Thoughts on rail mounted VHF antenna

Leeward Rail · May 9, 2023

VHF range is affected by the height of the antenna above the water...think of it as "line of sight"

I would always have a mast head mounted antenna for that reason.

As for running more wire up the mast ? Normal. No big deal. Our C22 had wiring for masthead, steaming and deck lights and rg8 VHF radio cable in the mast along with the halyards as normal. (I was going to install a cell booster antenna before I sold it)

More stuff in the way on the stern rail ? No thanks.

Especially on a small trailerable boat like a Catalina 22 where the stern rail is small and the mast is meant to be easily raised or lowered in 30 minutes.
It's not like you need a crane and it takes all afternoon to drop the mast.

Joe · May 9, 2023

I have had a vhf antenna similar to what you are intending for as long as I have owned this boat, 25 years. The benefit of mounting the antenna higher is obvious, but it is not critical, since many, many vessels have traditional fiberglass, fold down style antennae. In our area, coast guard and other VHF emergency services are broadcast from mountain top or tall tower locations. Here in San Diego we easily receive broadcasts from LA area. Ship to ship... it's gonna make a difference... but ask yourself who does all the chit chatting on VHF.... why, it's the fishermen, of course, and none of them have masthead antennas. So... don't worry about the line of sight distance. BTW my fiberglass antenna is mounted on the stern gunnel, about 10 ft above the water. No problems. BTW, I've always had the cheapo, plain, ratchet style mount, not sure about the advantage of the one you pictured. Plus, I'd prefer the deck mount, with the tallest antenna the sell, to insure good support.

dlochner · May 9, 2023

The value of a VHF is in an emergency when you need to communicate the emergency to as many vessels as possible. The higher the antenna, the further the signal travels.

Consider, an antenna 10' above the water has a LOS distance of about 6-7 miles. At 25 feet the LOS distance is about 10-11 miles. Calculating the area reached, at 10' a broadcast will cover about 150 square miles, at 25' it will cover about 370 square miles.
Another C22 with a mast head antenna will hear you at 22 miles.

The correct antenna for a mast head is a whip, Metz makes a good one and I believe Shakespeare also makes a whip.

Line of Sight Calculator - everythingRF

www.everythingrf.com

jviss · May 9, 2023

What do most sailboats have? Masthead VHF antennas. Says a lot.

Leeward Rail · May 9, 2023

morbidfollower said:
I do not have a conduit going thru the mast currently, for those of you with more stuff in there than I have currently do you have anything in there to keep the wiring away from the halyards?

My 87 Catalina 22 just had the wires run. No conduit.

The issue is the wires slapping inside the mast. It makes noise. Some people use uncut zip ties sticking out and touching the sides. or some other method to stop that. I didn't use the zip ties because that would make it a hassle to run new wires. I just put up with it, because it wasn't too bad due to the smaller diameter mast.

As long as the halyards weren't accidently wrapped around the wiring if/when I ran new wiring or new halyards, all was ok.

Fwiw: Last year I did install conduit in my c&c but the mast is 20 feet longer and bigger in diameter than that of a Catalina 22. The wiring bundle diameter was only a tiny bit bigger. So, it has more room to slap against the inside of the mast
Much more noise. Especially in the cabin with the mast being keel stepped.

Installing the conduit was a pain in the butt. The long term advantage is:
-no noise
-easier to run additional wire without having to use the marina crane to unstep the mast.
Neither of those are much of a problem with the c22

Joe · May 9, 2023

I get the line of sight rationale. A sailboat's mast is an advantageous place for a straight line wave broadcast. And the fixed mount's 25 watts give it the power to transmit farther too. But most fixed mount vhf's broadcast to other boats with similar height antennas, and also the radio tower or mountaintop coast guard/emergency broadcasters. So, it is not unsafe to forego a masthead antenna for a cabin top or rail mounted transmitter.

My question is: How far can I get from my buddy boat before we lose communication if we both have ten foot high antennas?

Leeward Rail · May 10, 2023

Joe said:
But most fixed mount vhf's broadcast to other boats with similar height antennas, and also the radio tower or mountaintop coast guard/emergency broadcasters. So, it is not unsafe to forego a masthead antenna for a cabin top or rail mounted transmitter.

Those both make assumptions on location.
With a rail mounted antenna, the coast guard here would be unreachable on much of the lake.
Other boats would need to radio relay to the coastguard

Our lake doesn't have many boats depending on location and season. A lake which often has no boats within handheld or rail mount range. It could definitely be unsafe depending on location.

Why use a rail mount, especially on a trailerable boat with a easily lowered mast, when you can easily use a.proven superior method for much the same price and not clutter the rail ?

Masthead= much better range and no clutter on the pushpit.
Rail mounted= less range and more clutter on the pushpit.
I fail to see why anyone would compromise.

Leeward Rail · May 10, 2023

Joe said:
My question is: How far can I get from my buddy boat before we lose communication if we both have ten foot high antennas?

There are plenty of VHF radio range calculators and formulas posted online, if you want to play with the numbers.

Keep in mind..while a specific setup.. in theory can reach a certain distance.. you may not be intelligible close to the end of that range.

jviss · May 10, 2023

It's obvious, well known, not debatable that in radio communication, especially at higher frequencies, the higher the antenna above the surface the better.

The benefits of putting a VHF antenna on the stern rail escape me. It will be in the way, if nothing else, more in the way than if it wasn't there. And the cost is reduced communication range.

The only benefit I can think of is that if you become dismasted you will lose that masthead antenna. I know world-cruisers who carry emergency antennas that mount on rails, but they are stored until needed.

I have two VHF antennas, one on the masthead and one on top of my stern pole mounted radome. I confess I don't know antenna the two radios or the AIS transponder are using! I will figure that out this Spring. I do have an AIS antenna splitter, so I can trace that out, too.

Joe · May 10, 2023

Leeward Rail said:
Why use a rail mount, especially on a trailerable boat with a easily lowered mast, when you can easily use a.proven superior method for much the same price and not clutter the rail ?

Masthead= much better range and no clutter on the pushpit.
Rail mounted= less range and more clutter on the pushpit.
I fail to see why anyone would compromise.

There's no argument, here. If there is, YOU WIN. The masthead is the preferable location for the vhf antenna. I thought I stated that earlier. Anyway, my point is that mounting an antenna in an out of the way location, such as a stern tower (or rail), is NOT dangerous, nor does it threaten your radio's function. Any reason for that option is acceptable. As stated, my antenna is mounted high off the stern. It has worked fine all these years. I have never missed a weather report, a Coast Guard or Military ship warning, a fisherman's chit chat with his buddies or a toddler clicking the button to everyone in the marina's irritation.
Some day I may change it. We'll see.

Leeward Rail · May 11, 2023

Joe said:
nor does it threaten your radio's function

That's the thing. On the lake I sail on, it does make the difference in getting a radio call out or not.
There just isn't enough people out there to assume someone is close enough to hear.

Boat and land tower density makes a difference in people hearing your emergency call, and that height can mean the difference between anyone hearing your call or not. In low density areas that extra range is a safety factor.

jviss · May 11, 2023

It depends on where you are, how close are other boats, how far offshore you wander, etc., etc. One size does not fit all.

Leeward Rail · May 11, 2023

jviss said:
One size does not fit all.

Technically a tall masthead one does.

captcoho · May 15, 2023

morbidfollower said:
Appreciate the feedback everyone. I do not have a conduit going thru the mast currently, for those of you with more stuff in there than I have currently do you have anything in there to keep the wiring away from the halyards? I will go with a masthead setup. Ive raised and lowered it a bunch but never on the water. Trailer is about 50 miles away, but I might go grab it. Thanks again.

On my c-22 I installed an antenna up at the masthead, but continued to use the handheld. I unscrewed the short whip antenna on the handheld and got an adapter from the PL259 to attach to the handheld. This gave me tremendous broadcast and reception without having to install a fixed transceiver and add to the amp hour load on the engine starting battery. And I could still use the handheld by putting the small antenna back on

Leeward Rail · May 15, 2023

captcoho said:
This gave me tremendous broadcast and reception without having to install a fixed transceiver and add to the amp hour load on the engine starting battery. And I could still use the handheld by putting the small antenna back on

That is a brilliant solution. :beer:

Jacktar · May 16, 2023

A A handheld will only give you 5 w max, 20% of regular radio, with obvious loss of coverage area.
B All mast mounted wiring should be quick disconnect regardless of trailered or not.