How to wire mast cables correctly?

[janis]

I recently purchased my first boat Scanmar 35 and I'm now working on some improvements and fixes. One of things I need to do is to install new wires in mast (VHF and electrical cables). I have Isomat NG51 mast with cable conduits already installed. Mast is keel stepped and I will need to remove it from time to time for winter storage.

What is unclear to me how to fasten cables near top of the mast where they exit cable conduits. So that there is some kind of support and all cable weight doesn't rest on cable connectors to lamps etc. I also had noticed that new wind sensor cable that was installed by previous owner already is chafed against halyards that are inside mast. So I need to somehow protect wires between cable conduit end and masthead (cable conduits end approx 1 meter from top).

If somebody also could share pictures of your wiring near mast head it would be really helpful.

[MicHughV]

You make a good point. I don't have any photo's, but I made up a harness of nylon twine which I wrapped around the cables and this was attached to the inside of the mast at the mast head to to some protruding bolts that held the upper shrouds.
The " harness" was simple to make. I simple wrapped the twine around the cable many times and formed a loop at the end. To make sure, everything would not rot or decay, I slathered it all in some water proof grease.
Years later, after I had sold the boat, the masts were taken down for transport and I had an opportunity to inspect my "harness" which still looked like the day I made it.

[janis]

I'm hesitant to bundle all wires together. If at some point in future I would need to replace one of cables it would be more difficult to remove individual cable. Would it be better option to put some kind of strain relief on each wire separately?

--

Adding to my previous question - my plan is to install rubber grommets in holes that are currently drilled in mast near mast feet and where cables exit from mast. Currently there is no chafe protection and wires are chafing against aluminum. I would also additionally need to drill bigger hole - approx 25 mm so I can pass through VHF connector. Do I risk weakening mast with such additional larger hole?

[Jammer]

https://www.mcmaster.com/products/cu...g-loop-clamps/


https://www.mcmaster.com/products/cable-support-grips/

[Jammer]

I like to seat a rivnut in the cable clamp then drill a hole in the mast and thread a screw with some loctite on it in from outside.

[Jammer]

Originally Posted by janis

Adding to my previous question - my plan is to install rubber grommets in holes that are currently drilled in mast near mast feet and where cables exit from mast. Currently there is no chafe protection and wires are chafing against aluminum. I would also additionally need to drill bigger hole - approx 25 mm so I can pass through VHF connector. Do I risk weakening mast with such additional larger hole?

25mm is big.


Some choices:


1) Feed the cables down through the mast step if possible.


2) Use a smaller diameter VHF connector, such as a TNC connector.


3) Use a bulkhead connector instead of a grommet for the VHF, see photo showing the mast cable for my previous boat with bulkhead connectors on both ends:

[capt jgw]

I would not drill that big a hole in the mast. Drill one just big enough for the cable and it's grommet and attach the terminal end afterwards. Many antennae that come with permanently attached cables come with the terminal end not installed for that reason, as well as letting you cut off any excess length. Soldering the terminal on is not that difficult. Same thing for both ends of the mast.

[jamhass]

I would not be too concerned about not wanting to bundle the cables in order to accommodate new wires in the future. Rather, I would think carefully about what you might want in the near future and add some additional cables to the bundle.

Possibilities might be deck lights, forward facing camera, other new sensors, additional colored anchor light (helps find your boat in a crowded anchorage at night), etc ???

[MicHughV]

https://www.mcmaster.com/products/cable-support-grips/

that's exactly what 1 did using my twine, worked great.

I would not be drilling a 25 mm hole...1"...that's for sure. I'd make the hole just big enough to fit the cable thru'.

If you are concerned about abrasion, wrap the cable in some electrical tape or duck tape, or even a plastic sleeve, slit open so you can get it around the cable.