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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

VHF antenna placement

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SRH_Catalina_Newbie
Deckhand

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11 Posts

Initially Posted - 03/28/2010 : 19:19:15

Has anyone mounted a VHF antenna on the mast? It looks like the best place for the bracket is right on the side of the aluminum masthead but that is exactly where the directions from Cat Direct say not to install it.

My only alternative is mounting it to the side of the mast about two feet down from the top to avoid the main stay.

Any suggestions would be welcome.

Edited by - on

John Russell
Master Marine Consultant

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USA
3444 Posts

Response Posted - 03/28/2010 : 20:18:42

Mine extends 8 feet above the mast. My kid fixes radios for Uncle Sam's Air Force and he said the higher the better and an 8' whip was my best choice.

Edited by - on

SRH_Catalina_Newbie
Deckhand

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Response Posted - 03/29/2010 : 04:14:36

Thanks John! Is it mounted to the mast or the mast head?

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John Russell
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Response Posted - 03/29/2010 : 07:04:49

It's mounted on at the masthead next to the anchor light and above everything else. It's on a "tab" that extends a couple of inches from the masthead.

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Even Chance
Captain

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Response Posted - 03/29/2010 : 08:08:11

It's true that the higher the better -- VHF is line-of-sight. Most sailboats use the 3' base-loaded whip. I'm not an electronics expert, but my understanding is that one of the antenna issues on a sailboat is the relationship between the dB rating and angle of heel. The higher the dB rating -- I think the 8' antenna that is being recommended is higher dB than the 3' -- the more concentrated the output signal is. That means you can be heard farther because the beam is narrower. However, if your boat is heeling, the narrower signal may go up over your intended target.

My 3' whip at the masthead can hear 30 miles away (depending on the height of the transmitting antenna, of course), and I've been able to transmit and be heard by another sailboat 20 miles away, even with the boat heeling significantly.

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islander
Master Marine Consultant

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USA
4017 Posts

Response Posted - 03/29/2010 : 09:13:04

Mine is mounted on a tab on the side if the masthead. I have a SS whip antenna. It is that round can looking thing ( the whip is removed in the photo) in the five o'clock position.

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OLarryR
Master Marine Consultant

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USA
3436 Posts

Response Posted - 03/29/2010 : 10:18:01

I was having an OGM LED Anchor Light installed and the brackets I had would not work for it. So, the mechanc that worked it for me had a shop make a stainless steel bracket with holes drilled for it and a tab coming off of it horizontally with a hole to attach the VHF antenna.

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Dave Bristle
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Djibouti
10005 Posts

Response Posted - 03/29/2010 : 10:28:09

An 8' whip on the mast-head is overkill IMHO, given the weight and windage it adds up there. Most sailors are satisfied with a 3' base-loaded whip on the mast-head, or an 8' fiberglass whip on the sternrail (eliminating the issue of snaking coax through the mast). It's true that higher "gain" (measured in dBs) produces a flatter transmission pattern that could reduce range somewhat at substantial heel angles. And bigger whips have higher gain.

The USCG has an array of tall antennas along the coast, and high-powered transmitters. They can hear you, and you them, from a long way out even when you're just using a hand-held with a rubber-ducky antenna. They can also triangulate on your signal to estimate your position. And contrary to what "line-of-sight" might mean to some people, VHF waves do bend somewhat over the horizon as well as over land masses and tree lines, just as waves in water go around islands and points. VHF just doesn't bounce of the ionosphere as AM and SW signals do. I regularly communicate over a 40'+ high land mass from my 12' high (at the midpoint) whip to a pumpout boat in a cove several miles away.

Edited by - Dave Bristle on 03/29/2010 10:34:38

OLarryR
Master Marine Consultant

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3436 Posts

Response Posted - 03/29/2010 : 10:44:58

Forgot to mention that my antenna is one of those shorty ones...perhaps 1-2 ft max above the mast top.

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 03/29/2010 : 13:09:10

I second Bristle, put a 3 footer at the masthead or an 8' whip on the rail. I have a 90º bracket on the starboard side of the mast, not the masthead fitting; it doesn't matter which side its on as long as there is room.

Edited by - Dave5041 on 03/29/2010 13:12:49

SRH_Catalina_Newbie
Deckhand

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11 Posts

Response Posted - 03/29/2010 : 20:35:07

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by islander
 Mine is mounted on a tab on the side if the masthead. I have a SS whip antenna. It is that round can looking thing ( the whip is removed in the photo) in the five o'clock position.

<hr height="1" noshade id="quote"></blockquote id="quote">
Thanks for the picture that really helps. I have a 3 foot whip and a similar round can as a base. It looks like you were able to install it next to or just above the main stay and clearly it didn't get in the way lowering the mast. Big help, Thanks.

Edited by - on

frog0911
Master Marine Consultant

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USA
1349 Posts

Response Posted - 03/29/2010 : 21:15:05

More pictures:

Edited by - on

SRH_Catalina_Newbie
Deckhand

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11 Posts

Response Posted - 03/30/2010 : 13:34:26

I want to thank everyone for your input. I think I will go ahead and mount my 3' antenna to the mast head even though C-Direct instructed me not to.

This looks like the best solution and nobody who did it is complaining about the results.

Thanks again!

Edited by - on

Voyager
Master Marine Consultant

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USA
5348 Posts

Response Posted - 03/30/2010 : 21:08:44

How will you do your deck fitting at the bottom of the mast? You should use a coaxial connector.

You have to make sure that the connector impedance (50 Ohms or 75 Ohms) matches the cable impedance.

Most boating stores and catalogs will carry them.

Edited by - on

JohnP
Master Marine Consultant

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1520 Posts

Response Posted - 03/30/2010 : 21:28:49

If you need details about the deck connector, you can find info in Don Casey's book "Sailboat Electrics Simplified". The coax connector is a critical component.

Edited by - on

Voyager
Master Marine Consultant

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5348 Posts

Response Posted - 03/31/2010 : 17:38:16

Here's a link for a thru cabin coax connector
http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/19502/377%20710/0/coax%20connector/Primary%20Search/mode%20matchallpartial/0/0?N=377 710&Ne=0&Ntt=coax connector&Ntk=Primary Search&Ntx=mode matchallpartial&Nao=0&Ns=0&keyword=coax connector&isLTokenURL=true&storeNum=5003&subdeptNum=3&classNum=30

Here's one you can screw down in place
http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/13552/377%20710/0/coax%20connector/Primary%20Search/mode%20matchallpartial/0/0?N=377 710&Ne=0&Ntt=coax connector&Ntk=Primary Search&Ntx=mode matchallpartial&Nao=0&Ns=0&keyword=coax connector&isLTokenURL=true&storeNum=5003&subdeptNum=3&classNum=30

Edited by - on

SRH_Catalina_Newbie
Deckhand

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11 Posts

Response Posted - 04/01/2010 : 08:28:16

Good question on the deck fittings and thanks for the links.

I bought the entire antenna kit from CD. I got the whole package from antenna, cable, fittings the works. The only thing that confused me was that they said specifically in the instructions NOT to mount the antenna to the mast head which is why I posted this Q to begin with.

This forum has been a fantastic resource for this rookie sailor. I will post pictures after I mount the antenna to the mast head and finish the job of running the antenna cable into the cabin.

Edited by - on

Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 04/01/2010 : 09:02:17

<blockquote id="quote">quote:<hr height="1" noshade id="quote">The only thing that confused me was that they said specifically in the instructions NOT to mount the antenna to the mast head <hr height="1" noshade id="quote"></blockquote id="quote">

Perhaps they were indicating it should be mounted to the bracket and not directly to the mast head. According to there web site they say:

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Ours installs at the masthead exactly where you want it.<hr height="1" noshade id="quote"></blockquote id="quote">
Classic doublespeak.

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