VHF Antenna Cable

BCC Forum
1

Ahoy All,

We’re preparing to replace CYMBA’s VHF radio and in the process of conducting a lot of research on the topic (being a neophyte to radios) I’ve learned that the radio is just a small piece of the radio, antenna, cable ‘system.’

As such, we also intend to replace the antenna and cable when we replace the radio. Quick question: I assume (hope) the cable from the masthead to the step is supported with some type of brackets within and doesn’t just have all of the weight of the cable hanging. Assuming that’s accurate, are there standard brackets within the masts of BCCs or are they all generally unique?

If they are standard, how does one access them in order to loosen them to run new cable through and replace the old?

Thanks for the help. Apologies if this is a ridiculous question.

Cheers,
Mike
S/V CYMBA
BCC #77

2

My experience is limited, Mike, but apart from a few trailer-sailers and sailboats around, or less than 20 ft, with only nav lights on the mast, most every aluminum mast I’ve worked on has had one or more runs of conduit (usually PVC conduit, the sort of thing used by electricians and plumbers) through which the cables (VHF, radar, masthead wind instrument, etc) and wires (electric power to masthead lights etc) run.

The conduit is then riveted to the mast. And remains fixed in place until a wee bit of corrosion takes out the pop rivet. That is heralded by banging of the unsupported conduit inside the mast.

The usual deal with cable thru conduit is to unstep the mast and either pull old cable out with a messenger line attached (which then can be used to lead new cable into the mast) or to haul out the old cable and fish either a messenger line or the cable directly.

At least theoretically you could haul new cable through a standing mast. I’ve seen that done with electrical wiring. I don’t remember seeing it done with VHF cable.

Attached might be a photo taken up Zygote’s mast about four years back when we ran new VHF cable and new wiring for the lights, See Up the mast.jpg.

up the mast.jpg
up the mast.jpg1500×979 221 KB

3

Thanks Bil, that picture is VERY helpful.

Do you recall what type of support/bracket held the weight of the VHF cable near the top of the mast? I assume it’s not just held by the weight of the connector?

Cheers,
Mike

4

Thanks Bil, that picture is VERY helpful.

I spoke to one of the older guys at my marina and he said, given the age of BCC77, that it is possible that if the mast has not been unstepped and conduit added, that you might just have bundles of cables + wires tapped together without conduit.

That person said he was not clear when conduit became the rule for aluminum mast extrusions.

Late addition: if you have conduit inside your mast, then the conduit is pop-rivetted to the mast every few metres. So if you see pop rivets running in a couple of lines up the mast, you have conduit.

The deal with conduit is that it supports cable and wiring, and stops them (among other things) slapping against the inside of the mast.

Yet another late addition: Zygote’s mast has two conduits. One runs to the masthead (with VHF cable, wind indicator cable, and wiring for the masthead light). The other runs to the hounds, carrying the radar cable (i.e. Zy has a mast-mounted radome) and wiring for deck lights and low-level sidelights (used when steaming). So Zy has two lines of pop rivets. You might only have one line if you only have cabling to the masthead.

Do you recall what type of support/bracket held
the weight of the VHF cable near the top of the
mast? I assume it’s not just held by the weight
of the connector?

No, you cannot have the weight of 13 metre of cable applying tension to the antenna connector.

Zygote’s VHF antenna is mounted on a bracket to starboard. The cable is lashed to that bracket with a couple of supposedly UV-resistant cable ties. Then the cable - surrounded by a supposedly UV-resistant sleeve, curves before it enters the mast. I think that the lashing plus the friction at entry to the mast does a fair bit of the supporting of the cable mass. I’m unclear about other support.

Another late addition: I don’t remember any other supporting structure (but I have trouble remembering what I did on the day before yesterday and occasionally I have to hunt for the car keys!

See (taken before the mast was re-stepped of course): masthead.jpg

masthead.jpg
masthead.jpg790×595 90 KB

5

Thanks Bil, I really appreciate your insights as always…wait a second…‘Given the age of BCC77’!?

Did you just call CYMBA an aged cruiser?

Would you call me an aged cruiser? No one would call her old, she’s stiff, weatherly, and fast. Very fast if well handled. No, CYMBA is not old…she’s in her prime! =)

Now if you’ll excuse me, there are many boat projects to complete and not a moment to lose!

Cheers,
Mike