05-2017, 12:35 PM
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Thanks again for the further explanation jhebert. I'm also curious to process of trimming?

And one other question while you're sharing. I plan to mount my radio in the electronic's box adjacent/beneath my hard t-top. 20' seems to be a standard length of wire provided. It seems like I've read that certain lengths are better/worse than others. Would shortening this length be adverse? I really only need about 3' or even less.
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