When Replacing Electrical Items in the Mast

Raymarine Wireless Tacktick Mast Head Fly

Raymarine Wireless Tacktick Mast Head Fly

Re-wiring and replacing the fixtures in the mast is a task that most of us boat owners need to face at some point. Let’s address what needs to happen during this process and what is the most efficient way to do this.

OGM Tri-Color Anchor Strobe w/ Photodiode

OGM Tri-Color Anchor Strobe w/ Photodiode

Forespar ML II w/ Light Guard

Forespar ML II w/ Light Guard

First, the mast needs to be un-stepped. Therefore it could be a smart idea to handle any other items that could benefit from the mast being out. Next, begin by removing the old masthead fixture, the old steaming light fixture, and the old VHF antenna. Now remove all of the old wires and any remaining hardware. In some cases there are electrical items that need to be re-used. These items could be a radar and cable, as well as a digital wind instrument. Be sure to carefully remove these items as well and inspect them closely (now’s the time).

Shakespeare Squatty Body VHF Antenna

Shakespeare Squatty Body VHF Antenna

Perko Spreader Light, Adjustable Mount

Perko Spreader Light, Adjustable Mount


Once all electrical items have been removed, you should check to see if there is a conduit present and how it may or may not be fastened. A properly installed conduit offers; no wire slap, clean wire runs, and most importantly, the ability to run additional wires or trouble shoot existing ones with ease, even when the mast is up.

Sailboat Mast Conduit

Properly Installed ConduitInstalling a conduit is a bit’ of a ‘trick of the trade’. It is best here to seek the assistance of a professional rigger if one needs to be installed. Make sure to ask your rigger what technique he or she might use. At T.R.C., we will use aluminum or PVC irrigation tubing. This type of tubing offers a sleeker connection at the joint. Our conduits are then riveted using a pair of aluminum rivets (to avoid dissimilar metals) every 3′ or so along the length of the mast. I like to counter sink these rivets because it makes it look more finished and also gives you no issues if there might be future sanding. Properly installed conduit   After the conduit is ready to go, you are now ready to fish-in a messenger line. From here you can begin to pull in your new wires. Always try and leave in a service messenger when finished. Unless the conduit is full of course, we don’t want to be misleading anyone in the future. I tend to make it a practice to pull-in the large wires or the wires with permanent ends first. Now go ahead and drill, tap, and dry fit your new fixtures. Make sure you take your time and think it through and follow the manufacturers guidelines. Never use sheet metal or self tapping screws, even if provided by some manufacturers. Always drill and tap, or rivet your fixtures along with a dab of sealant for a secure hold. marine grade electrical connectors and heat shrink tubing Forespar ML II Wiring Guide Make sure you use marine grade connectors that heat shrink. Additionally, before making any connections, slide on a piece of marine grade heat shrink tubing. Marine grade heat shrink tubing has an adhesive that is released when heated. After your connections are made and heat shrunk, make sure to provide some sort of strain relief for the cables (pictured below). Proper strain relief for electrical cables at mast headNext, install the fixtures permanently using a sealant as an isolation barrier. Pull out any remaining slack at the butt of the mast. Trim all of your cables to a neat and even length. Leave enough slack for service lengths. Finally test all of the light fixtures through the mast and label the cables accordingly. As always, don’t be afraid to ask, so leave a comment or ask a question, we will reply. Thanks for the read!

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23 Responses to When Replacing Electrical Items in the Mast

  1. Anonymous says:

    Our VHF antenna whip came off. The base is still up and fine. Mast is up and cannot be dropped now. Could a new whip just be screwed into the old base?

    • The Rigging Company, LLP says:


      It is likely that you may just be better off buying an entire new VHF and go aloft and install it. This should just screw into the new cable (if the fitting is still okay) and you’ll be all set. Hope that helps.

      Thanks for the Comment,

    • Steve Legal says:


  2. Steve Legal says:

    I replaced the mast light wire , which was copper, with the same ga. aluminum (18 ga.). Should I have upped it to 16 ga. or more?

    • The Rigging Company, LLP says:

      Hi Steve,

      This may be a better question for a marine electrician. We use 16 a lot and 14 or 12 for bigger boats. However I see no reason you can’t use 18 awg especially given that all lights are LED now.

      I think the answer may lie in how long the wire run is, and how much current draw does it need to support? I would like a second a opinion from a marine electrician on that one to be sure. Anyone? Bueler?

      Long answer short….as long as you used a marine grade wire, I’ll bet it will be fine.


      P.S. is the wire really aluminum? I thought it was tin coated copper no?

  3. bob fearn says:

    How do you hold on to the conduit when you are drilling the holes for the rivets? Also I assume you glue the PVC pipe together and then slide it into the mast? Could you put the messenger line in then or is their an easy way when the conduit is in the mast?
    Thanks for your help.

    • The Rigging Company, LLP says:

      Hi Bob,

      We would run the messenger via a Fish Tape after the conduit is in. Our drill bit would otherwise snag it when drilling to mount the conduit. Use thin wall’d irrigation tubing with bell ends, 1″ to 1-1/4″ should do it. We have glued them in the past, but now we just install with the bell facing the mast head. The fit is snug enough to keep everything in place until we slide it into the mast. Then once fastened (every 3-4′) it can’t come undone, plus gravity is working with us once the mas goes up.

      To pull the conduit to the mast wall once it is inside the mast (loose) we make a special tool that we call a “conduit hook” out of a very stiff piece of rod rigging measuring just under 3/16″ of an inch. You probably don’t have access to this, plus it is very hard to bend. Another technique is to figure how you want the conduit to run, then tape it onto the outside of the mast and drill all the way through the conduit and into the mast wall. Then remove the conduit from the outside of the mast. Counter sink all mast wall holes so that the rivet head will be submerged. Then, roll the mast with the holes facing down, this way gravity will work with you, line up the first set of holes and pop your rivet. If you lined it up right the next holes should be right there and so on…

      Hope that helps and good luck.


      • Bob Fearn says:

        Thanks for your ideas. Very clever.

        bob in Canada

        On Thu, Mar 9, 2017 at 7:01 AM, The Rigging Company wrote:

        > The Rigging Company, LLP commented: “Hi Bob, We would run the messenger > via a Fish Tape after the conduit is in. Our drill bit would otherwise snag > it when drilling to mount the conduit. Use thin wall’d irrigation tubing > with bell ends, 1″ to 1-1/4″ should do it. We have glued them in the p” >

  4. Tim says:

    I’m preparing to rewire the mast on my Beneteau First 456 with a keel stepped mast and have a few questions.

    1) Currently each of the electrical wires and antenna coax exits the mast just above the deck and then connect to a series of water tight deck fittings. Is there a smarter (lower loss, less damage prone) way to get the wires below deck? I’ve considered running the connectors internally to near the base and exiting there.

    2) My plan is to use RG-213 for the VHF, is there a better alternative?

    3) I don’t know if there is a wiring conduit on the boat currently. On a previous smaller (27 ft) boat I used 3M 5200 to glue pvc schedule 40 to the inside of the mast as conduit with good success. What are your thoughts/concerns on that as technique on a larger boat (air draft 65′)?

    4) Do you have any suggestions for illuminating the sails enough to see tell-tales at night without destroying the crews night vision? We frequently race at night and have tried several glow in the dark products but end up just shining a red lens flashlight on the sail periodically.

    • The Rigging Company, LLP says:

      Hi Tim,

      All good questions let’s see if we can address them…

      1. There are some other options. Depending on the mast step style, and granted the mast has been removed, you can remove the mast step, locate and drill a smart hole at the required diameter (1″ or so, depending on what your wire bundle requires), and weld a 2-3″ Hawse Pipe to step at this location. You can bring the wires into the boat this way and make the connections below deck. You can alternatively bring the connections above deck and inside the mast, but this will require an access cutout and door (big enough for your hand to fit into) to be made a few inches above the mast butt. This will give you access to connect and disconnect the wires before stepping and unstepping.

      Another way is to install a stainless steel Hawse Pipe (6-8″ long, again w/ a diameter big enough to accommodate the wire bundle) next to the mast. The piece of tubing needs to have 180 degree bend so that the opening faces the deck and forces the wire into a drip loop. Then have a round (donut style) base for the mounting welded to its straight end. The bend needs to face aft to dissuade any rushing water from entering the boat. Connections here are also made below deck.

      2. You may be able to get away with using RG8X. You are right on the edge given the boat’s size, depending on the wire length, signal degradation becomes a concern. We use RG8X more than any other wire when it comes to VHF cables, but most of our customers are in the 35-45 foot boat range…Chesapeake Bay. It uses up less space in the conduit and utilizes solder-less PL-259 connectors, easy-peasy. A marine electrician is a much better resource for this question.

      3. There is very likely a conduit for the Z Spar (US Spars) mast or the Sparcraft Masts. However, the way either of this companies secure the conduit is were the trouble lies. IF the conduit is still in good standing, and hasn’t become dislodged aloft (common issue with these, as they are split length wise and slid onto a “T” in the extrusion), gently pull out all of the old wires, one at a time. THEN, install a rivet (or a screw) right beneath the bottom of the conduit. This will ensure that it doesn’t slide down onto the wires when vertical (another common problem with the Bene’s).

      ….and no to the 5200 idea. If the conduit needs to be re-done it should be installed like the factory version with the stop at the bottom (like I just described). Or you can have it done the right way which is rivet the conduit to the mast wall every 3-4′ using two aluminum rivets. That is the best solution. You can call us for tips and tricks on this method if you like. We’d be glad to help discuss.

      4. I think a couple of cleverly mounted mast accent lights on top of the spreaders may do the trick for the main. Check out our friends over at OGM….https://orcagreenmarine.com/product/kis-led-swivel-uplight/. She has devised a pretty clever bracket that fits many applications an adjusts to almost any angle. I am willing to bet that if you call her she can come up with a luff light mount for the Genoa as well.

      Hope that helps!


  5. Don says:

    I have a 4″ x 6″ elliptical mast, .180″ thick. All my other new wires are IN the mast even the RG213 ant. cable . Now I have LED spreader lamps on both P & S , this is the ONLY wire that seemingly has to run externally from P to Stb. The spreader mounts are solid alum castings you see. So I reckon I need to drill 2 holes P & s in my mast for those leads to leave the mast and travel to the lamps externally? Any other ideas? alternatives? Thanks for the open forum !

    • The Rigging Company, LLP says:

      Hi Don,

      Thanks for asking and although your approach will work, yes you do have another, cleaner solution for this. The way we do it is drill a hole above the the spreader base, port and starboard. Then drill a hole on top of the spreader just outboard enough so that it won’t interfere with the spreader base when installed. Then on the underside of the spreader you drill the final wiring exit to go to the light, right beind the light. This will make for a cleaner look from the deck, no wires.

      I hope that answers what you were looking for. Let us know if not.


  6. Raul says:

    Have you come across any other method of attaching the conduit other than rivets and if so what are they?
    Why do you use PVC irrigation pipe instead of PVC conduit?

    • The Rigging Company, LLP says:

      Hi Raul. Yes, we have come across many versions of how conduit can be installed. Everything from U Bolts, spray in foam, cellular foam zip tied to wires every three feet or so, conduit cut length wise and slipped onto a groove inside the mast, if present,….non of which I’d recommend.

      As mentioned in the article, we like the PVC tubing over irrigation tubing is the connection joint is sleeker and allows for better mounting, flush to the inside of the mast wall.

      I hope that answers your questions.


  7. Justin Fremin says:

    If you rivet conduit inside the mast, won’t the rivet ends inside the conduit snag and maybe eventuallycut the wire cables? You rivet PVC too?

    • The Rigging Company, LLP says:

      Correct. No snags yet…20 years of doing it this way. The pulled end of the rivet usually ends up very rounded. So problems there. Yes, we rivet the PVC tubing. It is just to keep the PVC flush with the mast wall and hold it in place.

      Thanks for taking the time.


  8. Len says:

    I have forespar steaming/ deck light and separate spreader lights. My spreader lights. Can be switched on / off. My steaming lights can be switched on/ off. But I cannot get my deck light to come on with my spreader lights without lighting up several indicator lamps on my electrical panel.
    What am I doing wrong?

    • The Rigging Company, LLP says:

      mmmmm. Len, this type of question may be best suited for a marine electrician. Try Patrick Tewes over at MarineElectricSystems.net. They’re a very knowledgeable and helpful bunch.

      Thanks for taking the time.


  9. bob france says:

    Do you have the phone number to MISEA group. Their website is down and a I need an installation diagram of the wiring for their led anchor light. Thanks
    Also, In the above photo two cables are run through the mast without protection from abrasion.Unless by taping them together is good enough. Is their a thin push-in grommet of some sort?

    • The Rigging Company, LLP says:

      The MISEA Group split into two, OGM (443) 699-6348 and Signal Mate (410)-777-5550. Here are links to contact pages for both –


    • The Rigging Company, LLP says:

      and yes a rubber grommet would be a good idea there. Keep in mind not only is there the tape to handle the chafe protection. Ancor wires a covered in another white sheath which will further help with chafe protection.

      Thanks for the comments.


  10. Tom says:

    Hi, I have the same Forespar ML II steaming/spreader light you show above. With the relatively light weight wires in the fixture, I’m wondering how you provided strain relief for the wiring with this mount? I have 14GA triplex which seems may be heavy for the small wires to support inside the mast, but the light fixture doesn’t seem to provide a lot of space between it and the mast to accommodate the wiring and a clamp.



    • The Rigging Company, LLP says:

      Hi Tom,

      Thanks for the comment. A good question. I would butt connect the wires with marine grade heat shrink fittings and then heat shrink another service over the top of that. While everything is still warm, I ‘Z’ fold the first 4-5 inches or so coming out of the light. I pinch these 1-2 folds inbetween the light and the mast (just off of centerline either way there is usually a small amount of space for this) with the connection outside of the mast so that any strain is on the large wires, not the connection.
      If the light wire exit is below or above the light itself (vs. directly behind it), then a stainless steel cable clamp may be the best choice. The main thing is that the strain is always on the big wire and not the connection.
      14 gauge does seem thick for any boat smaller than 46′.


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