Advice on re-wiring a mast please?


New member
5 Apr 2007
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Does anyone have any tips on re-wiring a mast? I'm not too confident, never done anything like this before. Boat's been out the water for 5 years and also needs new anchor light (10 watts?) and mast light (25watts?).

What size/kind of wire should I use if power coming from 12v battery?

How should the wire be laid out inside the mast - and how do you get it all through the mast in the first place?

Sorry if anyone's asked this before - this is my first post on any forum, and couldn't see anything obvious in previous posts.

Would be grateful for any advice anyone can give.



Well-known member
20 Sep 2006
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First off, welcome to the forum. My experience was with my Westerly Centaur last year when I replaced the wiring for anchor and steaming lights (new cable) and also windything, radar and VHF (all cabled). The bottom 2m of he mast was foam filled so first off was punching a hole through that. Drilling holes as required and making sure that all cables run were grometted and sealed as well as possible (chafe, vibration etc -I'm not too keen on going up the mast). I used three core cable from the chandlery to provide a common neutral for the steamer and anchor, plus a positive for each. The cables were all then fed through an outer sleeve (PVC conduit from B&Q) which was pushed as far up the mast as the first exit through the mast itself (which was the steaming light). The conduit was used to avoid any internal rattling of cables. After that the mast foot was replaced, and up went the mast. The through deck work is another story. Hope this helps .............. by the way, so far so good /forums/images/graemlins/grin.gif


New member
13 Sep 2001
Whitby, Yorkshire, England
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Welcome to the forum
A few points from my experience
1. Buy the thickest cable you can to avoid voltage drop over this long cable run.
2. Buy the cable from an electrical or DIY store as it will be cheaper
3. Last time I used three core 13 amp flex and it has worked fine for years
4. The cable will "hang" down and this will put it under tension - I used a simple knot (in the wire) at the top to hold it and wrapped self amalgamating tape to protect and cushion it
5. The cable will slap the inside of the mast when at anchor etc which can be annoying - most people recommend fixing cable ties round the flex every few inches to hold the flex away from the sides of the mast
6. To thread the cable through the mast I used a lenght of stiff galvanised fencing wire which can be pushed through the inside of the mast. Tie thin cord to the end of the wire and pull it through then use the cord to pull the flex (all this if you cannot use the exisiting wire as a pull cord).
7Change the VHF aerial and other wires whilst you are at it.
8 Self amalgamating tape is really useful and versatile especially for extra sealing on deck and mast head fittings but put plenty on as it eventually decays in sun light. It is really good for protecting open ended fittings whilst the mast is down.
9 Dont worry too much about perfection - Just do it and with some care and you will almost certainly do a better job than the professionals and over time you will build your confidence in yourself and your boat