Best Practice To Terminate Wiring for Keel Stepped Mast

[Doug in Lakeview]

What is Best Practice To Terminate Wiring for Keel Stepped Mast?

Hi All,

Is the following doable? Any downsides? We are newbies here – just our 2nd sailing season.

We have a Beneteau First 38 with a keel stepped Isomat NG-60 mast. Mast total length is 55.5 feet. The mast is currently down and we are replacing lights, VHF antenna, and all wiring. The Isomat mast has a 1” diameter conduit from top to bottom for enclosing wiring. Also, there is collar of foam that was injected just above deck level to prevent any water from dripping down the mast and into the keel. Just above the collar of foam there are weep holes to allow any water which gets inside the mast to be discharged onto the deck.

Currently we are removing the mast each winter since we store the boat inside.

Existing:

1) 12 volt electrical wires (for anchor light) & 12 volt electrical wires (for masthead/steaming light & deck light) exit the mast just above the deck and then are routed thru a cable gland to the saloon ceiling.
2) VHF cable & navigation instrument wiring goes all the way to the base of the mast and exits the mast about 3 inches above the keel step just above the cabin sole.

Proposed:

Run ALL wiring to the base of the mast (exiting just above the cabin sole) and make connections there. 12 volt wiring would be connected to a terminal block (located under the settee) with new wiring to the DC panel. VHF cable would terminate at mast base (with 3 to 4 ft of extra cable) and be connected to 2nd run of cable connected to radio at nav station. Connection would be sealed with heat shrink connector.

Rationale for the above is (a) to eliminate cable glands on deck, and (b) to have all wiring from the mast terminate in a single location. Intention would be to disconnect all wiring myself before the boat is hauled each autumn by the marina.

We will be installing LED lights which per Blue Sea Circuit Wizard could use 18 AWG wiring. However we will be following Stu’s recommendations to use 14 AWG as a minimum. The cost delta is minimal and, more importantly, I fully concur that the thinner wire is more fragile and not really the best for a marine environment where there is always motion.

Doug in Lakeview
1984 Beneteau First 38 – Hull #178
Belmont Harbor – Chicago

 

[sailaway78]

What I did

I have a similar setup with my S37. I ran all wiring through the base outlet, but instead of making a terminal block there, I left enough wire length to make the connection up under the port berth, above the waterline. I just wasn't comfortable with a connection of any kind in the bilge.

 

[jibes138]

I just finished rewiring and new fixtures on my Isomat mast. All wires run to the base of the mast and terminate inside the boat. I have never seen a boat your size with wires connecting through the deck? I wonder if a previous owner customized it somehow? One problem is what size wire will the fixtures accommodate, the holes and grommets may not accept large diameter wire. I used all pre-tinned wire. Those conduits inside the mast should extend all the way down? Still waiting to receive my LED anchor light to finish the project. Also the slots in the mast at the top will only accept certain size antenna wire and electrical wire.

 

[shemandr]

I would try to terminate the mast wire run at eye level. That would make the bi-yearly connect/disconnect easier. And, make access for troubleshooting easy. This might be an esthetic issue, but access is beautiful.
How does the collar of foam and weep holes work?
I would also put an AM/FM antenna up there.

 

[Doug in Lakeview]

The existing 12 volt wiring exited the mast just above the deck and then went through the deck to the saloon ceiling where the wiring then snaked its way back to the DC panel. It all looks original and connects to 12 volt wiring hidden above the headliner. On this basis I am guessing that Beneteau did this so that the 12 volt wiring was far above the bilge where it might get wet.

I will route the wiring to exit the mast just a couple inches above the cabin sole and then head over to the port settee where I will terminate all of the various wiring under the settee in a storage compartment. Only 3 to 4 inches of cable will be visible when it exits the mast and then enters the compartment.

The terminal block will not be at eye level but definitely will not be down in the bilge. This will make it relatively easy to disconnect/connect each fall and spring. From the storage area under the settee I will then run new wiring to the nav station where the DC panel and VHF are located.

Inside the mast is a ~1 inch diameter plastic conduit which is held in place by a track on the aft side of the mast. This conduit runs from the mast top to about 2 foot below the deck. In this way the wiring is protected from any slapping halyards. At the deck there is a collar of what appears to be some type of foam which was sprayed inside the mast to prevent water from dripping down into the bilge area. The foam actually looks like the DOW polyurethane expanding foam that is used for insulation around windows. This collar does a very good job of keeping water out of the lower section of the mast/bilge. However, it is necessary to keep the weep holes clear so that any water on the top side of the foam drains onto the deck. I was surprised to see this feature when we took the mast down. This makes it far less critical to make any attempt to seal the top of the mast to keep water from entering the bilge area.

I will be using pre-tinned marine grade wire from Ancor. We are in Chicago and don’t need much of an antenna for AM/FM/TV as the antennas on the SEARS tower (110 floors?) do a pretty good job of getting signal out onto the lake.

Still working on this…………

Will post pics when done.

Doug in Lakeview
1984 Beneteau First 38 – Hull #178
Belmont Harbor – Chicago