Help ID Mystery wiring

[MollyJo]

Hi All
I have been systematically going through the wiring on my recently purchased 33 year old yacht. Lots of obsolete wires have been left behind when rewiring had been done.
Anyway, I found this little box in the cabin right below the mast foot which has cables running into the mast. Problem is I have no idea what it does.
I suspect something to do with the onboard radios but a) it's not coaxial cable and b) the antennas are mounted off the stern rail.
I have VHF and 27meg stations but the hull has ground plates so maybe there was an HF set at some time in her history.
Can anyone shed some light on this for me? Photo's attached.
Cheers
Dave

[noelex 77]

It is a junction box to allow disconnection of the wires when the mast is removed.

I would guess combination of nav lights and/or wind instruments.

Wind instruments typically need 5-7 wires and the navigation lights include tricolour, steering light. Windex light, anchor light, spreader lights etc.
There is not enough conductors for all of these options, but it will be some combination.

Radar and VHF/27MHZ aerials are also sometimes fitted on the mast, but the former requires a couple of thick conductors (as well as some thinner wires) and the later requires coax and you have already noted the aerials are not mast mounted.

What is fitted (or has been) fitted on the mast?

[beneteau-500]

that is your wind instrument wires and if its raymaine instrument look on there web site and it will give you voltage readings that should be present at these wires when powered up to check if working correctly

[MollyJo]

Thank you, yes wind instruments of course! There is the full compliment up there and separate heavier wires for nav, running and anchor lights.
Funny how obvious it becomes once pointed out.
I have to go up the mast soon to work out why the anchor light blows a fuse. It has an independent circuit and I have traced the cable through the boat without finding a fault. Any suggestions as to what could be the cause? It started happening this summer so I think unlikely to be moisture related.

[Jim Cate]

Originally Posted by MollyJo

Thank you, yes wind instruments of course! There is the full compliment up there and separate heavier wires for nav, running and anchor lights.
Funny how obvious it becomes once pointed out.
I have to go up the mast soon to work out why the anchor light blows a fuse. It has an independent circuit and I have traced the cable through the boat without finding a fault. Any suggestions as to what could be the cause? It started happening this summer so I think unlikely to be moisture related.

Your anchor light issue is likely due to a chafed wire shorting out. A possible place is where the wire enters the mast at the base or exits at the masthead. I've seen plenty of bad installations where no grommet was used and the wire bore against the sharp edge of a drilled hole in the aluminium.

Cheers,

Jim

[ohYes]

Originally Posted by Jim Cate

Your anchor light issue is likely due to a chafed wire shorting out. A possible place is where the wire enters the mast at the base or exits at the masthead. I've seen plenty of bad installations where no grommet was used and the wire bore against the sharp edge of a drilled hole in the aluminium.

Cheers,

Jim

Thanks for the tip, Jim. My anchor light is mysteriously flickering, and this sounds like a definite possibility.