Replace Marine Radio Coax & Mast Lights...

[SirMichael]

I have a 78 Hunter 28.5. It's about a 40' mast, plus the mast step in the cabin.

1. I found that the antenna match from my radio to my Marine antenna wasn't as good as it used to be (SWR was 1.2:1, recently over 4:1). I ran a "TDR" (Time Domain Reflectometer) and found that it was failing at about 26 feet up the coax). (So, I'm a ham radio geek, I know this kind of stuff...)

We went up the mast, changed the antenna (no problem) but the coax wouldn't move inside the mast. From the bottom of the mast the coax wouldn't move. From the top, we could pull out about 4' of excess coax out of the mast, through the hole. After that it's stuck! I'm guessing that it's stuck where the coax failure is (pinched line?)

OK, so we have to replace the coax. Not sure if I could run an electrician's fishing tape up (or down) the mast. Going up, how do I get it through the small hole at the top of the mast? I'd rather run it so I could pull the coax DOWN the mast, so I can have the coax connector already mounted on the coax (as opposed to trying to put the connector on up at the top of the mast!).

Does anyone have any experience with what's inside the mast? Should I be able to fish a line up or down the mast?

2. Also, I wanted to change the light bulb at the top of the mast. I had some regular 'festoon' bulbs (Pointed on the end), but this bulb has a dip on both ends for the two connections to press in. Reference the attached picture. I've tried to read the numbers on the bulb, but as close as I can make out, it's "A8CS25" or just "CS25". Of course I'd like to replace it with an LED bulb, if I could find one.
A. Any idea what the bulb may be and where I can find it? It's 1.75" long. 12V, 10W
B. Would I be better off replacing the whole mount?

3. The Anchor light (half way up the mast) is burned out and I guess I've just resigned myself to replacing the whole unit (3 3/4" between the mounting holes).

Sir Michael

 

[Mr. Dave]

You might, repeat, MIGHT find it worthwhile to pull the mast and work on it while horizontal, probably not horribly expensive and easier than swinging in a bosun's chair some 40 feet in the air, hauling tools and junk up and down in a bucket while yanking on a fish tape. Whole lot easier. Standing rigging notwithstanding...

Brand new wiring all around would be pretty easy while your in there. Plus figuring out what pinched your coax in the first place would be smart so the new one doesn't get screwed up and you have to do it all over again in a couple of years. New boot at the deck joint while you're at it? (my experience is all with deck stepped masts, no idea what's involved in waterproofing a keel-stepped mast, please don't everybody go getting excited...)

And I bet the guys at your local yard can ID the lightbulbs for you.

 

[Ron20324]

Did you try to pull on the halyard(s) at the same tme as the coax?

 

[dmax]

2) Festoon bulbs come in innies and outies (barrell and cone ends) - you just need an innie version. I replaced my anchor light (on the top of the mast) with a new Aqua Signal and bought an LED bulb for it here:

31mm, 37mm, 42mm, and 44mm LED Festoon Bulbs | SV8.5

31mm, 37mm, 42mm, and 44mm LED Festoon Bulbs | SV8.5 Cone end, Barrel end, Dimpled end

store.marinebeam.com

The anchor lights tend to get brittle after 20 years or so (mine crumbled in my hands), so if yours has any age to it, I would replace it (they are only about $25-30, you can swap the incandescent for an LED).
3) Half-way up the mast is your steaming light which may also have a built in deck light (very handy to have), I replaced mine with this from marine beam as well ($60 with LED bulbs):

Foredeck / Steaming Combination Navigation Light - Economy Series 25

Foredeck Light, Masthead Combo Eco Series LED masthead steaming navigation light fixture with deck, 225 degree 2NM 3NM

store.marinebeam.com

 

[jssailem]

All good ideas here Sir Michael, (once knighted?)

The idea of working with the mast horizontal is a whole lot easier. A 78 Hunter? Perhaps time to examine the standing rigging as well. Great winter project. You may have snagged the coax on a screw end. Things get attached to the mast. Sometimes owners screw in a "long" screw, when what is needed is one the thickness of the mast. Or they drill into the electrics channel in error. Coax does not like to be disturbed.

Once on the hard you can open the ends and with a bright light identify the issue. I would change out the coax. I ran LMR400 when I refit my mast in 2016. Love the low loss and flex around corners when installing.

The light on the from of the mast would be your steaming light. Anchor light is a 360degree light. Often on the mast but can be hung on the stern or from the boom.

"(b) A vessel of less than 50 meters in length may exhibit an all-round white light where it can best be seen instead of the lights prescribed in paragraph (a) of this Rule."​

​

On the front of the mast means you would not see it if coming up astern.

Go LED's if you want to reduce your energy consumption.

 

[Mr. Dave]

And to answer one of your first questions, you might find there's a foam plug in the mast somewhere (to keep the ocean out if you get knocked down), which would stop you fishing much of anything up or down in there if it wasn't run in a full conduit of some sort. May be why you can't extract the old coax. Again, not a problem with deck stepped, all my troubles with wiring involve how to transition out of the mast and into the cabin (drill holes in my boat, lots of holes, wah...)

 

[JRacer]

Second the idea of Marinebeam for all your lighting needs!

 

[Justin_NSA]

+1 vote for unstepping the mast first if it's practical. Especially since you have no idea what prevents the cable from pulling.
Light on top is the anchor light. Midway up is the steaming light. If it were me, I'd just replace both fixtures with new LED units and that have clear, not old and yellowed lenses. A combo steaming/deck fixture is nice.
MarineBeam set me up with everything I needed when I refurbed my mast lighting.

 

[SirMichael]

Actually, I’ve gone back and forth on pulling the mast, but at this point I’m going to find out if the lights wiring is OK. I’m going to replace the lights and it it works, then I’ll just move the antenna to the bimini. The lake we’re on is only about 20 miles, an even a handheld should be sufficient.

If that fails, then I’ll be forced to pull the mast.

Dmax, thanks for the link on the dimpled festoons!!!

Sir Michael

 

[Justin_NSA]

I went OCD when I tackled my mast wiring. My steaming/deck combo light was previously wired together with 2 wires, + & -. I pulled that wire and ran a 3-wire cable to power them individually. Both anchor light and combo light fixtures were reran with 16 gauge cable. Not for the electrical load, but for the mechanical load. On the control panel I replaced one light switch with a SPDT switch so either the anchor or steaming light could be turned on, not both. The deck lamp was left to its own dedicated switch. The anchor light fixture was replaced with a new LED one. The combo fixture got a fresh lens for the new LED steaming light, and the new LED deck light replaced the old incandescent bulb and lens. Everything was done with the mast down. My work here was done....except earlier this year I had to replace a broken Raymarine wind direction vane. I got both "sensors" in a kit.