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Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

VHF antennas: Mast vs. Stern Rail Mount

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sterngucker
Navigator

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USA
169 Posts

Initially Posted - 12/08/2004 : 19:36:30

I have searched the archives but I can't find any discussions on this topic. Frank posted this question in an antenna installation thread last July but nobody replied to it.

I realize that the mast head mount would increase your horizon, but wouldn't a longer antenna (is it 1/4 wave vs. 1/2 wave) on the stern rail increase your sensitivity?

Even though I sail on the ocean I am never really out of sight of land. The simpler installation of the stern rail location might out weigh the slight increase in range of the mast head mount? How much more range does a incease of about 25 feet in height give you?

For me, one less item to connect is a plus. Also, since I trailer everywhere I go, it seems to me the wear and tear on the masthead mounted antenna would be very high.

Charlie
"C Angel" 250WB #799

Edited by - on

Jeff McK
Captain

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USA
389 Posts

Response Posted - 12/08/2004 : 20:27:20

Charlie,

Please take a look at this link from WM's catalog. It addresses the antenna questions pretty thoroughly. http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorDisplayView?advisor=selecvhf.htm

VHF radios work on "line of sight". IMHO, your best move is put that sucker up on top of the mast. At 5' off the water (A handheld unit) your range can be as low as 5 miles to a similarly mounted antenna. If the antenna is 30+ feet off the water the range effectively extends to the visible horizon, possibly farther depending on the height of the reciever's antenna. There is a chart in the article that covers this in more detail.

Longer is NOT neccessarily better.

Also, there is a relatively new link in the C-250 forum right now that addresses the issue of through-deck coax connections you might find helpful.

Good luck.

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 12/08/2004 : 23:50:34

Charlie, in your case I'd just go with a stern rail mount with a quick release. Pull the antenna off and put it inside when trailering. Indiscipline has a high quality 8 foot antenna on the rail and a cheap 3 foot wire whip on the mast. The one on the rail works much better.

I know the line of sight is significantly less. If you're calling USCG in an emergency, their antenna is so high and their power is so large that they will hear you either way.

If you're calling Fleet 7 boats, well, we usually just talk on the 1 watt handhelds anyways with a 5 inch antenna. Works well up to about 3 - 4 miles. After that we go to the fixed VHF sets.

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Bill Holcomb
Admiral

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USA
769 Posts

Response Posted - 12/09/2004 : 08:43:26

Hi Charlie

Snickerdoodle has used the 8' stern mounted system all along. I regularly talk with boats 15 to 20 miles away with excellent reception. So, my vote is keep it simple skipper.

Bill Holcomb - C25 Snickerdoodle #4839

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tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 12/09/2004 : 09:24:48

One more vote for the rail mount f'glass antenna. I see no appreciable gain over the Metz mast mount, plus there is that much less weight aloft. I did have a problem with swr's with the Metz. And the problem of blowing the finals on one radio that I traced to it. I have been using an inexpensive Shakespear for several years, eight I think, and it's working for me. Made the mistake of grabing it for a hand hold once, thinking I had the backstay. Not a good idea.

Val on the hard DAGNABIT

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aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 12/09/2004 : 09:30:02

Charlie,

There is obviously some difference of opinion regarding this issue. Both antenna types have there pros and cons. I have had my antenna mounted on the mast head for 15 years with good service. I would recommened it for one reason, space on the stern pulpit. When you think about it, we tend to hang a lot of stuff from it - life sling, solar panel, GPS antenna, spare stern anchor, to name a few. At the same time, we need access to the swim ladder (if you have one), and in particluar, the outboard motor. The stern is also the place where you would retrieve an man-overboard, if you have a ladder mounted on the stern. That's a lot of function for a small area. In my opinion, only bare essentials should be mounted on the pulpit, and the radio antenna isn't one of them.

Mounting the antenna on the mast-head is not difficult. If you have a PVC tube for your mast wiring, the typical RGB8 cable will fit with the your standard mast wiring. You can pull it through using your head stay. I have also had leak-free service from my through-deck fitting.There are a number of reliable, easy-to-install models on the market. If I remember correctly, the whole process, including running cable from the through-deck fitting to the radio, took about 4 hours.

My suggestion is that you take a long look at what you intend using your stern pulpit for. I think you'll find that being an ocean coastal cruiser will require you to have a need for critical equipment there that may not be needed by the typical lake sailer.

Al
GALLIVANT #5801

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ronrryan
Admiral

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USA
561 Posts

Response Posted - 12/09/2004 : 11:46:24

Orion has the antenna on the stern rail for convenience of mounting, works OK for short ranges. Previous boats had masthead antenna, I used to regularly get radio checks from another sailor whose boat was about 35 miles away, masthead to masthead. You takes yer cherce, as they say, fair winds, ron srsk #2343 SW FL

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 12/09/2004 : 13:19:45

Last summer my masthead mounted 3db whip antenna failed so I borrowed my brother-in-law's spare 8ft 6db antenna from his powerboat to use until the end of the season when I could drop the mast.

I mounted this antenna to the stern rail as others have noted and it has worked fine although I took a few friendly ribbings from my fellow sailors about using a powerboat antenna on a sailboat, but hey, it works.

Edited by - on

Lee T
1st Mate

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26 Posts

Response Posted - 12/09/2004 : 13:50:32

This might be overkill for us, but alot of bigger cruising boats will have one of each. They act as backup to each other (if you have a mast failure you will almost certainly lose your mast-mounted antenna), and also the rail-mount can be good to use when you have the radio on all day and don't necessarily need to hear everyone in a 30 mile radius. Also, get an adapter and you can use the one not connected to your vhf on your am/fm radio. I also like the rail mount for it's simplicity: usually you can wire it up with no wire splices (the wire installed by the factory will reach all the way to the radio). As I said, possibly overkill, but for $40 might make sense.

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jwilliams
Captain

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USA
357 Posts

Response Posted - 12/10/2004 : 12:48:12

Hi all,

I have a temporary stern mount with a wingnut clamp I made this summer when my 3ft Metz fell off (I'll tell you in a minute) as a spare. I don't run both antennae at the same time, guess I could.

I was beating towards Sausalito between Alcatraz and Angel Is. and looking up at the windex noticed that the antennae was leaning way to leeward. Thought it was funny. A few minutes later I looked again it was gone. I made the temp. stern mount over the week so I had a two radios as usual for the next weekend (handheld and console). Looking at the masthead with the binocs I could see that the Metz coil was still there, just no antennae. Luckily I still had an old one. Paul hoisted me up in a bosuns chair and I found that the rubber boot and nut were still there, just the antennae wire was gone. Installed the new (old) one and used lots of rigging tape to tighten that sucker down.

Jim Williams
Hey Jude C25fk 2958
SF Bay

Edited by - on

Oscar
Master Marine Consultant

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USA
2030 Posts

Response Posted - 12/10/2004 : 13:18:44

Found the masttop antenna on the deck after this summers lightning strike. Radio was dead.....replaced the antenna,and the radio. (Wanted DSC anyway). As I am un-installing the old radio I find a fat fuse in the...negative wire...Guess what, it did it's job...radio is still alive. So a rail mounted antenna is now hooked up to the old radio. As I had a handheld already I now have THREE radios...

...the nav station looks very imressive....guess redundancy is a good thing.

Oscar
C42 # 76 "Lady Kay" (Ex. C250 WB #618)
Georgetown MD/Fort Lauderdale FL

"Hindsight is 20/20, if I knew then what I know now, I would now be living on a small wooden sailboat, making a few bucks here and there playing a guitar and singing songs in bars."

Edited by - on

At Ease
Admiral

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672 Posts

Response Posted - 12/10/2004 : 15:22:06

As is obvious from previous posts, you can get adequate reception with a stern rail mount. Bottom line is that it is line of site, therefore higher is better. However, the other factor is room and the antenna being in the way on the rail. Your call as to which is more important...a clean rail or better reception.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 12/10/2004 : 18:17:29

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by At Ease
 As is obvious from previous posts, you can get adequate reception with a stern rail mount. Bottom line is that it is line of site, therefore higher is better...<hr height="1" noshade id="quote"></blockquote id="quote">

Another factor to consider is the antenna type in relation to the transmitted signal. A 3db whip antenna outputs a broad beam which allows a sailboat to heel and still transmit towards the horizon whereas an 8ft 6db antenna transmits a relatively flatter signal, perpendicular to the antenna shaft. When heeled over, this flatter signal may shoot into the water on one side of the boat and head to the moon on the other.

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Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 12/10/2004 : 22:22:55

I have always thought of the radiation signal as a sideways figure 8. As the boat tips and rolls half of the sign is transmited into the water or ground. The higher the antena the beter beam that goes out.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 12/10/2004 : 23:03:37

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Douglas
 I have always thought of the radiation signal as a sideways figure 8. As the boat tips and rolls half of the sign is transmited into the water or ground. The higher the antena the beter beam that goes out.
<hr height="1" noshade id="quote"></blockquote id="quote">

The radiation pattern of a 3db antenna resembles a fully inflated inner tube whereas the 6db antenna radiation pattern resembles a flatter, deflated inner tube that stretches out farther than the fully inflated tube, with a considerably narrower beam.

Edited by - dlucier on 12/11/2004 00:34:28

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