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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

Installing a mast VHF Antenna

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stanirish
Deckhand

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USA
8 Posts

Initially Posted - 05/19/2021 : 16:40:07

I'm thinking about installing a VHF Antenna on my 1981 Cat 25. Surprised Catalina did not include the cable and antenna in it's price. De-stepping the mast seems difficult and hiring it out is expensive. Any ideas and experience with this issue appreciated.

Steve Milby
Past Commodore

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5882 Posts

Response Posted - 05/19/2021 : 18:58:49

New boats are like new cars. There are long lists of optional accessories that one can order. When I bought my new 1981 C25, stoves, sinks, porta potties, utility drawers, lifelines, boom vangs, and many other items were optional. Many people bought C25s to sail on small inland lakes, where very few people used vhf radios.

There are alternatives to installing an antenna at the masthead. You can use a handheld vhf, or you can install an antenna on the pushpit. Since getting my handheld vhf, I don't recall ever needing my fixed mount vhf. I used my handheld to communicate with marinas, restaurants and ships and barges, and for racing.

Stepping and un-stepping a C25 mast isn't as difficult as it seems, but you either need 3-4 reasonably strong helpers or you need an A-frame and a mast-up. You can find information on how to make an A-frame and mast-up at this link. http://catalina-capri-25s.org/tech/tech25/bearsad1.asp

At my lake, we always had ample people to help each other raise and lower masts, so I never needed an A-frame.

This link will take you to a good discussion of different methods to lower the mast. http://catalina-capri-25s.org/forum/topic.asp?TOPIC_ID=31883&SearchTerms=lower,mast

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Voyager
Master Marine Consultant

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USA
5320 Posts

Response Posted - 05/19/2021 : 19:08:33

Thinking about my VHF antenna at the top of the mast, I think about the length of the antenna, interference with the windvane, and how to install and mount the RG-58 cable.
The length of a quarter-wave antenna is about 30� plus the 6-8� length of the antenna base. The windvane is mounted on the backside of the mast top, so the antenna must be mounted forward on its own arm connected to the mast top bracket.

The cable passes through the cabintop with either a through connector or not, then it passes into the inside of the mast through a small hole near the base of the mast, lined with a rubber grommet. The cable passes through and up inside the mast until it comes to another small hole near the top of the mast, then it connects using an RF through connector onto the bottom of the antenna base.

It�s important to have (1) good solid connections and (2) very good weather-proofing to prevent any corrosion over time.

Corrosion will affect your effective radiated power on transmit and signal pull-in capability on receive.

If, over time corrosion happens, and your radio starts broadcasting at a lower power, then nobody will hear you when you need your folks the most. Best to test your radio twice a week during the season to avoid surprises.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain � Milford, CT

Edited by - Voyager on 05/19/2021 19:25:46

Leon Sisson
Master Marine Consultant

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1891 Posts

Response Posted - 05/20/2021 : 10:23:33

I agree with what Steve Milby and Bruce Ross, above.

Regarding adding or replacing any wiring inside the mast, I recommend installing PVC conduit to prevent it from slapping around. As I recall, there's a detailed procedure for doing this in Don Casey's book "This Old Boat" which I encourage every Catalina 25 owner to study.

While working on the mast wiring, consider replacing old worn incandescent mast lighting fixtures with new low current LED lights, and maybe switch to lighter gauge wiring.

Also, make some provision for supporting the weight of the wiring at the masthead, rather than letting it hang by its electrical connections.

While the mast is down would be a good opportunity for a thorough rig survey if it hasn't been done recently. Have the spreader sockets been upgraded to stainless steel? Are the turnbuckles open body, and turn freely? Does the standing rigging have any broken or badly rusted strands? Do the spreader boots need relashing or replacing? Are all fasteners in good condition? (That's not intended to be a complete list.)

"With careful planning, there's no boat project which can't be made more expensive and time consuming."

� Leon Sisson

islander
Master Marine Consultant

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USA
4012 Posts

Response Posted - 05/20/2021 : 10:34:39

Well since you don't want to drop the mast your next best thing is what Steve said. Use a handheld or mount an antenna on the pushpit railing.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

stanirish
Deckhand

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USA
8 Posts

Response Posted - 05/20/2021 : 11:39:40

Thanks Steve, Voyager, Leon and islander for the input...this is a cool forum!

Lee Panza
Captain

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USA
465 Posts

Response Posted - 05/20/2021 : 19:27:44

One of the big factors favoring a Catalina 25 is the ease of dropping the mast for maintenance. There's plenty of info about it on this forum, and I'd encourage you to look into it (BTW, just in case it's not entirely clear, the boom needs to be detached from the mast before the mast comes down).

Snaking a new cable into the mast is relatively easy using a "fish-tape" (every electrician has at least one, but if you might ever need to run a new wire through your boat for ANYTHING you'll find this a valuable tool to acquire).

VHF propagates pretty much on a line-of-sight basis, so the higher the antenna is the farther it can transmit/receive over a body of water large enough to extend past the visible horizon. Sailboat masts move around a lot, so a 3db antenna is usually preferred. This transmits in a pattern with a broad vertical dimension, compared with higher db antennas that transmit in flatter radial bands. A typical antenna for a sailboat mast will be only a little more than 3' long. Some of us consider the Metz Manta to be the "gold standard" for a small sailboat antenna, but Shakespeare offers alternatives.

The most common connectors for the coax cable are PL-259's, and it's easy to buy cable with those fittings on both ends (the male fittings will usually mate to the radio and to the antenna base). HOWEVER... you'll want to snake the cable through holes in the side of the mast, as well as through a minimal hole through the cabin top, and you'll probably want a male/female connector pair between the mast and the cabin top penetration to allow the mast to be removed easily, so you'll be better off with bare cable and separate fittings you add to it yourself. RG-58 cable is cheap and easy to run, although RG-8X provides less loss. RG-8/U or even LMR-400 provide far less loss, but at almost 1/2" diameter they are a bit more difficult to run.

Probably the most valuable advice would be to apply liberal quantities of dielectric grease in the connectors exposed to the weather (despite the name, dielectric grease is NON-conductive, so it simply excludes water from getting inside).

That's the basics. A hand-held is good for boat-to-boat communication, and for relatively short-distance ship-to-shore, but a good masthead antenna extends your reach and expands the potential recipients if you ever need to call for help. If you know that you'll never be distant from a prospective recipient, a hand-held is good enough. But a good mast-head installation, with a good cable to a fixed radio unit, adds a substantial measure of reliability if you ever need to call for help and nobody's nearby.

The trouble with a destination - any destination, really - is that it interrupts The Journey.

Lee Panza
SR/SK #2134
San Francisco Bay
(Brisbane, CA)

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