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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7 Responses to When Replacing Electrical Items in the Mast

  1. 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.


  2. 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.


  3. 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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