Are you up for practical jobs on your boat? Buying a boat and then adding new kit is all part of the fun. This month we look at boat antennae.

VHF radios, like all other marine electronics requiring antennae, need long runs of cable through the boat, often buried behind panels or above the headlining. This is fine until the antenna breaks and then there are two choices - either run new cable right through the boat (with all the disruption that entails) or connect the new antenna using the old cable and a watertight deck plug that also provides the opportunity to remove the antenna for storage during the winter.

If the VHF antenna is mounted at the top of the mast, the only cable runs needed are from top to bottom inside the mast itself. You can then install a new plug onto the new cable run, plug it in and the job is done. Even if the antenna is not mounted up the mast, there is no reason to tear the interior of the boat apart to run a new cable. Simply use the same type of plug and socket as is used at the base of the mast to connect the new antenna to the old cable. There is then the option to remove the antenna for winter storage if desired.

This was the case when I recently discovered that my 2.4-metre VHF antenna had snapped off about a foot above the stainless steel fitting while the boat was unattended. Although not mounted on the mast, I was still faced with the onerous task of running new cable throughout the boat. I decided to retain the original cable and fit a water-tight deck plug and socket to connect the new antenna. I then thought about how to make an emergency repair where there are no soldering facilities and found the solution along with my new plug and socket at Shakespeare Electronic Products Group, better known as V-Tronix.

If your antennae are mounted on stainless steel or plastic ratchet mounts, it is important to check the thread type on the mounting to ensure the thread is compatible with the new antenna. This is especially important if your mounts are 15 years old or more as there may be a conflict of thread types. My boat, being more motor than sail, has the antenna mounted on the side of the light mast and it was broken about a foot above the ratchet mount. This is how I went about fixing it . . .

The V-Tronix plug and socket laid out in order of assembly. From right to left: backing nut, washer, cable seal, insert, first insulating seal, second insulating seal, pin and body. Note also the watertight cover and the blanking plugs for keeping the plug and socket clean and dry when unplugged.

Begin with the plug that is fitted to the antenna cable as this can be done in the comfort of the cabin. The first task is to cut the old cable to allow the broken antenna to be removed. Remember to leave plenty of slack in the cable that is to remain to allow for easy fitting of the plug socket.

You may need to use pipe-grips to unscrew the old antenna.

Starting with the cable on the new antenna, snip the end off the cable cover. Keep the cut small so that it fits tightly over the cable.

Slip the cover over the cable and slide it back out of the way.

Next, slip the backing nut, washer and seal onto the cable.

Carefully cut the outer insulation without damaging the braid. Ideally use a wire stripper tool although a craft knife used carefully works equally well.

Lift off the insulation to reveal the braid.

Carefully turn the braid back over the remaining outer insulation.

Now slide the insert over the inner insulation so that the spigot passes inside the braid until it is up against the braid and outer insulation.

Using a pair of scissors, trim the braid until it is flush with outside edge of the insert.

Slide the first insulating washer over the inner insulation and up against the face of the insert.

Again, using the wire strippers, cut the inner insulation flush with the face of the first insulating seal.

Cut the inner cable to a length of about 5mm so that it fits right up inside the pin. Test the length by inserting it into the pin before cutting it too short.

Now tin the inner cable with electrical cored solder. Keep this to a minimum or the cable will not enter the pin.

Fit the pin and solder it into place through the tiny hole in the pin. This may result in blobs of solder on the outside of the pin. These must be cleaned off otherwise it will prevent the plug and  socket plugging together properly. Wipe it off with a damp rag while hot or otherwise use fine glass-paper when cold.

Fit the second insulating seal.

Offer up the plug body, push the cable seal into the body, follow this with the washer and finally enter the nut into the body and tighten it to compress the seal to make it water-tight.

Once completed, it should look like this and there should not be any bits left over.

That was the easy bit, now exactly the same procedure is followed with socket part. This is slightly more difficult as it has to be done outside in a rather more awkward position. Don’t even bother to attempt this in windy or freezing conditions, as even a commercial size soldering iron will not be able to maintain sufficient heat outside. The socket is the only different part of the set and although the work is almost identical, remember to place the rubber backing pad over the cable before beginning the assembly. (The pad can be cut and slipped over the cable if it does get forgotten).

Once all the connections have been made, fit the socket in the chosen position and bed it down on a little sealant for extra protection - especially if you have had to cut the backing pad.

Fit the antenna by screwing it tightly onto the mount, connect the plug and socket and slide the waterproof cover over the entire assembly. You might also like to make a note to clean and polish the mount in the spring!

The plug and socket is great when you have the time to spend on fitting it. But what about when you need a quick, 100 per cent reliable and permanent repair without solder. The answer is to use a cable splice. Here, it is laid out in order of assembly from left to centre: Backing nut, cable seal, insulator and body. There is a pin inside the body that passes into the inner cable when the fitting is assembled.

Cut the end of the cable flush and square using either scissors or side cutters.

Slip the backing nut, cable seal and insulator onto the cable.

Carefully push the cable end into the body of the fitting until it bottoms out inside the fitting. This ensures the internal pin has penetrated the inner cable.

Using a pair of pliers, squeeze the extending arms of the fitting so that they pierce the outer insulation and make contact with the braid.

It does not need a lot of pressure to satisfactorily pierce the braid.

Squeeze the arms together in pairs until they are all fairly even and the body of the fitting can be passed over them. Slide the seal up and screw the nut snugly onto the body.

Follow the same procedure for the other end and the job is completed.

For total security, seal the fitting with heat shrink. This is slipped over the fitting and heated gently with a hot air gun until it shrinks tightly against the fitting. A lesser alternative is to use self amalgamating tape.

in a nutshell
Time taken: two hours
Competence level: intermediate
Tool kit: basic electrical

Shakespeare Electronic Products
www.shakespeare-marine.com